Objectives: To estimate the prevalence of chronic hepatitis B virus (HBV) infection in Australia and attributable proportions associated with specific demographic groups at higher risk of infection.
Methods: Two methods were used to estimate prevalence of HBV surface antigen (HBsAg): (1) Population-based: results of a national serosurvey using sera collected opportunistically from laboratories across Australia were used for 1-59 year olds, with the HBsAg prevalence for 50-59 years extrapolated to the population aged 60 years and over; (2) Risk group-based: estimates for selected high-risk groups (injecting drug users, homosexual men, Indigenous Australians and people born in high-prevalence countries), using source data from antenatal HBV screening in central Sydney, HBV prevalence studies, and estimates for low-risk groups (first-time blood donors) were combined proportionally to their representation in the population.
Results: Prevalence of HBsAg in the national serosurvey increased, with age, from 0.0% for 1-4 and 5-9 year olds to 1.3-1.8% for the 40-49 year age group. Australian population HBsAg prevalence based on minimum and adjusted estimates from this serosurvey were 91,500 (0.49%) and 163,000 (0.87%) infections, respectively. The risk group method estimated an Australian HBsAg prevalence of 88,000 infections (0.47%). Approximately 50% of people with chronic HBV infection were estimated to be immigrants from either South-East Asia (33.3%) or North-East Asia (16.2%).
Conclusion: The range of estimates for chronic HBV infection in Australia is broad, reflecting the uncertainty in source data. A national blood survey encompassing a large and representative population sample may help to provide more accurate estimates. A large proportion of people with chronic HBV infection are Asian born.