Comparison of methodologies for detecting Trypanosoma cruzi parasites by microscopic observation of microhematocrit capillary tubes

Abstract INTRODUCTION: The microscopic examination of microhematocrit tubes (mHCT) has been proposed as the gold standard for acute and congenital Chagas disease diagnosis. We compared different mHCT methodologies detecting T. cruzi parasites in the blood. METHODS: The rotating method, water mount, and immersion oil methods were compared for their suitability, sensitivity, and specificity. RESULTS: The rotating method was easier, faster, and more sensitive than the others with 100% specificity. CONCLUSIONS: The rotating method is feasible for laboratory technicians with standard training in microscopic techniques and is recommended for the diagnosis of acute Chagas disease in primary health care facilities.

Vertical transmission of Trypanosoma cruzi in the Province of Choapa, IV Region, Chile: Preliminary Report (2005-2008)

Congenital Chagas disease acquired special importance in Chile after the certification of the control of Triatoma infestans and transmission by blood donors affected with Trypanosoma cruzi. In order to establish adequate protocols for intervention and control in infected mother-neonate pairs in endemic zones of Chagas disease, we present partial results (2005-2008) of a pilot project which is being carried out in the Province of Choapa, IV Region, Chile, whose objectives are: determine the current prevalence of the disease in pregnant women, estimate the incidence of vertical transmission of T. cruzi to newborns, determine the lineages of the parasite present in mothers who do and do not transmit the disease, determine the prevalence of Chagas disease in maternal grandmothers of neonates and study placental histopathology. Preliminary results indicated that in this study period, 3.7 percent of the women who gave birth in the Province have Chagas disease and 2.5 percent of their newborns were infected. The most frequent T. cruzi genotypes found in mothers studied during pregnancy were TCI and TCIId, either alone or in mixed infections. A high percentage (74.3 percent) of the grandmothers studied was infected with the parasite. In 29 placentas from mothers with Chagas disease we observed edema, necrosis, fibrinoid deposits and slight lymphoplasmocyte infiltration. In three placentas we found erythroblastosis and in one of them amastigote forms of T. cruzi; this was one of the cases of congenital infection. The evaluation of the diagnostic and control protocols generated will allow us to determine if it has been possible to modify the natural history of vertical transmission of T. cruzi in Chile.

Los fectos humanos estan capaces de generar una respuesta inmune T CD8 similar a la de los adultos / The human fetuses are be able to develep an adult-like immune CD8 T-cell response

Fetal/Neonatal immune responses are generally considered to be immature and weaker than in adults. We have sudied the cord blood T-cells of newborns congenitally-infected whith Tripanosoma cruzi, the protozoan agent of Chagas' disease. Our data demonstrate a predominant activation of CD8 T-cells expressing activation markers and armed to mediate effector functions. Indeed, we have detected parasite-specific CD8 T-cells secreting interferon-ã. Such response is enchanced in the presence of rIL-15. These findings point out that the fetal immune system is more competent than previously appreciated, since fetuses exposed to live pathogens are able to develop an adult-like immune CD8 T-cell response.