[Epidemiology of hepatitis B, C and D viruses among indigenous Parakanã tribe in the Eastern Brazilian Amazon Region].

This study sought to establish the prevalence of infection with the hepatitis B, C, and D viruses (HBV, HCV, and HDV) and to describe their transmission among the Parakanã, an indigenous tribe in Pará State, Brazil. This tribe's first contacts with broader Brazilian society occurred in the 1970s and 1980s. As of October 1992, the tribe consisted of 350 individuals, of whom 222 lived in the village of Paranatinga and 128 in the village of Maroxewara. Serum samples from 96.9% of this population were tested for markers of infection with the above-named viruses by means of enzyme immunoassays. Another 106 serum samples collected from Parakanã in the 1970s were also tested. The results obtained with the modern samples showed an overall prevalence of HBV infection of 84.7% among the residents of Paranatinga, 14.4% of whom were carriers. In Maroxewara, the overall prevalence of infection was only 17.7% and no carriers were detected in the study population. HBV carriers were negative for markers of HDV infection. The prevalence of HCV infection, confirmed by immunoblot, was 1.4% and 1.6% in Paranatinga and Maroxewara, respectively. Among the notable findings of this study were that horizontal transmission of HBV takes place at an early age in Paranatinga; that HBV infection prevalences differ greatly between two nearby villages belonging to the same tribe; that HCV infection was detected in both villages; and, from the historic sera, that the prevalence of HBV infection was low and HCV infection was absent during the first years in which the Parakanã people had outside contact.