EPIDEMIOLOGY OF HEPATITIS-C VIRUS-INFECTION AMONG INJECTING DRUG-USERS IN AUSTRALIA

Study objective-To review the epidemiology of hepatitis C virus (HCV) infection among injecting drug users (IDUs) in Australia, and consider needs for further research and prevention policies and programmes. De sign-(1) Review of the results of surveillance for HCV; (2) review of published Literature on prevalence, incidence, and risk factors for HC V among IDUs; and (3) reconstruction of incidence rates from prevalenc e studies of HCV in IDUs. Setting and Participants-Field and clinic ba sed studies of IDUs in Australia. Main results-HCV has been present at high prevalences (of the order of 60-70%) in populations of Australia n IDUs since at least 1971. Duration of injecting and main drug inject ed were the main predictors of seropositivity, the latter possibly a s urrogate for frequency of injecting and both together as surrogate for cumulative numbers of times injected. Risk of infection begins with f irst injection and continues as long as injecting does. Current incide nce is approximately 15 per 100 person years, and up to 40 per 100 per son years in some subpopulations. Incidence may have decreased through the 1980s as a result of behaviour change in relation to HIV, as it h as for hepatitis B, but not significantly so. Conclusions-Control of H CV infection in Australia will depend on effectiveness of measures to control HCV spread among IDUs. This will be a greater challenge than t he control of HIV in this population has been. Needs identified includ e improved surveillance, especially for recently acquired infection, b etter understanding of exact transmission modes, and urgent improvemen t in prevention strategies.