Temporal dynamics of hepatitis C virus (HCV) genotypes over a three-year hospital-based survey in Northern Italy

Introduction: HCV infection is one of the major public-health burden. Persistent HCV infection may cause liver cirrhosis, hepatocellular carcinoma, and death. HCV prevalence changes between geographic areas, age groups, transmission routes, and risk factors. Italy has the highest HCV infection prevalence in Europe, with 1.4 million infected-people. HCV genotypes 1-3 show a worldwide distribution, while genotypes 4-7 are limited to specific areas. This study aims to investigate the pattern of HCV genotypes and its association with viral load over three years (2013-2015) in the area of Parma (Northern Italy). Materials and Methods: serum/plasma from 825 individuals attending the University Hospital of Parma were subjected to HCV RNA quantification by COBAS AmpliPrep/COBAS TaqMan HCV v2.0 (Roche) and genotyped by VERSANT HCV Genotype 2.0 LiPA (Siemens) assays. Of these, 454 were males (55%; median age: 51 years), 371 females (45%; median age: 65 years), 738 (89.5%) Italians, and 87 (10.5%) foreigners mostly coming from Eastern Europe (59.8%) and Africa (19.5%). Results: HCV genotype (G) 1 (51.4%) prevailed, followed by G2, G3, G4, and G6 (22.9%, 17.4%, 8.2%, and 0.1%, respectively); subtypes 1b, 3a, and 1a (34.7%, 16.7%, and 16.5%, respectively) predominated. Among foreigners, subtypes 1b, 3a, 1a, 4a/4c/4d, 2a/2c, 4 not-subtypable (n-s), 2 n-s, 2b, and unusual subtypes 4e and 6 n-s (49.4%, 21.8%, 8.1%, 8.1%, 3.5%, 3.5%, 2.3%, 1.1%, 1.1%, and 1.1%, respectively) were found. Subtypes 1a and 3a predominated in males (P<0.0001). Subtype 1a prevailed in subjects aged less than 61 years (P<0.0001), while 3a in subjects aged less than 31 years (P<0.05). Subtypes 1b, 2a/2c, and 2 n-s prevailed in females (P<0.0001, P<0.05, and P<0.005, respectively), and in subjects older than 60 years (P<0.0001). The prevalence of subtype 1b increased during the study period, contrarily to that of subtypes 1a and 3a (P<0.05). Higher viremic HCV RNA titres were found in males infected with subtypes 2a/2c, 4a/4c/4d, and 4 n-s. Discussion and Conclusions: different HCV genotypes were observed in the area of Parma and subtypes 1b, 3a, and 1a prevailed. The high prevalence of subtype 3a found in young people suggests its epidemiological relevance in the future. The less-represented G4 and G6, mostly found in foreign residents, may become more frequent due to increasing migratory flows from endemic areas. Higher HCV viral loads assessed in males infected with subtypes 2a/2c, 4 n-s, and 4a/4c/4d evidence a greater viral replicative efficiency. The obtained results reinforce the need for structured epidemiological studies in order to better understand the dynamics of HCV circulation and improve preventive strategies.