Abstract. In 1991 and 1992, a prenatal screening of Trypanosoma cruzi infection was carried out using ELISA and indirect immunofluorescence techniques. A total of 840 blood samples from pregnant women, obtained at the Maternity Ward of the Hospital de Clínicas, National University of Asunción (Asunción, Paraguay), and 1,022 samples from the Regional Hospital of the San Pedro Department of Paraguay were examined. It was observed that 7.7% and 10.5%, respectively, of the pregnant women were serologically positive for infection with T. cruzi. When blood samples obtained from newborns on the day of birth or, at the most, on the first few days afterwards were examined by direct microscopic observation, an incidence of congenital transmission of 3% was found. These results are consistent with those of neighboring countries. When a serologic follow-up was conducted on the newborns until six months of age, the incidence of congenital transmission reached 10%. The same incidence rate was obtained when the samples collected during the first days after birth were examined by the polymerase chain reaction (PCR). Fiftyeight infants born to seropositive mothers were followed-up, two of which were positive by direct microscopic observation at birth, and four who were PCR-positive, but microscopy-negative at birth. None of the infants were positive for IgM at birth. The infected babies were treated with benznidazole and were followed-up by serology and PCR for four years. We conclude that the PCR has a clear advantage over conventional techniques for the early detection of congenital transmission of T. cruzi infection, and for monitoring infants undergoing chemotherapy.
Background: We present a picture of the biodiversity of Mycobacterium tuberculosis in Paraguay, an inland South American country harboring 5 million inhabitants with a tuberculosis notification rate of 38/100,000.
We describe a high frequency of the MIC null haplotype, HLA-B48-MICA-del-MICB*0107 N, in the Angaite Amerindian community in Paraguay. Of the 16 unrelated subjects, 9 (56.5%) had this haplotype. The structural analyses revealed this haplotype was similar to the previously reported Asian haplotype in that they had a large-scale deletion including the entire MICA gene and linked to MICB*0107 N and HLA-B*48. The novel recombination haplotype between this MIC null haplotype and HLA-B15, HLA-B15-MICA-del-MICB*0107 N, was also found in this community.
For the diagnosis of Chagas' disease, the trans-sialidase inhibition assay was able to resolve the results for samples with borderline results, to detect as positive 60% of samples that were negative by conventional serology, and to discriminate idiopathic from chagasic megaviscera or cardiopathy. No cross-reaction with sera from patients with other diseases was observed.
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