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

BackgroundChronic hepatitis C is a worldwide health problem. Intravenous drug users are the main risk group.ObjectivesTo 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 designTwo 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.ResultsGenotypes 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 (1%) 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).ConclusionsSince 1965 the common HCV genotype 3 has become less common in Italy. Genotype 4, an imported genotype, has become more common.