Epidemiology of hepatitis D virus (delta) infection in Melbourne over a 15-year period.

The prevalence of delta infection was studied in 3986 individuals seropositive for hepatitis B surface antigen (HBsAg), who were seen in Melbourne between 1971 and 1985. The group comprised 2004 patients with acute hepatitis B, 1820 asymptomatic HBsAg carriers, 139 HBsAg carriers with evidence of chronic liver disease, and 23 carriers who had suffered more than two separate attacks of acute hepatitis. Markers of delta infection were found almost exclusively among intravenous drug abusers and their close contacts. Studies of stored sera suggest that delta infection was introduced into this group about 1970. In carriers with no evidence of chronic liver disease, the prevalence of delta infection was highest among intravenous drug abusers (19.2%). In carriers with evidence of chronic liver disease, delta markers were present in 20.1% and all 23 carriers with recurrent acute hepatitis had evidence of infection with the delta virus.