Hepatitis B epidemiology and its relation to immunogenetic traits in South American Indians.

Serologic tests for hepatitis B prevalence and immunogenetic characterizations were carried out on a sample of 800 persons from several isolated tribes of the lower Amazon basin and the southern Andes. The prevalence of hepatitis B antigen carriers and of antibody to the surface antigen varied from one tribe to another, but were high in all the forest tribes. The serologic evidence indicated high infection rates early in life, but also an increasing proportion showing evidence of infection with increasing age. The frequency of past infections was not differentially associated with the antigen status of the mother or father. A higher proportion of infected males than females had antigenemia. Contrary to published reports, no association of antigenemia was found with any HLA-A, B or C antigen or immunoglobulin allotype, individually or interactively. Antibody prevalence, however, did differ in persons with different HLA haplotypes.