Seroprevalence of viral hepatitis in riverine communities from the westernregion of the Brazilian Amazon Basin

The western region of the Brazilian Amazon Basin has long been shown to be a highly endemic area for hepatitis B and hepatitis D viruses. Data concern ing the Prevalence of hepatitis C and E viruses in this region are still sc arce. In this study we investigated the presence of hepatitis A, B, C, D an d E viruses infection in communities that live along the Purus and Acre riv ers in the states of Acre and Amazonas within the Amazon Basin. A total of 349 blood samples were collected and tested for hepatitis A-E serological m arkers (antibodies and/or antigens) using commercial enzyme linked immunoso rbent assays. Anti-HCV positive sera were further assayed by an immunoblot. HBsAg positive sera were subtyped by immunodifusion. The overall prevalenc e for hepatitis A, B, C, and E were 93.7%, 66.1%, 1.7%, and 4%, respectivel y. A very high prevalence of delta hepatitis (66.6%) was found among HBsAg positive subjects. Hepatitis A, B and D viruses were shown to be largely di sseminated in this population, while hepatitis C and E viruses infection pr esented low prevalence rates in this region. The analysis of risk factors f or HBV infection demonstrated that transmission was closely associated with sexual activity.