[Hepatitis C virus infection. Epidemiology].

Hepatitis C virus (HCV) transmission is parenteral in 60 to 70% of cases, related either to blood transfusion or to intravenous drug use. Minor routes of infection have also been identified: sexual transmission, intrafamilial transmission, mother-to-infant transmission. In 30 to 40% of cases, no obvious risk factor for HCV contamination can be identified. Subjects at risk for HCV infection are patients who received transfusions of blood or blood products, hemophiliacs, patients under renal dialysis, patients who underwent organ transplantation, intravenous drug users and, to a lesser extent, healthcare workers. HCV is present everywhere in the world. The prevalence of HCV markers varies from 0.5% in Scandinavia or Switzerland to more than 5% in some developing countries. This prevalence is about 1% in France. The study of HCV genotypes shows that their distribution varies according to geographical localization and that some genotypes are associated with special routes of contamination.