Hepatitis B in Australian Aborigines and Torres Strait Islanders: georgraphical, age and familial distribution of antigen subtypes and antibody.

Hepatitis B antigen of subtype ay is prevalent in Australian Aboriginal populations, but only subtype ad was found in Torres Strait Islanders. Both subtypes were found in Caucasion hepatitis patients and blood donors from Brisbane. Antigenaemia in Aborigines was more prevalent in Northern Territory than in Queensland, and in males in all areas, but different age distributions were found in Queensland (maximal over 30 years) and Northern Territory (maximal under 30 years). Family clustering was striking in all populations where genealogies were known. In a limited survey antibody was found to be more common than antigen in all Aboriginal groups, the prevalence increasing with age with a peak at 11 to 30 years. Hepatitis B virus infection was equally common in some areas of high and low arbovirus activity providing some evidence against arthropod transmission of hepatitis B virus in these areas.