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Polymerase chain reaction (PCR) as a diagnostic tool for congenital Chagas disease is scarcely used. To assess the usefulness of PCR, a study in neonates was carried out to compare PCR with standard methods; that is bloodstream parasites by microhematocrit, and/or seroconversion by two conventional procedures. Seventeen neonates, born to mothers with positive Trypanosoma cruzi serology were analyzed by serologic, parasitological and molecular procedures, in blood samples taken at birth, and when aged 2-4 and 9 months. For a better comparison of sensitivity between both parasitological methods (microhematocrit and PCR), the number of samples of neonates studied at birth extended to 121. In children followed-up until 9 months of age, a 100% correlation between PCR and routine diagnosis was found, with PCR showing its highest sensitivity from Month 2 onwards. Comparative analysis between both parasitological methods, on samples taken at birth, showed a higher sensitivity of PCR respect the microhematocrit (P < 0.0008).

Abstract. We have evaluated blood samples of chronic and congenital Trypanosoma cruzi -infected patients from the city of Reconquista located in the northeast of Argentina where no information was previously obtained about the genotype of infecting parasites. Fourteen samples of congenital and 19 chronical patients were analyzed by hybridization with DNA probes of minicircle hypervariable regions (mHVR). In congenital patients, 50% had single infections with TcIId, 7% single infections with TcIIe, 29% mixed infections with TcIId/e, and 7% had mixed infections with TcIId/b and 7% TcIId/b, respectively. In Chronical patients, 52% had single infections with TcIId, 11% single infections with TcIIe, 26% had mixed infections with TcIId/e, and 11% had non-identified genotypes. With these samples, we evaluated the minicircle lineage-specific polymerase chain reaction assay (MLS-PCR), which involves a nested PCR to HVR minicircle sequences and we found a correlation with hybridization probes of 96.4% for TcIId and 54.8% for TcIIe.

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Given that cardiovascular risk factors (CRF), such as smoking, alcoholism and hypertension, may contribute to the development of heart lesions, chronically Trypanosoma cruzi-infected individuals were studied to explore the relationship between the presence of such CRF, cardiomyopathy and antibodies that have been proposed to play a pathogenetic role in Chagas' disease. The targets of these antibodies were T. cruzi antigens such as cruzipain (Cz), a P ribosomal antigen (P2), and a component of myelin sheaths also present in T. cruzi (sulphatide). Individuals were classified into four groups on the basis of specific serology and presence of CRF: subjects with T. cruzi infection and CRF; those with positive serology and no CRF; seronegatives with CRF; and seronegatives without CRF, were analysed. Seronegatives or seropositives with CRF showed a greater occurrence of heart involvement (chest X-ray and/or electrocardiogram abnormalities). Seropositives with CRF displayed significantly higher levels of antisulphatide antibodies than the three remaining groups and higher levels of antibodies against Cz and P2 compared to the seropositives without CRF. Increased amounts of anti-P2 and antisulphatide antibodies were also found in seropositives with marked heart involvement. The presence of CRF is associated with a different profile of antibody responses and degree of cardiac effects.