Prevalence of hepatitis B infections in a multiracial New Zealand community.

Plans to control hepatitis B virus (HBV) infections in a high risk mixed race community, included the need for prevalence studies of HBV markers. Accordingly 7901 subjects, 93% of the population of Kawerau, where European and non-European children are present in almost equal numbers, were tested for hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). Positive HBsAg sera were titred and tested for hepatitis B e antigen (HBeAg). Highest rates for HBsAg and anti-HBs combined, were found in the 15-19 year old age groups; 61.6% in Europeans and 74.5% in non-Europeans. HBsAg prevalence was 4.2% and 18.2% respectively in the same groups. Ninety-six point four percent of 503 HBsAg positives followed up were confirmed as carriers. Infectivity as shown by HBeAg prevalence and HBsAg titre was highest in 0-10 year olds and declined with age. Prevalences were low in children aged less than one year old, suggesting that perinatal transmission was not a major factor in childhood carriage. Therefore attempts to control acquisition of carriage by vaccinating only those children of HBeAg positive mothers are unlikely to be successful.