Acute hepatitis A, B and non-A, non-B in a Swedish community studied over a ten-year period

985 episodes of hepatitis representing 98% of all acute hepatitis episodes found in a Swedish city during a 10-year period were analyzed for anti-hepatitis A IgM antibodies and hepatitis B surface antigen. Hepatitis A was diagnosed in 311 episodes (32%), hepatitis B in 494 (50%), simultaneous acute hepatitis A and B in 12 (1.2%), and 168 episodes (17%) were classified as hepatitis non-A, non-B. The majority of the hepatitis A cases were drug addicts (58%), and all were concentrated in 3 outbreaks of 1-2 years duration. 16% of all hepatitis A cases were probably imported. Hepatitis B cases decreased significantly (p less than 0.001) between the first and second half of the study period. 47% were drug addicts. Hepatitis non-A, non-B was also dominated by drug addicts (61%). Approximately 20% of the cases in all 3 types of hepatitis had no identifiable source.