Changes in the prevalence of hepatitis C virus genotype among Italian injection drug users-Relation to period of injection started

Background: Chronic hepatitis C is a worldwide health problem. Intravenous drug users are the main risk group. Objectives: To determine the prevalence of HCV genotypes in Italian injecting drug users and the distribution of genotypes in relation to the period when the infection was acquired. Study design: Two hundred sera from patients with chronic hepatitis C and a history of intravenous drug use were assayed for HCV-RNA and genotyped by a commercial line probe assay. Results: Genotypes 1 (45.5%) and 3 (35%) were the most common genotypes, followed by genotypes 4 (15%) and 2 (3%). One genotype 5 (0.5%) was found. Two mixed infections (M) were detected. Subtype could be determined in 160 cases (80%): subtype 3a was the most prevalent (41.3%), followed by subtypes 1a (23.1%)and 1b (20.6%). A significant change in the distribution of prevalent genotypes occurred since 1965 (p = 0.020). Genotype 3 infections declined from 48/116 (41.4%) in 1965-1985 to 22/84 (26.2%) in 1986-2006. The prevalence of genotype 4 was significantly higher in patients infected after 1985 compared to patients infected before this year (11/116 [9.5%] vs. 19/84 [22.6%], respectively; p = 0.018). Conclusions: Since 1965 the common HCV genotype 3 has become less common in Italy. Genotype 4, an imported genotype, has become more common. (C) 2009 Elsevier B.V. All rights reserved.