Long-term outcome of acute hepatitis B and C in an outbreak of hepatitis in 1969-72.

The objective of this study was to investigate the epidemiology, etiology, and long-term outcome of an extended outbreak of acute hepatitis that occurred in an area of Sweden between 1969 and 1972. The outbreak was analyzed retrospectively by retesting stored frozen serum samples for the presence of hepatitis A, B and C markers. The results were compared with the diagnoses that had been determined during the outbreak. Of 180 patients, 29 (16%) had acute hepatitis A, 126 (70%) had acute hepatitis B, and eight (4.4%) had acute hepatitis C. The Australia antigen test used during the outbreak had failed to identify 21 patients with acute hepatitis B virus infection. Genotyping of the hepatitis B virus strains showed that genotype D was the most prevalent, irrespective of the transmission route. An attempt was made to follow up patients with unresolved hepatitis B virus infection, 25-27 years after the acute infection. None of the 100 patients with acute hepatitis B infection who were traced had become chronic carriers. In ten patients with hepatitis C virus infection, the follow-up showed considerable variation in the outcome, ranging from spontaneous resolution to death through liver cirrhosis. Intravenous drug users had a high prevalence of hepatitis C virus infection, with 52% testing positive for hepatitis C antibodies.