Chagas disease is caused by the infection of a protozoan parasite (Trypanosoma cruzi)
this condition is the result of a complex health problem typical of neglected tropical diseases and socially determined diseases
A missed or late diagnosis with absent or incomplete treatment and follow-up can transform this infection into a life-threatening condition
More than 7 million people worldwide are estimated to be infected with T
leading to more than 10 000 deaths every year
Although a condition of increasing global presence
Chagas disease is found mainly in endemic areas of 21 continental Latin American countries (1)
where transmission is largely related to the presence of the insect vector
more than 100 million people are considered at risk of infection
Chagas disease is named after Carlos Chagas
a Brazilian physician and researcher who on 14 April 1909 diagnosed the disease in a person for the first time
Chagas disease was once entirely confined to continental rural areas of the Americas
Due to socioenvironmental changes and increased population mobility
most infected people now live in urban settings and the infection has been detected in 44 countries (including Canada
and many European and some Western Pacific
African and Eastern Mediterranean countries)
cruzi parasites are mainly transmitted by contact with faeces/urine of infected blood-sucking triatomine bugs
These bugs typically live in the wall or roof cracks of homes and surrounding structures
Normally they hide during the day and become active at night when they feed on animal and human blood
They usually bite an exposed area of skin such as the face
The parasites enter the body when the person instinctively smears the bug’s faeces or urine into the bite
cruzi can also infect animals; common opossums are considered one of the most important wild reservoirs of infection
The initial acute phase lasts for about two months after infection
Although a high number of parasites can circulate in the blood
in most cases symptoms are absent or mild and non-specific (fever
people bitten by a triatomine bug show characteristic first visible signs
which can be either a skin lesion (chagoma) or a purplish swelling of the lids of one eye (Romaña’s sign)
the parasites are hidden mainly in the heart and digestive muscles
up to a third of patients suffer from cardiac disorders and up to 1 in 10 suffer from digestive (typically enlargement of the oesophagus or colon)
In later years these patients may experience the damage to the nervous system and muscles of the heart and digestive system
among other clinical manifestations and complications
Chagas disease can be treated with benznidazole or nifurtimox
Both medicines kill the parasite and are fully effective in curing the disease if given early
including in case of congenital transmission
the longer a person has been infected; also
adverse reactions are more frequent and potentially severe in older age
Treatment is also indicated for patients in whom infection has been reactivated (for example
including for girls and women of childbearing age (before or after pregnancy) to prevent congenital transmission
should be offered treatment because antiparasitic medicines can also prevent or curb disease progression
the potential benefits in preventing or delaying the development of Chagas disease should be weighed against the duration of treatment (up to 2 months) and possible adverse reactions (occurring in up to 40% of adults)
Benznidazole and nifurtimox should not be administered to pregnant women or people with kidney or liver failure
Nifurtimox is also contraindicated for people with a background of neurological or psychiatric disorders
life-lasting follow up and specific treatment for cardiac
digestive or neurological manifestations are usually required
The large number of triatomine bug species and wild animals (reservoirs) infected with T
cruzi throughout the Americas mean that the infection cannot be eradicated
the public health targets are elimination of the transmission to humans
early health-care access and life-long follow up of the infected people
There is no vaccine to prevent Chagas disease
reducing interaction between humans and vector insects
has been the most effective method of prevention in Latin America
Blood screening is necessary to prevent infection through transfusion
and to increase detection and care of the affected population all over the world
WHO recommends the following approaches to prevention and control:
The medical care cost of patients with chronic cardiac
neurologic or mixed forms of the disease has been calculated to be >80% higher than the cost of spraying residual insecticide to control vectors and prevent infection
beginning at the first level of care (primary health care)
have a crucial role in enhancing the detection
Assessment of the available diagnostics (including rapid serologic or chemiluminescence tests
molecular biology tests) and the most cost-effective algorithms is fundamental to increase early case detection.
and evaluation of new diagnostics and medicines can accelerate the path towards the elimination of the disease as a public health problem
psychosocial and environmental studies focused on the determinants and risk factors of Chagas disease is essential to identify novel approaches for prevention and control.
National information systems are essential to monitor the number of acute and chronic cases and the active transmission routes
they are only in place in 6 out of the 44 countries that have reported cases so far
Since the 1990s there have been successful intergovernmental initiatives in the Americas
leading to a substantial reduction in transmission and increased access to diagnosis and antiparasitic treatment for Chagas disease
cruzi transmission by transfusion has decreased sharply following the universal screening in all blood banks of continental Latin American countries
and progressively in other countries and continents.
WHO recognized Chagas disease as a neglected tropical disease (NTD) in 2005
This facilitated its greater recognition as a global public health problem and was instrumental to strengthen prevention
early diagnosis and antiparasitic treatment
It also promoted the fight against misinformation
the lack of social demand and the weak political commitment to face the burden of disease
the 72nd World Health Assembly established World Chagas Disease Day
The NTD road map 2021–2030 includes Chagas disease among the conditions targeted for elimination as a public health problem and proposes five targets:
To attain the goal of elimination of Chagas disease transmission to humans and provide health care for affected people worldwide
WHO aims to strengthen networking at the global level and reinforcing regional and national capacities
Metrics details
Twenty-three rural areas were selected for triatomines search and serological survey of the population. The analysis of triatomines consisted on identifying T. cruzi infection index by microscopy and kDNA-PCR followed by parasite genotyping through the use of multilocus PCR to characterize the discrete typing units (DTUS), and the identification of food sources using PCR directed to the 12S rRNA gene of vertebrates and sequencing.
Despite the reduced seroprevalence of the population, the epidemiological scenario of Chagas disease in both municipalities highlights the risk of the re-emergence of domestic vector-borne transmission. Ensuring continued entomological surveillance and vector control programs and providing access to diagnosis and treatment for the susceptible population are still needed.
municipalities of Pedro II and Oeiras and selected rural communities
(A) Map of Brazil indicating the state of Piauí
(B) Location of the two municipalities selected for triatomine collection in the state of Piauí
Tamboril III; (D) Collection points in Oeiras: 14
In both municipalities, the Chagas Disease Control Program (PCDCh) selected 23 rural communities for the present survey, according to epidemiological priority and established criteria to carry out the activities previously programmed (Fig. 1C and D)
A convenience sampling method was used to collect the questionnaires and blood samples of individuals living in the 23 rural communities of Pedro II and Oeiras (Fig. 1C and D)
All subjects gave written informed consent before their participation at the interview visit or sample collection
Blood drop was collected by finger-prick and spotted on filter paper Klabin 80® (Klabin S.A/Brazil)
Samples were stored individually in plastic bags at -20 ºC until processing
The population was screened for the detection of IgG antibodies against T
cruzi antigens by Indirect Immunofluorescence method (IIF) using the Chagas - IIF kit (Biomanguinhos/Fiocruz
Positive individuals were confirmed with the Chagatest recombinant ELISA kit v.4.0
Reactions were performed following the manufacturer’s recommendations
Positive individuals were defined as those whose samples were positive by both techniques
Manual collections were carried out from March to October 2021 and March/April 2022 by active search in the peridomicile and intradomicile
in 326 Household Units (HU) of Pedro II and Oeiras counties
Householders were informed about the aim of the research project
anticipated benefits and potential participation
Collections were performed during the day with the use of gloves
The intradomicile was surveyed for the presence of triatomines as well as potential ecotopes in the peridomicile environment
Collected insects were stored alive in plastic containers labelled with the collection site
and GPS (Global Positioning System) location of the HU and rural community
Prevalence ratios and 95% confidence intervals (CIs) were calculated
Fisher exact test was applied to determine the association between seropositivity for ChD (dependent variable) and age group
Of the 23 rural communities visited in Pedro II and Oeiras (comprising 326 household units)
7 presented individuals with positive results by IIF and ELISA
153 houses distributed in 13 communities were surveyed
resulting in two seropositive subjects out of 400 (0.5%); one resident in Cantinho IV and the other in Tamboril III
the serological survey and collection of sociodemographic data were performed in 173 houses from 10 rural communities
Thirteen (3.5%) individuals were tested positive and were distributed in the communities of Queiroz (4)
A total of 1,043 triatomines were collected in Oeiras and Pedro II municipalities
comprising the species Triatoma brasiliensis
The Rhodnius genus was only found in Pedro II and the individuals were submitted to molecular identification of species by DNA sequencing the 500 bp mtCytb gene
nasutus showing identities and query cover ≥ 99% (accession number MG735122.1)
so we used the designation ‘sp’ for these individuals
Numbers of triatomines collected in the study municipalities and their natural T
(A) Vectors recorded by municipality indicating the species
and the environments where the collections were done
The center of the graphs shows the total number of collections in each area
subdivided into collection environments (peridomicile and intradomicile) and then segregated by triatomine species and developmental stages
Each color refers to a species or collection environment
according to the legend included in the figure
(B) Natural infection rates by light microscopy and PCR
triatomine species and collection environment
Analyzed by municipality, 541/1,043 (∼ 52%) individuals were found in Pedro II and 502/1,043 (∼ 48%) in Oeiras (Fig. 2A)
pesudomaculata 167/498 (∼ 33%) as the most frequent species
besides representatives of the Rhodnius genus 11/498 (2.2%) and Panstrongylus 2/498 (0.4%)
lutzi 1/463 (∼ 0.2%) were captured in the peridomicile
there was no significant difference between Pedro II (43/541) and Oeiras (39/502) (χ2 = 0,011; p-value < 0.91)
Comparing only the 848 samples examined by both methods
90/848 (10.6%) were positive by PCR and microscopy was able to identify the parasite in 39/848 (4.6%) (χ2 = 189.47; p-value < 0.0001)
All PCR-negative samples were also negative by parasitological observation
cruzi DTUs in triatomines collected in the studied municipalities
(A) Triatomine species distribution relative to the identification of T
(B) Triatomine species distribution relative to the identification of T
TB: Triatoma brasiliensis (blue shading); TP: Triatoma pseudomaculata (yellow shading); R
(red shading); RN: Rhodnius nasutus (green shading); PL: Panstrongylus lutzi (purple shading); DTUs: Discrete Typing Units
On the left are indicated the flows from the triatomine species to the genotyped DTUs (on the right part)
In Oeiras eight T. brasiliensis samples were genotyped, 4/8 (50%) infected with TcI, 1/8 (12.5%) with TcV, and the others gave inconclusive results TcII/TcVI, TcV + TcII/TcVI (Fig. 3B)
Analysis of food sources in triatomines collected in the municipalities of Pedro II and Oeiras
Chord Diagram made with OriginPro 2023 software representing the distribution of food sources of triatomines
On the right half of the circle are represented the numbers of each triatomine species fed on vertebrate blood: T
Vectors’ distribution by environment (peridomicile in gray color
intradomicile in white color) and blood meal source are shown on the left side of the circle with the identification of the respective vertebrate species
cruzi-positive triatomines collected in Pedro II and Oeiras
Chord diagram made with OriginPro 2023 software representing the distribution of food sources in the T
cruzi-positive triatomines (A) collected in Pedro II
brasiliensis and Homo sapiens as blood-meal source
it is clear that this triatomine has a tendency to feed on humans (X² = 11.71; p-value < 0.0006)
although other vertebrate species were identified in the study areas
We investigated the triatomine fauna and risk factors associated to ChD in two municipalities of Piauí with physiogeographic characteristics extremely favorable for the presence of vector species typical of the semiarid territory and Caatinga biome
The study is pioneering in the state on the employment of molecular epidemiological approach to investigate local triatomine species
their natural infection status and its correlation with different T
A serological survey of a population sampling living in the selected areas was also performed
One of the limitations of our work was not being able to genotype the parasite using blood samples from the 15 individuals who reacted in the serological tests
As the study was carried-out during the early period following COVID-19 pandemic
blood collection for screening was obtained by finger prick rather than using a syringe
aiming for a quick and less invasive collection method capable of minimizing participants’ apprehension
The decision of those with a seropositive diagnosis not to consent to a new blood collection
prevented us from carrying out the molecular typing of T
the active search for insects inside houses was hampered by the limited time to stay in the houses
seeking to minimize physical contact with residents
Our results confirm the epidemiological relevance of Triatoma brasiliensis in rural communities of Piaui
cruzi genotypes found in the surveyed areas were identified in this species
which also turned out to be the most abundant in our fieldwork
The predominant parasite lineages were TcV and TcI
and this is the first report of TcV and TcVI infections in vectors of Piauí
Pedro II revealed greater diversity of host animal species acting as food sources and the highest prevalence of T
cruzi infected vectors feeding on human blood
The evidence of human dwellings colonization by T
brasiliensis in both counties brings a warning about the re-emerging risk of contracting ChD via the vectorial route of domestic T
these data enhance the need of continuous entomological surveillance with the intention of improving vector control strategies to prevent new cases of the disease
it is imperative to improve access to diagnosis for the vulnerable population residing in rural communities in the two municipalities investigated in Piauí
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The authors would like to express their sincere thanks to Vitor Ennes Vidal for intellectual support
CB was funded by Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro /FAPERJ (CNE E-26/201.213/2022) and National Council for Scientific and Technological Development/CNPq (304308/2019-3)
ARSL is research fellow of the Coordination for the Improvement of Higher Education Personnel of the Ministry of Education of Brazil/CAPES
RTR is graduated fellow of the National Council for Scientific
LD is research fellow of the National Council for Scientific
TAP and PFA are postdoctoral fellows of Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro/FAPERJ
Laboratory of Molecular Biology and Endemic Diseases
Rafaela Tavares dos Reis & Constança Britto
Department of Parasitology and Microbiology
José Henrique Furtado Campos & Vagner José Mendonça
Laboratory of Parasitology and Molecular Virology
Lileia Diotaiuti & Flávio Campos Ferreira
Assisted in the preparation of figures and data analyses
Carried out the field-triatomines collection; ALF: Assistance with data interpretation and field surveys
TAP: Sample processing assistance and writing the manuscript
JHFC: Processing of population clinical samples
PFA: Support on the parasite genotyping data
FCF: Sample processing assistance and writing the manuscript
VJM: Assisted in the writing and intellectual revision of the manuscript
The study was approved by the Human Research Ethics Committee of the Federal University of Piauí (protocol 4.343.423)
Participants were not identified and all individuals signed a statement agreement to participate in the research
Triatomine collection was registered and approved by the Biodiversity Authorization and Information System – SISBIO (Chico Mendes Institute for Biodiversity Conservation
The mentioned animals are the result of the identification of available vertebrate DNA sequences in the GenBank database
The authors declare no competing interests
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations
Below is the link to the electronic supplementary material
Profile of Trypanosoma cruzi Discrete Typing Units (DTUs) identified in triatomines collected in the municipalities of Oeiras and Pedro II
The table indicates the Trypanosoma cruzi DTUs identified in the triatomine species
following the results independently achieved for each PCR target (Flowchart)
intergenic region Spliced Leader gene; SL-IR I e II
intergenic regions I and II of the Spliced Leader gene; 24 S-α
Sequence identification of vertebrates representing sources of food of triatomines collected in Pedro II and Oeiras
Generated 12 S rRNA sequences with high identities (≥ 94%) to vertebrate sequences available in the NCBI database for each triatomine species analyzed by municipality
Questionnaire applied to participants in the seroprevalence survey living in the rural communities of Pedro II and Oeiras
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Volume 9 - 2022 | https://doi.org/10.3389/fmed.2022.852864
Chagas disease (CD) is among the top 10 causes of inability to blood donation
Blood donation centers screen for anti-Trypanosoma cruzi antibodies using highly sensitive immunoenzymatic (ELISA) or chemiluminescent methods
to avoid the loss of valuable blood donations
it is necessary to improve specificity without reducing the sensitivity of the tests used for blood screening
our group has developed four chimeric proteins (IBMP-8.1
and IBMP-8.4) that have been evaluated in phase I and II studies with high performance and low cross-reactivity rates
The study included a panel of 5,014 serum samples collected from volunteer blood donors at the Hematology and Hemotherapy Foundation of the State of Bahia (Brazil)
They were subjected to the detection of anti-T
using all four IBMP antigens individually and latent class analysis (LCA) as a reference test
since there is no gold standard test for this purpose
Sensitivity values ranged from 85.71% for IBMP-8.1 and 90.48% for IBMP-8.2–95.24% for IBMP-8.3 and 100% for IBMP-8.4
while specificity ranged from 99.98% for IBMP-8.3 and IBMP-8.4–100% for IBMP-8.1 and IBMP-8.2
Accuracy values ranged from 99.4 to 99.98%
The pretest probability for the molecules was 0.42
whereas the positive posttest probability ranged from 95.24 to 99.95% and the negative posttest probability ranged from 0.00001 to 0.0006% for all antigens
The higher odds ratio diagnosis was found for IBMP-8.4
which has been shown to be a safe single antigen for serological screening of CD in blood samples
The use of chimeric IBMP antigens is an alternative to reduce the number of bags discarded due to false-positive results
These molecules have high diagnostic performance and were shown to be suitable for use in screening CD in blood banks
isolated (IBMP-8.4) or in combination; and their use in blood banks could significantly reduce unnecessary disposal of blood bags or the risk of T
In blood banks, serologic screening for anti-T. cruzi antibodies should be performed using a high-sensitivity IVD (18, 19)
or synthetic peptides as antigens mainly in ELISA or CLIA diagnostic platforms
Commercial tests for screening CD should be able to identify T
cruzi antibodies regardless of genetic variability
and cross-reactivity with other infectious and parasitic diseases
The major challenge for blood banks in serological screening CD is to reduce both the number of blood bags that are incorrectly discarded due to false-positive results and the costs associated to assays used in the screening
Because the diagnostic potential of IBMP antigens has been extensively evaluated
the objective of this study was to evaluate the use of IBMP-8.1
cruzi antigens for serologic screening for Chagas disease in blood banks using a reference array of chimeric antigens as the gold standard
Constitution of the IBMP chimeric recombinant antigens
Anti-T. cruzi serology was performed by ELISA as described previously (30)
Assays were performed on transparent 96-well flat-bottom microplates (UV-Star® Microplate
Austria) coated with one of the chimeric IBMP antigens at concentrations of 12.5 ng (IBMP-8.2) or 25 ng (IBMP-8.1
and IBMP-8.4) per well in coating buffer (0.05 M carbonate bicarbonate
Coating and blocking were performed simultaneously with a synthetic buffer (WellChampion; Kem-En-Tec Diagnostics A/S
Denmark) according to the manufacturer's instructions
Serum samples were added to the coated wells diluted 1:100 in 0.05 M phosphate-buffered saline (PBS; pH 7.4)
and the microtiter plates were incubated at 37 °C for 60 min
all wells were washed with PBS-0.05% Tween-20 (PBS-T; pH 7.4) to remove non-adsorbed material and incubated again at 37 °C for 30 min with 100 μl of HRP-conjugated goat anti-human IgG (Bio-Manguinhos
100 μl of TBM substrate (Kem-En-Tec Diagnostics A/S
Denmark) was added to the wells to detect the formation of immune complexes
Incubation was then performed for 10 min at room temperature in the dark
The colorimetric reactions were stopped by adding 50 μl of 0.3 M H2SO4 to each well
Optical density was determined in a SPECTRAmax 340PC microplate reader with a 450 nm filter (Molecular Devices
and background values were subtracted from the measurement experiments
A total of 16 response patterns were identified
which were divided into five categories (P1 to P5)
Response patterns of chimeric antigens in latent class analysis (LCA) used in anti-T
cruzi ELISA tests in HEMOBA Foundation blood donor volunteers between December 2018 and August 2019
Figure 2. Flowchart depicting study design in accordance with the Standards for Reporting of Diagnostic Accuracy Studies (STARD) guidelines (46)
anonymized human serum samples were included in the study
The mean age of the population studied was 40.4 years [interquartile range (IQR): 28.3–58.2 years] and the female-to-male ratio was 0.75/1
At least one blood donation was performed in each microregion of Bahia
This represents 232 of 417 (55.6%) municipalities and a total population of 11,448,009 inhabitants (~77% of Bahia's population)
Seventy-nine samples were from blood donors from the Federal District (n = 2) and other Brazilian states: Rio Grande do Norte (n = 1)
Information on the geographic origin of the blood donors was missing in 26 samples
cruzi-positive blood donors was 41.0 (IQR: 30.0–50.5 years) and the female-to-male ratio was 0.62/1
Data stratified by sociodemographic variables and reactivity indices for chimeric IBMP antigens from all 21 blood donors classified as T
Following the serological definition of 5,014 samples as T. cruzi-positive or T. cruzi-negative by LCA, the performance parameters of chimeric IBMP proteins were determined (Figure 3; individual data points are available in the Supplementary Table 1)
Area under the curve (AUC) values were extremely high for all chimeric proteins
ranging from 98.68 (IBMP-8.2) to 100% (IBMP-8.4)
demonstrating excellent overall diagnostic accuracy for all chimeric proteins
all IBMP antigens showed similar performance
IBMP-8.4 provided the highest RI (reactivity index) values
while IBMP-8.1 had the lowest RI distribution
No significant differences were observed between the RIs of all four IBMP proteins
cruzi-negative samples yielded low mean RI values among all four chimeric antigens tested (<0.22)
Global RI analysis showed a significant difference between T
cruzi-positive and negative samples for all four proteins (p < 0.0001)
Graphical analysis of areas under the curve (AUC) ROC (left)
Reactivity index (middle) obtained with serum samples from Trypanosoma cruzi-positive (TcP) and Trypanosoma cruzi-negative (TcN) samples
The cut-off value is the reactivity index = 1.0 and the shaded area represents the gray zone (RI = 1.0 ± 0.10)
The horizontal lines and numbers for each group of results represent the geometric means (± 95% CI)
Performance parameters (right) obtained for all chimeric IBMP proteins
The diagnostic efficiency of antigens can also be assessed by the number of samples that fall into the gray zone
Considering a gray zone set as a cut-off value ± 10% (RI values of 1.0 ± 0.10)
only one sample (0.02%) was found in the gray zone for the proteins IBMP-8.2 (T
cruzi-negative sample; sample ID 5245; RI 0.92)
cruzi-negative sample; sample ID 7017; RI 0.97)
cruzi-negative sample; sample ID 6834; RI 0.92)
No result was found in the gray zone when both T
cruzi-negative samples were tested with IBMP-8.1 antigen
based on positive and negative likelihood ratios
Qualitative assessment of the results showed near-perfect agreement between all chimeric IBMP proteins using the Cohens' kappa method (κ ≥ 0.92)
with particular emphasis on IBMP-8.4 (κ = 0.98)
In addition to individual performance, the performance of pairs of all four chimeric IBMP proteins was also estimated in serial and parallel approaches (Table 3)
whereas minimum specificity and negative predictive values reached 99.9%
Positive predictive values ranged from 90.9 to 100%
sensitivity values ranged from 98.3 to 100% with a parallel scheme
no false-negative result was obtained when the positive samples were tested with IBMP-8.1/IBMP-8.4
no false-positive result was obtained using a parallel approach
Positive and negative predictive values were 100% for all IBMP pairs
except for the positive predictive value when IBMP-8.3/IBMP-8.4 was analyzed (99.8%)
Analysis of the diagnostic performance of the pair of chimeric IBMP proteins using serial and parallel approaches
only one sample that was anti-HBc positive (0.43%) was found to be inconclusive with the chimeric proteins IBMP-8.2 (sample ID 5245; RI 0.92) and IBMP-8.4 (sample ID 6834; RI 0.95)
Graphical analysis of cross-reactivity with IBMP antigens using non-negative samples screened by HEMOBA Foundation
Individual use of chimeric IBMP proteins for CD serological screening was also analyzed (Figure 5)
the criteria used by the HEMOBA Foundation were considered: (1) T
cruzi-positive samples: RI ≥ 1.00; (2) T
cruzi-negative samples: RI < 0.75; and (3) T
cruzi-inconclusive samples: 0.75 ≥ RI <1.00
cruzi-inconclusive samples are considered unsuitable for blood donation; therefore
while IBMP-8.3 and IBMP-8.4 classified one sample each as T
screening with IBMP-8.4 would discard a total of ten T
followed by eight bags screened with IBMP-8.3
and four bags screened with IBMP-8.1 protein
cruzi-positive blood bags were correctly identified as positive when tested with IBMP-8.4 protein
One positive sample yielded an inconclusive result when tested with IBMP-8.3
which triggered a warning signal with a clear risk of T
A danger signal was triggered when IBMP-8.1 and IBMP-8.2 proteins gave a negative result in three and two bags
Analysis of individual use of chimeric IBMP proteins for CD serological
The antigen IBMP-8.4 had the highest sensitivity value in the present study as well as in the previously performed studies, regardless of the population studied and the methodology used. This is due to the nature of the molecule, as it comprises a larger repertoire of epitopes compared to the others, making it responsive to a greater diversity of anti-T. cruzi antibodies (25, 30, 34, 35)
cruzi was less efficient in blood donors with IBMP-8.1
probably due to its limited repertoire of antigens
This result contrasts with the results of other studies that have used this molecule as an antigenic matrix
21 samples were predicted by LCA to be positive
This small number of positive samples has a strong influence on the determination of sensitivity
since each false-negative result corresponds to a 4.76% reduction in the sensitivity value
where a single false-positive sample would reduce the value by only 0.02%
Considering that this is a phase III study (blind study)
it was not possible to control the sample size of each group (positive and negative)
the accuracy values for all antigens were ≥99.4%
thanks to the large number of negative samples and the high specificity of all antigens (99.98 to 100%)
or synthetic peptide antigens have been used as solid phase in IVD for detection of anti-T
cruzi antibodies with acceptable sensitivity values for safe serological CD screening in blood banks
After analyzing the performance parameters of the four all IBMP antigens
an analysis of the individual use of each molecule in serological screening for CD
blood banks set the cutoff point at 20 to 25% of the manufacturer's specified value to reduce the possibility of transmission of bloodborne pathogens as much as possible; HEMOBA Foundation lowers the cutoff value to 25%
and nine bags were rejected as false positive for IBMP-8.1
The antigens IBMP-8.1 and IBMP-8.2 detected as false-negative four and two bags
indicating that their use alone in serological screening of CD in blood banks is not recommended because of the possibility of transmission during transfusion
the combined use of these molecules is safe because the false-negative or exclusion zone results are not the same when the four assays are compensated
Despite the greater number of bags discarded when the IBMP-8.4 molecule was used
this was the safest molecule to be used alone in serological screening in blood banks
This gap could be easily closed by using the four antigens
would eliminate all false-negative results
then IBMP-8.1 or IBMP-8.2 can be used to exclude false-positive results
we would have a more effective and safer diagnosis
which would result in a lower number of blood bag disposals and reduce the cost of monitoring blood quality for transfusions
this was a phase III study evaluating the four chimeric recombinant antigens IBMP-8.1
and IBMP-8.4 for serological diagnosis of chronic Chagas disease
The molecules exhibited high diagnostic performance and were shown to be suitable for screening CD in blood banks
Their use in blood banks could significantly reduce unnecessary disposal of blood bags or the risk of T
The original contributions presented in the study are included in the article/Supplementary Material
further inquiries can be directed to the corresponding author
The studies involving human participants were reviewed and approved by Institutional Review Board (IRB) for Human Research at the Gonçalo Moniz Institute
Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements
and NZ designed the experimental procedure
PC expressed and purified the chimeric recombinant antigens
FS prepared the figures and supervised the work
All authors contributed substantially to the work described in this article
and agreed to the published version of the manuscript
This research was supported by the Coordination of Superior Level Staff Improvement-Brazil (CAPES; Finance Code 001)
the Research Support Foundation of the State of Bahia (FAPESB); and Inova Fiocruz/VPPCB (Grant Number VPPCB-008-FIO-18-2-20)
and FS are CNPq research fellows (Grant Numbers 590032/2011-9
Funders had no influence on the study design
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations
Any product that may be evaluated in this article
or claim that may be made by its manufacturer
is not guaranteed or endorsed by the publisher
We are grateful to the Hematology and Hemotherapy Foundation of the State of Bahia (Hemoba Foundation - BA) and its Serology Laboratory staff for their assistance in collecting the serum samples
We would like to express our gratitude to Larissa de Carvalho Medrado Vasconcelos
and Gabriela Agra for technical support at the Gonçalo Moniz Instituto (FIOCRUZ-BA)
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fmed.2022.852864/full#supplementary-material
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Copyright © 2022 Santos, Silva, Freitas, Leony, Daltro, Santos, Almeida, Araújo, Celedon, Krieger, Zanchin, Reis and Santos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY)
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For years, a rumor has circulated that Ludwig van Beethoven's Fifth Symphony had been shown to kill 20% of cancer cells in lab tests without affecting healthy cells. For example, someone posted about it on Facebook on Dec. 23, 2024 (archived):
Researchers found that Beethoven's Symphony No
5 destroyed 20% of cancer cells in lab tests:Scientists at the Instituto de Biofísica Carlos Chagas Filho
are exploring whether music could play a role in cancer treatment
the team exposed both healthy and cancerous cell cultures to different music genres
5 destroyed about 20% of cancer cells in just a few days
A similar effect was observed with György Ligeti's Atmosphères
though Mozart's Sonata for Two Pianos showed no measurable impact
The exact mechanism behind these effects remains unknown
are planned to uncover more about this intriguing phenomenon
it offers a fascinating glimpse into the potential of music as a noninvasive cancer therapy
This post had garnered 66,000 reactions as of this writing, as well as 26,000 reshares. But the claim is not new. A search revealed such claims have been circulating since at least 2011
The rumor originated from a 2011 article published in O Globo
The article said that when exposed to a half hour of Beethoven's Fifth
one in five cells in a culture of MCF-7 cells — an estrogen-
progesterone- and glucocorticoid- receptive human breast cancer cell line isolated in 1970
and one of the most studied cancer cells in the world — had died
many had shrunk or lost "granularity," or complexity
Ligeti's "Atmosphères" had similar results, the story added, though the first movement of Mozart's Sonata for two pianos barely had any effect
The article asserted that the experiment could open new avenues for cancer treatment
"We were happy with the result," the article quoted the lead researcher
"We believed that the symphonies would only provoke metabolic alterations
The news story said that the team would soon move on to studying the effects of samba and Brazilian funk on the same cells
Later, the story was picked up by Improbable Research, a website that compiles unusual research in science, medicine and technology and hands out, every year, the Ig Nobel Prizes
the article in O Globo did not link to published research articles describing the experiment or its results
A Snopes email exchange with Capella revealed that while the story had reported some facts correctly
The research was based on previous findings that suggested the effects of music may not be solely emotional and through auditory cells
some evidence existed that the pressure of sound on fluids that surround cells could affect non-auditory cells
Capella and her team set out to show whether music could affect "cellular morpho-functional parameters
The team exposed cancer cell cultures in petri dishes to the three musical pieces via speakers
as well as to silence as an experimental control
The researchers repeated each experiment at least four times to confirm the results
They reported finding a statistically significant increase in cell death and a reduction in size and granularity in cells exposed to Beethoven's Fifth
but not for the controlled condition of silence or for Mozart's Sonata
the research suggested that music or sound can get in the way of how "hormones bind to their targets," affecting physiological processes
Neither journal article had reported on the number of dead cells
nor did they make claims about the therapeutic power of these musical pieces on cancer
Neither claimed to have tested the music on healthy cells
Both articles said that the cell lines in the experiments shared characteristics with epithelial cells — which line various parts of the body and act as a first barrier to prevent infections — making them good models to test
The research team wrote that the experiments merely aimed to "better understand the direct effects of acoustic vibrations in the form of music in human cells in culture."
Capella emphasized that she and her team had conducted these experiments on cells in petri dishes
and that the results "could not be extended to human beings." In other words
while the musical piece was shown to kill cancer cells in a controlled lab setting
this did not mean the music could be used to treat cancer
she said that it was not correct that one in five (or 20%) cells had died after being exposed to Beethoven's Fifth Symphony
"The methods we used did not allow us to quantify cellular death," she said
she told Snopes that she had never planned further experiments with Brazilian funk or samba
she gave an interview to CNN Radio to dispel the confusion
adding that the reach of the CNN interview had been much smaller than that of the viral claims
she stopped investigating the effects of music on cells because she said it became difficult to find funding
Snopes could not find the CNN interview with Capella
Snopes also reached out to Renato Grandelle
the journalist who wrote the initial report
He said in a WhatsApp exchange that he remembered finding out about the study on EurekAlert.org
a nonprofit news-release distribution platform operated by the American Association for the Advancement of Science
News releases on EurekAlert are shared by "universities
and other organizations engaged in all disciplines of scientific research," and can include findings before they are published in peer-reviewed journals
EurekAlert does not guarantee the accuracy of the news releases
Grandelle told Snopes that no one from the Instituto de Biofísica Carlos Chagas Filho had contacted him to correct the story after its publication
Snopes could not find the original EurekAlert news release
We contacted the press department of the institute asking if they had kept a press release about this in their archives and will update the story should they respond
https://improbable.com/ig/about-the-ig-nobel-prizes/
'Direct Effects of Music in Non-Auditory Cells in Culture'
https://improbable.com/2011/04/13/music-against-cancer-in-brazil/
'Células tumorais expostas à "Quinta Sinfonia"
https://oglobo.globo.com/saude/ciencia/celulas-tumorais-expostas-quinta-sinfonia-de-beethoven-perderam-tamanho-ou-morreram-2804700
'Exposure to Music Alters Cell Viability and Cell Motility of Human Nonauditory Cells in Culture'
Evidence-Based Complementary and Alternative Medicine
'Brazilian Scientists Investigate Beethoven's Cancer-Fighting Properties'
https://gizmodo.com/brazilian-scientists-investigate-beethovens-cancer-figh-5792703
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is a potentially life-threatening illness caused by the protozoan parasite Trypanosoma cruzi
An estimated 6 to 7 million people worldwide are infected with T
Chagas disease is found mainly in endemic areas of 21 continental Latin American countries
where it is mostly transmitted when humans come into contact with faeces and/or urine of infected blood-sucking triatomine bugs (vector-borne transmission)
Chagas disease was once entirely confined to the Region of the Americas
In the last decades the epidemiological pattern of the disease changed from a rural to a mostly urban disease
increased number of cases have been detected in Canada and the United States of America
Eastern Mediterranean and Western Pacific countries
Due to the high number of people who remain undiagnosed or untreated
combined with the areas with remaining active transmission
put an estimated 75 million people at risk of infection
Triatomine bugs typically live in the wall or roof cracks of poorly constructed homes in rural or suburban areas
The parasites enter the body when: i) the person inadvertently smears the bug’s waste into the bite or another skin break
the eyes or the mouth; ii) by consumption of food that has been contaminated with waste from infected triatomine bugs
typically infecting groups of people (causing outbreaks or oral transmission) with a higher frequency of severe disease and number of deaths
Everywhere Chagas disease can be also transmitted through blood or blood product transfusion from infected donors; by congenital (mother to child) transmission during pregnancy or childbirth; by organ transplantation from infected donors; and also by laboratory accidents
following up on decision of the 72nd World Health Assembly
the World Chagas Disease Day was established to be celebrated on 14 April (the date of the year 1909 when Carlos Chagas diagnosed the first human case of the disease
After the infection is transmitted there is an initial
acute phase that lasts for about two months
symptoms are absent or mild and unspecific
characteristic first visible signs of infection
such as a skin lesion or a purplish swelling of the lids of one eye (the so-called Romaña sign)
During the chronic phase that succeeds the acute phase
up to 30% of patients suffer from cardiac disorders and up to 10% experience digestive
the infection can lead to sudden death principally due to heart arrhythmia or heart failure caused by the destruction of the heart muscle and its nervous system
Chagas disease can be treated with two antiparasitic medicines: benznidazole and nifurtimox
Both medicines are nearly 100% effective in curing the disease if given soon after infection
including the cases of congenital transmission
the longer a person has been infected and the adverse reactions are more frequent at older age
Treatment is also indicated for those in whom the infection has been reactivated due to immunosuppression
and for patients during the early chronic phase
should be offered treatment because antiparasitic treatment can also prevent or curb disease progression and prevent congenital transmission in pregnant women
In other cases the potential benefits of medication in preventing or delaying the development of Chagas disease should be weighed against the duration of treatment (up to 2 months) and possible adverse reactions (occurring in up to 40% of treated adult patients)
Benznidazole and nifurtimox should not be taken by pregnant women or by people with kidney or liver failure
or digestive or neurological manifestations may be required
World Chagas Disease Day 2024: urging early diagnosis and care for life
World Chagas Disease Day 2023 to focus on integrating universal care and surveillance at the primary care level
World Chagas Disease Day: finding and reporting every case
WHO and Bayer renew longstanding collaboration to accelerate control and elimination of neglected tropical diseases
Interrupting transmission of Chagas disease to humans
Implementing an information and surveillance system of Chagas disease
education and communication for key people involved in Chagas disease control
Providing care to populations affected by Chagas disease
the World Health Organization (WHO) published a new road map to address the burden of disease and death imposed by neglected tropical..
decided to establish World Chagas Disease Day
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Human African trypanosomiasis (sleeping sickness)
PAHO calls for first level of care to be strengthened to ensure early detection and treatment of disease that affects more than 6 million people globally
are not diagnosed or receive medical care until they develop a chronic infection
the Pan American Health Organization (PAHO) calls for first level of care to be strengthened to improve the detection and treatment of this neglected disease
Time to integrate Chagas disease into primary health care is the theme of this year's World Day
highlighting the low detection rates and frequent barriers to accessing adequate medical care
health personnel and community workers to make additional efforts to work together and focus attention on most vulnerable populations
so so that we can soon eliminate Chagas as a public health problem.”
Chagas affects more than 6 million people worldwide
the disease is increasingly detected in other countries and continents
Around 30,000 new cases and 10,000 deaths are reported in the Latin American region each year
It is mainly transmitted through contact with a vector insect known as a kissing bug
It can also be transmitted via blood transfusion or organ transplantation
Chagas disease is almost 100% curable if detected and treated early
interim Director of PAHO's Department of Prevention
“We need to involve the community and support primary care professionals with training and critical supplies to manage the disease,” he said
up to 30% of patients can develop irreversible complications to the nervous system
since 1990 countries of the region have made progress in controlling Chagas
This includes measures to control the vector
application of universal screening in blood banks and in pregnant women and improved housing standards
However, given the continued circulation of the vector and the silent nature of the disease, Chagas continues to be endemic in 21 countries of the Americas and is one of more than 30 diseases and conditions that PAHO and countries seek to eliminate by 2030
It is estimated that around 1.1 million women of childbearing age are infected with the T
9,000 children contract Chagas through mother-to-child transmission
This week, PAHO organized a webinar in which experts discussed experiences and strategies to end congenital Chagas disease
PAHO recommends universal Chagas screening for pregnant women
and testing of newborns to determine serological status
The Organization also recommends treating positive mothers and babies after delivery
a Brazilian doctor and researcher who discovered the disease in 1909
World Chagas Disease Day was established by the World Health Assembly in 2020
and since then has been celebrated every 14 April – the day Carlos Chagas diagnosed the first human case of the disease in 1909
World Chagas Disease Day 2025 shines a global spotlight on the suffering caused by Chagas disease and calls for equitable access to healthcare and long-term care services
The theme 2025 emphasizes a collective responsibility in prevention
Primarily affecting poor populations in Latin America
Often called a “silent and silenced disease”
most infected individuals remain asymptomatic
making detection and treatment a challenge
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a neglected parasitic disease caused by Trypanosoma cruzi
poses a significant health threat in Latin America and has emerged globally because of human migration
Trypanosoma cruzi infects humans and over 100 other mammalian species
which are important sentinels for assessing the risk of human infection
cruzi in dogs is still impaired by the absence of commercial tests
we investigated the diagnostic accuracy of four chimeric recombinant T
employing indirect ELISA with the chimeric antigens
LCA was utilized to establish a latent variable as a gold standard for T
revealing distinct response patterns for each antigen
The IBMP (Portuguese acronym for the Molecular Biology Institute of Paraná) antigens achieved area under the ROC curve (AUC) values ranging from 90.9% to 97.3%
The highest sensitivity was attributed to IBMP-8.2 (89.8%)
The highest specificity was observed for IBMP-8.4 (98.6%)
Predictive values varied according to prevalence
indicating higher effectiveness in endemic settings
Our findings underscore the remarkable diagnostic performance of IBMP-8.2 and IBMP-8.4 for the serodiagnosis of Trypanosoma cruzi in dogs
representing a promising tool for the diagnosis of CD in dogs
These chimeric recombinant antigens may not only enhance CD surveillance strategies but also hold broader implications for public health
contributing to the global fight against this neglected tropical disease
The limitations are even greater for dogs because of the lack of commercial tests
we investigated the diagnostic performance of four chimeric recombinant T
cruzi antibodies in dogs by in-house ELISA
nucleotide sequences were cloned into the pET28a vector and expressed in Escherichia coli BL21-Star DE3
These cells were cultured in lysogeny broth (LB) supplemented with 0.5 M isopropyl-β-d-1-thiogalactopyranoside (IPTG)
bacterial cell lysis was achieved using microfluidification
and the antigens were purified through affinity and ion exchange chromatography
The quantification of chimeric antigens was carried out using fluorimetry with the Qubit 2.0 instrument (Invitrogen Technologies
This figure illustrates the study design in accordance with the Standards for Reporting of Diagnostic Accuracy Studies (STARD) guidelines
Key abbreviations include N/n (number of samples) and LCA (latent class analysis)
Flat-bottom 96-well polystyrene microtiter plates (Nunc Maxisorp®
USA) were coated with one of the chimeric IBMP antigens at concentrations of 25 ng per well in 100-µl coating buffer (0.05 M carbonate/bicarbonate buffer solution
and blocking were concurrently performed using a synthetic buffer (batch 130,703; WellChampion; Kem-En-Tec Diagnostics A/S
Denmark) according to the manufacturer’s instructions
diluted 1:100 in 0.05 M phosphate-buffered saline (PBS; pH 7.4)
and the microtiter plates were incubated at 37 °C for 60 min
the wells were washed five times with 250 µl of wash solution (PBS-Tween; 10 mM sodium phosphate
the plates were incubated again at 37 °C for 30 min with 100 µl HRP-conjugated anti-dog globulin IgG (Bio-Manguinhos
Brazil) diluted at 1:20,000 (IBMP-8.3) and 1:40,000 (IBMP-8.1
100 µl of chromogenic TBM substrate (Kem-En-Tec Diagnostics A/S
and microtiter plates were incubated for 10 min in the dark at room temperature
The colorimetric reactions were interrupted by adding 50 μl of 0.3 M H2SO4 to each well
Optical density (OD) was measured in a microplate reader equiped with a 450-nm filter (SPECTRAmax 340PC®; Molecular Devices
with background values subtracted from the measurement experiments
Response patterns for the four chimeric Trypanosoma cruzi antigens
a posteriori probabilities for Chagas disease diagnosis from the LCA
and classification of canine serum samples for Chagas disease diagnosis
The samples are denoted as P1–P5 based on their respective response patterns in the chimeric assay
Negative and positive outcomes for a specific chimeric antigen assay are represented by blue and red squares
Key abbreviations include LCA (latent class analysis)
PP (a posteriori probability associated with anti-T
The results of the LCA were used as a gold standard to obtain a reliable estimate of the performance of each chimeric assay
AUC analysis yielded values ranging from 90.9% for IBMP-8.1 and 93.8% for IBMP-8.3 to 97.1% for IBMP-8.2 and 97.3% for IBMP-8.4
These findings indicate a high overall capacity of all four IBMP chimeric antigens to accurately identify T
Assessment of chimeric recombinant Trypanosoma cruzi antigen performance using ELISA
A Graphs illustrating the reactivity index for each antigen assessed against a panel comprising 49 positive and 288 negative samples
and the shaded area represents the gray zone
The horizontal lines for each result group denote the medians along interquartile range (IQR)
B Receiver-operating characteristic curve (ROC) and calculated AUC for each IBMP antigen
C Performance parameters for antigens determined using the assays depicted in panel A
Acc: accuracy; AUC: area under the ROC curve; Sen: sensitivity; Spe: specificity; Tc-Neg: T
Considering RI values within the range of 1.0 ± 0.10 as the inconclusive gray zone interval for results
our observations revealed that only seven negative samples (2.4%; 7/288) fell into the inconclusive zone when tested with IBMP-8.2
10 samples (3.5%; 10/288) tested with IBMP-8.1
and 9 (3.1%; 9/288) with IBMP-8.4 were classified as inconclusive
we observed the following number of samples in the gray zone: five (10.2%; 5/49) when tested with IBMP-8.2
six (12.2%; 6/49) each when tested with IBMP-8.1 or IBMP-8.4
Overall analysis showed that 3.6% (12/337) of samples tested with IBMP-8.2
and 6.8% (23/337) of samples with IBMP-8.3 had RI values within the gray zone
The assays employing IBMP antigens exhibited an accuracy of 97% for IBMP-8.2
due to the high number of both false-negative and -positive results in samples assayed with IBMP-8.1
the accuracy of this antigen was significantly lower
Cohen's kappa index indicated substantial agreement (κ = 0.62 for IBMP-8.1 and κ = 0.70 for IBMP-8.3) and almost perfect agreement (κ = 0.88 for IBMP-8.2 and κ = 0.87 for IBMP-8.4) with the results obtained from LCA
IBMP-8.4 and IBMP-8.2 demonstrated superior performance
as evidenced from the parameters derived from ROC analysis
IBMP-8.2 exhibited the highest sensitivity
while IBMP-8.3 and IBMP-8.4 demonstrated superior specificity
Estimations of positive and negative predictive values across various prevalence scenarios for Trypanosoma cruzi seropositivity in dogs
providing insight into the diagnostic accuracy of tests under different epidemiological conditions
NPV: negative predictive value; PPV: positive predictive value
A thorough analysis of the ratio of false positives/negatives to true positives/negatives across a range of hypothetical prevalence scenarios provided a comprehensive perspective on the performance of testing in different epidemiological settings. As depicted in Table 1
the analysis revealed that the probability of false-negative outcomes
was consistently low for all diagnostic tests and across various prevalence scenarios
was significantly more frequent at lower prevalence rates (0.1% and 1%)
this trend was reversed in areas with higher prevalence levels
where the probability of false positives notably decreased at prevalences of 5% and 10%
the use of IBMP-8.1 alone is not recommended for reliable diagnosis in dogs
unless it is used in the latent class model
underscores the urgency of developing an accurate diagnostic test
applicable across all prevalence rates for efficient CD surveillance
Our findings suggest that the IBMP-8.2 and IBMP-8.4 may be promising tools in various epidemiological contexts
the reliance on serum samples from dogs in Brazil means these findings might not be universally reproducible in all geographic locations
considering the heterogeneous distribution of different T
It is important that this last limitation be addressed in future studies that consider comprehensive samples from other Brazilian states
and from different Latin American endemic countries
our analysis confirmed the remarkable performance of these chimeric antigens for detecting anti-T
with IBMP-8.2 and IBMP-8.4 proteins showing higher accuracy
To further improve the performance metrics of the IBMP antigens
our group will conduct additional studies incorporating mixtures of IBMP antigens
Our study represents a substantial step towards the development of a reliable serological test for detecting anti-T
Such a test could have applications in both public health (animal health surveillance) and veterinary medicine (CD diagnosis in dogs)
and IBMP-8.4) displayed remarkable capability in accurately distinguishing positive from negative samples
This finding is particularly significant because of the current lack of specialized commercial tests for canine CD diagnosis
The use of a LCA approach in our analysis further underscores the reliability of these antigens as effective diagnostic tools
The promising results obtained with these chimeric IBMP antigens may improve surveillance and control strategies in areas where CD is endemic
thereby addressing a key challenge of this neglected tropical disease and ultimately to reducing its impact on affected communities
Data supporting the conclusions of this study are included in the manuscript
Standards for Reporting of Diagnostic Accuracy Studies
Access to care for Chagas disease in the United States: a health systems analysis
Trypanosoma cruzi clonal diversity and the epidemiology of Chagas’ disease
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Strong host-feeding preferences of the vector Triatoma infestans modified by vector density: implications for the epidemiology of Chagas disease
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Trypanosoma cruzi connatal transmission in dogs with Chagas disease: experimental case report
Domestic dogs and cats as sources of Trypanosoma cruzi infection in rural northwestern Argentina
Incidence of Trypanosoma cruzi infection among children following domestic reinfestation after insecticide spraying in rural northwestern Argentina
Shelter dogs as sentinels for Trypanosoma cruzi transmission across Texas
The potential of canine sentinels for reemerging Trypanosoma cruzi transmission
Household prevalence of seropositivity for Trypanosoma cruzi in three rural villages in northwest Argentina: environmental
Sustainable vector control and management of Chagas disease in the Gran Chaco
Reservoir host competence and the role of domestic and commensal hosts in the transmission of Trypanosoma cruzi
High levels of Trypanosoma cruzi DNA determined by qPCR and infectiousness to Triatoma infestans support dogs and cats are major sources of parasites for domestic transmission
Chagas disease: a silent threat for dogs and humans
Pathology of experimental Chagas disease in dogs
O cão como modelo experimental para o estudo da história natural da doença de Chagas
Technological advances in the serological diagnosis of Chagas disease in dogs and cats: a systematic review
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and IBMP-8.4 chimeric antigens to diagnose Chagas disease
Performance of recombinant chimeric proteins in the serological diagnosis of Trypanosoma cruzi infection in dogs
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Download references
The authors extend their sincere gratitude to Dr
Adriana Lanfredi and her team at FIOCRUZ-BA for generously offering access to their electron microscopy facility during the renovation of our laboratory
We also acknowledge the support of the FIOCRUZ-PR program and the Platform for Protein Purification and Characterization (RPT-15A) for their invaluable technical assistance
This study was funded by several Brazilian institutions: Coordination of Superior Level Staff Improvement-Brazil (CAPES; Grant Number Finance Code 001
National Council for Scientific and Technological Development (CNPq; 128257/2021-0)
Inova Fiocruz/VPPCB (Grant Number VPPCB-008-FIO-18-2-20)
Foundation for Research Support of the State of Bahia (FAPESB; Grant Numbers BOL0298/2020 and BOL0543/2020)
Santos are CNPq research fellows (Grant Numbers 304167/2019-3 and 306448/2023-8
The funding bodies played no role in study design
Ângelo Antônio Oliveira Silva & Fred Luciano Neves Santos
Interdisciplinary Research Group in Biotechnology and Epidemiology of Infectious Diseases (GRUPIBE)
Filipe Dantas-Torres & Kamila Gaudêncio da Silva Sales
Department of Clinical and Toxicological Analysis
Postgraduate Program in Pharmaceutical Sciences
Antônia Cláudia Jácome da Câmara & Vicente Toscano de Araújo-Neto
Molecular Biology of Trypanosomatids Laboratory
Laboratory of Structural Biology & Protein Engineering
Integrated Translational Program in Chagas disease from Fiocruz – Fio-Chagas
Nilson Ivo Tonin Zanchin & Fred Luciano Neves Santos
All authors made substantial contributions to this work
and NITZ conceptualized the experimental design
NITZ identified Trypanosoma cruzi epitopes and developed the chimeric recombinant IBMP proteins
PAFC was responsible for expression and purification of these proteins
FDT and KGSS collected and characterized samples from Pernambuco
while ACJC and VTAN did the same for Rio Grande do Norte
NDF and FLH executed the ELISA experiments
and interpretation were carried out by NDF
with LDAFA conducting the latent class analysis
All authors reviewed and approved the final manuscript
This study obtained ethical approval from the Ethics Committee for the Use of Animals at the Instituto Gonçalo Moniz—Fiocruz/BA
The authors declare no commercial or financial relationships that could be construed as a potential conflict of interest in this research
unless otherwise stated in a credit line to the data
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DOI: https://doi.org/10.1186/s13071-024-06376-5
Volume 2 - 2023 | https://doi.org/10.3389/fpara.2023.1260224
This article is part of the Research TopicPolymerase Chain Reaction technique for Chagas Disease: challenges and limitationsView all 6 articles
Chagas disease (CD) caused by Trypanosoma cruzi remains a Neglected Tropical Disease with limited access to diagnosis and treatment
particularly for chronically infected patients
Clinical trials are underway to improve treatment using new drugs or different regimens
and Real-Time PCR is used to assess the parasitological response as a surrogate biomarker
PCR-based strategies have limitations due to the complex nature of T
The parasite exhibits asynchronous replication
making it challenging to determine optimal timeline points for monitoring treatment response
This mini-review explores factors that affect PCR-based monitoring and summarizes the endpoints used in clinical trials for detecting treatment failure
Serial sampling and cumulative PCR results may improve sensitivity in detecting parasitemia and treatment failure in these trials
Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, poses a significant public health threat in many regions worldwide (WHO, 2023)
Transmission to humans primarily occurs through triatomine vectors
but other routes such as in utero transmission
CD remains classified as a Neglected Tropical Disease
with limited access to efficient diagnosis and treatment
hampering efforts to control its impact on affected populations
Current available therapies, such as benznidazole (BZN) and nifurtimox (NFX) have limitations in efficacy and safety, particularly in chronic adult CD patients (Moraes et al., 2014)
Clinical trials using different drug regimens and exploring new drugs in the pharmaceutical industry portfolio are underway to address this issue (Morillo et al., 2015; Morillo et al., 2017; Villar et al., 2019; Cafferata et al., 2020; Alonso-Vega et al., 2021; Torrico et al., 2021; Altcheh et al., 2023)
One of the challenges in assessing treatment efficacy is the reliance on molecular methods, particularly Real-Time PCR, to detect parasitic loads in peripheral blood (Schijman et al., 2011; Moreira et al., 2013; Ramírez et al., 2015)
and non-detectable findings cannot confirm parasitological eradication
Only detectable results can indicate treatment failure
This limitation hampers the ability to accurately determine the success of therapeutic interventions
Another critical factor in treatment response is the genetic diversity and population structure of T. cruzi. CD patients may be infected with multiple parasite strains and clones, each with different tissue tropism (Macedo and Pena, 1998)
The presence of parasites in the bloodstream may not necessarily reflect the ones responsible for clinical manifestations and drug susceptibilities
Different subpopulations of the parasite may be responsible for variations in treatment responses observed in multicenter trials
Moreover, certain life-cycle stages may be less sensitive to treatment, and the ability of parasites to reside in metabolically distinct tissue compartments can significantly affect drug susceptibility (Barrett et al., 2019)
These complexities highlight the need for more comprehensive approaches when evaluating treatment efficacy and drug response in CD
Benznidazole and nifurtimox exhibit pleiotropic properties with multiple effects on the target organism
This complexity can give rise to resistance in various ways
It is important to note that T.cruzi resistance observed in laboratory settings where in vitro resistance is generated may differ significantly from the resistance patterns observed in natural populations
This underscores the need of considering the interplay between laboratory studies and real-world observations when addressing drug resistance in T.cruzi
cruzi in vivo is more intricate than previously assumed
revealing varying degrees of drug susceptibility among different parasite stages
The research conducted by Moraes et al. (2014) highlights that trypomastigote forms have a higher capacity to withstand the trypanocidal effects of BZN and NFX compared to replicative epimastigotes and amastigotes
epimastigotes and amastigotes are more susceptible to a cumulative
Revollo et al. (2019) investigated the susceptibility patterns of T. cruzi stages to BZN and NFX in vitro using a range of twenty-one T. cruzi strains from three different DTUs (Discrete Typing Units) isolated from patients, reservoirs, and triatomines across various geographical origins (Revollo et al., 1998). On the basis of the Epidemiological cut-off value (CO wt) (Kahlmeter, 2014)
the authors computed the susceptibility threshold (COwt) of the T
cruzi life cycle forms against BZN and NFX from a panel of previously characterized strains and observed that the trypomastigote form exhibits higher tolerance to the toxic effects of both drugs compared to the other stages
In vitro experiments conducted by MacLean et al. (2018) demonstrated that strain PAH179 (TcV) exhibited marked resistance to posaconazole
This reduced sensitivity was attributed to the slow doubling and cycling time of this strain
which resulted in ergosterol biosynthesis inhibition by posaconazole only after multiple rounds of division
The lack of effect of posaconazole on the non-replicative trypomastigote form further supported this observation
they possess a remarkable resilience to compounds that are highly effective against the actively replicating parasites
the drug concentration within the host cell may be depleted before it can effectively target the core amastigotes
contributing to the survival and persistence of the dormant parasites
Such a phenomenon would pose challenges in completely eradicating T
cruzi infections and underscore the need for novel therapeutic approaches targeting these drug-resistant persister subpopulations
This insight sheds light on the dynamics of T
cruzi infection and the potential mechanisms of persistence within the host
Quantitative PCR would permit establishing a minimal difference in parasitic loads between subsequent samples of a same patient under follow-up to interpret it as a true decrease or increase in parasitemia and accordingly treatment response improvement or failure
the concept of the “minimum clinically significant difference” (MCID) is often used to determine whether a change in a measured parameter
The MCID is the smallest change in a measurement that is considered to be clinically relevant and not just due to random variability
including the specific parasite population
It is essential to consider the sensitivity and precision of the testing method
this has not been done in the context of Chagas disease trials
Harmonization and agreement on criteria for using PCR in clinical trials for Chagas disease can be challenging due to various factors, including scientific, practical, and logistical considerations. Some debatable points that may arise during discussions and negotiations for harmonization are presented in Table 1
Table 1 Debatable points regarding harmonization and agreement on criteria for using Polymerase Chain Reaction (PCR) in clinical trials for Chagas disease
This difference could be related to the distribution of parasite strains and DTUs (Discrete Typing Units)
which can have different gene dosage for the molecular targets used in PCR
Comparison of PCR positivity between individual samples did not show significant differences
indicating that collecting 5 ml or 10 ml of blood did not impact PCR results in that cohort of chronically infected patients
when cumulative results from the combination of the first two samples were computed
higher PCR positivity rates were observed in both cohorts
In cases where samples 1 and 2 were PCR negative
the inclusion of the third sample collected one week later increased sensitivity
increasing the number of samples during screening allows enrolling a higher number of patients within the same project period
In the MSF-DNDi PCR Sampling Optimization Study (Parrado et al., 2019)
three samples were taken from all patients regardless of the PCR results in the first two
No statistical differences were observed when testing individual samples
when the cumulative PCR positivity of sample 1 plus 2 was compared to the positivity of either of them as a single test
This was also true when considering the combination of all three samples
The fluctuation of PCR positivity and non-detectable results can be attributed to the low parasitic burden in chronic Chagas disease patients
which often falls below the limits of detection and quantification of available PCR techniques
quantitative PCR results showed fluctuations in parasitic loads among positive PCR samples from the same patient
with some samples falling below the limit of quantification
The decision on the optimal opportunity to take an additional sample for PCR testing is currently based on operational and logistical factors rather than in the probability of detecting a particular percentage of additional positives based on the replicative dynamics of the parasite population
This is also applicable to the detection of treatment failure
as conducting more PCR determinations increases the chances of detecting failures
the measurement of DNAemia at the end of treatment (EOT) regimens was not useful for assessing treatment response
there was a rapid response in all treatment arms at EOT
but differences in the degree of treatment failure became clear approximately 100 days after treatment initiation
Parasitemia appeared to remain dynamic for up to 6 months after treatment and became more stable afterward
This is likely because some time was needed for refractory or resistant parasite populations to reach a detectable parasitic load threshold in the bloodstream using available PCR procedures
Different clinical trials have used PCR as an endpoint to evaluate treatment efficacy. In the BENDITA trial, sustained parasitological clearance at six months, defined as persistent negative qualitative PCR results since EOT, was the primary endpoint (Torrico et al., 2018)
Currently, clinical trials include PCR measurements at six and twelve months after EOT as common timepoints for post-treatment PCR assessments (Table 2)
Table 2 PCR timeline points in current clinical trials evaluating regimens of BZN or NFX in chronic CD adult patients
including the coexistence of multiple clones
and discrete typing units in a specific geographic region and patient cohort
as well as the differential histotropism and lack of synchrony among life-stage cycles
poses challenges in predicting an optimal timeline for Real-Time PCR monitoring and assessing the overall parasitological response to treatment
it is reasonable to maintain PCR tests at baseline
as well as at six and twelve months post-treatment
in order to facilitate the comparison of parasitological responses among different drugs and treatment regimens
This approach allows for a more comprehensive evaluation of treatment efficacy and response in CD clinical trials
The author declares that financial support was received for the research
and/or publication of this article from PICT2020-00862
Argentina and LEG ID39002 Small Grant Programme from PAHO
The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest
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Citation: Schijman AG (2023) Unveiling challenges in real-time PCR strategies for detecting treatment failure: observations from clinical trials on chronic Chagas disease
Received: 17 July 2023; Accepted: 04 September 2023;Published: 26 September 2023
Copyright © 2023 Schijman. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY)
*Correspondence: Alejandro G. Schijman, YXNjaGlqbWFuQGluZ2ViaS1jb25pY2V0Lmdvdi5hcg==
and more than 10,000 deaths per year can be attributed to this significant public health problem
it was adopted as an annual awareness day on April 14 by the World Health Organization as of 2020
because of the immunosuppression required for a transplant
cruzi parasites will most likely occur and should be monitored closely
Not everyone is at risk for Chagas disease. Currently, the Pan American Health Organization (PAHO) recommends screening persons who were born in or lived longer than 6 months in highly endemic regions
anyone who was born to a mother who lived in highly endemic regions may be at risk from congenital transmission and may want to be tested
but who have lived in the Southern United States and have spent a lot of time outdoors camping or hunting
or have lived in poorly constructed housing
This is especially true if the person is able to readily identify kissing bugs as an insect they have seen before in or around their sleeping areas
There is a need for increased Chagas disease screening across the U.S., however, meeting the need will require more awareness by healthcare providers.
Infectious Diseases: Epidemiology and Prevention
Volume 7 - 2019 | https://doi.org/10.3389/fpubh.2019.00166
Carlos Chagas discovered American trypanosomiasis
also named Chagas disease (CD) in his honor
He described the clinical aspects of the disease
characterized by its etiological agent (Trypanosoma cruzi) and identified its insect vector
CD occurred only in Latin America and was considered a silent and poorly visible disease
CD became a neglected worldwide disease with a high morbimortality rate and substantial social impact
emerging as a significant public health threat
it is crucial to better understand better the epidemiological scenarios of CD and its transmission dynamics
involving people infected and at risk of infection
Although efforts have been made by endemic and non-endemic countries to control
the cure or complete eradication of CD are still topics of great concern and require global attention
also affecting non-endemic places such as Canada
in this review we aim to describe the spread of CD cases worldwide since its discovery until it has become a global public health concern
the transmission occurs mainly through blood transfusion
organ transplantation or vertical transmission from mother to child
the only treatment option is heart transplantation
Despite efforts to understand the parasitic tropism for certain tissues
the factors involved in the clinical progression from indeterminate to symptomatic forms are still unknown
Chronic CD is considered a disabling disease responsible for the most significant morbidity and mortality among parasitic diseases (9), leading to a global expenditure of USD$627.5 million per year in health care costs (10). The estimated cost per patient at the early stages of the disease is $200, but in the chronic symptomatic form, this value can reach 4,000 to 6,000 dollars (11)
Considering that the current scenario of CD is changing to also affecting non-endemic countries
in this review we aimed to describe the spread of CD cases worldwide from its discovery to its current status as a global public health concern
He headed the Oswaldo Cruz Institute for 17 years (from 1917 until his death in 1934) and coordinated a campaign against the Spanish flu epidemic in Brazil (1918)
On February 14th, 1909, Chagas consulted a patient that would be the first CD case described in the literature: a 2-year-old child, Berenice (Figure 1), who had a high fever, hepatosplenomegaly, face edema and presence of the parasite in the blood (12)
Berenice remained asymptomatic throughout her life and died at 73 years from other causes
She was included in several clinical studies of CD from the age of 55 to 71 years old
(A) Berenice: the first patient diagnosed with Chagas disease
(B) Brazilian newspaper reporting the history of Chagas disease and Berenice
saying “Chagas disease was discovered here” (up)
and: “And this is the first case” (down)
Source: Archives of the Instituto Oswaldo Cruz
Despite dating to the pre-Columbian period
which makes the findings of Carlos Chagas a unique achievement in the history of parasitology and medicine
He alone described the most important features of a new tropical disease: the vector
the pathogen and its different stages of development
epidemiology and even the prophylaxis of the disease
Timeline with the first human cases of Chagas Disease (CD) reported in Latin America
Following the report of the first patient confirmed with CD (Berenice) in Brazil by Carlos Chagas in 1909
cases were reported in several countries such as El Salvador
with essential findings in paleoparasitology field
the Romaña signal was associated with the acute form of CD and the xenodiagnosis was proposed
government programs were implemented to control CD in Latin America
According to Lannes-Vieira et al. (31)
the history of CD can be divided into three important phases
is characterized by the brilliant work of Chagas and the controversy regarding the definition and legitimation of the disease as a scientific fact and social problem
falls after the death of Chagas when Mazza and Romaña confirmed the acute form of the disease in Argentina and when Evandro Chagas (Chagas' son) and Emmanuel Dias identified the endemic and chronic character of the disease
from 1961 to present day represents a challenge for both the control and the understanding of CD in diverse aspects
in which the implementation of national and international health policies became a constant need
CD is caused by the protozoan parasite Trypanosoma cruzi
With complex pathophysiology and a dynamic epidemiological profile
CD remains an important public health concern and is an emerging disease in non-endemic countries
According to the World Health Organization (3), there are 1,124,930 women between 15 and 44 years old infected with T. cruzi in Latin America, and the overall risk of congenital T. cruzi infection in children born from infected mothers is around 5% (46). The success of maternal-fetal transmission depends mainly on parasite genetic variability and maternal-fetal immune responses (43)
Although in many cases, both megacolon and megaesophagus decrease patient's quality of life, when the concomitant development of CCC occurs, characterizing cardiodigestive form, the prognosis is limited (57)
It is important to emphasize that the cure rate and its confirmation depend on factors such as phase and duration of disease, age of the patient, the tests used for the evaluation of therapeutic efficacy and the time of follow-up after treatment, associated comorbidities, and even the susceptibility of the T. cruzi genotype to the anti-parasitic drugs used (71)
Estimated number of infected individuals and people at risk of infection in Latin America from 1980 to 2010
While the prevalence of CD in Latin America has been reduced in recent decades, a dramatic increase in the number of CD cases in non-endemic countries have been observed, turning the disease into a worldwide public health concern (9, 87)
the real significance and public health implications of CD in this new epidemiological scenario are still unclear
Figure 3. Current estimated number of immigrants with T. cruzi infection in non-endemic countries. Estimation based on data for the United States (2007) and Canada (2006) (93), Europe (2008–2011) (94), Japan (2007) (95), Australia (2011), and New Zealand (2006) (92)
the results indicate a growing number of CD cases in non-endemic countries and therefore the requirement for more attention and efforts toward disease control
The number of international migrants worldwide has continued to overgrow. In 2017, the Department of Economic and Social Affairs of the United Nations reported that around 26 million of Latin America and Caribbean migrants were living in Northern America (89)
it is thought that the number of immigrants with CD living in the U.S
A total of 5,553 (3.5%) of the 156,960 Latin American immigrants living in Canada in 2006 were estimated to be infected with T. cruzi (93). Of these, the vast majority came from Colombia (1,293), followed by Argentina (968) and El Salvador (913). It is expected that about 1,111 of those immigrants may need medical attention due to CD (93)
Currently, as well as in the U.S., there is a large number of immigrants living in Europe, with around 5 million people from Latin America (89), most of them in Spain, Italy, France, United Kingdom, and Switzerland (103)
In non-endemic countries, T. cruzi transmission may occur through blood transfusions and organ transplants from infected donors as well as congenital transmission from mother-to-child during pregnancy. Newly acquired T. cruzi infections by those routes have been reported in non-endemic areas such as U.S, Spain, Switzerland, and, most recently, Japan (96, 103)
more financial support is required to research new drugs
more efforts are needed to improve the screening for comorbidities in patients with CD in order to provide interventions to tackle reversible disorders
CD patients must have an adequate medical follow-up to improve patient's quality of life and avoid a more substantial financial impact on the health system
In 110 years since its discovery and characterization in Latin America
CD continues to be a topic of great concern in endemic and non-endemic countries
and the cure or complete eradication of this disease are still some aims to be achieved
a multidisciplinary approach is essential to address this challenging disease
in order to achieve better control strategies
development of new diagnostic tools and medications
and investigation and treatment of comorbidities associated with chronic CD
and MB participated in the writing of the manuscript
KL and FA developed the graphic design of figures
IM-R and TS revised and edited the final manuscript
This work was supported by research grants from Fundação Araucária (CP 01/2016 Programa Pesquisa para o Sistema Único de Saúde: Gestão Compartilhada em Saúde - PPSUS Edição 2015 Fundação Araucária- PR/SESA- PR/CNPq/MS-Decit)
The authors also acknowledge support by Deutsche Forschungsgemeinschaft and Open Access Publishing Fund of University of Tübingen
from Johns Hopkins Bloomberg School of Public Health
for critically reading the manuscript and suggesting substantial improvements
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the global community is celebrating World Chagas Disease Day
Chagas disease, also called American trypanosomiasis
has been termed as a “silent and silenced disease”
not only because of its slowly progressing and frequently asymptomatic clinical course but also because it affects mainly poor people who have no political voice or access to health care.
Chagas disease is now present in many others
It was on this date in 1909 that the first patient
a Brazilian girl named Berenice Soares de Moura
was diagnosed for this disease by Dr Carlos Ribeiro Justiniano Chagas.
Raising awareness and the profile of this neglected tropical disease
which is often diagnosed in its late stages
is essential to improve the rates of early treatment and cure
together with the interruption of its transmission
Chagas disease is prevalent mainly among poor populations of continental Latin America and affects 6–7 million people
it has been increasingly detected in the United States of America and Canada and in many European and some Western Pacific countries
Chagas disease can lead to severe cardiac and digestive alterations and become fatal
The disease can be transmitted by vectorial transmission (T
typically live in the wall or roof cracks of poorly-constructed homes in rural or suburban areas
Normally they hide during the day and become active at night when they feed on human blood
The parasites enter the body when the person instinctively smears the bug faeces or urine into the bite
passage from an infected mother to her newborn
and organ transplantation and even laboratory accidents
WHO to continue support for Chagas disease programme that promotes patient self-care
Making available free paediatric medicine can accelerate elimination of congenital Chagas disease
Special Programme for Research and Training in Tropical Diseases
The Special Programme for Research and Training in Tropical Diseases (TDR)
is a global programme of scientific collaboration that helps facilitate
support and influence efforts to combat diseases of poverty
It is co-sponsored by the United Nations Children’s Fund (UNICEF)
the United Nations Development Programme (UNDP)
the World Bank and World Health Organization (WHO)
What is Chagas disease and how do humans and dogs become infected
MEDIA CONTACT: Taylor Bacon | Public Relations and Marketing Coordinator | 405-744-6728 | taylor.bacon@okstate.edu
The 72nd World Health Assembly today approved the designation of a World Chagas Disease Day which aims
to raise public awareness of this neglected tropical disease (NTD) that affects mainly poor people
“An annual day celebrated at global level is bound to attract international attention,” said Dr Pedro Albajar Viñas
“\"These days can help to provide visibility and commit countries to enhance control interventions for a disease that has remained largely neglected
but still present in many countries.”
has also been termed as a “silent and silenced disease”
not only because of its slowly progressing clinical course but also because it affects mainly poor people who have no political voice or access to health care
World Chagas Disease Day will be observed on 14 April
was diagnosed for this disease by Dr Carlos Ribeiro Justiniano Chagas
“A World Chagas Disease Day is an opportunity to collectively raise the profile of NTDs and the resources needed to control
eliminate or eradicate them as we prepare the new NTD Roadmap for 2021–2030,” said Dr Mwelecele Ntuli Malecela
WHO Department of Control of Neglected Tropical Diseases
A vector-borne disease caused by the parasite Trypanosoma cruzi and transmitted by the faeces and urine of triatomine bugs
Chagas disease is prevalent mainly among poor populations of Latin America and affects 6–7 million people
This is explained by the fact that although the infected vector has only been detected in the Americas
the disease can also be transmitted by contaminated food
The proposal for a World Chagas Disease Day was initiated by the International Federation of Associations of People Affected by Chagas Disease
and was supported by several health institutions
national or international nongovernmental platforms
Raising awareness and the profile of this silent disease
Integrated interventions are being carried out with malaria and other haemoparasites
HIV/AIDS and other communicable and noncommunicable health programmes to enhance cost-effectiveness of implementation
WHO supports treatment of Chagas disease through donations of nifurtimox and benznidazole
which are made possible thanks to agreements with Bayer and Insud Pharma
WHO also supports global awareness-raising on the extent of illness
disability and death associated with all NTDs
Celebrating World Chagas Disease Day on 14 April will provide a unique opportunity to add a global voice in favour of this and other forgotten diseases
“"These days can help to provide visibility and commit countries to enhance control interventions for a disease that has remained largely neglected
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Explaining Chagas disease through the stories of patients in Latin America
Although Chagas disease was discovered more than a century ago
it remains a major public health challenge
Chagas disease affects approximately six million people
less than 1% of affected individuals receive proper anti-parasitic treatment
and current tools to fight the disease are outdated and inadequate
Chagas disease often affects poor and marginalized communities
The disease can be silent for decades until it may become fatal
leading to severe cardiovascular and gastrointestinal complications in up to 30% of patients - the second leading cause of chronic heart failure in Latin America
Chagas disease has been coined a “silent and silenced disease,” not only because it progresses slowly
but also because it affects deprived people who have no political voice or access to healthcare
Yet, for the first time in history, the global community officially celebrated World Chagas Disease Day in April 2020 to raise awareness of people living with the disease
and the resources needed to move toward elimination
Novartis is committed to reimagining the fight against Chagas Disease and advocating for an integrated
See how Chagas disease impacts the lives of people and their families
Women living in Amazon River communities now have increased access to breast cancer screening along even its most remote banks
thanks to two new mammography units installed on Brazilian navy ships.
Procured by the UN-backed International Atomic Energy Agency (IAEA)
the mammography units will triple the current capacity for such tests in the remote region
already started delivering services along the vital South American waterway
and will soon be joined by the second vessel
breast cancer represents almost 30 per cent of all types of cancer with approximately 40 per cent of patients only diagnosed in the advanced stages of the disease
Screening is used to detect cancers at an early stage when they can be treated most effectively
The first stage in the screening involves an X ray (mammogram). With the two new units, each ship is able to perform up to a thousand such screenings per year
stressed the importance of screening to step up the global fight against cancer
timely and effective breast cancer services can now be delivered also to these remote areas in Brazil,” he said
the two ships will carry out eight journeys of up to 45 days each
They will travel from the Amazon River delta to the borders of Colombia
whose communities could also benefit from such services
navy ships can navigate along the narrow and shallow waters to bring much-needed healthcare directly to women living by the river’s banks
Women in the Amazon River region could previously only access mammography services by travelling to the nearest health facility - sometimes gruelling trips lasting several days
to receive such screening services at the healthcare centre in Manaus
the capital of the Brazilian state of Amazonas
The two mammography units were procured and installed on the ships in 2021 through the IAEA Technical Cooperation programme
The Agency also provided funds for training of personnel operating the equipment
Despite the COVID-19 pandemic, Soares de Meirelles succeeded in performing around 300 mammograms in 10 cities in October 2021.
Delivering cancer screening services to one of the most remote areas in the world is an example of the IAEA’s assistance in increasing access to cancer care globally.
Last week, the agency announced a new initiative, called Rays of Hope
to support Member States with diagnosis and treatment using a range of radiation technologies
beginning with African countries most in need
The IAEA supports countries in establishing radiotherapy services and in integrating these into comprehensive national cancer control plans
It also offers training for nuclear and radiation medicine personnel
and assists in the financing and procurement of equipment
The UN atomic watchdog reached an agreement with Iran on Sunday allowing the Agency access to surveillance cameras inside its atomic facilities.
This year’s theme is Finding and reporting every case to defeat Chagas disease
the global case detection rate for Chagas disease is low (estimated to be around 10%)
posing a substantial barrier to accessing treatment and care and in preventing transmission
Often termed as a “silent and silenced disease”
many people with Trypanosoma cruzi infection (the parasite that causes the disease) develop no symptoms or unspecific mild symptoms
many countries with cases lack systems to track the number of affected people and active transmission routes
According to the World Health Organization (WHO)
an estimated 6–7 million people are infected with T
In his message to commemorate World Chagas Disease Day 2022
reaffirmed WHO’s commitment to working alongside countries to defeat the disease
“WHO is committed to working side-by-side with all affected countries to increase their ability to prevent
report and provide care for every single case
Chagas disease remains a public health problem
especially in several endemic areas of continental Latin America
where the burden on health systems is high
The disease is curable when treatment is provided soon after infection
“Reporting each acute and chronic case is crucial to break the epidemiological silence of Chagas disease,” said Dr Pedro Albajar Viñas
who leads WHO’s global Chagas disease programme
we can overcome the prejudice and neglect associated with this disease.”
Chagas disease has been detected in several countries outside Latin America
including the United States of America and Canada and in many European and some African
Left undiagnosed and untreated in its chronic phase
Chagas disease can result in arrythmias and dilated cardiomyopathy
with relatively frequent digestive clinical manifestations and thrombotic vascular accidents and neurological sequela
the Seventy-second World Health Assembly decided to establish World Chagas Disease Day
to raise public awareness about the disease
The road map for neglected tropical diseases 2021–2030 identifies five main objectives to achieve the targets for elimination of Chagas disease by 2030:
Faster data exchange and monitoring are making it possible to share updated information
Better diagnostic tools and protocols can accelerate the detection of patients
cruzi transmission and provide health care for infected people or those suffering from the disease in both endemic and non-endemic areas
it is critical to increase networking globally and to reinforce regional and national capacities
is a potentially life-threatening illness caused by the protozoan parasite T
cruzi parasites are mainly transmitted by contact with faeces/urine of infected blood-sucking triatomine bugs (vectorial transmission)
These bugs typically live in the wall or roof cracks of homes and peridomiciliary structures
they hide during the day and become active at night when they feed on animal blood
The triatomine bug usually bites an exposed area of skin such as the face (hence its common name
then defecates or urinates close to the bite
Oral transmission with contaminated food is another potential means of transmission together with vectorial transmission
the disease remained a Latin American problem of rural populations
the movement of people from rural to urban areas – and eventually to other continents – has increased the relevance of other transmission channels
congenital transmission and organ transplantation
There is no vaccine against Chagas disease
Domiciliary vectorial control and transfusional control
together with active screening of girls and women of childbearing age to prevent congenital transmission
remain the most effective control tools in Latin America
Chagas disease was named after Carlos Ribeiro Justiniano Chagas
a Brazilian physician and researcher who discovered the disease in 1909
World Chagas Disease Day is about remembering a century-old discovery and confronting a modern-day global health challenge that remains largely in the shadows
the world pauses to observe World Chagas Disease Day
a crucial date in the calendar of global public health
Far from the spotlight that shines on more prominent illnesses
Chagas disease—also known as American trypanosomiasis—remains a neglected tropical disease that silently affects millions
Named after Brazilian physician Carlos Ribeiro Justiniano Chagas
primarily in Latin America but increasingly worldwide due to globalization and migration
Chagas disease is caused by the parasite Trypanosoma cruzi
which is primarily transmitted through the bite of infected triatomine insects
commonly known as “kissing bugs.” These bugs are found in rural
where they hide in cracks in walls and roofs and emerge at night to feed on human blood
Although vector-borne transmission is the most common route
Chagas disease can also be spread through:
-Blood transfusion or organ transplantation-Congenital transmission (from mother to baby during pregnancy)-Consumption of contaminated food or drink-Laboratory accidents
the parasite can remain undetected for years
it goes unnoticed or is misdiagnosed.2.Chronic Phase – Without treatment
the disease may lie dormant for 10–30 years before manifesting serious complications
heart failure)-Digestive complications (megacolon
megaesophagus)-Neurological disorders-Sudden cardiac death
It is estimated that 30–40% of people infected with T
cruzi will develop life-threatening complications later in life
the Chagas parasite can remain undetected for years (Image:Freepik)
While the World Health Organization (WHO) classifies Chagas disease as a neglected tropical disease (NTD)
it is no longer confined to tropical or subtropical regions
and international travel have brought Chagas into non-endemic countries like the United States
It is estimated that more than 300,000 people are living with Chagas in the U.S
most of whom are unaware of their condition
yet it remains underdiagnosed and undertreated—even in countries with the capacity to respond
Less than 10% of those infected are diagnosed
and fewer than 1% receive adequate treatment
it is a disease not just of the heart but of inequality
World Chagas Disease Day was officially recognized by the WHO in 2019
with the first global observance held in 2020
The date—April 14—marks the day in 1909 when Carlos Chagas diagnosed the first human case of the disease in a Brazilian child named Berenice
The discovery was unprecedented in medical history: Chagas identified the pathogen
the disease he named and fought remains underfunded
-Raise awareness of the disease among the public
and policymakers-Promote early screening and diagnosis-Encourage national programs to monitor
and treat the disease-Combat the stigma and social discrimination associated with Chagas-Advance research and innovation to develop better diagnostics
“Finding and Reporting Every Case to Defeat Chagas Disease,” emphasizes the importance of visibility
Chagas has been a disease of the unseen and unheard for too long
It affects people in rural farming communities
and undocumented workers—those who often lack access to regular health care
Many learn of their infection only after experiencing debilitating heart symptoms
thriving in communities with substandard housing and limited health infrastructure
where migrants and marginalized populations fall through the cracks of the healthcare system
Women of childbearing age face additional challenges
passing the disease silently to the next generation
up to 5% of babies born to infected mothers are also infected
perpetuating a cycle of transmission and suffering
efforts to eliminate Chagas disease face numerous barriers:
-Low awareness among healthcare professionals: In many countries
medical training does not adequately cover Chagas
leading to misdiagnosis or missed diagnoses.-Stigma and discrimination: Fear of deportation or job loss can prevent migrants from seeking testing or care.-Limited treatment options: The two primary drugs—benznidazole and nifurtimox—are most effective in the acute phase
they are often poorly tolerated by adults and unavailable in some regions.-Lack of investment in research: Chagas receives a fraction of the funding allocated to other diseases with similar health burdens.-No vaccine: While promising efforts are underway
there have been meaningful strides in recent years:
-Vector control programs in Latin America have dramatically reduced transmission in countries like Brazil
and Uruguay.-Screening programs for blood donors and pregnant women are reducing transmission in several regions.-International organizations such as the Drugs for Neglected Diseases initiative (DNDi)
and Médecins Sans Frontières are actively working to improve access to care and develop new treatments.-Mobile health clinics and telemedicine are being used to reach underserved communities in remote and urban areas.-Innovative diagnostics using molecular and serological testing are in development
the WHO also launched its roadmap for neglected tropical diseases (2021–2030)
which sets ambitious targets for the control and elimination of Chagas
-Interrupting transmission in all endemic countries-Ensuring access to diagnosis and treatment for at least 75% of infected people-Eliminating congenital Chagas disease through systematic screening and maternal care
These goals are achievable—but only with sustained political will
This means:1.Expanding screening programs in both endemic and non-endemic countries
particularly among at-risk populations.2.Training healthcare providers to recognize
and treat Chagas disease effectively.3.Ensuring access to safe
especially in low-income and migrant communities.4.Investing in research for new drugs
and rapid diagnostics.5.Raising public awareness to reduce stigma and encourage proactive health-seeking behavior
affected communities must be at the center of the response
Empowering people with knowledge about the disease and access to care is the only way to break the cycle of invisibility
let us remember that diseases do not discriminate—but health systems often do
Let April 14 be more than a date on the calendar
Let it be a call to action for policymakers
Awareness is the first step in the fight against Chagas disease
but action is what will make the difference
we can ensure that no more lives are lost in silence
(Note: Dr (Prof) Sadhana Kala is a USA-trained robotic & laparoscopic surgeon
and National Icon Endoscopic Surgeon of India
She is rated as India's Best Gynecologist by Google.)
(Disclaimer: The views expressed in this article are the personal opinions of the author.)
Jagran English brings you all the latest and breaking news from India and around the world
Follow english.jagran.com to stay updated with the latest English news
the World Health Organization (WHO) has called for comprehensive and equitable access to health care and services to everyone affected by Chagas disease
An estimated 6 to 7 million people worldwide are infected by Trypanosoma cruzi - the parasite that causes the disease
“It is sad to note that despite progress
millions of people still remain undiagnosed
with limited or no access to healthcare” said Dr Ren Minghui
Division for Universal Health Coverage/Communicable and Non-Communicable Diseases
“We need to improve detection and diagnosis rates which currently are at unacceptably low levels1 and we need to provide equitable access to treatment and health services to everyone.”
Chagas disease remains a public health problem in several endemic areas of continental Latin America where the burden on the health system is high
Canada and in many European and some African
Chagas Disease is curable if treatment is initiated soon after infection
Left undiagnosed and untreated in its chronic phase Chagas disease can result in arrythmias
“The NTD road map for 2021-2030 provides for a series of objectives to accelerate progress in the prevention and control of Chagas disease
including the elimination of its congenital form and providing 75% coverage of antiparasitic treatment to eligible populations everywhere” said Dr Mwelecele Ntuli Malecela
Department of Control of Neglected Tropical Diseases
“We are confident that this day will boost activities that will help to improve visibility and awareness of the disease.”
either in the acute phase after infection or in the life-lasting chronic phase
without a successful antiparasitic treatment
It can take decades before an infected person develops chronic clinical manifestations
with the current pandemic and the risk of presenting severe COVID-19 clinical manifestations
detection of people with Chagas disease should be prioritized and provided with access to vaccination
integrated interventions with malaria and other haemoparasites
HIV/AIDS and other communicable and noncommunicable health programmes are improving implementation in a cost-effective manner
Monitoring and verification of achievements through data exchange and information sources2 have opened possibilities to share and make accessible information
Better research and diagnosis tools can accelerate the screening of patients (including blood transfusion
screening of girls and women of childbearing age
and pregnant women and their newborns and children)
the 72nd World Health Assembly endorsed the designation of a World Chagas Disease Day to raise public awareness and information about what is often termed as a ‘silent and silenced disease’
is a potentially life-threatening illness caused by the protozoan parasite Trypanosoma cruzi (T
It is found mainly in endemic areas of 21 continental Latin American countries and regions3
the disease was strictly a Latin American problem of rural populations
but movement of people from rural to urban areas and to other continents expanded the reach of disease transmission channels towards non vectorial routes
remain the most effective methods of preventing transmission in Latin America
under-diagnosis of Chagas disease cases can be as high as 90% or even more
and this includes congenital and paediatric cases
2The open-source WHO information system to control/eliminate Chagas disease and other NTDs is contributing to gather and analyze real-time data/information on Chagas disease
2The open-source WHO information system to control/eliminate Chagas disease and other NTDs is contributing to gather and analyze real-time data/information on Chagas disease
Metrics details
It is 101 years since Carlos Chagas discovered the parasite responsible for the disease that now bears his name
What progress has been made since this discovery
Here Julie Clayton gives the low-down on Chagas disease
Chagas disease is a condition caused by the parasite Trypanosoma cruzi
which enters the body through broken skin and mucous membranes
and causes acute but often mild symptoms such as fever
In poor rural areas of South and Central America
where the disease is endemic and health-care facilities are inadequate
the acute infection spontaneously subsides in the majority of patients; however
the chronic infection can persist unnoticed for >30 years before causing complications such as abnormal heart rhythm
digestive problems and sudden cardiac death
About one in three carriers develop these chronic symptoms
which can be the first time they are diagnosed with T
The Brazilian physician Carlos Chagas identified T
cruzi as the causative agent of the disease in 1909
and later determined its clinical manifestations
epidemiology and entire life cycle in vectors
Image courtesy of Centers for Disease Control and Prevention
A triatomine picks up the parasitic infection by feeding on the blood of an infected animal or human
the parasite divides rapidly in the insect gut before emerging in its faeces
When the triatomine takes another blood meal
The parasite is able to penetrate the new host if the skin is broken — by the bite of the bug or through other cuts and abrasions — or through the soft skin of the eyes and mouth
It can infect the cells of the soft tissues below
and then enter the blood stream and circulate to reach other body tissues
The parasite is not fussy — it can infect all mammalian cells
The fruit of the açaí palm is another common source of contamination
as it is harvested and pressed in the Amazon forest
Triatomine bugs do not exist in Europe and are less common in North America, but people can still pass on the infection to others through blood or organ donation. Mothers can also unwittingly pass the parasite onto their babies at birth, which is likely to affect infants worldwide (see Chagas disease: a new worldwide challenge on page S6)
The only existing options for >40 years have been the drugs benznidazole and nifurtimox
These are especially effective at curing infection in the early
provided that patients complete a full 60-day course at the correct dose
The drugs are considered less effective in patients who have been chronically infected for >10 years — although this is the subject of considerable debate
given that their side effects can be severe
many physicians prefer not to prescribe these drugs
and many harbour the belief that they might be useless anyway
the traditional diagnostic methods were examination of blood samples by microscopy
and (for research purposes) laboratory culture of blood samples and xenodiagnosis
in which blood is fed to triatomine bugs whose faeces are then analysed for the presence of T
These methods frequently failed to detect T
cruzi in the blood of patients with chronic heart problems or other complications
Yet serum antibodies could still be detected
These observations led people to conclude that chronic Chagas disease is an autoimmune condition
which is sparked initially by the parasite but then becomes self-sustaining
as the immune system goes on to attack the body tissues
and can circulate in the blood in relatively low numbers
which coincides with chronic complications
Yet clinicians still lack clear guidelines on whether and when to treat chronic carriers
As well as the controversies over its pathology
Chagas disease has suffered from an inadequate R&D pipeline
Many commentators attribute this to a lack of interest from pharmaceutical firms in producing drugs for diseases that mostly affect the world's poorest
There also appears to be a lack of government commitment — even in many countries where Chagas disease is endemic — and therefore little investment in basic research and infrastructure for clinical trials
The Global Funding of Innovation for Neglected Diseases (G-FINDER) survey of 2009 highlights that
of the US$132 million spent globally in 2008 on diseases caused by kinetoplastid parasites (including T
only US$15.6 million was invested in Chagas disease R&D
with less than US$5 million being used for new diagnostics
BENEFIT uses real-time PCR and serological tests
and aims to provide precise figures on the cure rate with benznidazole in chronic disease
it will test whether curing Chagas disease — or even just reducing the parasite load — can prevent or reduce the severity of cardiac complications
technical obstacles remain that have hampered drug research in the past
particularly the difficulty of demonstrating treatment success (cure or no cure)
It is easier to show treatment failure — that is
cruzi and the appearance of drug-resistant parasite
Overcoming these obstacles will be an important goal in the coming years if significant progress is to be made against Chagas disease
Box 1: Did Darwin have Chagas disease?Charles Darwin wrote in his journal The Voyage of the Beagle about having been bitten by the Triatoma kissing bug when visiting Chile in 1835
The presence of gastric symptoms and his ultimate demise from cardiac problems have led some scholars to propose that Darwin was suffering from Chagas disease
although certain other factors suggest otherwise — including the fact that the parasite is not transmitted directly in the bite of the insect
The many other explanations put forward include stress
allergies and lactose intolerance — an inability to digest milk and dairy products
The truth might be unattainable without exhuming Darwin's body from Westminster Abbey in London
to look for the presence of Trypanosoma cruzi DNA
Quantitative Estimates of Chagas Disease in the Americas [OPS/HDM/CD/425-06] 1–28 (Pan American Health Organization
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Julie Clayton is a freelance writer based in Bristol
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Chagas Disease can and must be treated. This is the message that the Global Coalition for Chagas Disease
wishes to underline on the occasion of International Chagas Day next April 14.
Most of the people infected (more than 99%) remain without access to diagnosis and treatment
and 70 million are at risk of contracting it.
Even if there are only two available treatments -benznidazole and nifurtimox- their efficacy is high if the infection is detected early
The tools for diagnosis and treatment must be made available to the population affected by the disease
both in endemic countries and in those countries where the disease has spread due to migratory flows
where hundreds of thousand affected people live. Even if there are only two available treatments -benznidazole and nifurtimox- their efficacy is high if the infection is detected early
more efforts and resources should be allocated to the early diagnosis of the disease
1.2 million women are currently infected and more than 8,000 children are born with the disease every year as a result of congenital transmission
It is important to remind health care workers both in endemic and non-endemic areas that Chagas can be treated
it becomes a chronic problem that affects vital organs in 30% of infected people
the approval of benznidazole in countries such as USA and Mexico gives reasons to hope that these countries will commit to increasing the number of diagnosed and treated patients
which in turn will help them achieve the UN-approved Sustainable Development Goals concerning neglected diseases.
Keeping in mind that Chagas disease can be treated is the cornerstone to overcoming misconceptions: the disease is not unavoidable
It is also a stimulus for those affected and their relatives to speak out with an increasingly stronger and united voice.
The Global Coalition for Chagas Disease was funded in December 2012 by the Barcelona Institute for Global Health
the Drugs for Neglected Diseases Initiative (DNDi)
the Science and Applied Studies for Health and Environment Development (CEADES) Foundation
the Texas Children’s Hospital Center for Vaccine Development
and the Tropical Medicine School at the Baylor College of Medicine
numerous partners have joined.
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14\n April 2020 | Geneva −− Today the global community celebrates the first \nWorld Chagas Disease Day
The event makes visible one of the most \nneglected tropical diseases prioritized by the World Health Organization\n (WHO) as it continues to affect millions
Chagas disease was\n discovered more than a century ago but stayed largely ignored
“Chagas\n disease has been associated for a long time with mainly poor
rural and\n marginalized populations and is characterized by poverty and exclusion” said Dr Mwelecele Ntuli Malecela
“It\n is time we end this neglect and the social stigma associated with \ninfection that stands as a major barrier to effective screening
The\n social consequences of stigma associated with Chagas disease lead to \nsocial rejection
People who suffer from the disease can face work \nrestrictions because it is often associated with poor health and \npotential difficulties in performing work
\ncreating a fear of financial losses by employers
it is \nfor these reasons that people are reluctant to seek medical help – \nleading to more serious clinical manifestations and final complications \nand further spread of the disease
Chagas disease has been mostly transmitted to humans by \ncontact with the faeces or urine of particular species of triatomine \nbugs infected with the parasite Trypansosoma cruzi.\n
These\n bugs typically live in the wall or roof cracks of homes in rural or \nsuburban areas
Normally they hide during the day and are active at \nnight when they feed on human blood by biting an exposed area of skin
\nsuch as the face (hence its local name ‘kissing bug’
the bug defecates or urinates close \nto the bite
The parasites enter the body when the person instinctively \nreacts to the bite while smearing the bug faeces or urine into the bite \nor any other skin break
the eyes and the mouth or by contamination of \nfood during its preparation
frequently causing\n outbreaks of oral transmission with higher morbidity and mortality \nrates
But\n with rapid urbanization and movement of populations between Latin \nAmerica and other countries outside the region
the disease spread to \nurban areas and to other countries and continents
Chagas disease is not transmitted by triatomine bugs \nas it does in Latin America – but rather through other (non-vectorial) \nways” said Dr Pedro Albajar Viñas
“These\n include blood or blood products transfusion
mother-to-child \n(congenital) and organ transplantation and even laboratory accidents.”
In\n recognition of this growing public health problem and the need to \ncreate awareness on ways to increase detection and prevent its spread
\nthe Seventy-second World Health Assembly – WHO’s decision-making body – \nagreed to designate 14 April as World Chagas Day
Chagas\n disease is named after Carlos Ribeiro Justiniano Chagas
a Brazilian \nphysician and researcher who discovered the disease in 1909.\n\n
The\n disease is poorly understood by health professionals in non-endemic \nareas
with many who consider it to be a tropical disease restricted to \nsome territories of Latin America
patients infected with T.cruzi\n in non-endemic areas may not be aware of their condition which can lead\n to further transmission through non-vectorial routes of transmission
“Training\n health personnel to facilitate diagnosis
using all possible \nopportunities of systematic integration with other neglected tropical \ndiseases and other chronic communicable and non-communicable diseases
\ntogether with the provision of adequate medical care can greatly help to\n mitigate transmission and improve prognosis” said Dr Albajar Viñas
“Lack\n of awareness and knowledge about the disease
are clear obstacles to promoting health-seeking \nbehaviour.”
This\n year is the first opportunity for the global community to better \nunderstand and make visible the health
psycho-social and economic \ndimensions of this long-forgotten and ignored disease.
Metrics details
Triatomine bugs transmit Chagas disease across Latin America
where vector control-surveillance is increasingly decentralized
Locally run systems often deal with highly diverse native-vector faunas—plus
domestic populations of non-native species
Flexible entomological-risk indicators that cover native and non-native vectors and can support local decision-making are therefore needed
We present a local-scale entomological-risk score (“TriatoScore”) that leverages and builds upon information on the ecology-behavior and distribution-biogeography of individual triatomine bug species
We illustrate our approach by calculating TriatoScores for the 417 municipalities of Bahia state
we (i) listed all triatomine bug species recorded statewide; (ii) derived a “species relevance score” reflecting whether each species is native/non-native and
whether/how often it invades/colonizes dwellings; (iii) mapped each species’ presence by municipality; (iv) for native vectors
weighted presence by the proportion of municipal territory within ecoregions occupied by each species; (v) multiplied “species relevance score” × “weighted presence” to get species-specific “weighted scores”; and (vi) summed “weighted scores” across species to get municipal TriatoScores
we then grouped municipalities into high/moderate/low entomological-risk strata
TriatoScores were higher in municipalities dominated by dry-to-semiarid ecoregions than in those dominated by savanna-grassland or
Bahia’s native triatomines can maintain high to moderate risk of vector-borne Chagas disease in 318 (76.3%) municipalities
Historical elimination of Triatoma infestans from 125 municipalities reduced TriatoScores by ~ 27% (range
infestans since Bahia was certified free of Trypanosoma cruzi transmission by this non-native species
Entomological-risk strata based on TriatoScores agreed well with Bahia’s official disease-risk strata
but TriatoScores suggest that the official classification likely underestimates risk in 42 municipalities
Of 152 municipalities failing to report triatomines in 2006–2019
two and 71 had TriatoScores corresponding to
TriatoScore can help control-surveillance managers to flexibly assess and stratify the entomological risk of Chagas disease at operationally relevant scales
local-scale dwelling-infestation or vector-infection frequencies
or the functioning of control-surveillance systems) is also straightforward
TriatoScore may thus become a useful addition to the triatomine bug control-surveillance toolbox
we present an entomological-risk score (“TriatoScore”) that leverages and builds upon information on the ecology
and biogeography of individual triatomine bug species and can help control-surveillance managers to assess
and monitor Chagas disease entomological risk at operationally relevant scales
To illustrate the use of TriatoScore in practice
we applied our approach to the 417 municipalities of Bahia state
where native vectors are highly diverse and Chagas disease remains a major public health concern
We then applied this approach to the 400+ municipalities of the northeastern Brazilian state of Bahia; below we (i) briefly describe the setting and data used for this illustrative study; (ii) provide a step-by-step guide to calculating municipality-specific entomological-risk scores (“TriatoScores”); and (iii) show how TriatoScores can then be used to flexibly stratify and map Chagas disease entomological risk at the municipality scale
The relief map shows altitude (meters above sea level
MASL) and major topographic features: São Francisco River valley
Calculation of TriatoScores for the 417 municipalities of Bahia state involved the following six steps:
List all triatomine bug species recorded statewide (see above and Table 1);
For each species and municipality, multiply “species relevance score” by “weighted presence” to get “weighted scores” (Additional file 1: Table S4); and
Sum “weighted scores” across species to get municipal TriatoScores (Additional file 1: Tables S4
Note also that these analyses are mathematically equivalent to assigning a zero “species relevance score” to T
Spatial patterns of triatomine bug species richness across the 417 municipalities of Bahia state
a Including records of non-native species (Triatoma infestans since interruption of Trypanosoma cruzi transmission by this species was certified in 2006 and T
rubrofasciata); b including only records of native species
TriatoScores and predominant habitat classes across the 417 municipalities of Bahia state
TriatoScore values for individual municipalities; box plots show medians (thick horizontal lines)
inter-quartile ranges (box upper-lower limits)
and values that fall within 1.5 times the interquartile range (whiskers); red circles are means
The dotted horizontal lines highlight the overall TriatoScore mean value and the mean ± 1 standard deviation (SD) band; in our main entomological-risk stratification scheme
we considered municipalities with TriatoScores > 1 SD above the mean as being at high risk
those with TriatoScores > 1 SD below the mean as being at low risk
and those with values within ± 1 SD of the mean as being at moderate risk
Stratification of the entomological risk of Chagas disease across the 417 municipalities of Bahia state
a Risk stratification based on TriatoScore values computed with the main dataset
which includes records of non-native species (Triatoma infestans since interruption of Trypanosoma cruzi transmission by this species was certified in 2006 and T
b Risk stratification based on TriatoScore values computed with the dataset including only native species
In a and b the strata are defined as follows: high entomological risk in municipalities with TriatoScores > 1 SD above the mean
moderate risk in those with values within ±1 SD of the mean
and low risk in those with TriatoScores > 1 SD below the mean
in c we map the current official disease-risk strata as defined by Bahia state’s health department; note that this stratification uses entomological
socioeconomic and environmental indicators
whereas TriatoScore is only based on vector data
“TriatoScore-plus”: integrating housing quality data into the assessment of entomological risk
a Raw TriatoScore-plus values across the 417 municipalities of Bahia state
b Geospatial hotspot/coldspot analysis of TriatoScore-plus values
c Risk strata based on TriatoScore-plus: high risk in municipalities with TriatoScores > 1 SD above the mean
moderate risk in those with values within ± 1 SD of the mean
TriatoScore is a single-figure measure of Chagas disease entomological risk that (i) covers both native and non-native triatomine bug species
(ii) tackles the issue of locally incomplete vector-occurrence records
and (iii) is designed to support decision-making at the spatial scale most relevant to decentralized control-surveillance systems
Our approach leverages the best available knowledge on the ecology-behavior and distribution-biogeography of individual triatomine bug species to compute local (e.g.
which can in turn be used to stratify and map entomological risk over larger spatial units
risk stratification becomes a fundamentally dynamic exercise—changes in local vector faunas (or in our knowledge about them) are automatically accounted for as local spatial units are reassigned to risk strata relative to the recalculated average risk across all units in the region of interest
Although the most basic version of TriatoScore uses only vector data
or operational information is straightforward
TriatoScore may hence become a useful addition to the Chagas disease vector control-surveillance toolbox
the initial step of our approach thus entails eliciting expert opinion on the relevance of each triatomine bug species known to be present in the region of interest
with special attention paid to relative relevance
A non-exhaustive list of examples might include local-scale measures of (i) the frequencies of dwelling infestation with triatomines or of T
cruzi infection in humans or vectors; (ii) the levels of poverty or human development; (iii) the patterns and dynamics of land-use change and deforestation; (iv) the demographics of urban/rural populations; or (v) whether control-surveillance systems are adequately funded
and flexible means to this end—and one that
can be easily extended to integrate operationally relevant information beyond vector data
All data are available in the article and its Additional files
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Download references
Staff of the Epidemiological Surveillance Office at Bahia’s state health department curated the SESAB triatomine bug surveillance database we used
Etienne Waleckx and César Augusto Cuba Cuba for suggestions and comments
Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB) # 014 2013 (PET0023/2013)
Fiocruz Bahia—IGM—scientific initiation scholarship
or in the decision to submit the paper for publication
Gilmar Ribeiro-Jr and Fernando Abad-Franch contributed equally to this work
Reis and Rodrigo Gurgel-Gonçalves are joint senior authors
Fernando Abad-Franch & Rodrigo Gurgel-Gonçalves
Coordenação Geral de Vigilância de Zoonoses e Doenças de Transmissão Vetorial
Centro de Atenção à Saúde José Maria de Magalhães Neto
Laboratório de Parasitologia Médica e Biologia de Vetores
MGR raised funds and administered the project
RG-G and MGR contributed to the design of the methods
FAF and RG-G curated the dataset and analyzed the data
RG-G and MGR drafted the first version of the manuscript
All authors contributed to the interpretation of results
The project was reviewed and approved by the Research Ethics Committee of the Gonçalo Moniz Institute—Fiocruz Bahia
The authors declare that there are no conflicts of interest associated with this study
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DOI: https://doi.org/10.1186/s13071-021-04954-5
Volume 12 - 2022 | https://doi.org/10.3389/fcimb.2022.835383
This article is part of the Research TopicInsights in Parasite and Host: 2021View all 9 articles
Canis lupus familiaris (domestic dog) represents a reliable sentinel for the occurrence of a well-established transmission cycle of Trypanosoma cruzi among wild mammals in the surroundings and
Serological diagnosis is the chosen method to identify T
rarely present positive parasitological tests
The use of recombinant chimeric parasitic antigens results in a sensitive and specific serological diagnostic test in contrast to the use of crude T
Our objective was to evaluate the Chagas/Bio-Manguinhos Lateral Flow Immunochromatographic Rapid Test (Chagas-LFRT) for the diagnosis of T
cruzi infection in domestic dogs and the potential of application of this diagnostic platform to wild canid species
Two recombinant proteins (IBMP-8.1 and IBMP-8.4) that displayed the best performance in the enzyme immunoassay (ELISA) in previous studies were tested in a platform with two diagnostic bands
A panel of 281 dog serum samples was evaluated: 133 positive for T
including 20 samples with positive blood cultures belonging to different discrete typing units (DTUs); 129 negative samples; and 19 samples from dogs infected by other trypanosomatids: Leishmania infantum
Trypanosoma caninum and Crithidia mellificae
in addition to samples infected by Anaplasma platys
that were employed to evaluate eventual cross-reactions
We also evaluated the Chagas-LFRT to detect T
cruzi infection in 9 serum samples from six wild canid species
We observed that the intensity pattern of the bands was directly proportional to the serological titer observed in IFAT
the specificity was 91% according to the ROC curve
and the defined cutoff was an optical density of 4.8
The agreement obtained was considered substantial by the kappa analysis (84%)
The test was efficient in recognizing infections by five of the six T
Cross-reactions were not observed in infections by L
they were observed in sera of dogs infected by Crithidia mellificae
A strong reaction was observed when serum samples from wild canids were submitted to the Protein A affinity test
confirming its applicability for these species
This test will allow rapid preventive actions in areas with high risk to the emergence of Chagas disease in a safer
without the need for more complex laboratory tests
it will bring benefits mainly to locations where access to a more complex laboratory test is limited
it was evaluated the performance of recombinant chimeric antigens (IBMP-8.1 and IBMP-8.4) for the detection of anti-T
cruzi IgG antibodies in dog sera using Chagas-LFRT
All procedures performed with wild and domestic animals received authorization from IBAMA (wild canids) and followed protocols approved by FIOCRUZ’s Animal Use Ethics Committee (P0007-99; P0179-03; P0292/06; L0015-07; L-050/2016; LW-81/12)
Serum samples from species of the order Carnivora were submitted to the Protein A affinity test to validate the use of the Chagas/Bio-Manguinhos Lateral Flow Immunochromatographic Rapid Test (Chagas-LFRT) for domestic and wild canids
The species tested were Canis lupus familiaris (n = 4)
Speothos venaticus (n = 1) and Cerdocyon thous (n = 3)
These samples were submitted to the Bio-Manguinhos Canine Visceral Leishmaniasis DPP LVC® Rapid Test kit
and the intensity in the control band marking was used to classify the strength of the interaction between the antibodies of the dog species and this protein
regardless of the marking of diagnostic bands
The affinity of the interaction with Protein A of these samples was classified as strong (++++)
This material is kept at -20°C in the LABTRIP serum bank
Sera were aliquoted and each aliquot thawed only once
Table 1 Distribution of wild and domestic canids in the Brazilian biomes based on molecular characterization of parasite populations isolated in blood cultures
the total number examined by blood cultures and serological tests
Figure 1 Scheme showing the serum samples from wild and domestic canids with previous serological diagnosis (IFAT and ELISA) selected to compose the panel of positive and negative samples and serum samples with different parasitic infections used in the Chagas lateral flow immunochromatografic test (Chagas-LFRT)
All samples of dogs serum used in the cross-reaction panel were subjected to immunofluorescence antibody test (IFAT) and ELISA to diagnose T
cruzi and Leishmania infantum infection and those positive for T
The Chagas rapid test works with lateral flow immunochromatographic labeling, employing a combination of a protein conjugated with colloidal gold particles and T. cruzi antigens (recombinant proteins IBMP-8.1 and IBMP-8.4) bound to a solid phase (nitrocellulose membrane) (Silva et al., 2020)
The sample to be analyzed is applied to a specific area of the plastic holder (cassette)
followed by the addition of a running buffer
The buffer provides lateral flow of released components
promoting the binding of antibodies to antigens
Four different formulations of running buffer with and without blocking were tested
with modifications to the buffer formulation: high
medium or low blocking of nonspecific reactions in the tests and TR DPP LVC® canine visceral leishmaniasis from Bio-Manguinhos kit buffer
LBT 12079 (+; DTU TcIV); Canis lupus: LBT 4838 (+); LBT 8599: sample from a domestic dog with seroconversion event (2009 and 2016)
The automated reader expresses the results quantitatively (ranging from 0 to 100) in optical density (OD)
performing the reading for both diagnostic bands and the control band
These values were used to define the cutoff by the ROC curve
All data analyses were performed using RStudio software version 1.2.5033 and R version 3.6.3
and a p-value under 5% (p < 0:05) was considered significant
In the Protein A affinity test of samples from different species
a strong interaction was demonstrated for the species Canis lupus familiaris
This result allowed the choice of Canis lupus familiaris for the standardization of the Chagas rapid test for T
in addition to this animal being considered an important sentinel of infection in different areas of study
Among the four formulations of running buffer with different types of blocking tested
the buffer selected was the original of the commercial kit of Chagas Rapid Test (with blocking) because it presented greater intensity in the labeling of the chimeric proteins IBMP-8.1 and IBMP-8.4
The selected buffer showed a high intensity recognition profile
visually classified as P3 for the two chimeric proteins and for the test control band
Figure 3 shows the mean optical density values (OD 1.61) in serum samples from dogs with negative serological diagnosis
The mean of the optical density values of the samples from dogs infected by T
cruzi was 45.36 against the chimeric antigens IBMP-8.1 and IBMP-8.4
Among the positive samples considering the cutoff point OD ≥ 4.8
the IBMP-8.1 antigen was positive in 68% and the IBMP-8.4 antigen in 60% of the samples tested
and an agreement of 45% was observed between the IBMP-8.1 and 8.4 antigens in the positive samples against T
This result highlights the importance of combining two antigens in a single test to increase the test sensitivity in the diagnosis of T
only one (OD 5.1) reacted against the IBMP-8.1 antigen and means (OD 1.49)
and four were false positive against the IBMP-8.4 antigen (OD ≥ 4.8 and ≤ 10.9) and the mean of the negative samples (OD 1.18)
Figure 3 BoxPlot with the distribution of mean values of optical densities and mean values of negative and positive samples from dogs infected by Trypanosoma cruzi against the chimeric antigens IBMP-8.1 and IBMP-8.4
The optical densities obtained by the negative and positive samples were directly proportional to the serological titer by IFAT. The automated reading of the Chagas rapid test showed a pattern in which the optical density increased as the IFAT serological titer increased, mainly demonstrated by the means (Figure 4)
Figure 4 Mean of negative and positive samples from dogs infected by Trypanosoma cruzi against the chimeric antigens IBMP-8.1 and IBMP-8.4
Number of samples (n) and mean optical densities obtained by serological titer (A - negative
Table 2 Relationship of agreement between visual reading according to serological titers given by IFAT and Chagas rapid test positive P1
Of the samples with positive blood cultures, 90% (18/20) had a positive result through visual and automated reading in the Chagas-LFRT. Samples from wild and domestic canids infected with the DTUs TcI, TcII, TcIII, TcIII/TcV and TcIV were considered positive by the test. Only two samples from domestic dogs with positive blood cultures (DTU TcI), with titers of 1/40 and 1/80, had a negative result in Chagas-LFRT (Figure 2B)
Figure 5 (A) Receiver operating characteristic (ROC) curve and area under the curve (AUC) of cutoff point value 4.8 and (B) AUC of cutoff (-) >1/20 cutoff (-) >1/40
Table 3 Summary and statistical parameters
considering cutoff 4.8 for the chimeric antigens IBMP-8.1 and IBMP-8.4
As this test proved to be highly viable for the diagnosis of the parasite in dogs in our study
cruzi infection in dogs will allow area monitoring in real time
signaling areas with transmission of the parasite in the wild environment and perhaps also undetected human cases
accurate situational diagnosis is still in the field
our test that relies on gold-labelled Staphylococcus aureus protein A conjugate that may be easily adapted to other wild species thus
This is especially important in investigation of disease outbreaks
our test is opening the possibility of the diagnosis not only of T
cruzi in dogs but also of other trypanosomatids species infections in other species that domestic dogs
Leony et al. (2019) used three reference strains (Colombian, Y and Berenice), known to have TcI and TcII DTUs, for experimental infection of domestic dogs with T. cruzi. This study was successful in diagnosing the parasite using the chimeric proteins through ELISA. Here we emphasize that, in addition to expanding the recognition panel of DTUs different from those analyzed by Leony et al. (2019)
our study showed the possibility of using a rapid test platform with chimeric proteins to detect T
cruzi in naturally infected domestic and wild dogs
The breadth of the serological profile of the samples used in our study
which included samples with recent and older infections and with different serological titers
indicates that the cutoff point found in our study for dog samples was 4.8
indicating the high diagnostic accuracy of the chimeric proteins IBMP-8.1 and IBMP-8.4 for dog and wild carnivore infections
A sample of serum from a domestic dog from Guarapari (Espírito Santo) was included in two panels: panel of negative samples in the serological diagnosis (IFAT and ELISA) with titer of 1/20 in the RIFI
below the cut-off point and panel of positive samples in the parasitological examination
This type of phenomenon is not uncommon and suggests an initial infection
when the immune response is not yet established
we propose the use of Chagas-LFRT for the serological diagnosis of T
cruzi infection in dogs as a screening test in the field to monitor the area and that a second confirmatory test (IFAT and/or ELISA) has to be used for individual diagnosis
since there would be no need to repeat tests on the same sample
There are hundreds of wild mammal species in which T
cruzi is capable of infecting and sampling
and diagnosing infection in free-living wild fauna is still a huge challenge
One of the biggest obstacles is the lack of diagnostic improvement
As a result of the anthropocentric view of health
only products for serological diagnosis of humans and animals of economic interest are commercially found
the potential to perform the diagnosis through Protein A or G linked to colloidal gold in a rapid test will multiply the application
since a specific antibody is not necessary to reveal the antigen-antibody reactions as in conventional serological tests
It will bring benefits mainly for the diagnosis of wild mammal fauna
We propose here the spatiotemporal monitoring of infection in domestic dogs as an environmental diagnostic tool through Chagas-LFRT to be used as a first measure in the identification of areas where there is a potential risk of transmission of T
The sole use of Chagas-LFRT can be used for an environmental diagnosis
while a second confirmatory test has to be employed for the individual diagnosis
Domestic dogs are animals that are easy to handle
in addition to having spatial and temporal traceability
The collection of blood from these animals does not require large infrastructure and cost
especially with the use of the rapid test for T
a point-of-care technology that is fast and easy to handle
Chagas-LFRT proved to be sensitive for use as a first environmental diagnostic tool for the presence of T
cruzi for early monitoring of the risk of new human cases
Our main contribution was to validate and expand the use of the rapid Chagas test, which was developed in Bio-Manguinhos for the diagnosis of Chagas disease in humans (Silva et al., 2020)
cruzi infection in domestic dogs and to evaluate its potential of application to wild canid species
Our motivation was to implement in the field work routine
a quick test that is easy to perform (point-of-care exam)
which does not require technical training and is not dependent on a complex laboratory infrastructure for its execution
as in the conventional diagnostic tests available (ELISA and IFAT)
One of the great advantages is to have one same type of test that can be used under the same conditions for the diagnosis of T
The surveillance system as a whole will benefit because it will have in its hands a specific and reliable rapid test for “in loco” diagnosis of infected dogs and proximity or presence of infected triatomines
the signalling of an expressive enzootic cycle of T
Chagas-LFRT will allow rapid diagnosis in a safer
reliable and low-cost manner without the need for more complex laboratory tests
The detection of “hot areas” of enzootic transmission detected by the test will streamline the decision-making process by allowing quick mapping of target areas for implementation of prevention measures
The datasets presented in this article are readily available. Requests to access the datasets should be directed to Samanta Xavier,c2FtYW50YUBpb2MuZmlvY3J1ei5icg==
The animal study was reviewed and approved by IBAMA (wild canids) and followed protocols approved by FIOCRUZ’s Animal Use Ethics Committee (P0007-99; P0179-03; P0292/06; L0015-07; L-050/2016; LW-81/12)
Written informed consent was obtained from the owners for the participation of their animals in this study
All authors have read and agreed to the published version of the manuscript
SCCX has received financial support from CNPq (MCTIC/CNPq No
process number 422489/2018-2) and from Faperj ARC_2016 - Auxílio ao Pesquisador Recém-contratado (E-26/010.000249/2017)
is the result of the collaboration of several Fiocruz units
Nilson Zanchin from the Carlos Chagas Institute (ICC/Fiocruz-PR)
who developed the proteins and improved the processes of expression and purification
and the Ageu Magalhães Institute (IAM-Fiocruz-PE)
Gonçalo Moniz Institute (IGM-Fiocruz-BA)
Institute of Molecular Biology of Paraná (IBMP) and Oswaldo Cruz Institute (IOC-Fiocruz- RJ)
Julio Israel Fernandes and the staff of the Veterinary Hospital of Universidade Federal Rural do Rio de Janeiro (UFRRJ) for serum samples of dogs infected by Anaplasma platys
Fundação Parque Zoológico de São Paulo and Programa de Conservação Mamíferos do Cerrado (PCMC)
Brazil; Cristiane Varella for the COLTRYP isolate characterization and to the Scientific Initiation Scholars of the PIBITI Program of the Oswaldo Cruz Institute
Victoria Brigido Lamim and Ana Carolina Ferreira de Carvalho for the contributions during this study
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fcimb.2022.835383/full#supplementary-material
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Differential Binding Properties of Protein A and Protein G for Dog Immunoglobulins
Development and Assessment of an Improved Recombinant Multiepitope Antigen-Based Immunoassay to Diagnose Chronic Chagas Disease
First Report of Human Trypanosoma Cruzi Infection Attributed to TcBat Genotype
Trypanosoma Cruzi TcI and TcII Transmission Among Wild Carnivores
Small Mammals and Dogs in a Conservation Unit and Surrounding Areas
Importância Dos Animais Domésticos Sentinelas Na Identificação De Áreas De Risco De Emergência De Doença De Chagas
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Trypanosoma Cruzi Transmission Cycle Among Wild and Domestic Mammals in Three Areas of Orally Transmitted Chagas Disease Outbreaks
Sánchez-Camargo
Comparative Evaluation of 11 Commercialized Rapid Diagnostic Tests for Detecting Trypanosoma Cruzi Antibodies in Serum Banks in Areas of Endemicity and Nonendemicity
Highly Accurate Chimeric Proteins for the Serological Diagnosis of Chronic Chagas Disease: A Latent Class Analysis
Performance Assessment of Four Chimeric Trypanosoma Cruzi Antigens Based on Antigen-Antibody Detection for Diagnosis of Chronic Chagas Disease
Performance Assessment of a Trypanosoma Cruzi Chimeric Antigen in Multiplex Liquid Microarray Assays
Accuracy of Chimeric Proteins in the Serological Diagnosis of Chronic Chagas Disease–a Phase II Study
Assessment of Liaison XL Murex Chagas Diagnostic Performance in Blood Screening for Chagas Disease Using a Reference Array of Chimeric Antigens
Chronic Chagas Disease Diagnosis: A Comparative Performance of Commercial Enzyme Immunoassay Tests
Development of a New Lateral Flow Assay Based on IBMP-8.1 and IBMP-8.4 Chimeric Antigens to Diagnose Chagas Disease
Chagas Disease: Recombinant Trypanosoma Cruzi Antigens for Serological Diagnosis
Measuring the Accuracy of Diagnostic Systems
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Considering Dogs as Complementary Targets of Chagas Disease Control
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Lower Richness of Small Wild Mammal Species and Chagas Disease Risk
Silva ED and Xavier SCC (2022) Chagas Immunochromatographic Rapid Test in the Serological Diagnosis of Trypanosoma cruzi Infection in Wild and Domestic Canids
Received: 14 December 2021; Accepted: 02 February 2022;Published: 22 February 2022
Copyright © 2022 Rodrigues, Santos, Silva, Barros, Bernardo, Diniz, Rubim, Roque, Jansen, Silva and Xavier. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY)
*Correspondence: Samanta C. C. Xavier, c2FtYW50YUBpb2MuZmlvY3J1ei5icg==
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March 22 (Thomson Reuters Foundation) — Jose Andres Celis was picking limes on his plot in southern Mexico when he felt a strong pain in his chest
the first sign of a deadly disease that would not be diagnosed for two years
a parasitic disease that afflicts about 7 million people globally and is known as a silent killer because it so often goes undetected
The 54-year-old Mayan farmer got medication after his diagnosis
Most of Mexico's infected are never tested or treated
putting them at risk of an enlarged heart and sudden death
Some live with Chagas for decades without symptoms
this disease doesn't give you more time," he told the Thomson Reuters Foundation as he sat on a hammock in his home in Yucatan state
lots of people are dying because of heart [problems] these days."
spread mostly via the feces of blood-sucking bugs
is one of the neglected tropical diseases (NTDs) that affect 1.7 billion people around the world
according to the World Health Organization (WHO)
Chagas patients are more likely to be cured if they are treated soon after infection
But the coronavirus pandemic slowed Mexico's already limited testing and the number of diagnoses more than halved in 2020 compared to 2019 as COVID-19 overwhelmed the health system
head of vector-borne diseases at Mexico's disease control agency CENAPRECE
attributed the fall to chronic patients delaying seeking help and fewer people donating to blood banks
He also said the government's capacity to process tests had been curtailed
discovered by Brazilian doctor Carlos Chagas more than a century ago
can be difficult to find because symptoms in the acute phase are similar to other illnesses
the lack of proactive testing and a bureaucratic health system mean detection is low
with rural Indigenous communities also facing language and distance barriers
Between 2003 to 2020 Mexico's government confirmed just 11,980 Chagas cases
according to data obtained through a freedom of information request
Academics have estimated that Mexico has 1 to 2 million cases
If treated quickly with one of two medications
But neither is available commercially in Mexico
where the only way to get them is through the health ministry
Last year the number of people treated fell to just 391 from more than 850 in both 2018 and 2019
"It's a disease that stays invisible and silent in the body," said Javier Sancho
head of the Global Coalition for Chagas Disease
"You have to look for it actively and that requires time
a tropical Mayan village in the Yucatan where brightly colored bungalows sit alongside traditional dwellings
Hermelinda May said her last Chagas medical appointment was canceled when the pandemic hit
May and farmer Celis are among the 36 patients diagnosed by doctor and academic Adriana Gonzalez and colleagues in Yucatan state's Oxkutzcab municipality in the course of their research into Chagas
with many local doctors failing to spot or help Chagas patients due to lack of training
but in the villages we see something completely different is happening," Gonzalez said
CENAPRECE's Sanchez said the government would soon start testing children and women of childbearing age in 78 high-risk areas to find newer acute cases
and wider testing to find all chronic cases would not make epidemiological sense
NTDs affect more than 1.7 billion people around the world
often trapping individuals in a cycle of poverty and exclusion
the WHO set out global targets to tackle 20 of the diseases including Chagas by 2030
with governments committing to sustain efforts that have seen 42 countries each eradicate at least one NTD in the last decade
Experts have warned that the pandemic could reverse some of that progress
"Even on a good day we're neglected compared to malaria and HIV/AIDs
but now with COVID it's been really tough," said Peter Hotez
Dean of the National School of Tropical Medicine in the United States
Hotez and colleagues at the Texas Children's Center for Vaccine Development have been working with scientists at Texas' Baylor College of Medicine and partners to create a vaccine against the disease
administered to infected people to stop the disease progressing
"Fortunately we're now in a very enthusiastic phase," said Roberto Tapia
They hope to start clinical trials in 2022
but are still years away from a shot that could be distributed
the Drugs for Neglected Diseases Initiative is running trials to try to reduce treatment time from eight to two weeks
Traditionally thought of as a disease affecting South America's rural poor
Chagas is increasingly found in urban areas and richer countries like the United States and Spain
Women sufferers can pass the disease to their babies
a researcher with the Mexican government's National Institute for Public Health
estimates that 40% of people infected in Mexico will have a shortened life
was initially misdiagnosed before medics in the capital ran tests confirming he had Chagas
"It's a killer that no one knows," he said
"This disease doesn't give you many chances," he said
(Reporting by Christine Murray; editing by Claire Cozens
Please credit the Thomson Reuters Foundation
that covers the lives of people around the world who struggle to live freely or fairly
The World Health Organization (WHO) is shifting its focus towards active screening of girls and women of childbearing age to detect the presence of Trypanosoma cruzi
Recent evidence1,2 demonstrates that diagnosing and treating women of this age group before pregnancy can effectively prevent congenital transmission
“Identifying pregnant women already infected with the parasite
has been a major challenge in both endemic and non-endemic countries” said Dr Pedro Albajar Viñas
“With the progressive control of transmission by vectors and through blood transfusion
reinforcing and expanding standardized screening measures for congenital transmission make absolute sense.”
control and prevention strategies for Chagas disease largely relied on the early detection and treatment of infected newborns and siblings of pregnant women
But a recent shift in approaches to prevent transmission globally – including in non-endemic countries – is through active
systematic screening of girls and women at risk of infection and provides excellent opportunities for prevention of posterior transmission throughout pregnancy and birth
“There are several instruments through which detection can be done and these can be complemented in combination with biomedical and psychosocial strategies,” said Dr Manuel Segovia3
Director of the Regional Unit of Tropical Medicine
Hospital Clínico Universitario Virgen de la Arrixaca
“Once infection is confirmed in a patient
physical and complementary examinations are needed to determine the clinical presentation of the disease,” Dr Segovia added
it is estimated that under-diagnosis of Chagas disease cases is as high as 90%
with under-diagnosis of congenital transmission believed to be even higher
This constitutes the most frequent means of transmission
especially in areas where infection through insect vectors is not transmitted and where transmission through blood transfusion has been interrupted
Accelerating the elimination of congenital transmission will mean implementing strategies and methods to detect
screen and diagnose all infected pregnant women as well as infected newborns and their siblings and to treat them as soon as possible
It will also imply implementing similar strategies for all women of childbearing age
ideally at paediatric age (under 19 years old ) when the effectiveness of antiparasitic treatment is confirmed much more frequently and rapidly than in adults and with fewer adverse reactions
““Implementing universal screening programmes requires appropriate laboratory protocols that
should include old and new diagnostic tests
such as standardized and validated chemiluminescence,” said Dr Amadeo Sáez-Alquezar4
“This also implies building capacity and assessing the costs of implementation of screening and diagnosis as well as the necessary follow-up of patients.”
It will also be important to set up internal and external quality control of laboratories in order to optimize the laboratory protocols for screening and diagnosis with the available commercialized tests and permit the verification of interruption of transmission.\n
The details were discussed during an international technical meeting convened by WHO at the Clinical University Hospital of Virgen de la Arrixaca in Murcia
Experts attending the Second WHO Technical Consultation on the Control of Congenital Chagas disease in non-endemic countries also analysed the need to improve information and surveillance systems on congenital Chagas disease by notifying all cases
which can definitely help in measuring coverage and verifying the interruption of transmission
The meeting was organized in collaboration with National Centre of Tropical Medicine
Health Institute Carlos III of Spain and the Regional Centre of Tropical Medicine
Clinical University Hospital of Virgen de la Arrixaca
The global strategy to eliminate Chagas disease is supported by the donation to WHO of the two available and alternative antiparasitic medicines for treatment of Trypanosoma cruzi infection
has been distributed free of charge for patients of all ages since 2008
will be distributed freely to treat patients aged under 19 years.\n
Chagas disease is found mainly in endemic areas of 21 Latin American countries5 where infection is transmitted mostly by vectors to humans by contact with faeces or urine of triatomine bugs (known as “kissing bugs”
the disease was strictly a Latin American disease of rural populations
but movement of people from rural to urban areas and to other continents
despite significant advances in vectorial control
has expanded the reach of disease transmission channels towards non vectorial routes
congenital transmission and organ transplants
Chagas disease has been detected in the United States of America
Canada and in many European and some Western Pacific countries due mainly to migration
cases of infection have been reported among travellers returning from Latin America and even in adopted children
About 6 to 7 million people worldwide are estimated to be infected with Trypanosoma cruzi
a Brazilian physician and researcher who discovered the disease in 1909.\n
Risk factors and primary prevention of congenital Chagas disease in a nonendemic country
Trypanocide treatment of women infected with Trypanosoma cruzi and its effect on preventing congenital Chagas
doi:10.1371/journal.pntd.0003312.\n3Member
WHO Technical Group 5 on prevention and control of congenital transmission and case management of paediatric infections with Trypanosoma cruzi/Chagas disease.\n4Member
WHO Technical Group 2 on prevention of blood transfusional and organ transplantation transmission of Trypanosoma cruzi.\n5Argentina
Uruguay and Venezuela (Bolivarian Republic of)
Metrics details
Chagas disease is an important disease affecting millions of patients in the New World and is caused by a protozoan transmitted by haematophagous kissing bugs
It can be treated with drugs during the early acute phase; however
effective therapy against the chronic form of Chagas disease has yet to be discovered and developed
We herein tested the activity of solenopsin alkaloids extracted from two species of fire ants against the protozoan parasite Trypanosoma cruzi
Although IC50 determinations showed that solenopsins are more toxic to the parasite than benznidazole
the drug of choice for Chagas disease treatment
the ant alkaloids presented a lower selectivity index
the parasites became swollen and rounded in shape
with hypertrophied contractile vacuoles and intense cytoplasmic vacuolization
possibly resulting in osmotic stress; no accumulation of multiple kinetoplasts and/or nuclei was detected
Overexpressing phosphatidylinositol 3-kinase—an enzyme essential for osmoregulation that is a known target of solenopsins in mammalian cells—did not prevent swelling and vacuolization
nor did it counteract the toxic effects of alkaloids on the parasites
Additional experimental results suggested that solenopsins induced a type of autophagic and programmed cell death in T
Solenopsins also reduced the intracellular proliferation of T
cruzi amastigotes in infected macrophages in a concentration-dependent manner and demonstrated activity against Trypanosoma brucei rhodesiense bloodstream forms
which is another important aetiological kinetoplastid parasite
The results suggest the potential of solenopsins as novel natural drugs against neglected parasitic diseases caused by kinetoplastids
which is within the scope of the present investigation
studies concerning the activity of alkaloids from animal venoms against protozoan parasites have never been performed
we tested the effects of piperidine alkaloids known as solenopsins against different life forms of T
The alkaloids were extracted from the venom of the invasive fire ants Solenopsis invicta and Solenopsis saevissima
The protozoans were lab-cultured and observed for morphological and biochemical changes following exposure to alkaloids in the different lifecycle stages epimastigotes (i.e.
replicative non-infecting forms from the insect vector) and amastigotes (i.e.
the replicative infective form from inside mammalian cells)
Chemical structure of all tested compounds used in the present study. Chemical structure of the solenopsins (I–VI), benznidazole (VII) and miltefosine (VIII). Additional information about the solenopsin alkaloids I–VI and their relative abundance in the venom of Solenopsis invicta and S. saevissima can be found in Table 1
indicating that the replication inhibition induced by solenopsins is reversible
Effects of solenopsins in the cell-cycle of axenically grown epimastigote forms of Trypanosoma cruzi
Giemsa stained epimastigotes (500 per each day) obtained from cultures maintained in absence (CTL
dark grey bars) or presence of 0.3 µM solenopsins from S
and 7 (D) for the presence of 1 kinetoplast and 1 nucleus (1k/1n)
Bars represent the mean % of two independent experiments
Nomarsky differential interferential light microscopy of Trypanosoma cruzi epimastigote forms incubated in the absence or presence of solenopsins
Cultures of wild type (A–C) or overexpressing PI3K (D–F) CL-Brener epimastigotes maintained for 48 h in the absence (A
D) or presence of 0.3 µM of solenopsins from S
washed in PBS and processed for observations in light microscopy as detailed in M&M
Effects of solenopsins in the polyphosphate chains accumulated by epimastigotes forms of Trypanosoma cruzi
After cultivation for 48 h in the absence (NEG) or presence of 0.3 µM of solenopsins from Solenopsis invicta (INV) or S
CL-Brener epimastigotes were collected and the short chain (A) and long chain (B) polyphosphates (PolyP) were extracted and quantified as described in Methods
Bar plots indicate mean values where dots are the raw data (nmoles.10–7 parasites) of three independent experiments
Statistics: Results were compared by non-parametric Kruskal–Wallis
and treatments are grouped by statistical similarity at alpha = 0.05 where indicated with brackets
For details refer to supplementary R script file
F) or the accumulation of long-chain polyP (not shown)
Transmission electron microscopy of Trypanossoma cruzi epimastigotes incubated in the absence or presence of solenopsins
Epimastigotes of the CL-Brener strain were incubated for 48 h in BHI–FCS medium in the absence (A
B) or presence of 0.3 µM solenopsins (C–F)
The parasites were processed and observed by transmission electron microscopy as described in M&M
B) Control untreated parasites showing the nucleus (n)
mitochondrion (m) flagellum (f) and tubular structures with vesicles which presumably correspond to the spongiome (sg) surrounding a space that can be part of the contractile vacuole (cv) bladder
(C–F) Epimastigotes after treatment with solenopsins showed intense vacuolization of the cytoplasm (*) and an eventual hyperthrophic contractile vacuole (cv) but no mitochondrion swelling (m)
Cells also presented vacuolar structures displaying complex double membrane invaginations or vesicles that resemble autophagosomal structures (white arrow heads)
Labelling of Trypanossoma cruzi epimastigotes with monodansylcadaverine (MDC) after treatment in the absence or presence of solenopsins
After cultivation for 48 h in BHI–FCS medium (A
or BHI–FCS medium supplemented with 0.3 µM of solenopsins from Solenopsis invicta (C
CL-Brener epimastigotes were collected and incubated with 50 μM of MDC for 1 h at 28 °C
and examined in an epifluorescence microscope as described in Methods
5 × 107 parasites treated as described were lysed in Tris-HCl (pH 8.0) with 1% SDS
and fluorescence from the supernatants measured with a microplate reader
Plot (E) presents the mean ± SD fluorescence values (in % relative to BHI) of three independent experiments
Statistics: treatments were compared with Kruskal–Wallis at alpha = 0.05; INV (light-grey bar) and SAE (dark-grey bar) indicates statistically similar treatment results; an asterisk indicates values statistically different from the control (BHI)
Detection of free DNA 3′-OH ends after incubation of Trypanossoma cruzi epimastigotes in the absence or presence of solenopsins
After cultivation for 24 h in BHI–FCS medium alone (A
BHI) or supplemented with either 0.07% TX-100 (B
TX-100) or 2.5 µM of solenopsins from Solenopsis invicta (C
suspended in PBS (around 2 × 107 cells mL−1)
allowed to adhered to a poly-l-lysine embedded slide
The obtained differential interference contrast images enable the comparison of unstained parasites with normal morphology (A)
parasites with altered morphology that do not have any colour (B) that is compatible with necrosis induction
and stained parasites that also have altered morphology (C
D) that is compatible with the induction of apoptosis
The graphics (E) represent the mean ± SD of pixels intensity for parasites for each treatment: BHI (white bar)
SAE (dark-grey bar) from three independent experiments
Statistics: treatments were compared with Kruskal–Wallis at alpha = 0.05; the BHI/TX-100 and INV/SAE bars indicate statistically similar treatment results; an asterisk indicates values statistically different from controls
Effects of the solenopsins on macrophages infected with Trypanossoma cruzi
Mouse peritoneal macrophages plated on glass cover slips in 12-well plates were incubated with tissue culture trypomastigotes (TCTs) at a multiplicity of infection of 3 parasites per cell
wells were washed 5 × and the cultures were incubated in the absence (C+) or presence of solenopsins from Solenopsis invicta (INV) and S
saevissima (SAE) (A) or benznidazole (BENZ) (B) as indicated in the bottom of each graph
and the cells were fixed and stained with InstantProv haematological stain
The infection index based in the percentage of infected macrophages and the number of amastigotes per infected macrophage was estimated by direct counting of ≥ 300 fields
Bar plots are means and different letters on the bars indicate significant difference between the treatments by nonparametric Dunn's test posthoc to Kruskal–Wallis at alpha = 0.05 (n = 2)
the venom alkaloids of ants have remained untested against trypanosomatids
exposure to solenopsins did not induce the formation of multinucleate cells
several environmental stresses can generate a delay in cell cycle progression of different cells
the observations reported here delineate the scope of the mechanisms of action of solenopsins acting on T
Notwithstanding such hypothetical structure–function correlations between solenopsins and ether-lipid analogues
additional studies are still needed to elucidate the pathways targeted by solenopsins in T
this interpretation that solenopsins cause osmotic imbalance was not in principle supported by the observed greater susceptibility of the CL-Brener strain
as it overexpresses PI3K that should provide augmented adaptability to osmotic stress
We therefore interpret the increased long-chain polyP levels as a physiological stress response to exposure to solenopsins
saevissima proved slightly stronger against amastigote T
perhaps as a result of greater macrophage penetration because of the shorter alkyl chain length
This is an interesting hypothesis pending further experimentation
4% thioglycollate solution (Sigma-Aldrich) was injected intraperitonially into C57BL/6 mice
and peritoneal cells were collected by chilled RPMI washes 4 days after injection to obtain the elicited macrophages
The protocol for animal use was approved by the Ethics Committee from Centro de Ciências da Saúde of UFRJ (number IBCCF-085) and all methods were performed in accordance with the relevant guidelines and regulations
The macrophages were seeded in a 12 well plate with coverslips in the bottom of each well and the adherent cells obtained after a period of 24 h were used for the infection experiments with tissue culture-derived T
cruzi trypomastigotes (TCTs) described further below
and were used here to infect murine peritoneal macrophages as described below
The alkaloids were further quantified by GC–MS using spiked known amounts of the methylxantine alkaloid caffeine (Sigma-Aldrich
Sample quantification was determined by dividing the total peak area of each alkaloid by the peak area of the internal standard
multiplied by the amount of standard added to the sample
cell viability was quantified by the ability of living cells to reduce the yellow dye 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazoliumbromide (MTT) to a purple Formazan product
The cells were plated in 24 well plates (7 × 104 cells mL−1) and alkaloids dissolved in dimethyl sufoxide (DMSO; Pierce
USA) stock solution were tested in triplicate at 1:1 ascendant dilution (varying from 1 to 80 µM) in DMSO (final DMSO concentration was 0.1%)
the supernatant was replaced by fresh medium containing MTT (0.5 mg mL−1) and 3 h later
the Formazan product was dissolved in DMSO and absorbance was measured at 595 nm in a DTX-880 spectrophotometer (Beckman Coulter
cultures were incubated in 24 well plates for 72 h in the absence or presence of alkaloids as above
and the supernatants were collected (~ 900 µL)
Reactions were prepared in a 96 well plate containing 80 µL of supernatant and 120 µL of PBS buffer supplemented with 0.7 mM NADH (Bioexpress
at 340 nm were quantified in a Spectra Max 250 micro plate reader (Molecular Devices
The positive control was the supernatant of cell cultures kept for two hours in the presence of 0.1% of Triton X-100
After incubation for up to 8 days in BHI–FResultsCS medium
the parasites were collected by centrifugation to 3,000g for 10 min at 4 °C
suspended into fresh media free of solenopsins
Daily counts and viability evaluations of the parasites in the cultures were done as above
Murine peritoneal macrophages seeded onto round glass coverslips slides in 12 well plates were co-cultured with TCTs at a ratio of 1:3
the macrophages were washed 5 × with 1 mL PBS to remove the non-internalized parasites and incubated in the absence or presence of solenopsin for 2 days as described above for the mammalian cell viability tests
stained with InstantProv hematological stain (NewProv
Brazil) and the slides observed under a light microscope
The infection index values (the number of infected macrophages X number of intracellular amastigotes/ total number of macrophages) were estimated by direct counting of at least 300 fields
Observations and micrographs were taken in a Zeiss AxioPlan II light microscope using the AxioVision software coupled to an AxioCam MRC3 digital camera (Oberkochen
For observations using transmission electron microscopy (TEM)
washed three times in PBS and fixed in 2.5% (v/v) glutaraldehyde (Merck
Germany) in 0.1 M sodium cacodylate buffer pH 7.4 for 1 h at room temperature
After three washes in 0.1 M sodium cacodylate buffer pH 7.4
post fixation was carried out in 1.0% (w/v) osmium tetroxide (Merck
5 mM CaCl2 in 0.1 M sodium cacodylate buffer pH 7.4 for 1 h in the dark
Samples were progressively dehydrated with ethanol (Merck
Ultrathin sections (70 nm thick) were stained with uranyl acetate (Merck
and finally examined with a JEOL 1200EX electron microscope operating at 80 kV
The released Pi was measured by the malachite green assay
USA) (5.0–100.0 µM) and of 4′,6-diamino-2-phenylindole (DAPI; Molecular Probes
USA) (1.5–100.0 µM) were added to each experimental condition
Negative control samples had no salmon sperm DNA
After incubation for 30 min at room temperature
each well was read (about five readings) on a Varian Cary Eclipse fluorescence plate reader (λEx 545 nm
Compound assessments were conducted in triplicates (or more) with each well acting as its own control well (no agent = 100% fluorescence; no DNA = 0% fluorescence)
Results are presented as the percentage of fluorescence decrease which represents the percentage of intercalator displacement relative to the control wells
An aliquot of 10% of each cellular suspension was collected
fixed in 4% formaldehyde-PBS solution (PBS/formaldehyde) for 10 min at room temperature
and images of the parasites were acquired using an epifluorescence Zeiss AxioPlan II microscope (Oberkochen
The rest of the cell suspensions (90%) were then washed four times with PBS and suspended in 10 mM Tris-HCl
Intracellular incorporated MDC was measured by fluorescence photometry (λEx 380 nm
λEm 525 nm) in a Spectra Max 250 micro plate reader (Molecular Devices
USA) and expressed as arbitrary units per number of cells
To normalize the measurements to the number of cells present in each well
a solution of EtBr was added to a final concentration of 0.2 mM and the DNA fluorescence was measured (λEx 530 nm
Mostly due to limited numbers of repetitions no parameters for data distribution were assumed
Statistical differences using non-parametric Kruskal–Wallis followed by Dunn’s Multiple Comparison Test (in comparing multiple treatments) or by Wilcoxon–Mann–Whitney Test (in comparing two treatments)
Our conclusions were also compatible with general patterns obtained by parametric methods (not shown)
data and associated protocols are promptly available to readers without undue qualifications in material transfer agreements
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Chaetocin is a nonspecific inhibitor of histone lysine methyltransferases
Chaetocin-A histone methyltransferase inhibitor-impairs proliferation
arrests cell cycle and induces nucleolar disassembly in Trypanosoma cruzi
Spectrum of activity and molecular correlates of response to phosphatidylinositol ether lipid analogues
Exploiting knowledge on Leishmania drug resistance to support the quest for new drugs
Naphthoimidazoles promote different death phenotypes in Trypanosoma cruzi
Ether-lipid (alkyl-phospholipid) metabolism and the mechanism of action of ether-lipid analogues in Leishmania
Na+-ATPase and protein kinase C are targets to 1-O-hexadecylphosphocoline (miltefosine) in Trypanosoma cruzi
Identification of novel serine/threonine protein phosphatases in Trypanosoma cruzi: a potential role in control of cytokinesis and morphology
Acidocalcisomes and the contractile vacuole complex are involved in osmoregulation in Trypanosoma cruzi
The role of acidocalcisomes in the stress response of Trypanosoma cruzi
Inorganic polyphosphate: essential for growth and survival
Novel assay reveals multiple pathways regulating stress-induced accumulation of inorganic polyphosphate in Escherichia coli
Autophagy in parasitic protists: unique features and drug targets
The peptidases of Trypanosoma cruzi: digestive enzymes
and mediators of autophagy and programmed cell death
Natural programmed cell death in Trypanosoma cruzi epimastigotes maintained in axenic cultures
Different cell death pathways induced by drugs in Trypanosoma cruzi: an ultrastructural study
Sülsen, V. P. et al. Mode of action of the sesquiterpene lactones psilostachyin and psilostachyin C on Trypanosoma cruzi. PLoS ONE 11, e0150526. https://doi.org/10.1371/journal.pone.0150526 (2016)
Alkaloids induce programmed cell death in bloodstream forms of Trypanosomes (Trypanosoma b
Chemical modifications of capuramycins to enhance antibacterial activity
TRAIL-R as a negative regulator of innate immune cell responses
Viral cell death inhibitor MC159 enhances innate immunity against Vaccinia Virus infection
Golgi UDP-GlcNAc:polypeptide O-α-N-acetyl-D-glucosaminyltransferase-2 (TcOGNT2) regulates trypomastigote production and function in Trypanosoma cruzi
Continuous cultivation of Trypanosoma brucei bloodstream forms in a medium containing a low concentration of serum protein without feeder cell layers
rapid method for the extraction of whole fire ant venom (Insecta: Formicidae: Solenopsis)
Re-investigation of venom chemistry of Solenopsis fire ants
Identification of novel alkaloids in Solenopsis richteri
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Trypanosoma cruzi proline racemases are involved in parasite differentiation and infectivity
Fluorescent intercalator displacement analyses of DNA binding by the peptide-derived natural products netropsin
Assays to assess autophagy induction and fusion of autophagic vacuoles with a degradative compartment
using monodansylcadaverine (MDC) and DQ-BSA
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Antileishmanial lead structures from nature: analysis of structure–activity relationships of a compound library derived from caffeic acid bornyl ester
Download references
This study was funded by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES
Finance Code 001) and grants from Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)
Financiadora de Estudos e Projetos (FINEP) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) INCTEM (150895/2010-0)
These authors contributed equally: Rafael C
Instituto de Biofísica Carlos Chagas Filho
Ednildo de Alcântara Machado & Norton Heise
National Institute of Allergy and Infectious Diseases
Instituto de Bioquímica Médica Leopoldo de Meis
Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular
School of Medicine and Biological Sciences
Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem
Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr
wrote the main manuscript text and prepared all figures; R.C.M.C.S.
contributed reagents/materials/analysis tools; R.C.M.C.S.
analyzed the data; all authors revised and gave critical input on the manuscript
The authors declare no competing (financial and non-financial or lack thereof) interests
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DOI: https://doi.org/10.1038/s41598-020-67324-8
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There are so many illnesses in the world that we just don’t think about here in the United States
I learned about this in veterinary school more than 35 years ago
And now I am finding out it is becoming much more common in our southern states
Originally discovered by a Brazilian physician
Chagas disease is actually caused by a protozoa Trypanosoma cruzi
This protozoan is spread by the triatomine bug known as a “kissing bug.”
they began a kissing bug community science program in 2012
more than 7,000 kissing bugs have been sent in by 1,500 people for scientific research
About 55% of those bugs were found to be positive for Trypanosoma cruzi
Kissing bugs feed on blood and are active at night
They can live up to two years and grow to be 1 inch in size
and the victim probably won’t know they are being bitten
They feed on humans (it is a human health hazard)
cruzi in their gut and pass the protozoa in their feces
Dogs can catch the protozoa by eating the kissing bug or its feces
it will poop at the site of the bite and the protozoa will enter the broken skin
Clinical signs of the disease vary and can be nondescript
While many dogs that are exposed do not show any symptoms
While there are medications for treating Chagas disease
treatment involves treating the symptoms of illness
Limiting exposure to the vector insects is important
This can be done by maintaining a clean area for pets
Keep brush away from the house and make sure all screens are secure in windows so these bugs can’t creep in at night
so their use may help prevent infection of the pet
Any dogs with the symptoms of heart failure that have been in areas where Chagas is endemic should be tested
Two options for testing include the IFA antibody test and the PCR
The IFA antibody test demonstrates exposure to the virus at some time in the life of the dog
The PCR test looks for parasite DNA in the blood sample
While Chagas disease is not high on the list of things to worry about in our community
it is out there and it never hurts to be aware
The little-known parasite is a huge problem across Latin America
The little-known parasite that causes Chagas disease is a huge problem across Latin America
infecting five times as many people as HIV
Scientists at Baylor College of Medicine in Houston are working on a therapeutic vaccine
Chagas disease is caused by a parasite that enters the blood stream and sometimes lives quietly for decades. But up to 30 percent of people will later develop complications, such as heart disease. The microscopic parasite can create little nests inside the cells of the heart muscle, causing cardiac problems and even death, according to Dr. Peter Hotez
dean of Baylor's National School of Tropical Medicine
"This is a disease that has been around a long time
but it's mostly affecting people living in poverty," Hotez said
"So we really haven't paid much attention to the enormity of the problem."
Poor people tend to be affected because it's transmitted by the kissing bug
an insect that hides in the cracks and crevices of poor-quality houses in tropical climates
On Wednesday, the Carlos Slim Foundation in Mexico announced a $2.6 million grant to scientists at Baylor who are working on a therapeutic vaccine for Chagas
Although a therapeutic vaccine won't stop someone from getting the parasite
it could slow down the damage to the heart
we're seeing it for instance in the dogs in Texas," Hotez said
"One in ten dogs has Chagasic heart disease
We hear the story every time of people go hunting with their bird dogs and the bird dogs drop dead while running."
Baylor will share its research findings and technology with two universities in Mexico
and future clinical trials will be conducted there
"What is important is these types of interventions have to reach the people that need it," said Dr. Maria Elena Bottazzi, deputy director of the vaccine center and associate dean of the National School of Tropical Medicine at Baylor.
"It's going to be probably unlikely that the United States will be the sole producer, or distributor, or even developer of such therapeutic vaccine. So it's very important that you transfer the know-how and the technology to organizations that will be really able to advance it and take it on."
Houston Public Media is supported with your gifts to the Houston Public Media Foundation and is licensed to the University of Houston
Chagas disease can be divided into acute and chronic phases
The vector tends to feed on blood from the mucous membranes of the eye or the mouth
Infection takes place by rubbing the insect feces that contain the trypomastigotes in to the wound or mucous membranes Figure 1)
Local inflammation can lead to swelling of the eyelids (Romaña’s sign
Inflammation around the insect wounds at other sites is referred to as Chagoma
Acute Chagas disease is subclinical in most individuals
it may manifest as a flu-like illness which can last several weeks
acute Chagas can result in encephalitis and myocarditis
Romaña’s sign in child with right eye swelling
Most of the morbitity and mortality due to Chagas disease is due to the chronic phase of the illness
According to World Health Organization (WHO) estimates
there are approximately 10 million people with chronic infection
About 20-30% of infected persons develop chronic disease
Chronic Chagas disease should be suspected in any patient with a history of potential exposure such as living or traveling to endemic areas and who presents with manifestations such as idiopathic cardiomyopathy
The clinical characteristics of chronic Chagas disease relate to the organs affected
Individuals with cardiomyopathy may present with a history of heart failure or arrhythmias
An EKG may show conduction abnormalities and/or arrhythmias
Echocardiography may show left and/or right ventricular dilation or hypokinesis
Individuals with gastrointestinal (GI) involvement may present with difficulty swallowing
Barium swallow may show esophageal dysmotility
Atypical presentations can be seen in immunocompromised persons such as those with HIV infection and who have undergone organ transplantation
The diagnosis of Chagas can be made during the acute phase of the disease by performing a Giemsa-stained thick or thin blood smear and looking for the trypomastigotes
The latter are more common during the acute phase of the infection but are rarely seen during the chronic phase
The most reliable method of diagnosis is by serology
Several tests have been developed but any single test lacks sensitivity and specificity
both an ELISA and indirect fluorescent antibody (IFA) tests are are available through the CDC
Transmission takes place in rural areas where sylvatic areas have been cleared to give way to human habitat
Infection usually occurs by the bite of triatomine blood-sucking insect vectors that typically feed on areas of the face such as the conjunctiva and thus are frequently referred to as the kissing bug
They tend to reside in crevices of house walls constructed of mud or in thatched roofs
The vector and the parasite are also endemic in the southern United States but infection of humans is rare
perhaps due to living conditions not being conducive to vector habitation
or low infectivity of the local parasite strains
Other less frequent means of transmission include blood transfusions
Infected humans as well as a variety of animals serve as reservoirs for infection of the vector
and its clinical features were first described by the Brazilian physician Carlos Chagas (Figure 3)
Chagas disease is caused by the parasite Trypanosoma cruzi transmitted by triatomine vectors of the subfamily Reduviidae
(Reprinted with permission from Bern et al
invade muscle and nerve tissues of organs such as the heart and the gastrointestinal tract
causing conduction abnormalities and myopathy leading to dilatation and contractile dysfunction
acute Chagas disease can result in encephalitis and myocarditis which can be fatal
The most important systemic manifestions of chronic Chagas disease are cardiac (cardiomyopathy presenting with a history of heart failure or arrhythmias) and GI (presenting with difficulty swallowing
or history of constipation due to any combination of esophageal dysmotility
Benznidazole and nifurtimox are the drugs available for treatment
Neither one is licensed in the US and both are available only from the CDC Division of Parasitic Diseases Public (Tel 770-488-7775; email: ncidpdbpi@cdc.gov) or the CDC Drug Service (Tel 404-639-3670) under investigational protocols
Benznidazole is frequently associated with rashes secondary to photosensitization
In some cases severe exfoliative dermatitis can occur in which case the drug should be discontinued immediately
peripheral neuropathy can occur late in the course of treatment
Nifurtimox frequently causes GI symptoms including anorexia
Peripheral neuropathy can also occur late in the course of treatment
Due to the risk of bone marrow suppression and hepatitis with both drugs it is recommended that complete blood count and liver enzymes be obtained prior to and periodically during treatment
Benznidazole is considered first line due to its more acceptable side effect profile
All individuals with acute infection should be treated
The success rate is better for treatment of acute infection than of chronic infection
the objective of therapy is to prevent cardiomyopathy which is the main cause of mortality
Treatment is recommended for chronically infected individuals of up to 50 years who do not have advanced cardiomyopathy
nonblinded study of benznidazole verus no treatment in patients 30 to 50 years showed decreased progression to cardiomyopathy
It is unclear whether patients with cardiomyopathy benefit from therapy
The answer to this question will have to await the results of an ongoing trial due out in 2012
for treatment of individuals older than 50 the benefits of therapy should be weighed against the risk of side effects
Patients with advanced Chagas cardiomyopathy or GI complications should be managed in accordance to established guidelines for the conditions
patients with arrhythmias should be managed with antiarrythmic agents and if necessary implantable defibrillators
consideration should be given to cardiac transplantation
In patients with megaesophagus or megacolon
consideration for surgical correction should be given
Atypical presentations can be seen in immunocompromised persons
such as those with HIV infection and who have undergone organ transplantation
in immunocompromised hosts central nervous system manifestations can occur frequently and include meningoencephalitis or mass lesions
diagnosis and prognosis of chronic Chagas disease: insight gained in Argentina”
(This article reviews the management of Chagas cardiomyopathy in Argentina.)
“sEvaluation and treatment of chagas disease in the United States: a systematic review”
(This is an excellent general review of the evaluation and treatment of patients with Chagas disease.)
“Long-term cardiac outcomes of treating chronic Chagas disease with benznidazole versus no treatment: a nonrandomized trial”
nonblinded clinical trial of benznidazole versus no treatment showing the benefit of treatment.)
(The CDC web site has many resources for physicians treating patients with Chagas disease and for their patients.)
“Parasitic central nervous system infections in immunocompromised hosts”
(Good review of atypical presentation of Chagas disease in immunocompromised patients.)
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Volume 11 - 2021 | https://doi.org/10.3389/fcimb.2021.768450
Chagas’ disease is caused by the protozoan Trypanosoma cruzi
described in the early 20th century by the Brazilian physician Dr
There was a great amount of research devoted to diagnosis
One of the most important discoveries made since then
impacting the understanding of how the parasite interacts with the host’s immune system
capable of masking the parasite’s presence from the host
while at the same time dampening the activation of CD8+ T cells
the most important components of the immune response
Since the description of Chagas’ disease in 1909
extensive research has identified important events in the disease in order to understand the biochemical mechanism that modulates T
cruzi-host cell interactions and the ability of the parasite to ensure its survival
The importance of the trans-sialidase enzyme brought life to many studies for the design of diagnostic tests
cruzi have many genes that are unique to the parasite
it relies on multiple copies of them and the difficulty in providing epitopes that result in effective and robust immune responses
we aim to convey the importance of trans-sialidase as well as to provide a history
including the initial failures and the most promising successes in the chasing of a working vaccine for a disease that is endemic in many tropical countries
Chagas disease is an anthropozoonosis caused by the flagellated protozoan Trypanosoma cruzi. American trypanosomiasis received this name in honor of Dr. Carlos Chagas, who described in his work, in 1909, the etiologic agent of the disease, the evolutionary cycle of the parasite as well as the vectors and clinical manifestations of the acute phase (Chagas, 1909)
According to the World Health Organization
Chagas disease is classified as a neglected tropical disease with an estimated 8 million people infected worldwide and almost 100 million at risk of infection
only group I members that exhibit enzymatic activity and are referred to here as TS protein are the focus of this review
Figure 1 Effects of Trypanosoma cruzi trans-sialidase (TS) on the host immune system
The TS enzyme can be secreted by parasite or anchored in the membrane of trypomastigote forms of T
The active form incorporates sialic acid from host sialoglycoproteins to acceptor molecules in the parasite membrane
The inactive form has no enzymatic activity and functions as a lectin
This sialylation allows the escape of parasite from detection by the immune system
allowing its survival and the establish the infection
aiming towards the discovery of new agents for the cure of Chagas’ disease
Since Sia cannot be synthesized by the parasite
and acts as an essential molecule for both communication and invasion of host cells
further studies are needed to better understand the catalytic mechanisms of the enzyme to favor the rational design of potential TS inhibitors
cruzi subculture that has an obligatory intracellular cycle
vaccines with live parasites pose a challenge for large-scale production as well as storage and distribution
vaccine candidates with recombinant proteins present a more promising proposal for success against T
an artificial amplification of the immune response to subdominant antigens could be a strategy to improve the immunity induced by vaccination
This would explain why CD8 T cells respond to only a reduced pool of TS peptides
Intranasal administration of vaccines is even more advantageous since DNA vaccines are degraded and/or are not well absorbed via the mucosa
the possibility of modulating MDSC could be an interesting tool for the design of vaccines and adjuvants in TS-based vaccines
these factors must be taken into account when developing TS-based vaccines
This cross-presentation is enhanced with the use of a new generation of adjuvants as IMX and ISPA
being essential for a long-lasting protective response in subunit vaccine
these new adjuvants showed rapid and persistent antigenic delivery to APC as well as a robust Th1 response similar to FCA without causing adverse effects on immunization
it is normal for antibody titers to decrease over time in immunized and unstimulated individuals
reinforcing the contribution that cellular response can make at the onset of infection
an exacerbated inflammatory response can induce intense tissue inflammation
producing unwanted clinical manifestations
vaccine candidates need to have a brake on the pro-inflammatory response
This function seems to be performed by the Treg cells in a murine model
which can be stimulated by reducing the MDSC population
TS-based candidates have achieved high survival rates in animal model and reduced parasitemia
The increase in survival is essential but reducing the number of parasites is also an important parameter because it is associated with reduction of clinical symptoms in the chronic phase
Figure 2 Immune response model for trans-sialidase (TS)-based vaccines
In the immunization of mice with vaccines based on recombinant TS
exogenous antigens are usually processed and presented by antigen presenting cells (APC) via MHC class II
This pathway will stimulate B cells to produce and secrete TS-specific antibodies (Humoral response)
Certain types of APC such as dendritic cells can process and present exogenous antigens via MHC class I
Both TS-specific CD8 and CD4 T cells can differentiate into cells with cytotoxic activity capable of killing Trypanosoma cruzi-infected cells as macrophage (Effector response)
a group of specific-TS CD4 T cells (Foxp3) known as regulatory T cells are responsible for controlling the pro-inflammatory response in the host (Regulatory response)
The immunization of animals with vaccines based on TS has reduced parasitemia
tissue damage and consequently the mortality rate
suggesting the possibility of highly conserved sequences
we hope to have listed the strengths and weaknesses of TS-based vaccines and we believe that this protein due to its immunogenicity and conserved sequences still constitutes a great target to produce of a vaccine based on recombinant proteins that are cost effective on large scales and are safer when compared to other formulations
KC and LM searched the bibliographic materials
All authors contributed to the article and approved the submitted version
The study was supported by Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro and Conselho Nacional de Desenvolvimento Científico e Tecnológico
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Mammalian Cell Sialic Acid Enhances Invasion by Trypanosoma Cruzi
Protection Against Malaria by Immunization With Plasmid DNA Encoding Circumsporozoite Protein
DNA-Based Immunization With Trypanosoma Cruzi Complement Regulatory Protein Elicits Complement Lytic Antibodies and Confers Protection Against Trypanosoma Cruzi Infection
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Costimulation of Host T Lymphocytes by a Trypanosomal Trans-Sialidase: Involvement of CD43 Signaling
The Trans-Sialidase From Trypanosoma Cruzi Induces Thrombocytopenia During Acute Chagas’ Disease by Reducing the Platelet Sialic Acid Contents
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Received: 31 August 2021; Accepted: 12 October 2021;Published: 26 October 2021
Copyright © 2021 da Costa, Marques da Fonseca, dos Reis, Santos, Previato, Mendonça-Previato and Freire-de-Lima. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY)
*Correspondence: Lucia Mendonça-Previato, bHVjaWFtcEBiaW9mLnVmcmouYnI=; Leonardo Freire-de-Lima, bGVvbGltYUBiaW9mLnVmcmouYnI=; Kelli Monteiro da Costa, a2VsbGltYzg1QGJpb2YudWZyai5icg==
†These authors have contributed equally to this work
Don't be fooled by the kissing bug's innocent name
especially for human babies, people with immune deficiencies and puppies
And the insect lives throughout Texas
This bug actually is many insects from a family of bugs that can all carry a parasite that infects mostly people
dogs and small mammals with Chagas disease
they vary in diameter from the size of a penny to a quarter
with dark backs that sometime are orange- or fringed in red
Variations of this triatomine bug are called the conenose bug, bloodsucker, Walapai tiger, and Hualapai tiger. Hispanic communities in Texas may refer to it as chinché mala, according to an online publication by Texas A&M University
Studies indicate between 50 percent and 64 percent of kissing bugs carry the deadly parasite that causes Chagas
which is considered a major neglected tropical disease
National Library of Medicine. The World Health Organization estimates that 8 to 10 million people are infected worldwide
The noncontagious disease is named after Carlos Chagas
Chagas was listed as a disease that must be reported to the Texas Department of State Health Services
but Chagas is not reportable in dogs
the Centers for Disease Control and Prevention awarded $544,329 grant to the University of Texas Health Science Center at Houston School of Public Health to conduct outreach and education on Chagas disease in South Texas
"The kissing bug is everywhere," said Paula Stigler-Granados
an assistant professor in the Department of Management
Policy & Community Health at the School of Public Health in San Antonio
And many people infected with the disease have been bitten many times."
Stigler-Granados leads the 100-member Chagas Task Force
Their goal is specifically focused on the disease in Texas
with an emphasis on raising awareness among healthcare providers about this important but neglected health threat that is under-reported and often misunderstood
The Chagas Task Force just published a guide to help Texans learn more and guard against the health risks for themselves and their pets.
WHERE IS THE KISSING BUG FOUND?The bug is most prevalent in Mexico
Central and South America. But it has been found in 27 southern United States
Once restricted to rural and blighted areas in the United States, the kissing bug's range is expanding into urban and suburban neighborhoods
assistant professor of epidemiology at the Arnold School of Public Health at the University of South Carolina
One recently was discovered in an urban Houston home
who researched Chagas in humans for years at Baylor College of Medicine
Stigler-Granados has seen the insidious vector near her San Antonio home.
Researchers at Texas A&M University College of Veterinary Medicine have collected more than 5,000 kissing bugs since 2012
Many came from outdoor patios and dog kennels
a percentage were collected from inside homes
according to researchers at the Hamer Lab at Texas A&M University
"We generally let folks know that approximately 55-65 percent of the kissing bugs that we test are positive for (the Chagas parasite)," said the Hamer Lab's Rachel Curtis-Robles
with the Department of Veterinary Integrative Biosciences College of Veterinary Medicine at Texas A&M
They mostly are seen during warmer months around dog kennels
under tree bark and in outdoor sheds or patios
They are sometimes attracted to outdoor lights
The first confirmed case of chagas known to have been contracted within the United States occurred in Corpus Christi in 1955
Scientists concluded the 10-month-old girl was infected in a home where kissing bugs lived
Researchers say about one in 6,500 Texan are infected with chagas and most show no symptoms
This infection rate is higher than thought before
Most Texas Chagas cases occur around San Antonio
But they also have been found along the U.S
The Centers for Disease Control and Prevention estimates more than 300,000 people in the United States have the disease and 315 babies are born with Chagas in the United States annually
more than 70 confirmed human locally acquired infections in the United States have been published
These published studies are a good indicator that physician awareness is improving
More than 90 Chagas infections were reported to the Texas Department of State Health Services from 2013 to 2016
The CDC estimates 8-10 million people have Chagas in Mexico
where the disease is considered endemic
But it has been infecting people and dogs in the United States for decades
Many of these victims show mild or no symptoms
Researchers suspect a growing number of infections in the United States are coming from home-grown kissing bugs.
In additional to geographic and socioeconomic risk factors
people who are most susceptible to Chagas live in poverty or rural settings
Patients with HIV or who are immune compromised also are at greater risk.
HOW DOES THE KISSING BUG INFECT VICTIMS?The insect's contradictory label derives from its habit of accessing human blood near the mouth
This often occurs when the victim is asleep
aided by the insect first numbing the injection area
sometimes infecting the victim with the chagas parasite through the wound
The parasite resides in the insect's digestive tract
The parasite can be transmitted by blood transfusions; from an infected mother to her child during pregnancy; or from the consumption of uncooked food contaminated with feces from an infected insect
No cases have been confirmed from blood transfusions in the United States since 2007
HOW DO I KNOW IF I'VE BEEN BITTEN BY A KISSING BUG?Unlike a mosquito bite or bee sting
you may not know immediately or ever whether you've been bitten
Some victims experience brief episodes of low-grade fever or a non-itchy skin rash
Heart and digestive problems may develop years
WHAT ARE THE SYMPTOMS OF CHAGAS?Infections may result in mild or no symptoms
The most common signs of infection are fever and swelling around the site of the bite
but may result in severe inflammation of the heart muscle or the brain
Many infected people may not show symptoms for life
An estimated 30 percent of infected people will develop debilitating and sometimes life-threatening conditions
Complications of chronic Chagas disease may include: heart rhythm abnormalities that can cause sudden death; dilated heart that doesn’t pump blood well; a dilated esophagus or colon
leading to difficulties with eating or passing stool
The most severe symptom of chronic Chagas is heart failure
About 30 percent of Chagas patients who are diagnosed with heart failure are likely to die within three years
There is no vaccination that protects against Chagas for either dogs or humans. Treatment in infants younger than 1 is an effective cure, according to the Chagas Coalition. The U.S
Food and Drug Administration recently approved benznidazole for use in children 2-12 years old
is available to physicians through the CDC. Studies have documented that treatment is only effective when given prior to the onset of heart disease.
THE ECONOMIC IMPACT OF CHAGASChagas-related heart failure in the United State costs nearly $1 billion annually, according to Research America.
The kissing bug can infect all dogs of all breeds
either from feces deposited after a bite; by ingesting the insect or its feces; and by congenital transmission from mom to puppies
Infections are found in both rural and urban areas. Young dogs seem to be most susceptible
but this may be the result of puppies eating the bug
most dogs with the disease may show no obvious symptoms for a time
Common symptoms of acute Chagas include diarrhea
Chronic symptoms include lethargy
increased heart rate or abnormal heart rhythm
the disease is silent for years while it damages the heart and other organs
Consult a licensed pest control professional
The insects can live in cracks and crevices of wood and rocks
They are attracted to the heat and carbon dioxide emissions coming from mammals and are most active at night
though a new drug is undergoing FDA review
Texas Chagas Task Force Field Guide on Facebook: https://www.facebook.com/TexasChagasTaskforce
Get the Kissing Bug Smartphone App at https://itunes.apple.com/us/app/tamu-kissing-bug/id1269671095?mt=8
The well-known Argentine painter and artist
Nestor Favre-Mossier today donated two of his famous paintings to the World Health Organization (WHO) as part of his commitment to raising awareness about neglected tropical diseases (NTDs)
particularly Chagas disease which affects millions of mainly poor people in Argentina and in other countries of the Americas
\"This artwork calls for reflection about a preventable disease that ruins the lives of people and welfare of families\" said Dr Anne Marie Worning
who received the artworks in the presence of Dr Lorenzo Savioli
Director of the Department of Control of Neglected Tropical Diseases
The two paintings - 'Donde Como' (Where How) and 'Mala Sangre' (Bad Blood) - visually communicate Mr Favre-Mossier's message about Chagas disease which crossed his life on several occasions
making him particularly sensitive to the sufferings of people
It has been more than 100 years since the disease was first discovered by and named after Carlos Ribeiro Justiniano Chagas
What has most affected Mr Favre-Mossier is the fact that despite having been known for over 100 years
this disease has remained hidden and its victims suffer in silence
without having the opportunity to voice out their feelings and rights
Mr Nestor Favre-Mossier visited and lived with people of the Chaco region which borders northern Argentina
This visit inspired a series of 14 paintings on Chagas disease
is a potentially life-threatening illness caused by the protozoan parasite
where it is mostly transmitted to humans by the faeces of triatomine bugs
An estimated 10 million people are infected worldwide
mostly in Latin America where Chagas disease is endemic
More than 25 million people are at risk of the disease
It is estimated that in 2008 Chagas disease killed more than 10 000 people
"This artwork calls for reflection about a preventable disease that ruins the lives of people and welfare of families" said Dr Anne Marie Worning
Metrics details
The cellular and molecular basis to understand the relationship between Chagas disease (CD)
a common psychiatric comorbidity in CD patients
Clinical studies show an association between CD and depression and preclinical evidence suggests that depressive-like behaviors in T
mechanistic studies regarding this issue are still lacking
we present and discuss the state of art of data on CD and depression
and revise the mechanisms that may explain the development of depression in CD
We also discuss how the knowledge generated by current and future data may contribute to the discovery of new mechanisms underlying depressive symptoms associated with CD and
to the identification of new therapeutic targets
which ultimately may change the way we see and treat CD and its psychiatric comorbidities
the aims of this review article are: (i) to review the preclinical and clinical data showing the occurrence of depression in CD
providing new insights into their relationship; (ii) to review the shared pathways that underpin Chagas disease and comorbid depression; and (iii) to discuss how the understanding of the neuropsychiatric aspect of CD is key to an in-depth view of its pathogenesis and to develop novel approaches to treat it
We used Pubmed (MEDLINE) as the database to collect the studies available in this review
The search strategy comprised the use of following terms
alone or in combination: “major depressive disorder” [MeSH]
Articles resulting from these searches and relevant references cited in those articles were reviewed
and considered papers regardless of the year of publication
pre-clinical studies show that Chagas disease induced by type I T
cruzi is accompanied by depressive and anxiety-like behaviors in the chronic phase of disease
which are not a result of sickness behavior or acute inflammation
clinical studies show that Chagas disease is accompanied by psychological and mood disturbances
specifically the mild form of major depressive disorder
and that the status of the patients may be influenced by psychosocial factors
prolonged tryptophan depletion has detrimental implications for immunity and behavior
suggesting that depletion of tryptophan affects the biosynthesis of monoamines
An important issue that deserves attention is that inhibition of IDO activity may not work as a therapeutic strategy in Chagas disease and comorbid depression
since inhibition of IDO would also block its beneficial effects
the neuro-immune pathways in Chagas disease (including pro-inflammatory cytokines and increased neurotoxic TRYCATs) might drive depression
cruzi infection and depression activation of immune-inflammatory pathways are observed
which results in peripheral and CNS inflammation and mood changes
reduced antioxidant capacity may underlie depressive symptoms in Chagas disease and depression
raising the possibility that depression in CD may also be caused by gut microbiota changes
whether these changes also occur in the brain and affect mood and behavior still demands further research
it is conceivable that mitochondrial dysfunction is a shared mechanism in Chagas disease and depression and may underlie depressive symptoms
due to increased IO&NS pathways seen in Chagas disease
leading to changes relevant to the explanation of how the observed mood alterations arise in chagasic subjects
although these results should be interpreted with caution
Depression is a common psychiatric comorbidity in Chagas disease and occurs in varying degrees of severity
it compromises the quality of life of chagasic patients
both Chagas disease and depression are often underdiagnosed
the possibility of treating Chagas disease and comorbid depression at an early stage is very unlikely and demands more efficacious screening and disease control
this can be achieved by combining the knowledge of neuropsychiatry when tackling Chagas disease
activation of (neuro)immune-inflammatory pathways occur
activation of cell-mediated immunity (CMI) resulting in activation of marophages
Th-1 and Th-17-mediated immune responses with consequent secretion of pro-inflammatory cytokines (PICs)
and activation of indoleamine-2,3-dioxygenase (IDO) with production of TRYCATs catabolites
such as quinolinic acid (QUINA) and 3-hydroxykynurenin (3-HK)
decreased levels of dehydroepiandrosterone (DHEA) are also observed (not shown)
As a consequence of immune-inflammatory pathways activation
oxidative and nitrosative stress (O&NS) pathways are also activated
le2ading to increased production of reactive oxygen species (ROS) and reactive nitrogen species (RNS)
high levels of inducible nitric oxide synthase (iNOS) (not shown)
this may leads to the formation of neopitopes and increased autoimmunity as well as mitochondrial dysfunction and reduced ATP production (not shown)
The parasite can reach other body sites via the bloodstream (not shown)
gastrointestinal tract (GIT) and the brain
Once established in the aforementioned sites
the parasite triggers the activation of IO&NS pathways
cruzi induces heart dysfunction via inducing inflammation
the parasite triggers gut microbiota changes (here presented as black bacteria) and due to increased O&NS
the epithelial lining of the intestine is loosened
allowing gram-positive bacteria/LPS to translocate to the mesenteric lymph nodes (MLNs) or the bloodstream
where they activate toll-like receptor 2 (TLR2) or TLR4
which further triggers the activation of IO&NS pathways
IL-17 and IL-22 cause increased blood-brain barrier (BBB) permeability
allowing cytokines to reach the brain more easily
leading to activation of microglia and IDO
further activating IO&NS and neuroinflammation pathways in the brain
excitotoxicity and cell death are observed
these changes in different organs may contribute to the depressive symptoms observed in both Chagas disease and MDD
Immunoneuroendocrine interactions in Chagas disease
Trypanosoma cruzi-induced central nervous system alterations: from the entry of inflammatory cells to potential cognitive and psychiatric abnormalities
Human acute chagas disease: Changes in factor vii
activated protein C and hepatic enzymes from patients of oral outbreaks in par state (Brazilian Amazon)
behavioural and socioeconomic characteristics of migrants with Chagas disease in a non-endemic country
and depression among patients with indeterminate chronic Chagas disease and symptoms of pulmonary hypertension
Trypanosoma cruzi-induced depressive-like behavior is independent of meningoencephalitis but responsive to parasiticide and TNF-targeted therapeutic interventions
Behavioural alterations are independent of sickness behaviour in chronic experimental Chagas disease
Revisão: aspectos cognitivos e psicossociais associados a Doença de Chagas
Depressão e doença de Chagas TT - depression and Chagas disease
Quality of life and depressive symptoms in Chagas disease patients
Evidence for an immune response in major depression: a review and hypothesis
IDO and interferon-à-induced depressive symptoms: a shift in hypothesis from tryptophan depletion to neurotoxicity
Depression and sickness behavior are Janus-faced responses to shared inflammatory pathways
Novel insights into the mechanisms underlying depression-associated experimental autoimmune encephalomyelitis
Sleep and memory deficits in the rat produced by experimental infection with Trypanosoma cruzi
Formas encefalopaticas de enfermedad de Chagas cronica observadas en Argentina
TT - Encephalopathic form of chronic Chagas’s disease observed in Argentine
Cognitive impairment in human chronic Chagas’ disease
Estresse e resiliência em doença de Chagas
Depressão e doença de Chagas: Um estudo preliminar do estado emocional em pacientes chagásicos
Mechanistic explanations how cell-mediated immune activation
inflammation and oxidative and nitrosative stress pathways and their sequels and concomitants play a role in the pathophysiology of unipolar depression
Endogenous kynurenines as targets for drug discovery and development
A guide to immunometabolism for immunologists
Diverse roles of mitochondria in immune responses: novel insights into immuno-metabolism
Tryptophan kynurenine metabolism as a common mediator of genetic and environmental impacts in major depressive disorder: the serotonin hypothesis revisited 40 years later
The new “5-HT” hypothesis of depression: cell-mediated immune activation induces indoleamine 2,3-dioxygenase
which leads to lower plasma tryptophan and an increased synthesis of detrimental tryptophan catabolites (TRYCATs)
The kynurenine pathway: a finger in every pie
Understanding the role of the kynurenine pathway in human breast cancer immunobiology
Tryptophan catabolites along the indoleamine 2,3-dioxygenase pathway as a biological link between depression and cancer
Major depression model induced by repeated and intermittent lipopolysaccharide administration: Long-lasting behavioral
neuroimmune and neuroprogressive alterations
IgA/IgM responses to tryptophan and tryptophan catabolites (TRYCATs) are differently associated with prenatal depression
physio-somatic symptoms at the end of term and premenstrual syndrome
Interferon α blocks the growth of Toxoplasma gondii in human fibroblasts by inducing the host cells to degrade tryptophan
Potential role of human brain microvascular endothelial cells in the pathogenesis of brain abscess: inhibition of Staphylococcus aureus by activation of indoleamine 2,3-dioxygenase
Indoleamine 2,3-dioxigenase (IDO) is critical for host resistance against Trypanosoma cruzi
Immunotherapy with interferon-alpha in patients affected by chronic hepatitis C induces an intercorrelated stimulation of the cytokine network and an increase in depressive and anxiety symptoms
Depression and cardiovascular disease: a clinical review
Chagas disease as a mechanistic model for testing a novel hypothesis
Central autonomic network mediates cardiovascular responses to acute inflammation: relevance to increased cardiovascular risk in depression
Multiple aberrations in shared inflammatory and oxidative & nitrosative stress (IO&NS) pathways explain the co-association of depression and cardiovascular disorder (CVD)
and the increased risk for CVD and due mortality in depressed patients
Shared mechanisms between coronary heart disease and depression: findings from a large UK general population-based cohort
Increased plasma peroxides and serum oxidized low density lipoprotein antibodies in major depression: Markers that further explain the higher incidence of neurodegeneration and coronary artery disease
Increased plasma levels of tumor necrosis factor-α in asymptomatic/“indeterminate” and Chagas disease cardiomyopathy patients
Cytokine profiling in chagas disease: towards understanding the association with infecting Trypanosoma cruzi discrete typing units (A benefit trial sub-study)
IL-17 produced during Trypanosoma cruzi infection plays a central role in regulating parasite-induced myocarditis
Alternative Th17 and CD4+CD25+FoxP3+ cell frequencies increase and correlate with worse cardiac function in Chagas cardiomyopathy
Human TH17 lymphocytes promote blood-brain barrier disruption and central nervous system inflammation
Increased serum tumor necrosis factor alpha concentrations in major depression and multiple sclerosis
Peripheral cytokine and chemokine alterations in depression: a meta-analysis of 82 studies
but cell-mediated immune activation is the key component of depression
Priming astrocytes with TNF enhances their susceptibility to Trypanosoma cruzi infection and creates a self-sustaining inflammatory milieu
Interferon-gamma promotes infection of astrocytes by Trypanosoma cruzi
Oxidative & nitrosative stress in depression: why so much stress
Nonsteroidal anti-inflammatory is more effective than anti-oxidant therapy in counteracting oxidative/nitrosative stress and heart disease in T
SIRT1-PGC1α-NFκB pathway of oxidative and inflammatory stress during Trypanosoma cruzi infection: benefits of SIRT1-targeted therapy in improving heart function in Chagas disease
Nitric oxide synthase and oxidative-nitrosative stress play a key role in placental infection by Trypanosoma cruzi
Nitric oxide is involved in control of Trypanosoma cruzi-induced parasitemia and directly kills the parasite in vitro
Acute Chagas disease induces cerebral microvasculopathy in mice
Innate immune responses and antioxidant/oxidant imbalance are major determinants of human Chagas disease
Increased myeloperoxidase activity and protein nitration are indicators of inflammation in patients with chagas' disease
Increased oxidative stress is correlated with mitochondrial dysfunction in chagasic patients
Severity of chronic Chagas disease is associated with cytokine/antioxidant imbalance in chronically infected individuals
The anti-oxidant defence response in individuals with the indeterminate form of Chagas disease (American trypanosomiasis)
The central nervous system and the gut microbiome
Increased IgA and IgM responses against gut commensals in chronic depression: Further evidence for increased bacterial translocation or leaky gut
The gut-brain barrier in major depression: intestinal mucosal dysfunction with an increased translocation of LPS from gram negative enterobacteria (leaky gut) plays a role in the inflammatory pathophysiology of depression
and skin microbiota of children with Chagas disease treated with benznidazole
Experimental Chagas disease-induced perturbations of the fecal microbiome and metabolome
and the immune system-How are they linked in affective disorders
Mitochondrial complex III defects contribute to Inefficient respiration and ATP synthesis in the myocardium of Trypanosoma cruzi-infected mice
Impaired mitochondrial respiratory chain and bioenergetics during chagasic cardiomyopathy development
Gene expression analysis in mitochondria from chagasic mice: Alterations in specific metabolic pathways
Oxidative modification of mitochondrial respiratory complexes in response to the stress of Trypanosoma cruzi infection
Defects of mtDNA replication impaired mitochondrial biogenesis during Trypanosoma cruzi infection in human cardiomyocytes and chagasic patients: the role of Nrf1/2 and antioxidant response
Selective decrease of components of the creatine kinase system and ATP synthase complex in chronic Chagas disease cardiomyopathy
IgM-mediated autoimmune responses directed against multiple neoepitopes in depression: New pathways that underpin the inflammatory and neuroprogressive pathophysiology
Autoimmunity in depression: increased antiphospholipid autoantibodies
Increased autoimmune activity against 5-HT: A key component of depression that is associated with inflammation and activation of cell-mediated immunity
and with severity and staging of depression
epstein-barr and cytomegalovirus antibodies
and soluble interleukin-2 receptors in depressive patients
Autoimmunity in Chagas’ disease: Identification of cardiac myosin-B13 Trypanosoma cruzi protein crossreactive T cell clones in heart lesions of a chronic Chagas’ cardiomyopathy patient
Heat-killed Trypanosoma cruzi induces acute cardiac damage and polyantigenic autoimmunity
Trypanosoma cruzi calreticulin: a possible role in Chagas’ disease autoimmunity
Neuropathy of gastrointestinal Chagas' disease: immune response to myelin antigens
Evidence for cross-reactivity between antigen derived from Trypanosoma cruzi and myelin basic protein in experimental chagas disease
The compensatory immune-regulatory reflex system (CIRS) in depression and bipolar disorder
Immune-neuroendocrine and metabolic disorders in human and experimental T
cruzi infection: New clues for understanding Chagas disease pathology
Hypothalamus-pituitary-adrenal axis during Trypanosoma cruzi acute infection in mice
Immunoneuroendocrine alterations in patients with progressive forms of chronic Chagas disease
endocrine and metabolic markers is associated to more severe human chronic chagas cardiomyopathy
Altered salivary dehydroepiandrosterone levels in major depression in adults
Adrenal steroid secretion and major depression in 8- to 16-year-olds
Influence of cortisol/DHEA ratio at presentation on subsequent rates of disappointing life events and persistent major depression
Serum dehydroepiandrosterone (DHEA) and DHEA-sulfate (S) levels in medicated patients with major depressive disorder compared with controls
Inflammation and depression: a causal or coincidental link to the pathophysiology
Glucocorticoid receptors in major depression: relevance to pathophysiology and treatment
Hypothalamic-pituitary-adrenal axis hypoactivity in depressive illness
Alterations of the HPA axis observed in patients with major depressive disorder and their relation to early life stress: a systematic review
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The authors express their gratitude to Oswaldo Cruz Foundation of Pernambuco (FIOCRUZ-PE)
Research Excellence Program—Aggeu Magalhães Institute (IAM PROEP#400208/2019-9)
Knowledge Generation Program—Oswaldo Cruz Foundation (FIOCRUZ; #VPPCB-007-FIO-18-2-17)
the Brazilian National Institute of Science and Technology on Neuroimmunomodulation (INCT-NIM; #465489/2014-1) and Brazilian National Council for Scientific and Technological Development (CNPq; #301777/2012-8) for research support
This study was funded in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001
as well as FOCEM/Mercosur (Grant 003/2011)
Aggeu Magalhães Institute) for the critical review of the manuscript
Eduardo Duarte-Silva & Christina Alves Peixoto
Postgraduate Program in Biosciences and Biotechnology for Health (PPGBBS)
Universal Scientific Education and Research Network (USERN)
National Institute of Science and Technology on Translational Medicine (INCT-TM
National Institute of Science and Technology on Neuroimmunomodulation (INCT-NIM)
Wilson Savino & Christina Alves Peixoto
Rio de Janeiro Research Network on Neuroinflammation
wrote the manuscript and created the figures and table under the supervision of C.A.P
M.M and W.S contributed to the writing of the manuscript and critically reviewed the manuscript
All authors approved the final version of this paper
The authors declare that they have no conflict of interest
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations
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DOI: https://doi.org/10.1038/s41398-020-01105-9