RESUMEN
ABSTRACT Trypanosoma vivax caused between 1995 and 1997 a devastating disease in Bolivian and Brazilian Pantanals. These regions are very important beef cattle breeding in Brazil and Bolivia. The principal clinical signs of bovine trypanosomosis in livestock were anemia, severe leucopenia, and abortion. The purpose of the present study was to analyze the risk factors of the natural bovine trypanosomosis in the Bolivian and Brazilian Pantanals. We concluded that the principal risk factors related to T. vivax transmission in the Bolivian and Brazilian Pantanals were the transportation by foot, because the conditions for acquisition or transmission of T. vivax were greatest at the numerous resting places along the route, the use of contaminated needles during vaccinations, and transmission by tabanids during the rainy season. The fauna contamination should be also considered. Key-words: Bovine trypanosomosis, Trypanosoma vivax, risk factors, Bolivia, Brazil ABORDAGEM SOBRE OS FATORES DE RISCO DA TRIPANOSOMOSE BOVINA DEVIDO AO Trypanosoma vivax NOS PANTANAIS BOLIVIANO E BRASILEIRO RESUMO O Trypanosoma vivax causou entre 1995 e 1997 doença devastadora nos Pantanais da Bolívia e Brasil. Estas regiões são importantes criatórios de bovinos de corte nos dois países. Os principais sinais clínicos da tripanosomose bovina foram anemia, leucopenia severa e aborto. O propósito do
RESUMEN
ABSTRACT Trypanosoma vivax caused between 1995 and 1997 a devastating disease in Bolivian and Brazilian Pantanals. These regions are very important beef cattle breeding in Brazil and Bolivia. The principal clinical signs of bovine trypanosomosis in livestock were anemia, severe leucopenia, and abortion. The purpose of the present study was to analyze the risk factors of the natural bovine trypanosomosis in the Bolivian and Brazilian Pantanals. We concluded that the principal risk factors related to T. vivax transmission in the Bolivian and Brazilian Pantanals were the transportation by foot, because the conditions for acquisition or transmission of T. vivax were greatest at the numerous resting places along the route, the use of contaminated needles during vaccinations, and transmission by tabanids during the rainy season. The fauna contamination should be also considered. Key-words: Bovine trypanosomosis, Trypanosoma vivax, risk factors, Bolivia, Brazil ABORDAGEM SOBRE OS FATORES DE RISCO DA TRIPANOSOMOSE BOVINA DEVIDO AO Trypanosoma vivax NOS PANTANAIS BOLIVIANO E BRASILEIRO RESUMO O Trypanosoma vivax causou entre 1995 e 1997 doença devastadora nos Pantanais da Bolívia e Brasil. Estas regiões são importantes criatórios de bovinos de corte nos dois países. Os principais sinais clínicos da tripanosomose bovina foram anemia, leucopenia severa e aborto. O propósito do
RESUMEN
Information on infection with hepatitis C virus (HCV) in South America is scarce. The seroprevalences of antibodies to HCV among urban, rural and Amerindian populations from Venezuela, and the genotypes of the HCV isolates recovered, were therefore determined. A total of 2592 sera were tested with an immuno-assay which was developed in-house and based on synthetic peptides. Each reactive sample was then re-tested, using other enzyme immuno-assays and a reverse-transcription, nested PCR, and any sample confirmed positive (in any test) was considered HCV-positive. Genotypes were determined by analysis of RFLP. Overall, 39 (1.5%) of the samples were found HCV positive. The results of the immuno-assays indicated that the seroprevalence of HCV markers among the Amerindians investigated (23/1082, or 2.1%) was significantly higher than that among the other subjects (16/1510, or 1.1%; P = 0.02). No such difference was observed in the numbers of subjects confirmed positive by PCR, however (6/1082 v. 10/1510), and some of the anti-HCV reactivity observed among Amerindians may have been the result of cross-reactivity with parasitic infections. The relative low prevalence of active HCV infection (16/2582, or 0.6%) and the HCV genotypes observed (mainly genotype 1) are in agreement with the results of previous studies indicating that HCV is not autochthonous to South America. However, it is clear that the virus may now be found even in isolated Amerindian populations. The in-house, synthetic-peptide-based immuno-assay seems to be a valuable tool for epidemiological studies.