Molecular epidemiology of hepatitis C virus among injection drug users in Iran: a slight change in prevalence of HCV genotypes over time.

Injecting drug users (IDUs) are the main at-risk population for hepatitis C virus (HCV) transmission. We studied HCV infection, risk factors, and genotype distribution in relation to the year of first injection among Iranian IDUs. Of a total of 126 specimens positive for HCV antibody, 93 (74 %) had detectible HCV RNA, and the NS5B gene was sequenced for 83, with genotype 3a (n = 48, 58 %) being predominant, followed by 1a (n = 35, 42 %). Tattooing was an independent predictor for HCV infection. No significant difference was found between HCV genotypes and IDU characteristics. Although there was no change in the distribution of prevalent genotypes before and after 1997, a slight variation in the prevalence was observed (p = 0.71). The difference in the prevalence of subtypes 1a and 3a (9.1 % in the period 1984-1996 and 18.2 % in the period 1997-2009) during 25 years was 9.1 %. These findings indicate a high prevalence of HCV infection among Iranian IDUs and highlights HCV-3a as the most prevalent subtype for the past 25 years. Harm-reduction strategies appear to be the most important measures to reduce the transmission of HCV in Iran.