Distribution of hepatitis C virus genotypes in Croatia--a 10 year retrospective study of four geographic regions.

The aim of this 10-year retrospective study was to investigate the distribution of HCV genotypes in patients with chronic hepatitis C monitored in the largest center for molecular diagnostics of HCV infection in Croatia. The study enrolled 1163 anti-HCV positive adults with detectable HCV RNA in the plasma. The patients were classified in four regions: Zagreb and surrounding continental area, Split, Slavonija and Rijeka. HCV genotyping was performed by using VERSANT HCV Genotyping Assay (LIPA) (Bayer Diagnostics, Puteaux Cedex, France). Statistical analysis was performed by using Statistica for Windows V.5.1. The majority of HCV infections in the study population were caused by genotypes 1 (58.8% of infected patients) and 3 (35.6%). Percentages of patients infected with subtypes 1b and 1a were 37.4% and 13.1%, respectively. Genotypes 2 and 4 were present in a very low percentage of patients (2.2% and 3.4%, respectively) while genotypes 5 and 6 were not detected. Analysis of regional differences in the distribution of HCV genotypes revealed similar percentages of subtype 3a and 1b infections in the Split region while the majority of infections in other regions were caused by subtype 1b. Infections with genotypes 2 and 4 were present in less than 5% of patients in all geographic regions. Analysis of an association between risk factors for infection and distribution of genotypes and subtypes in a subset of patients from the Split region confirmed the association between IVDU and subtype 3a. We conclude that the prevalence of HCV genotypes and subtypes follows the pattern of other Southern and Eastern European Countries with the predominance of subtypes 1b, 3a and 1a.