Incidence of infection with hepatitis B virus in 56 patients with haemophilia A 1971-1979.

During each of the four-year periods 1971-1975 and 1975-1979, the annual incidence of hepatitis B infection has been assessed in 56 patients with haemophilia A by measuring plasma HBsAg, anti-HBs and anti-HBc levels. Infection rates of 7% and 9.5% per annum respectively were observed for each four-year period despite the screening of individual blood donations for HBsAg by techniques up to the sensitivity of reversed passive haemagglutination. The highest incidence of seroconversion was amongst severe haemophiliacs many of whom had received treatment predominantly with cryoprecipitate. Of the 16 patients in whom serological evidence of hepatitis B infection was obtained only one had an accompanying clinical episode of hepatitis. We conclude that haemophiliacs are still at high risk of infection by hepatitis B virus despite the screening of individual blood donors for HBsAg.