The Seroepidemiology of Hepatitis A and B in the Asia-Pacific Region

Abstract

Published studies of the serological markers of hepatitis A (anti-HAV) and hepatitis B (HBsAg, anti-HBs, and anti-HBc) in populations of the Asia-Pacific region have been tabulated and analysed for information about the extent and pattern of virus exposure, with a view to identifying areas in need of further study, and to formulating strategies for eventual immunisation programmes. Hepatitis A infection is shifting to older age groups as it slowly disappears from developed countries such as Australia and Japan, and poses the paradox of fewer but potentially more severe illnesses. Except for some small island populations of Oceania, where it may strike periodically in epidemic fashion, hepatitis A continues to be an endemic, ubiquitous childhood infection in the rest of the Asia-Pacific region. As subclinical or mild infection is the rule in children, indiscriminate immunisation of the general population does not seem advisable. Hepatitis B infection is also least common in Australia, and only moderately more frequent in New Zealand and Japan, which can probably afford to restrict immunisation to high-risk population subsets. Taiwan, southeast China, and most of the perimeter countries of the Western Pacific, show an early, high prevalence of infection, which when considered in the light of the high frequency of chronic hepatitis and hepatocellular carcinoma in these countries, justifies nation-wide immunisation programmes carried out in early childhood. Infection is also widespread among Oceanic populations, but as there is little or no information for most of these populations about the frequency of late sequelae of hepatitis B, immunisation may not be urgent, or even appropriate.