Factors associated with hepatitis C virus infection in injection and noninjection drug users in Italy.

We describe the prevalence of hepatitis C virus (HCV) infection among noninjection users of heroin in Italy and compare the prevalence of HCV infection among noninjection drug users (NIDUs) and injection drug users (IDUs). Multiple logistic regression analysis of data from NIDUs showed that hepatitis B virus (HBV) infection status was the only independent predictor of HCV seroprevalence. Among IDUs, the number of years of drug use and HBV and human immunodeficiency virus infection status were independent predictors of HCV seropositivity. We found an HCV infection prevalence of 20% among NIDUs. This rate was much lower than that for IDUs, who are 11 times more likely to have antibodies against HCV. The prevalence of HCV infection was much higher than that of HBV infection among the IDUs. In contrast, the prevalence of HBV infection was slightly higher than that of HCV infection among unvaccinated NIDUs. The prevalence of HCV infection among long-term IDUs approached true population saturation; among long-term NIDUs, however, it appeared to plateau at approximately 40%. Additional research on HCV infection among NIDUs is needed to develop a strategic prevention program for this patient subgroup.