Dogs play a major role in the domestic cycle of Trypanosoma cruzi, acting as reservoirs. In a previous work we have developed a model of vaccination of dogs in captivity with nonpathogenic Trypanosoma rangeli epimastigotes, resulting in the production of protective antibodies against T. cruzi, with dramatic decrease of parasitaemia upon challenge with 100,000 virulent forms of this parasite. The aim of this work was to evaluate the immunogenicity of this vaccine in dogs living in a rural area. Domestic dogs, free from T. cruziinfection, received three immunisations with fixed T. rangeliepimastigotes. Dogs were not challenged with T. cruzi, but they were left in their environment. This immunisation induced antibodies againstT. cruzi for more than three years in dogs in their natural habitat, while control dogs remained serologically negative.

In America, there are two species of Trypanosoma that can infect humans: Trypanosoma cruzi, which is responsible for Chagas disease and Trypanosoma rangeli, which is not pathogenic. We have developed a model of vaccination in mice with T. rangeli epimastigotes that protects against T. cruzi infection. The goal of this work was to study the pattern of specific immunoglobulins in the peritoneum (the site of infection) and in the sera of mice immunized with T. rangeli before and after challenge with T. cruzi. Additionally, we studied the effects triggered by antigen-antibodies binding and the levels of key cytokines involved in the humoral response, such as IL-4, IL-5 and IL-6. The immunization triggered the production of antibodies reactive with T. cruzi in peritoneal fluid (PF) and in serum, mainly IgG1 and, to a lesser magnitude, IgG2. Only immunized mice developed specific IgG3 antibodies in their peritoneal cavities. Antibodies were able to bind to the surface of the parasites and agglutinate them. Among the cytokines studied, IL-6 was elevated in PF during early infection, with higher levels in non-immunized-infected mice. The results indicate that T. rangeli vaccination against T. cruzi infection triggers a high production of specific IgG isotypes in PF and sera before infection and modulates the levels of IL-6 in PF in the early periods of infection.

Chagas disease, which is caused by Trypanosoma cruzi, affects nearly 16 million people in Latin America and causes 75-90 million people to be at risk of infection. The disease is urbanizing and globalizing due to frequent migrations. There are regions of high prevalence of infection, including the north-eastern provinces of Argentina and the entire phytogeographic region known as the Gran Chaco. In the province of Chaco, Argentina, there are places inhabited by native populations such as the Wichi and Toba communities, among others. Many Creole populations resulting from miscegenation with European colonists and immigrants coexist within these communities. It has been widely accepted that in the chronic phase of the disease, between 25-30% of individuals develop some form of cardiac disease, with the right bundle-branch block being the most typical condition described so far. The aim of this work was to study the prevalence of Chagas infection and its electrocardiographic profile in the Wichi and Creole populations of Misión Nueva Pompeya, in the area known as Monte Impenetrable in Chaco, to determine the prevalence and the pattern of heart diseases produced by Chagas disease in this region.

INTRODUÇÃO: A doença de Chagas é causada pelo Trypanosoma cruzi e os mamíferos periantrópicos e silvestres mantêm o ciclo de infecção/transmissão, tanto no ambiente natural, como no peridomicílio. O objetivo deste trabalho foi mostrar os resultados de um estudo de roedores silvestres do centro e norte da Província de San Luis, Argentina, para avaliar a prevalência da infecção. MÉTODOS: Estabeleceram-se lugares de caça com armadilhas tipo Sherman entre os 32º - 33º de latitude S e 65º - 66º de longitude W. Identificou-se taxonomicamente os roedores, isolou-se os hemoflagelados e fizeram-se estudos morfológicos, biométricos, moleculares, cultivo in vitro, infecção a animais de laboratório, histologia de músculo cardíaco e de zona de inoculação. Observou-se parasitas em sangue circulante: Calomys musculinus, Graomys griseoflavus, Phyllotis darwini e Akodon molinae. A identificação dos parasitas foi feita utilizando critérios biológicos e, em alguns, realizou estudos moleculares por PCR que confirmaram a caracterização desses hemoflagelados como Trypanosoma cruzi. RESULTADOS E CONCLUSÕES: Dos 25 isolados, 44% foram identificados como Trypanosoma cruzi e 56% como Trypanosoma cruzi like. Este achado nos induz a considerar a importância dos ratos do mato infectados com Trypanosoma cruzi y Trypanosoma cruzi like, em área de baixa endemicidade.

INTRODUCTION: Chagas disease is caused by Trypanosoma cruzi. Wild and perianthropic mammals maintain the infection/transmission cycle, both in their natural habitat and in the peridomestic area. The aim of this paper was to present the results from a study on wild rodents in the central and northern regions of San Luis province, Argentina, in order to evaluate the prevalence of this infection. METHODS: Sherman traps were set up in capture areas located between latitudes 32º and 33º S, and longitudes 65º and 66º W. The captured rodents were taxonomically identified and hemoflagellates were isolated. Morphological, biometric and molecular studies and in vitro cultures were performed. Infection of laboratory animals and histological examination of the cardiac muscle and inoculation area were also carried out. Parasites were detected in circulating blood in Calomys musculinus, Graomys griseoflavus, Phyllotis darwini and Akodon molinae. The parasites were identified using biological criteria. Molecular PCR studies were performed on some isolates, which confirmed the characterization of these hemoflagellates as Trypanosoma cruzi. RESULTS AND CONCLUSIONS: Forty-four percent of the 25 isolates were identified as Trypanosoma cruzi, and the remaining 56% as Trypanosoma cruzi-like. These findings provide evidence that wild rats infected with Trypanosoma cruzi and Trypanosoma cruzi-like organisms are important in areas of low endemicity.

In our laboratory, we have developed a model of vaccination in mice with Trypanosoma rangeli, a non-pathogenic parasite that shares many antigens with Trypanosoma cruzi. The vaccinated mice were protected against infection with virulent T. cruzi. The goal of the present work was to study the protective activity of strains of T. rangeli of different origin, with the aim of analysing whether this protective capacity is a common feature of T. rangeli. BALB/c mice were vaccinated with live or fixed epimastigotes of two T. rangeli strains, Choachi and SC-58. Vaccinated (VM) and control mice (CM) were infected with virulent T. cruzi, Tulahuen strain. The results showed that the levels of parasitemia of VM, vaccinated with the two strains of T. rangeli were significantly lower than those developed in CM. The survival rate of VM was higher than that CM. Histological studies revealed many amastigote nests and severe inflammatory infiltrates in the heart and skeletal muscles of CM, whereas in the VM only moderate lymphomonocytic infiltrates were detected. Altogether, the results of the present work as well as previous studies show that the antigens involved in the protection induced by T. rangeli are expressed in different strains of this parasite. These findings could prove useful in vaccine preparation.

Se descrevem 3 gestantes com a doença de Chagas aguda. Duas gestantes infetadas no 3º trimestre de gestação não tiveram crianças infetadas. O 3º filho, doquella madre foi infetada no 1º trimestre, nasceu com doença de Chagas congénita. Estes resultados inducem a investigação sobre os fatores de riscos da transmição e sobre as desições médicas na conducção dos casos de gestantes com a doença de Chagas aguda.

We studied three pregnant women with acute chagasic infection. Two patients, infected in the third trimester of pregnancy, had uninfected children. The third patient, infected earlier, had an infected newborn. These results encourage research on risk factors of transmission and on medical decisions concerning pregnant women with acute Chagas' disease.

Oral mucosal transudate (OMT) is a biological fluid that can be obtained by an absorbent pad placed between lower cheek and gum, and contains20% IgG, 40% IgA and 10% IgM comparing with serum. The aim of this work was to analyse the performance of OMT as biological material to detect antibodies in Chagas' disease and Toxoplasmosis. Sera of ambulatory patients, pregnant women and healthyvolunteers were tested for Chagas and Toxoplasmosis employingImmunofluorescence, ELISA andHemagglutination.OMT of the same patients were assayed by ELISA, and the results compared to determinate sensibility, specificity and predictive value. In Chagas serology, three different commercial kits were assayed. The sensibility ranged from 91 to 100%,specificitybetween 90 and 100%. The predictive values oscillate between 95% and 99%. The studies in Toxoplasmosis did not shown false positive results. The sensibility was 95%, specificity 100% and the predictive values between 98% and100%. Sera from neonates born from Toxoplasmosis infected mothers were also studied, and the results were in agreement with reference tests. These results suggest that OMT could be a suitable alternative biological fluid in immunoepidemio-logical surveys, and also as screening test in the diagnosis and prevention of materno-fetal transmission of infectious diseases.

El Trasudado Mucoso Oral (TMO) es un fluido biológico que puede obtenerse mediante una almohadilla absorbente colocada entre la encía y la mejilla inferior y que contiene 20% de IgG, 40% de IgA y 10% de IgM en relación al suero. El objetivo del trabajo fue analizar la confiabilidad del TMO como muestra biológica para la detección de anticuerpos en Chagas y Toxoplasmosis. Sueros de pacientes ambulatorios, embarazadas y voluntarios sanos fueron estudiados para Chagas y Toxoplasmosis empleando Inmunofluorescencia, ELISA y Hemaglutinación. Las muestras de TMO fueron estudiadas por ELISA y los resultados comparados con los métodos de referencia para determinar sensibilidad (S), especificidad (E), valor predictivo positivo (VPP) y valor predictivo negativo (VPN). En Chagas, la sensibilidad osciló entre 91% y 100% con tres diferentes equipos ensayados, mientras la especificidad varió entre 90 y 100%, el VPP entre 95% y 96% y el VPN entre 97% y 99%. En Toxoplasmosis no se detectaron resultados falsos positivos (S 95%, E 100%, VPP 100% y VPN 98%). Estos resultados sugieren que el TMO puede ser un fluido biológico alternativo adecuado para estudios inmunoepidemiológicos y también servir como screening en el diagnóstico y prevención de la transmisión vertical de enfermedades infecciosas.