EPIDEMIOLOGIC SURVEY OF INFECTION WITH HEPATITIS-B VIRUS IN THE SAVANNA AND WETLANDS (PANTANAL) OF CENTRAL BRAZIL

An epidemiological survey of the prevalence of hepatitis B virus (HBV) was conducted in the county of Nossa Senhora do Livramento, Mate Gros so state, central Brazil. This rural county has a largely stationary p opulation of low socio-economic status, and is divided into savannah-t ype vegetation and wetland. Overall, 740 subjects aged > 9 years were selected at random, interviewed and bled so that seropositivities of v arious HBV markers (surface antigen and antibodies to this antigen and to core antigen) could be determined. At least one marker was found i n 169 (22.8%) of the subjects but only nine (1.2%) carried the surface antigen. Vegetation type (wetland v. savannah) was not associated wit h HBV infection but male gender, increasing age, and having had sexual experience were each associated with the infection. The prevalence of HBV markers was higher in immigrants (32.5%) than in native individua ls (21.1%), many immigrants apparently having acquired the infection b efore settling: in the study area.