Hepatitis C (HCV) is considered in part as a sexually transmitted infection (STI). A marked decrease in its incidence has been observed for several years, coinciding with the availability of new direct acting antiviral treatments (DAA). However, people are increasingly infected with the hepatitis C virus, especially HIV-positive MSM. This increase is explained by new sexual practices that are particularly at high level of risk, despite the widening accessibility of new DAA. Prevention also plays an important role in implementing an effective risk reduction policy. New methods of prevention must therefore be developed. For this purpose, it is imperative to know the natural history of acute hepatitis C, the different behaviours at risk of HCV transmission, and the demonstration of socio-sexual networks (clusters) thanks to virological phylogenetic studies. In order to improve hepatitis C prevention, we wish to establish a descriptive study focusing on :
* Descriptive analysis of the natural history of hepatitis C,
* Identification of patient clusters (phylogenetic analysis)
* Description of the sexual behaviors of infected patients, through a semi-directed interview.
