Characterization of adverse reactions to benznidazole in patients with Chagas disease in the Federal District, Brazil

Abstract INTRODUCTION: Benznidazole is used for treating Chagas disease (CD). This cross-sectional study aimed to characterize the adverse drug reactions (ADRs) of benznidazole at a public hospital in Brazil's Federal District. METHODS: Medical records were analyzed and ADRs were categorized by type, intensity, seriousness, and causality. RESULTS: Of the 62 patients who started benznidazole treatment for CD, 41 (66%) presented with 105 ADRs; 23 (37%) discontinued the treatment. Most reactions were classified as probable (81%), severe (63%), serious (67%), and dose-dependent (56%). CONCLUSIONS: The high incidence of ADRs because of treatment withdrawal revealed the need for safer alternatives for CD treatment.

Therapeutic drug monitoring of benznidazole and nifurtimox: a systematic review and quality assessment of published clinical practice guidelines

Abstract The pharmacological management of adults with chronic-phase Chagas disease is challenging despite it being the recent focus of extensive research. One of the challenges in the current clinical practice guidelines (CPGs) landscape is the existence of non-evidence-based recommendations for the use of laboratory tests in treatment monitoring. This study aimed to systematically assess the quality and consistency of recommendations of CPGs on the pharmacological management of adults with chronic-phase Chagas disease. Systematic literature searches were conducted in MEDLINE, EMBASE, SciELO and Google to identify all published CPGs relevant to the pharmacological management of Chagas disease, between January 2010 and March 2016. Three independent reviewers assessed the quality of each CPG using the Appraisal of Guidelines Research and Evaluation (AGREE) II instrument. A total of five CPGs were included and the overall quality of the guidelines for therapeutic drug monitoring of Chagas disease was moderate-to-low. There was considerable variation in the quality of the CPGs across the AGREE II domains. The domains of scope/purpose, stakeholder involvement, and clarity of presentation were rated well, and the domains of applicability and editorial independence received poor ratings. This review showed that the methodological quality of CPGs for Chagas disease was generally inappropriate, and there was no explicit link between the best available evidence and current recommendations.

Pharmacotherapeutic follow-up of patients with Chagas disease using benznidazole: drug-related problems and pharmaceutical interventions

Abstract INTRODUCTION Benznidazole (BNZ) is a drug available for the etiological treatment of Chagas disease. However, this drug is toxic and has a limited effectiveness on the chronic phase of this disease, often leading to poor treatment adherence. METHODS: This is a descriptive and exploratory study conducted at the Pharmaceutical Care Service for Chagas disease patients of the Federal University of Ceará. Drug-related problems (DRPs) and pharmaceutical interventions (PIs) were classified according to the Second Consensus of Granada. RESULTS: The average age of patients with Chagas disease was 62 years, with the majority residing in the Ceará countryside (86.7%), and having low education levels (63.3% with elementary school education). Regarding family income, most patients belonged to a household that earned ≤1-2 times the minimum wage per month. Approximately 73% of these patients complied with the BNZ treatment, and nearly 7% underwent therapy interruption after medical evaluation. A total of 189 DRPs were identified, of which 51.9% (n=98) were classified as potential, and 48.1% (n=91) as actual. The most frequent DRPs were related to safety (qualitative safety; n=70; 37%), necessity (non-adherence; n=52; 27.5%), and effectiveness (qualitative effectiveness/non-optimal drug selection; n=45; 23.8%). Among the 216 PIs conducted, the majority were related to patient education (n=168; 77.8%) and pharmacological strategy (n=42; 19.4%). CONCLUSIONS: This study indicates the need for pharmacotherapeutic monitoring in patients with Chagas because of the high number of therapeutic interventions, DRPs (approximately 3 DRPs/patient), BNZ adherence, and polypharmacy.

Chronic Chagas cardiomyopathy: a review of the main pathogenic mechanisms and the efficacy of aetiological treatment following the BENznidazole Evaluation for Interrupting Trypanosomiasis (BENEFIT) trial

Chagas cardiomyopathy is the most frequent and most severe manifestation of chronic Chagas disease, and is one of the leading causes of morbidity and death in Latin America. Although the pathogenesis of Chagas cardiomyopathy is incompletely understood, it may involve several mechanisms, including parasite-dependent myocardial damage, immune-mediated myocardial injury (induced by the parasite itself and by self-antigens), and microvascular and neurogenic disturbances. In the past three decades, a consensus has emerged that parasite persistence is crucial to the development and progression of Chagas cardiomyopathy. In this context, antiparasitic treatment in the chronic phase of Chagas disease could prevent complications related to the disease. However, according to the results of the BENEFIT trial, benznidazole seems to have no benefit for arresting disease progression in patients with chronic Chagas cardiomyopathy. In this review, we give an update on the main pathogenic mechanisms of Chagas disease, and re-examine and discuss the results of the BENEFIT trial, together with its limitations and implications.

High seroconversion rates in Trypanosoma cruzi chronic infection treated with benznidazole in people under 16 years in Guatemala

Abstract INTRODUCTION: Geographical, epidemiological, and environmental differences associated with therapeutic response to Chagas etiological treatment have been previously discussed. This study describes high seroconversion rates 72 months after benznidazole treatment in patients under 16 years from a project implemented by Doctors without Borders in Guatemala. METHODS: An enzyme-linked immunosorbent assay was used to detect Trypanosoma cruzi IgG antibodies in capillary blood samples from patients 72 months after treatment. Fisher's exact test was used to establish association between characteristics, such as sex, age, and origin of patients, and final seroconversion. Kappa index determined concordance between laboratory tests. The level of significance was set to 5%. RESULTS: Ninety-eight patients, aged 6 months to 16 years, were available for follow-up. Sex and origin were not associated with seroconversion. Individuals older than 13 were more prone to maintain a positive result 72 months after treatment, although results were not highly significant. Laboratory tests presented elevated Kappa concordance (95% CI) = 0.8290 (0.4955-1), as well as high (97%) seroconversion rates. CONCLUSIONS: The high seroconversion rate found in this study emphasizes the importance of access to diagnosis, treatment, and follow-up of individuals affected by Chagas disease. Moreover, it contradicts the idea that it is not possible to achieve a cure with the currently available drugs. This study strongly supports expanding programs for patients infected with T. cruzi in endemic and non-endemic countries.

Chronic Heart Disease after Treatment of Oral Acute Chagas Disease / Cardiopatia Crônica após Tratamento de Doença de Chagas Aguda Oral

Abstract We describe the recurrence of cardiac abnormalities in a patient treated during the acute phase of Chagas disease after outpatient follow-up of 5 years.

Resumo Descreve-se a recorrência de alterações cardíacas em paciente tratado na fase aguda de doença de Chagas, após seguimento ambulatorial de 5 anos.

Serological based monitoring of a cohort of patients with chronic Chagas disease treated with benznidazole in a highly endemic area of northern Argentina

This study aimed to evaluate well-documented diagnostic antigens, named B13, 1F8 and JL7 recombinant proteins, as potential markers of seroconversion in treated chagasic patients. Prospective study, involving 203 patients treated with benznidazole, was conducted from endemic areas of northern Argentina. Follow-up was possible in 107 out of them and blood samples were taken for serology and PCR assays before and 2, 3, 6, 12, 24 and 36 months after treatment initiation. Reactivity against Trypanosoma cruzi lysate and recombinant antigens was measured by ELISA. The rate of decrease of antibody titers showed nonlinear kinetics with an abrupt drop within the first three months after initiation of treatment for all studied antigens, followed by a plateau displaying a low decay until the end of follow-up. At this point, anti-B13, anti-1F8 and anti-JL7 titers were relatively close to the cut-off line, while anti-T. cruzi antibodies still remained positive. At baseline, 60.8% (45/74) of analysed patients tested positive for parasite DNA by PCR and during the follow-up period in 34 out of 45 positive samples (75.5%) could not be detected T. cruzi DNA. Our results suggest that these antigens might be useful as early markers for monitoring antiparasitic treatment in chronic Chagas disease.

Modulation of Trypanosoma cruzi-specific T-cell responses after chemotherapy for chronic Chagas disease

The aim of this review is to describe the contributions of the knowledge of T-cell responses to the understanding of the physiopathology and the responsiveness to etiological treatment during the chronic phase of Chagas disease. T-helper (Th)1 and interleukin (IL)-10 Trypanosoma cruzi-specific T-cells have been linked to the asymptomatic phase or to severe clinical forms of the disease, respectively or vice versa, depending on the T. cruzi antigen source, the patient’s location and the performed immunological assays. Parasite-specific T-cell responses are modulated after benznidazole (BZ) treatment in chronically T. cruzi-infected subjects in association with a significant decrease in T. cruzi-specific antibodies. Accumulating evidence has indicated that treatment efficacy during experimental infection with T. cruzi results from the combined action of BZ and the activation of appropriate immune responses in the host. However, strong support of this interaction in T. cruzi-infected humans remains lacking. Overall, the quality of T-cell responses might be a key factor in not only disease evolution, but also chemotherapy responsiveness. Immunological parameters are potential indicators of treatment response regardless of achievement of cure. Providing tools to monitor and provide early predictions of treatment success will allow the development of new therapeutic options.

Biomarkers of therapeutic responses in chronic Chagas disease: state of the art and future perspectives

The definition of a biomarker provided by the World Health Organization is any substance, structure, or process that can be measured in the body, or its products and influence, or predict the incidence or outcome of disease. Currently, the lack of prognosis and progression markers for chronic Chagas disease has posed limitations for testing new drugs to treat this neglected disease. Several molecules and techniques to detect biomarkers in Trypanosoma cruzi-infected patients have been proposed to assess whether specific treatment with benznidazole or nifurtimox is effective. Isolated proteins or protein groups from different T. cruzi stages and parasite-derived glycoproteins and synthetic neoglycoconjugates have been demonstrated to be useful for this purpose, as have nucleic acid amplification techniques. The amplification of T. cruzi DNA using the real-time polymerase chain reaction method is the leading test for assessing responses to treatment in a short period of time. Biochemical biomarkers have been tested early after specific treatment. Cytokines and surface markers represent promising molecules for the characterisation of host cellular responses, but need to be further assessed.

Avaliação das quimiocinas e da expressão de seus receptores em células mononucleares de pacientes portadores da doença de Chagas submetidas à infecção in vitro com Trypanosoma cruzi e tratamento com benzonidazol / Evaluation of chemokines and their receptors expression in patient mononuclear patients of Chagas disease undergoing in vitro infection with Trypanosoma cruzi and treatment with benznidazole

Atualmente o Brasil apresenta 3 milhões de indivíduos portadores da cardiomiopatia chagásica. Porém, tratamento etiológico com o fármaco Benzonidazol (BZ) na fase crônica da doença ainda não está elucidado. Acredita-se que a recomendação do BZ nessa fase, pode prevenir ou retardar a evolução clínica da cardiomiopatia na Doença Chagas (DC). Assim o objetivo do estudo é avaliar a produção de quimiocinas e expressão de seus receptores em Células mononucleares do sangue periférico - PBMC (de portadores crônicos da doença de Chagas) submetidas in vitro ao tratamento com BZ, após a infecção com T.cruzi. Foram selecionados 11 pacientes na fase crônica da doença. Amostras de sangue desses pacientes foram coletadas para obtenção de PBMC, em que foram cultivadas em placas de cultivo na concentração de 106 células/ml por poço. Após a adesão das células aderentes (principalmente macrófagos), as células não aderentes (principalmente linfócitos) foram removidas e as formas tripomastigotas foram adicionadas ao cultivo para infecção das células aderentes. Subsequente a incubação, as células não aderentes foram adicionadas novamente ao cultivo juntamente com o fármaco Bz (1µg/mL), ficando um co-cultivo de células aderentes infectadas com T.cruzi, células não aderentes e o BZ (C+T+BZ). As placas de cultura foram incubadas por períodos de 24h e 5 dias. Para uma análise fidedigna da ação do BZ nas células aderentes e não aderentes foi necessário a criação dos controles: células (C), células e tripomastigotas (C+T) e células e o BZ (C+BZ). Após o cultivo, foram coletados os sobrenadantes das culturas, para avaliação da produção de quimiocinas (CCL2, CXL9, CXL10, CCL5 e CXCL8) por CBA (Cytometric Bead Array). Posteriormente foi realizada a imunofenotipagem...

Experiencia terapéutica en un centro para la enfermedad de Chagas / Therapeutic experience in a Chagas disease center

American Trypanosomiasis or Chagas Disease is a major public health problem, endemic in the American continent since prehistoric times. Its natural course is towardschronicity in the immunocompetent host, often leading to severe cardiopathy or bowelinvolvement. Pharmacologic therapy is restricted to two drugs and only one of themis currently available in Chile. Both have poor effectiveness in the chronic stages ofthe disease and cause frequent adverse reactions. Many physicians avoid their use,despite published evidences about the usefulness. We herein report the experienceof our Center in the treatment of Chronic Chagas Disease in adults using the drugnifurtimox, emphasizing its degree of acceptability and its secondary effects.

Evaluation of the ELISA-F29 test as an early marker of therapeutic efficacy in adults with chronic Chagas disease / Avaliação do tratamento tripanossomicida em coorte de adultos chagásicos crônicos através de técnicas sorológicas convencionais e ELISA-F29

This work compared the time at which negative seroconversion was detected by conventional serology (CS) and by the ELISA-F29 test on a cohort of chronic chagasic patients treated with nifurtimox or benznidazole. A retrospective study was performed using preserved serum from 66 asymptomatic chagasic adults under clinical supervision, and bi-annual serological examinations over a mean follow-up of 23 years. Twenty nine patients received trypanocide treatment and 37 remained untreated. The ELISA-F29 test used a recombinant antigen which was obtained by expressing the Trypanosoma cruzi flagellar calcium-binding protein gene in Escherichia coli. Among the untreated patients, 36 maintained CS titers. One patient showed a doubtful serology in some check-ups. ELISA-F29 showed constant reactivity in 35 out of 37 patients and was negative for the patient with fluctuating CS. The treated patients were divided into three groups according to the CS titers: in 13 they became negative; in 12 they decreased and in four they remained unchanged. ELISA-F29 was negative for the first two groups. The time at which negativization was detected was significantly lower for the ELISA-F29 test than for CS, 14.5 ± 5.7 and 22 ± 4.9 years respectively. Negative seroconversion was observed in treated patients only. The results obtained confirm that the ELISA-F29 test is useful as an early indicator of negative seroconversion in treated chronic patients.

Este trabalho comparou os tempos de soroconversão negativos obtidos pela sorologia convencional (CS) e teste ELISA-F29 em uma coorte de pacientes chagásicos crônicos tratados com nifurtimox ou benznidazol. Um estudo retrospectivo foi realizado com soro preservado de 66 adultos chagásicos assintomáticos com acompanhamento clínico e sorológico semestral ao longo de um seguimento médio de 23 anos. 29 pacientes receberam tratamento tripanossomicida e 37 outras permaneceram sem tratamento. O teste ELISA-F29 usou um antígeno recombinante obtido por expressão do gene de uma proteína flagelar de Trypanosoma cruzi de ligação de cálcio em Escherichia coli. Entre os pacientes não tratados, 36 mantiveram os títulos da CS. Um paciente apresentou sorologia duvidosa em alguns controles. ELISA-F29 apresentou reatividade constante em 35/37 e foi negativo no paciente com CS flutuante. Os pacientes tratados foram agrupados de acordo com os títulos da CS, em três grupos: 13 tornaram-se negativos, 12 diminuíram e quatro permaneceram inalterados. ELISA-F29 foi negativo nos dois primeiros grupos. O tempo de negativização foi significativamente menor para o teste ELISA-F29 do que para CS (14,5 ± 5,7 e 22 ± 4,9 anos, respectivamente). A soroconversão negativa foi observada somente nos pacientes tratados. Os resultados obtidos confirmam que o teste ELISA-F29 é útil como um indicador precoce de soronegativação em pacientes crônicos tratados.

Eficacia de nifurtimox para el tratamiento de pacientes con enfermedad de Chagas crónica / Efficacy of nifurtimox for the treatment of chronic Chagas disease

Background: Most Chagas patients belong to the chronic indeterminate stage, in which pharmacological treatment has an inconclusive outcome. Objective: To evaluate the efficacy of nifurtimox treatment in chronic asymptomatic Trypanosoma cruzi infection. Methods: We performed a systematic review and meta-analysis of electronically published literature, with no language, type of study, age or gender restrictions, until September 2010. Studies of chronic asymptomatic Chagas disease patients treated exclusively with nifurtimox were included in the analysis. Treatment efficacy was evaluated using parasitological or serological parameters. Results: Of 463 identified studies, 7 were finally selected: 6 observational studies and 1 randomized clinical trial; 4 of the studies were in adults, 3 in children < 14 years. In 6 studies, outcomes were defined by serological techniques. Summary estimate (log odds) was 0.37 (CI9 -1.32 - 2.07). Conclusions: The analyzed studies gave discordant results. Those might be explained by differences in the populations studied, follow-up periods, diagnostic techniques, and sample size. More studies are necessary to obtain conclusive results about treatment efficacy of nifurtimox in this clinical phase of T. cruzi infection.

Introducción: La mayoría de los pacientes con enfermedad de Chagas se encuentran en fase crónica indeterminada donde los resultados de tratamiento farmacológico no han sido concluyentes. Objetivo: Evaluar la evidencia que apoya la eicacia del tratamiento con nifurtimox en la infección crónica por Trypanosoma cruzi asintomática. Método: Revisión sistemática y meta-análisis de literatura publicada en forma electrónica, sin restricción de lenguaje, tipo de estudio, edad y género, hasta septiembre de 2010. Se incluyeron estudios de pacientes con enfermedad de Chagas crónica asintomáticos que recibieron tratamiento exclusivo con nifurtimox. La eicacia del tratamiento fue evaluada mediante métodos parasitológicos o serológicos. Resultados: Se identiicaron 463 estudios primarios seleccionando inalmente siete: seis observacionales y un ensayo clínico randomizado; cuatro en pacientes adultos y tres en niños bajo14 años de edad. En seis estudios los resultados se midieron mediantes técnicas serológicas. La medida resumen (log de la chance) fue de 0,37 (IC95% -1,32 -2,07). Conclusiones: Los resultados son discordantes. La incertidumbre se maniiesta por las diferencias en las poblaciones estudiadas, periodos de seguimiento, técnicas diagnósticas y tamaño de las muestras. Es necesario realizar nuevos estudios que consideren las fuentes de incertidumbre para obtener resultados concluyentes sobre la eicacia del nifurtimox en esta fase clínica de la infección por T. cruzi.

Co-infection Trypanosoma cruzi/HIV: systematic review (1980 - 2010) / Coinfecção Trypanosoma cruzi/HIV: revisão sistemática (1980 - 2010)

INTRODUCTION: The co-infection Trypanosoma cruzi/HIV has been described as a clinical event of great relevance. The objective of this study wasto describe clinical and epidemiological aspects published in literature. METHODS: It is a systematic review of a descriptive nature from the databases Medline, Lilacs, SciELO, Scopus, from 1980 to 2010. RESULTS: There were 83 articles (2.8 articles/year) with a total of 291 cases. The co-infection was described in 1980 and this situation has become the defining AIDS clinical event in Brazil. This is the country with the highest number of publication (51.8 percent) followed by Argentina (27.7 percent). The majority of cases are amongst adult men (65.3 percent) native or from endemic regions with serological diagnosis in the chronic stage (97.9 percent) and indeterminate form (50.8 percent). Both diseases follow the normal course, but in 41 percent the reactivation of the Chagas disease occurs. The most severe form is the meningoencephalitis, with 100 percent of mortality without specific and early treatment of the T. cruzi. The medication of choice was the benznidazole on doses and duration normally used for the acute phase. The high parasitemia detected by direct or indirect quantitative methods indicated reactivation and its elevation is the most important predictive factor. The lower survival rate was related to the reactivation of the Chagas disease and the natural complications of both diseases. The role of the antiretroviral treatment on the co-infection cannot yet be defined by the knowledge currently existent. CONCLUSIONS: Despite the relevance of this clinical event there are still gaps to be filled.

INTRODUÇÃO: A coinfecção Trypanosoma cruzi/HIV vem sendo sistematicamente descrita como um evento clínico de grande relevância. O objetivo deste estudo foi descrever aspectos clínicos e epidemiológicos publicados na literatura científica. MÉTODOS: Trata-se de revisão sistemática, de natureza descritiva, a partir da busca nas bases Medline, Lilacs, SciELO, Scopus, de 1980 a 2010. RESULTADOS: Identificou-se 83 artigos (2,8 artigos/ano), com um total de 291 casos registrados. A coinfecção foi descrita em 1980 e, no Brasil, tornou-se evento clínico definidor de AIDS. Este é o país com maior número de publicações (51,8 por cento), seguido pela Argentina (27,7 por cento). A maioria dos casos é de homens adultos (65,3 por cento), naturais ou procedentes de regiões endêmicas, com diagnóstico sorológico, na fase crônica (97,9 por cento) e na forma indeterminada (50,8 por cento). As duas doenças evoluem naturalmente, mas em 41 por cento dos casos ocorreu reativação da doença de Chagas. A forma mais grave é a meningoencefalite, com 100 por cento de letalidade nos casos sem tratamento específico e precoce do T. cruzi. O medicamento indicado foi benznidazole, nas doses e duração utilizadas na fase aguda em imunocompetentes. O diagnóstico da reativação foi comprovado por alta parasitemia, detectada por métodos diretos ou indiretos quantitativos, sendo a sua elevação considerada fator preditivo para reativação. A menor sobrevida nacoinfecção esteve relacionada à reativação da doença de Chagas e às complicações naturais de ambas as doenças. O papel do tratamento antirretroviral sobre a evolução da coinfecção ainda não pode ser definido pelo conhecimento existente. CONCLUSÕES: Apesar da relevância deste evento clínico, ainda persistem lacunas a serem preenchidas.

Estado actual en el tratamiento de la enfermedad de Chagas / Update on the treatment of Chagas' disease

Efficient drugs against Chagas' disease must have an effect on the amastigote forms or intracellular reproduction elements of Trypanosoma cruzi (T. cruzi). Trypomastigote and epimastigote forms derive from the former and their response to medications is less marked. The only drugs used in humans are nifurtimox (NF) and benznidazole (BNZ). Other useful medications are allopurinol and itraconazole. NF acts producing free radicals and BNZ inhibits the synthesis of macromolecules. There is consensus that Chagas' disease must be treated in all its periods, since T.cruzi DNA is detected by polymerase chain reaction in chronic cases, even when microscopy is negative. The pharmacological treatment modifies the natural evolution of the disease. It also helps to solve a public health problem, considering that there is a high number of subjects with Chagas' disease. Subjects with chronic chagasic cardiomyopathy with terminal heart failure are the only cases without indication for treatment. Due to the digestive and skin secondary effects of the drugs, treated patients must be controlled clinically and with complete blood counts and hepatic proiles before, during and after the therapy. Approximately 30 percent of patients will experience secondary effects. Children have a better tolerance to the drugs. Congenital or acquired acute, intermediate and chronic cases should be treated.

Enfermedad de Chagas / Chagas disease

La enfermedad de Chagas es una antropozoonosis provocada por un protozoo flagelado el Trypanosoma cruzi, que se transmite a través de vectores hematófagos infectados. En nuestro país los vectores son Triatoma infestans y spinolai (vinchuca). Su reservorio es humano y alrededor de 150 especies de mamíferos. Se distribuye en toda América pero mayoritariamente en el Cono Sur, con al menos 12 millones de personas infectadas. Los mecanismos de transmisión son principalmente vectorial, transplacentario, transfusional, otras formas de contagio menos frecuentes son el trasplante de órganos, accidentes de laboratorio, transmisión oral y uso de jeringas contaminadas drogadictos). Esta enfermedad dependiendo de si afecta a personas inmunocompetentes presenta tres etapas: aguda, latente y crónica, afectando en forma variable a diversos órganos, principalmente corazón y el tubo digestivo. El compromiso cardíaco se caracteriza por dilatación progresiva y alteración del aparato exitoconductor provocando arritmias y bloqueos auriculoventriculares (AV). A nivel digestivo afecta principalmente al esófago y colon; ocasionando acalasia llevando a dilatación y alteración de la motilidad progresiva, cuyo síntoma clave es la disfagia que se asocia también a odinofagia y regurgitación. A nivel del colon, el Chagas provoca dilatación progresiva por denervación parasimpática intramural, llegando a formar el megacolon chagásico, el síntoma principal es la constipación. Los métodos diagnósticos son clínicos, imagenológicos y la detección de la infección parasitaria, ya sea a través de métodos directos o indirectos, dependiendo de la etapa de la infección. El tratamiento se basa en antiparasitarios principalmente el nifurtimox y benznidazol, ambos son tripanomicidas, con una efectividad de hasta el 76 por ciento dependiendo de la etapa en que se usa.

Chagas disease is an anthropozoonosis caused by the flagellate protozoan Trypanosoma cruzi. It is transmitted in our country by the infected haemophagic vectors Triatoma infestans and Triatoma spinolai. 150 mammal species and the human serve as reservoir of T. cruzi. Chagas disease is distributed throughout the Americas, mostly in the Southern Cone, with at least, 12 million of people infected. Transmission mechanisms are mainly vectorial, transplacentary and transfusional. Other less frequent sources of transmission are organ transplantation, laboratory accidents, oral ransmission and the sharing of contaminated needles among drug users. This disease, depending on the immune state of the affected subject, has three stages of development: acute, latent and chronic, involving several organs at different levels, mostly the heart and gastrointestinal tube. Heart involvement is characterized by progressive dilatation and alteration of the electrical conduction system causing arrhythmia and atrioventricular (AV) block. The digestive compromise affects mainly esophagus and colon. It causes achalasia of the esophagus which causes dilatation and alteration of the propulsive motility with dysphagia being associated to odinophagia and regurgitation. Chagas disease causes progresive colonic dilatation by intramural parasympathetic denervation, reaching Chagasic megacolon with constipation as the characteristic symptom. Diagnostic techniques are clinic, imagenologic, and the detection of the parasitary infection through direct or indirect methods, depending on the stage of the infection. Treatment is based on antiparasitic drugs, mainly Nifurtimox and Benznidazol, both are trypanomicides, with up to 76 percent efficacy, depending on the stage of the disease when they are used.

In vitro and in vivo experimental models for drug screening and development for Chagas disease

Chagas disease, a neglected illness, affects nearly 12-14 million people in endemic areas of Latin America. Although the occurrence of acute cases sharply has declined due to Southern Cone Initiative efforts to control vector transmission, there still remain serious challenges, including the maintenance of sustainable public policies for Chagas disease control and the urgent need for better drugs to treat chagasic patients. Since the introduction of benznidazole and nifurtimox approximately 40 years ago, many natural and synthetic compounds have been assayed against Trypanosoma cruzi, yet only a few compounds have advanced to clinical trials. This reflects, at least in part, the lack of consensus regarding appropriate in vitro and in vivo screening protocols as well as the lack of biomarkers for treating parasitaemia. The development of more effective drugs requires (i) the identification and validation of parasite targets, (ii) compounds to be screened against the targets or the whole parasite and (iii) a panel of minimum standardised procedures to advance leading compounds to clinical trials. This third aim was the topic of the workshop entitled Experimental Models in Drug Screening and Development for Chagas Disease, held in Rio de Janeiro, Brazil, on the 25th and 26th of November 2008 by the Fiocruz Program for Research and Technological Development on Chagas Disease and Drugs for Neglected Diseases Initiative. During the meeting, the minimum steps, requirements and decision gates for the determination of the efficacy of novel drugs for T. cruzi control were evaluated by interdisciplinary experts and an in vitro and in vivo flowchart was designed to serve as a general and standardised protocol for screening potential drugs for the treatment of Chagas disease.

Chagas disease: Present status of pathogenic mechanisms and chemotherapy

There are approximately 7.8 million people in Latin America, including Chile, who suffer from Chagas disease and another 28 million who are at risk of contracting it. Chagas is caused by the flagellate protozoan Trypanosoma cruzi. It is a chronic disease, where 20 percent-30 percent of infected individuals develop severe cardiopathy, with heart failure and potentially fatal arrhythmias. Currently, Chagas disease treatment is more effective in the acute phase, but does not always produce complete parasite eradication during indeterminate and chronic phases. At present, only nifurtimox or benznidazole have been proven to be superior to new drugs being tested. Therefore, it is necessary to find alternative approaches to treatment of chronic Chagas. The current treatment may be rendered more effective by increasing the activity of anti-Chagasic drugs or by modifying the host's immune response. We have previously shown that glutathione synthesis inhibition increases nifurtimox and benznidazole activity. In addition, there is increasing evidence that cyclooxygenase inhibitors present an important effect on T. cruzi infection. Therefore, we found that aspirin reduced the intracellular infection in RAW 264.7 cells and, decreased myocarditis extension and mortality rates in mice. However, the long-term benefit of prostaglandin inhibition for Chagasic patients is still unknown.