High prevalence of hepatitis B virus and hepatitis D virus in the western Brazilian Amazon.

Severe cases of hepatitis caused by hepatitis B virus (HBV) or hepatitis D virus (HDV) are often seen in the Brazilian Amazon, but there is a paucity of epidemiologic studies on viral hepatitis in this area. Thus, a cross-sectional study to investigate the prevalence of markers for HBV and HDV was performed. Serum samples were collected after participants completed an epidemiologic questionnaire. Markers for HBV and HDV were analyzed with an enzyme-linked immunosorbent assay. The HBV genotype was determined by sequencing of the gene for hepatitis B surface antigen (HBsAg). Of 2,656 samples, 89 (3.3%) were positive for HBsAg and 1,628 (61.5%) were positive for IgG antibody to hepatitis B core antigen. Markers for HDV were found in 47 cases (1.7%). Antibodies to HDV were associated with Amerindian ethnic origin, a lower educational level, a history of acute viral hepatitis, a history of malaria, male sex, a history of tattooing, and older age. The most frequent HBV genotypes were A and F. This study showed a high prevalence of HBV and HDV in the western Brazilian Amazon, as well as the predominance of HBV genotypes A and F.