Viral hepatitis in the United States, 1970-1973: an analysis of morbidity trends and the impact of HBS Ag testing on surveillance and epidemiology.

Morbidity and surveillance data on viral hepatitis cases in the United States since 1970 has revealed plateauing of case rate, continued failure to observe seasonal variation, more general geographic distribution of cases, and persistence, although at progressively lower levels, of highest rates in males 15-29 years of age. Based on results of HBS Ag testing, as much as 24 per cent of hepatitis B may be misdiagnosed by physicians and from 18 to 46 per cent of reported cases can be classified hepatitis B, thus suggesting that hepatitis B may account for up to one-half the recognized viral hepatitis in this country. HBS Ag-negative hepatitis still seems commonly acquired through close personal contact; hepatitis B patients 15-29 years of age also commonly have personal contact association. Parenteral drug abuse and transfusion of blood and blood products continue to play a role in dissemination of hepatitis B, but hepatitis B seems to account for only about one half of all reported transfusion-associated hepatitis. Case fatality rates for reported cases appear to increase with age but are not higher for HBS Ab positive patients than for negative patients.