Epidemiology of hepatitis C virus infection.

The availability of the anti-HCV assay has confirmed most of the suspicions and predictions regarding the epidemiology of NANB hepatitis virus made before the discovery of HCV. It is now clear that HCV is responsible for the majority of cases of post-transfusion and sporadic NANB hepatitis, as well as of most cases of unidentified chronic liver disease. It seems plausible that HCV may act as a negative co-factor in other chronic liver diseases, especially those caused by alcohol, other hepatitis viruses, and so-called 'autoimmune hepatitis'. The issue of perinatal and sexual transmission of HCV has not yet been clarified, and further studies are urgently needed. Finally, the high prevalence of anti-HCV detected in HCC suggests that HCV is a major co-factor in the development of HCC and again raises the issue of viral persistence and neoplastic transformation, an issue that for HBV has not yet been elucidated.