Occurrence and distribution of hepatitis B infection in the aboriginal population of Western Australia.

In 1986, the prevalences of hepatitis B surface antigen (HBsAg), and other serological markers of infection with hepatitis B virus in the Western Australian adult Aboriginal population, were estimated using a stratified random sample of 1,150 subjects. When the estimates were standardised to the age and sex distribution of the total population of aborigines aged 12 years or over, the prevalence of HBsAg was 7% (95% confidence interval 6-9%). The prevalence of any marker, that is HBsAg and/or hepatitis surface antibody (anti-HBs), was 49% (44-54%). The follow-up blood specimens obtained from three-fifths of the antigenemic subjects indicated that 96% (88-99%) were hepatitis B carriers. Male subjects had twice the prevalence of HBsAg (10%; 7-13%) when compared with females (4%; 3-6%). However, there was only a modest elevation of the prevalence of any marker in men (53%) compared with women (46%). There was evidence that the prevalence of HBsAg increased with age, but this was not the case with any marker. Geographically, there was substantial variation in hepatitis B infection rates. The Eastern Goldfields region had the highest prevalence (HBsAg 12%; any marker 66%), followed by the Kimberley, Pilbara and Central regions (HBsAg 7-9%; any marker 56-59%). The lowest rates were evident in Perth and the South West (HBsAg 3-5%; any marker 23-25%). The highest prevalence of markers in any discrete community was observed in the desert people of Warburton (HBsAg 22%; any marker 85%). These data indicate that, according to World Health Organisation criteria, the aboriginal population of Western Australia has an intermediate to high risk of infection with hepatitis B.