Application of WHO International Biological Reference Standards to evaluate commercial serological tests for chronic Chagas disease

BACKGROUND Chagas disease, resulting from Trypanosoma cruzi infections, continues to be a health concern mainly in Latin American countries where the parasite is endemic. The laboratory diagnosis of a chronic infection is determined through serological assays for antibodies against T. cruzi and several tests are available that differ in key components, formats and methodologies. To date, no single test meets the criteria of a gold standard. The situation is further complicated by the difficulties associated with performance comparisons between different immunoassays or methodologies executed at different times and geographical areas. OBJECTIVE To improve the diagnosis of Chagas disease, the WHO coordinated the development of two International Biological Reference Standards for antibodies against anti-T. cruzi: NIBSC 09/186 and NIBSC 09/188 that respectively represent geographical regions with the highest prevalence of TcII and TcI lineages of the parasite. METHODS The principle goal of this study was to verify the behavior of these standards when assayed by several commercially available serological tests that employ different methods to capture and detect human anti-T. cruzi antibodies. FINDINGS AND MAIN CONCLUSIONS The results reinforce the recommendation that these standards be considered for performance evaluations of commercialised immunoassays and should be an integral step in the development of new test components or assay paradigms.

Linear mixed model for weight analysis in mice infected by Trypanosoma cruzi

The use of linear mixed models for nested structure longitudinal data is called hierarchical linear modeling. Thismodeling takes into account the dependence of existing data within each level and between hierarchical levels. The process of modeling, estimating and analyzing diagnoses was illustrated through data on the weights of mice experimentally infected by Trypanosoma cruzi, divided into different treatment groups, with the purpose of verifying the evolution of their body weight as a result of usingdifferent types of biotherapeutics produced from Gallus gallus domesticus(chicken) serum to treat Trypanosoma cruzi. Through the model selection criteria AIC and BIC and the likelihood ratio test, a model was chosen to describe the data correctly. Model diagnoses were then performed by means of residual analysis for both levels and an analysis of influential observations to verify if any observations were signaled as influencing the fixed effects, the components of variance and the adjusted values. After the analysis, it was possible to notice that the observations that were signaled as influential had little impact on the Model chosen initially, so it was maintained, with no differences being evidenced between the treatments with the biotherapeutics tested; only the Time variable and the Random intercept were necessary to describe the weight of the mice.

Analyzing weight evolution in mice infected by Trypanosoma cruzi

Concerning the specificities of a longitudinal study, the trajectories of a subject's mean responses not always present a linear behavior, which calls for tools that take into account the non-linearity of individual trajectories and that describe them towards associating possible random effects with each individual. Generalized additive mixed models (GAMMs) have come to solve this problem, since, in this class of models, it is possible to assign specific random effects to individuals, in addition to rewriting the linear term by summing unknown smooth functions, not parametrically specified, then using the P-splines smoothing technique. Thus, this article aims to introduce this methodology applied to a dataset referring to an experiment involving 57 Swiss mice infected by Trypanosoma cruzi, which had their weights monitored for 12 weeks. The analyses showed significant differences in the weight trajectory of the individuals by treatment group; besides, the assumptions required to validate the model were met. Therefore, it is possible to conclude that this methodology is satisfactory in modeling data of longitudinal sort, because, with this approach, in addition to the possibility of including fixed and random effects, these models allow adding complex correlation structures to residuals.

Morte súbita em Doença de Chagas ­conceitos atuais e perspectivas de novos avanços / Sudden cardiac death in Chagas Heart Disease- current concepts and perspectives for new advances

A Doença de Chagas atinge milhões de pessoas na América Latina e a evolução para cardiopatia crônica tem como seu principal desfecho a morte súbita cardíaca (MSC). Neste artigo, revisamos, sob a luz da medicina baseada em evidências, os principais aspectos sobre marcadores prognósticos clínicos e de imagem (especificamente a análise da fibrose em ressonância magnética) e terapêutica existente no tratamento e prevenção da MSC, como terapia farmacológica, evidências sobre dispositivos implantáveis e tratamento invasivo de arritmias ventriculares

Chagas disease affects millions of people in Latin America and its evolution to heart disease has the sudden cardiac death (SCD) as one main outcome. In this article, we sought to review the essential evidence-based aspects about prognostic markers and treatments for SCD, including farmacological treatment, use of implantable devices and invasive treatment of ventricular arrhthymias

Clinical and epidemiological characteristics of Chagas disease in an endemic area of Sergipe State, Brazil

Abstract INTRODUCTION: We evaluated clinical and epidemiological characteristics of Trypanosoma cruzi infection in Sergipe. METHODS: In this cross-sectional study, we collected serum samples to identify serological markers of Chagas disease. A questionnaire was used, and electrocardiogram, echocardiogram, chest radiography, and contrast radiography of esophagus and colon were performed. RESULTS: T. cruzi infection seroprevalence was 12.1%, mean age of subjects was 55 years, 90% had an elementary school education, 78.6% were agriculture workers, and 60.5% had electrocardiographic abnormalities. CONCLUSIONS: A high prevalence of T. cruzi infection was observed in mostly elderly individuals.

Trypanosoma cruzi seroprevalence among solid organ donors in Ceará State, Brazil

Abstract INTRODUCTION: The transmission of Chagas disease (CD) through blood transfusion, organ transplantation, and oral transmission has gained greater visibility as a result of intensified vector control activities in endemic regions and to control CD in non-endemic regions. In Brazil, Ceará is one of the states that perform the most organ transplants. Therefore, the objective of this study was to assess the prevalence of Trypanosoma cruzi infection in organ donor candidates. METHODS: A retrospective analysis was performed on data from potential organ donors at the Center of Transplantation of the State of Ceará from 2010 - 2015. RESULTS: Data from a total of 2,822 potential donors were obtained, of which 1,038 were effective donors and 1,784 were excluded, likely due to lack of family authorization or medical contraindication. The prevalence of T. cruzi infection among these potential donors was 1.3% (n = 29). The majority of infected donors were males aged 41 - 60 years, residing in the interior of the state. Interestingly, 72.4% (n = 21) had positive or inconclusive serology for additional infections, such as cytomegalovirus, hepatitis B and C, and toxoplasmosis. Probability analysis revealed that stroke was the most common cause of death among potential donors with CD. CONCLUSIONS: There was a high prevalence of CD and other coinfections among potential solid organ donors in Ceará, and statistical tests have shown that these individuals are at increased risk of stroke when compared to potential non-reactive donors. This work highlights the importance of screening DC infection in potential donors.

Anti-serum validation for use in immunohistochemistry for Trypanosoma cruzi detection

Abstract INTRODUCTION: The detection of Trypanosoma cruzi in tissue samples is important in many situations, such as testing of the reactivation of the infection. The detection of T. cruzi nests in endomyocardial biopsies (EMB) may be useful to evaluate graft rejection. Given their scarcity, such nests are not routinely identified. To increase the diagnosis sensitivity, immunohistochemistry (IHC) may serve as a promising strategy. Here, we validate an antiserum for the detection of T. cruzi infection by IHC. METHODS: We used 1) positive controls (PCs) - 13 EMB, 12 skin biopsies, and 1 heart with T. cruzi nests as sections stained with hematoxylin and eosin (HE); 2) negative controls - a) 10 explant hearts and 10 EMB with no amastigote nests or clinical/laboratory signs of chagasic infection; and b) eight samples with leishmaniasis, toxoplasmosis, or histoplasmosis; and 3) Cases - 31 EMB of chagasic patients with no parasite nests in HE sections but detected positive for T. cruzi DNA by polymerase chain reaction. As a primary antibody, a hyperimmune serum from T. cruzi-infected rabbits was used. RESULTS: IHC results were positive for 21 of 26 PCs (80.8%) and one case of cutaneous leishmaniasis. In 4 of 31 cases, IHC revealed nests (12.9%), which were undetected by conventional histological examination. CONCLUSIONS: This study shows that IHC with the tested antiserum increases the sensitivity of the diagnosis and may be recommended for routine use in EMB analyses of cardiac transplant patients with Chagas disease.

Antibodies anti-trypanosomatides in domestic cats in Paraná: who is at highest risk of infection? / Anticorpos anti-tripanossomatídeos em gatos domésticos no Paraná: quem está em maior risco de infecção?

Abstract The aim of this study were to detect antibodies anti-Leishmania spp. and anti-Trypanosoma cruzi in two different populations of domestic cats (Felis catus domesticus) from North Paraná referred for surgical castration and to determine which characteristics of the animals studied may be associated with seropositivity. Serum samples from 679 cats were analyzed using enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence antibody test (IFAT) in series. Associations between age, sex, race, year of care and animal group were verified using the simple logistic regression. Percentage of 8.5% (58/679) of cats were positive for Leishmania spp. and 7.6% (51/673) for T. cruzi by the tests ELISA and IFAT. Animals collected by non-governmental animal protection organizations presented more seropositivity for Leishmania spp. (p<0.0001). Results shown that Leishmania spp. and T. cruzi are present in domestic cats in the northern part of the state of Paraná, as well as, owners of non-governmental animal protection organizations may be more exposed to leishmaniasis when compared to other animal owners evaluated in the present study.

Resumo O objetivo desse estudo foi detectar a presença de anticorpos IgG anti-Leishmania spp. e anti-Trypanosoma cruzi em duas populações de gatos domésticos (Felis catus domesticus) do Norte do Paraná encaminhados para castração cirúrgica e determinar quais as características dos animais estudados que podem estar associadas à soropositividade. Amostras de soro de 679 gatos foram analisadas utilizando-se os testes imunoenzimático (ELISA) e a reação de imunofluorescência indireta (RIFI), em série. Associações entre idade, sexo, raça, ano de atendimento e grupo animal ​​foram verificadas usando regressão logística simples. Um percentual de 8,5% (58/679) dos gatos apresentou positividade para Leishmania spp. e 7,6% (51/673) para T. cruzi pelos testes ELISA e RIFI. Gatos mantidos em organizações não governamentais de proteção animal apresentaram maior sororeatividade para Leishmania spp. (p<0.0001). As sorologias reativas para Leishmania spp. e Trypanosoma cruzi mostram que esses agentes estão presentes em gatos domésticos na parte norte do estado do Paraná, bem como, os proprietários de organizações não governamentais de proteção animal podem estar mais expostos à leishmaniose quando comparados com outros proprietários de animais avaliados no presente estudo.

Systematic neonatal screening for congenital Chagas disease in northeast Brazil: prevalence of trypanosoma cruzi infection in the southern region of Sergipe

Abstract INTRODUCTION: Chagas disease is caused by the flagellate protozoan Trypanosoma cruzi, being one of the leading causes of morbidity and mortality in the Americas with an estimated six to seven million infected people worldwide. In Brazil, the improvement in vector control and blood donor screening has evidenced the important epidemiological role of congenital transmission of Chagas disease. METHODS: A serological survey for Chagas disease was performed in 3,952 newborns in the southern region of Sergipe using paper filter disks of dried blood samples. The newborns were screened using the Sergipe State Neonatal Screening Program between July 2015 and July 2016, and 3,749 and 750 blood samples were obtained for the IgG enzyme-linked immunosorbent assay and indirect immunofluorescence assay, respectively. In addition, mothers of the children who presented initial reagent serology were examined. RESULTS: Among 3,749 blood samples, samples of two children were positive for the enzyme-linked immunosorbent assay; however, their confirmation test results were negative, suggesting passive transfer of the mother's antibody. One puerpera was identified with Chagas disease, with a prevalence of 0.02%. CONCLUSIONS: Congenital Chagas disease was not observed in newborns in the Southern region of Sergipe. However, Chagas disease was observed in women of reproductive age. Therefore, effective measurements for monitoring and systematic evaluation should be conducted. The Neonatal Screening Program proved to be an effective public health strategy for the prevention and control of Chagas disease.

Vimentin and Anti Vimentin Antibodies in Chagas' Disease / Vimentina e Anticorpos Anti-Vimentina na Doença de Chagas

Abstract Background: Vimentin is a main structural protein of the cell, a component of intermediate cell filaments and immersed in cytoplasm. Vimentin is mimicked by some bacterial proteins and anti-vimentin antibodies occur in autoimmune cardiac disease, as rheumatic fever. In this work we studied vimentin distribution on LLC-MK2 cells infected with T. cruzi and anti-vimentin antibodies in sera from several clinical pictures of Chagas' disease or American Trypanosomiasis, in order to elucidate any vimentin involvement in the humoral response of this pathology. Objective: We standardized an indirect immunofluorescence assay (IFI) to determine sub cellular expression in either parasites and host cells, and ELISA to evaluate anti-vimentin antibodies in sera fron chagasic patients. Methods: We analyzed the distribution of vimentin in culture cells using indirect fluorescent assays, using as external controls anti-T. cruzi sera, derived from chronic infected patients for identification of the parasites in the same model. After infection and growth of T.cruzi amastigotes, those cells express larger amounts of vimentin, with heavy staining of cytoplasm outside the parasitophorous vacuole and some particle shadowing patterns, suggesting that vimentin are associated with cell cytoplasm. Anti-vimentin antibodies were present in most American trypanosomiasis samples, but notably, they are much more present in acute (76, 9%) or clinical defined syndromes, especially cardiac disease (87, 9%). Paradoxically, they were relatively infrequent in asymptomatic (25%) infected patients, which had a clearly positive serological reaction to parasite antigens, but had low frequency of anti-vimentin antibodies, similar to controls (2,5%). Conclusion: Our current data revealed that anti-vimentin antibodies induced during T. cruzi infection could be a marker of active disease in the host and its levels could also justify drug therapy in American Trypanosomiasis chronic infection, as a large group of asymptomatic patients would be submitted to treatment with frequent adverse reactions of the available drugs. Anti-vimentin antibodies could be a marker of cardiac muscle cell damage, appearing in American Trypanosomiasis patients during active muscle cell damage.

Resumo Fundamento: A Vimentina é uma proteína estrutural importante da célula, um componente dos filamentos celulares intermediários e imersa no citoplasma. Algumas proteínas bacterianas imitam a Vimentina e anticorpos anti-vimentina ocorrem em doenças cardíacas auto-imunes, como a febre reumática. Neste trabalho, estudamos a distribuição de vimentina em células LLC-MK2 infectadas com T. Cruzi e anticorpos anti-vimentina em soros de várias imagens clínicas da doença de Chagas ou tripanossomíases americanas, a fim de elucidar qualquer implicação da vimentina na resposta humoral desta patologia. Objetivo: padronizamos um teste de imunofluorescência indireta (IFI) para determinar a expressão subcelular em parasitas e células hospedeiras, e ELISA para testar anticorpos anti-vimentina em soros de pacientes chagásicos. Métodos: analisamos a distribuição de vimentina em células de cultura usando ensaios fluorescentes indiretos, utilizando como controles externos soros anti-T. Cruzi, derivados de pacientes com infecção crônica para a identificação de parasitas no mesmo modelo. Após a infecção e o crescimento de amastigotas de T. Cruzi, essas células expressam grandes quantidades de vimentina, com forte coloração do citoplasma fora da vacuola parasitófora e alguns padrões de sombreamento das partículas, sugerindo que a vimentina está associada ao citoplasma da célula. Os anticorpos anti-vimentina estavam presentes na maioria das amostras americanas de tripanossomíases, mas estão notavelmente mais presentes em síndromes agudas ou clinicamente definidas (76,9%), especialmente em doenças cardíacas (87,9%). Paradoxalmente, eram relativamente infrequentes em pacientes infectados assintomáticos (25%), que apresentavam uma reação sorológica claramente positiva aos antígenos parasitas, mas apresentavam baixa frequência de anticorpos anti-vimentina, semelhante aos controles (2,5%). Conclusão: Nossos dados atuais revelaram que os anticorpos anti-vimentina induzidos durante a infecção por T. Cruzi poderiam ser um marcador de doença ativa no hospedeiro e seus níveis também poderiam justificar o tratamento farmacológico em infecção crônica com tripanossomíase americana, uma vez que um grande grupo de pacientes assintomáticos seria submetido a tratamento com reações adversas frequentes aos medicamentos disponíveis. Os anticorpos anti-vimentina poderiam ser um marcador de danos nas células do músculo cardíaco, que aparece em pacientes com tripanossomíase americana durante o dano das células musculares ativas.

Natural infection by Trypanosoma cruzi in triatomines and seropositivity for Chagas disease of dogs in rural areas of Rio Grande do Norte, Brazil

Abstract INTRODUCTION: Chagas disease is caused by the protozoa Trypanosoma cruzi. Its main reservoir is the domestic dog, especially in rural areas with favorable characteristics for vector establishment and proliferation. The aims of this study were to collect data, survey and map the fauna, and identify T. cruzi infection in triatomines, as well as to assess the presence of anti-T. cruzi antibodies in dogs in rural areas of the municipality of Mossoró, Brazil. METHODS: An active entomologic research was conducted to identify adult specimens through an external morphology dichotomous key. The analysis of natural infection by T. cruzi in the insects was performed by isolation in culture and polymerase chain reaction. The antibody testing for T. cruzi in dogs was performed by enzyme-linked immunosorbent assay and indirect immunofluorescence assay. RESULTS: A total of 68 triatomines were captured, predominantly the Triatoma brasiliensis brasiliensis (Neiva 1911) species. The vector mapping displayed areas with greater risk for parasite transmission. Of the examined triatomines (51 specimens), 41.2% (21/51) were positive on polymerase chain reaction, and all were negative on culture. In the serum testing, 11% (25/218) of dogs were seropositive, but no association was found between the serologic results and the presence and infection by T. cruzi in triatomines. CONCLUSIONS: This study demonstrated the movement of T. cruzi in the studied area, by the presence of vectors and naturally infected domestic reservoirs. The mapping of the studied rural area demonstrates the risk of disease transmission.

Anticuerpos anti-Trypanosoma cruzi en migrantes latinoamericanos en tránsito por el cruce fronterizo entre México y los Estados Unidos / Anti-Trypanosoma cruzi antibodies in Latin American migrants in transit through the México-USA border

Resumen Introducción. En los últimos años, la tripanosomiasis americana se ha convertido en un problema de salud pública emergente en países receptores de poblaciones migrantes, como México, Estados Unidos, Canadá y los países europeos. Objetivo. Analizar la prevalencia de anticuerpos anti-Trypanosoma cruzi mediante técnicas serológicas, en los migrantes latinos en su paso hacia Estados Unidos y Canadá. Materiales y métodos. Se hicieron análisis serológicos mediante ELISA y la prueba de hemaglutinación indirecta (HAI) para detectar anticuerpos anti-T. cruzi, y encuestas socioeconómicas para determinar los factores asociados a los casos seropositivos que favorecieron la transmisión en el país de origen de los migrantes. Resultados. La seroprevalencia total en la población estudiada fue del 20 % (24/120). La prevalencia más alta se encontró en migrantes de Guatemala, con 37,5 % (6/16), seguidos de los de Honduras (22,6 %; 12/53), El Salvador (16 %; 4/25) y México (8,7 %; 3/23). De los 120 migrantes encuestados, 105 (87,5 %) reconocieron el vector y 62 (59 %) afirmaron haber sido picados por este. La asociación de la infección con los materiales de construcción de las paredes de las viviendas, así como con la presencia de mascotas (perros) en los hogares, fue muy significativa (p≤0,01). La asociación con el material de construcción del patio, los servicios básicos precarios, así como la cría de animales dentro de corrales en la periferia de los hogares, también fue significativa (p≤0,05). Conclusión. Los países no endémicos que reciben migrantes de zonas endémicas deben mejorar o desarrollar políticas de salud para prevenir la transmisión del parásito por transfusión o por vía congénita.

Abstract Introduction: In recent years, American trypanosomiasis has become an emergent public health problem in countries receiving migrant populations such as México, USA, Canada or those in Europe. Objective: To analyze the prevalence of anti-Trypanosoma cruzi antibodies in Latin American migrants on their way to USA and Canada by means of serological techniques. Material and methods: ELISA and IHA were performed to detect anti-T. cruzi antibodies. Also, each participant filled out a socioeconomic questionnaire to determine the associated factors with seropositive cases, which could facilitate the transmission in the migrants' country of origin. Results: Total seroprevalence among the studied population was 20% (24/120). The highest prevalence was found in migrants from Guatemala with 37.5% (6/16), followed by Honduras (22.6%; 12/53), El Salvador (16%; 4/25), and México (8.7%, 3/23). From the total 120 surveyed migrants, 105 (87.5%) recognized the vector of Chagas' disease, and 62 (59%) assured having been bitten by it. Highly significant statistical associations were found between infection and the construction materials for walls and the presence of pets (dogs) inside houses (p≤0.01), as well as with the building materials for backyards, inadequate basic services, and animal breeding inside corrals built around dwellings (p≤0.05). Conclusion: Non-endemic countries receiving migrants from endemic areas should enhance or develop better health policies to prevent transfusion-transmitted Chagas or congenital parasite transmission.

Costos de la prueba de tamización para la enfermedad de Chagas en donantes de dos bancos de sangre de Colombia, 2015 / Costs of Chagas' disease screening test in blood donors in two Colombian blood banks, 2015

Resumen Introducción . La transfusión es un mecanismo de transmisión de la enfermedad de Chagas. No se han hecho estudios de costos de la prueba de tamización en bancos de sangre de Colombia. Objetivo. Estimar los costos de la prueba de tamización para la enfermedad de Chagas en donantes de bancos de sangre de Colombia, 2015. Materiales y métodos. Se hizo un estudio de costos desde la perspectiva del prestador de servicios en los bancos de sangre de la Cruz Roja, seccional Bolívar, y del Hospital de Yopal, Casanare, que incluyó: 1) gastos administrativos, es decir, costos de servicios públicos y seguros asignados según los metros cuadrados de las instalaciones del banco de sangre; 2) costos de capital, es decir, edificación y equipos, anualizados con una tasa de descuento de 3 % y considerando una vida útil de 20 y cinco años, respectivamente; 3) costos de insumos y materiales ajustados al nivel de producción, y 4) costos del recurso humano encargado del procesamiento de las pruebas. Se reportó, asimismo, el costo de las bolsas y de las pruebas de inmunohematología. Resultados. En el banco de sangre de la Cruz Roja, seccional Bolívar, el costo de la prueba fue de COP$ 37.804 (USD$ 12), mientras que la bolsa y la prueba de inmunohematología costaron COP$ 25.942 (USD$ 8,2) y COP$ 6.800 (USD$ 2,2), respectivamente. En el banco de sangre del Hospital de Yopal, los costos ascendieron a COP$ 77.384 (USD$ 24,6), COP$ 30.141 (USD$ 9,6) y COP$ 12.627 (USD$ 4), respectivamente. La mayor participación en el costo de la prueba correspondió al recurso humano (47,5 % en Cartagena y 55,7 % en Yopal). Conclusiones. Estos resultados son importantes para la planificación de los servicios y los análisis de costo-efectividad de la prueba de tamización para la enfermedad de Chagas en los bancos de sangre.

Abstract Introduction: Transfusion is a mechanism of transmission of Chagas' disease. There are no studies on the costs of the screening test in Colombian blood banks. Objective: To estimate the costs of the screening test for Chagas' disease among blood donors in two Colombian blood banks, 2015. Materials and methods: We conducted a micro-costing study from the perspective of the health care provider to estimate the cost of Chagas' disease testing in two blood banks, Banco de Sangre de la Cruz Roja, Seccional Bolívar, and Banco de Sangre del Hospital de Yopal, Casanare, taking into account four cost categories: 1) Administrative costs: public services and insurance costs were calculated based on the blood bank area in square meters; 2) capital costs: building and equipment costs that were annualized using a 3% discount rate and a lifespan of 20 years for building and five for equipment; 3) costs of Chagas' disease test materials and reagents adjusted by blood bank production level, and 4) costs of staff in charge of Chagas' disease test processing. The costs of transfusion bags and immunohematology tests are also reported. Results: The cost of Chagas' disease test in the blood bank of Seccional Bolívar was COP$ 37,804 (USD$ 12), and the blood bag and immunohematology test costs were COP$ 25,941 (USD$ 8.2) and COP$ 6,800 (USD$ 2.2), respectively. In the blood bank of Yopal, Casanare, the costs were COP$ 77,384 (USD$ 24.6), COP$ 30,141 (USD$ 9.6) and COP$ 12,627 (USD$ 4), respectively. Personnel cost accounted for the highest percentage of the total cost for both blood banks (47.5% in Seccional Bolívar, and 55.7% in Yopal, Casanare). Conclusion: Our results are an important input for the planning of services and cost-effectiveness studies for screening tests for Chagas' disease in Colombian blood banks.

Looking for combination of benznidazole and Trypanosoma cruzi-triosephosphate isomerase inhibitors for Chagas disease treatment

BACKGROUND The current chemotherapy for Chagas disease is based on monopharmacology with low efficacy and drug tolerance. Polypharmacology is one of the strategies to overcome these limitations. OBJECTIVES Study the anti-Trypanosoma cruzi activity of associations of benznidazole (Bnz) with three new synthetic T. cruzi-triosephosphate isomerase inhibitors, 2, 3, and 4, in order to potentiate their actions. METHODS The in vitro effect of the drug combinations were determined constructing the corresponding isobolograms. In vivo activities were assessed using an acute murine model of Chagas disease evaluating parasitaemias, mortalities and IgG anti-T. cruzi antibodies. FINDINGS The effect of Bnz combined with each of these compounds, on the growth of epimastigotes, indicated an additive action or a synergic action, when combining it with 2 or 3, respectively, and an antagonic action when combining it with 4. In vivo studies, for the two chosen combinations, 2 or 3 plus one fifth equivalent of Bnz, showed that Bnz can also potentiate the in vivo therapeutic effects. For both combinations a decrease in the number of trypomastigote and lower levels of anti-T. cruzi IgG-antibodies were detected, as well clear protection against death. MAIN CONCLUSIONS These results suggest the studied combinations could be used in the treatment of Chagas disease.

Seroprevalence of human Trypanosoma cruzi infection in the North of Estado de Mexico

Abstract INTRODUCTION: Chagas disease is a neglected public health problem in Mexico; however, detailed studies to determine the seroprevalence in some states have not been performed. METHODS: A total 1,504 human serum from thirteen communities in Estado de Mexico, were analyzed with three diagnostics techniques. RESULTS: The overall seroprevalence was 9.1%, with high prevalence among people aged 51-60 years, while people aged 0-29 years were seronegative against T. cruzi. CONCLUSIONS: Our data demonstrated the seroprevalence of T. cruzi in the North of the Estado de Mexico, an area considered as non-endemic; however, epidemiological conditions necessary for natural transmission were found.

Detección de anticuerpos contra Trypanosoma cruzi en pacientes multitransfundidos, Colombia / Detection of Trypanosoma cruzi antibodies in multitransfused patients in Colombia

Resumen Introducción. La enfermedad de Chagas es un problema de salud pública en Latinoamérica y, aunque la transmisión vectorial es la más importante, deben evaluarse otras formas de transmisión, como la de las transfusiones. Objetivo. Describir la prevalencia de infección con Trypanosoma cruzi en pacientes sometidos a múltiples transfusiones o multitransfundidos. Materiales y métodos. Se detectaron anticuerpos IgG contra T. cruzi mediante dos inmunoensayos en muestras tomadas de pacientes sometidos a múltiples transfusiones en cuatro hospitales de Bogotá y Medellín, Colombia. Se analizó la asociación de factores de riesgo conocidos y se calcularon las razones de momios (odds ratio, OR) con un intervalo de confianza de 95 % (IC) utilizando el programa Stata 11(tm). Resultados. Se evaluaron 479 muestras. La prevalencia de anticuerpos contra T. cruzifue de 1,88 % (nueve pacientes): cinco pacientes remitidos de oncohematología, dos de hemodiálisis, uno tenía talasemia y uno había sufrido pérdida súbita y abundante de sangre. No se halló ningún paciente con hemofilia que resultara positivo, ni relación de los factores de riesgo de infección asociados con la transfusión de componentes sanguíneos, como el número de transfusiones, la cantidad de unidades de sangre y el tipo de componente, con la presencia de anticuerpos anti-T. cruzi. Solo se encontró relación entre la infección con el virus de la hepatitis C y la presencia de anticuerpos anti-T. cruzi (OR=5,68; IC95% 1,36-23,63). Conclusión. La frecuencia de infección por T. cruzi hallada en este grupo de pacientes sugiere que el riesgo de infección por transfusiones en Colombia es bajo. No se encontró relación entre los factores de riesgo asociados con la transfusión y la presencia de anticuerpos anti-T. cruzi.

Abstract Introduction: Chagas disease is a public health problem in Latin America. Even though vector-borne infection is the most important transmission mode for this disease, other modes such as transfusions require evaluation. Objective: To describe the prevalence of T. cruzi infection in multitransfused patients. Materials and methods: We detected IgG antibodies against T. cruzi by two immunoassays in samples from multitransfused patients in four hospitals located in Bogotá and Medellín, Colombia. We analyzed the association with known risk factors, and we calculated the odds ratios (OR) with 95% confidence intervals using Stata 11(tm) statistical software. Results: In total, 479 samples were tested. Overall, T. cruzi antibody prevalence was 1.88% (nine patients). Five were onco-hematological patients, two were hemodialyzed, one had thalassemia, and one had suffered acute blood loss. We found no hemophilia patients. There was no association between known risk factors for transfusion-transmitted infection (such as the number of transfusion events, number of blood units and type of blood component) and the presence of anti-T. cruzi antibodies in this study. Only the hepatitis C virus infection showed a positive association with the presence of anti-T. cruzi antibodies (OR=5.68, 95% CI: 1.36-23.63). Conclusions: The results of this study showed a low frequency of T. cruzi infection in multitransfused patients, suggesting that the risk of transfusion infection in Colombia is low. Known risk factors for transfusion-related infection were not associated with the presence of anti-T. cruzi antibodies.

Sexual transmission of American trypanosomiasis in humans: a new potential pandemic route for Chagas parasites

BACKGROUND The Trypanosoma cruzi infection endemic in Latin America has now spread to several countries across four continents; this endemic involves triatomine vector-free protists. We hypothesised that the sexual transmission of T. cruzi contributes to the ongoing spread of Chagas disease. OBJECTIVES A short-term longitudinal study was conducted to evaluate this hypothesis. METHODS The study population comprised 109 subjects from four families, among whom 21 had been diagnosed with acute Chagas disease by direct parasitological analysis. Blood mononuclear cells and serum samples were obtained from each study subject once per year for three consecutive years. Enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence serological examinations were used to detect specific T. cruzi antibodies. Polymerase chain reaction of T. cruzi DNA revealed 188-nucleotide bands, which hybridised to a specific radiolabelled probe and were confirmed by cloning and sequencing. RESULTS Three independent assessments at different time points revealed T. cruzi nuclear DNA footprints in 76% (83/109) of the study population with active infection. In contrast, the ELISA and indirect immunofluorescence assays detected the T. cruzi antibody in 28.4% (31/109) of the study samples. Moreover, the semen from 82.6% (19/23) of subjects people revealed harboured the 188- bp base pair T. cruzi footprint. Interestingly, the ejaculates of nuclear DNA-positive Chagas patient transmitted the T. cruzi upon peritoneal injection or infusion in the vagina of mice, and amastigotes were detected in the skeletal muscle, myocardium, vas deferens, and uterine tube. MAIN CONCLUSIONS T. cruzi infections can be transmitted from females or males to naïve mates through intercourse, and progeny showed discrepancies between the ratios of nuclear DNA footprints and specific antibody that can be explained by the tolerance attained during early embryo growth. Additional studies are needed to develop drugs to eradicate the infections. Additionally, the importance of a vigorous education, information, and communication program to prevent sexually transmitted Chagas disease in humans cannot be underemphasised.

Prevalence of Trypanosoma cruzi/HIV coinfection in southern Brazil

Abstract Chagas disease reactivation has been a defining condition for acquired immune deficiency syndrome in Brazil for individuals coinfected with Trypanosoma cruzi and HIV since 2004. Although the first coinfection case was reported in the 1980s, its prevalence has not been firmly established. In order to know coinfection prevalence, a cross-sectional study of 200 HIV patients was performed between January and July 2013 in the city of Pelotas, in southern Rio Grande do Sul, an endemic area for Chagas disease. Ten subjects were found positive for T. cruzi infection by chemiluminescence microparticle immunoassay and indirect immunofluorescence. The survey showed 5% coinfection prevalence among HIV patients (95% CI: 2.0-8.0), which was 3.8 times as high as that estimated by the Ministry of Health of Brazil. Six individuals had a viral load higher than 100,000 copies per µL, a statistically significant difference for T. cruzi presence. These findings highlight the importance of screening HIV patients from Chagas disease endemic areas.

Analysis of the seroprevalence of and factors associated with Chagas disease in an endemic area in Northeastern Brazil

ABSTRACT INTRODUCTION: Chagas disease (CD) is currently considered a neglected disease; hence, identifying the factors associated with its high prevalence is essential. This study aimed to identify the seroprevalence of and the possible factors associated with CD in inhabitants of the City of Limoeiro do Norte, Northeastern Brazil. METHODS: Between April and November 2013, blood collection was conducted and a semi-structured questionnaire was administered. Blood samples that showed positive or possible serology for anti-Trypanosoma cruzi antibodies based on indirect immunofluorescence, hemagglutination indirect, and an enzyme-linked immunosorbent assay were analyzed. Associations between CD positivity and the study variables were analyzed using prevalence ratios (PR) with 95% confidence intervals (CI). RESULTS: A total of 812 individuals were analyzed, of which T. cruzi seropositivity was determined in 4.2% (34 individuals). Sociodemographic variables showing a significant association with T. cruzi positivity included age >50 years (PR = 27.6; 95% CI = 6.66-114.4), elementary level education (PR = 5.15; 95% CI = 1.83-14.47), and retirement (PR = 7.25; 95% CI = 3.72-14.14). Positivity for T. cruzi was 6.17 times higher in those who had a history of living in rammed earth houses compared with those who did not (95% CI = 2.19-17.37). There was no evidence of vertical transmission in the individuals studied. Among the individuals infected with T. cruzi, the majority reported having a comorbidity (p < 0.01). CONCLUSIONS: This study demonstrated the seroprevalence of CD and identified factors associated with a high prevalence of CD.