Seroepidemiology of hepatitis B virus in a population of injecting drug users. Association with drug injection patterns.

To investigate the epidemiology of hepatitis B virus (HBV) infection among injecting drug users, the authors assessed the prevalence of HBV seromarkers among 2,558 injecting drug users recruited through street outreach in Baltimore, Maryland, in 1988-1989. Eighty percent of the drug users had at least one HBV seromarker. HBV seropositivity was associated with increasing age, duration of injecting drug use, African-American ethnicity, injecting drugs at least once daily, and sharing needles or visiting "shooting galleries" during the previous 11 years, but not with high-risk sexual behaviors or a history of sexually transmitted disease. This finding is possibly due to the relative inefficiency of sexual transmission as compared with parenteral transmission in injecting drug users. In addition, HBV seropositivity was strongly associated with seropositivity for hepatitis C virus and human immunodeficiency virus. The authors conclude that HBV transmission among injecting drug users occurs primarily through the sharing of contaminated drug injecting equipment rather than through sexual relations, and that efforts to prevent HBV infection must target injecting drug users early in their injecting careers.