Hepatitis C virus in intravenous drug users.

Sera from 172 intravenous drug users were tested for the presence of antibodies to hepatitis C virus (anti-HCV). The results were analysed in relation to aspects of the history of drug use and evidence of liver disease. The presence of anti-HCV was strongly associated with duration of intravenous drug use. Two-thirds of patients were anti-HCV seropositive within two years of commencing regular intravenous drug use, and there was 100% seropositivity among people injecting drugs for more than eight years. Seropositivity for hepatitis C virus closely paralleled exposure to hepatitis B virus, which was also endemic in this population. In contrast, only one patient tested positive for antibodies to the human immunodeficiency virus. The presence of anti-HCV correlated poorly with biochemical markers of hepatitis. About half the patients with anti-HCV had normal serum levels of alanine aminotransferase, whereas an abnormal liver biochemistry was frequently observed in anti-HCV seronegative subjects. Previous studies of non-A, non-B hepatitis that have used abnormal liver biochemistry as a marker have underestimated the prevalence of chronic hepatitis among intravenous drug users; the use of a specific screening test reveals that infection with hepatitis C virus is very common in this population.