Epidemiology of hepatitis C and surveillance strategies.

Transmitted mainly by infected blood, the hepatitis C virus (HCV) has sprea d in a silent way during several decades by blood transfusion. Subsequently , if was introduced in the infra venous drug user community where it explod ed. HCV is now becoming a nosocomial viral infection. In France HCV seropre valence is estimated to be around 1.1%, with 500,000 to 650,000 people affe cted, among whom 80% are chronic carriers of the virus. In 1994 the proport ion of HCV infected patients who knew their HCV serostatus ranged from 20 t o 25%. Ti;ris number has improved since but it remains not well quantified HCV prevalence varies by region and appears to be greater in the Provence-A lpes-Cote d'Azur region (1.7%). The prevalence increases with age, particul arly after 50 years among women probably because of frequent blood transfus ions after delivery during the 60 and 70s. Even if the risk after transfusi on is controlled for (the residual risk is estimated at 3.6 per million blo od donations in France), transmission among drug users remains high despite the implementation of a program of harm reduction. Nosocomial transmission has been documented in recent years. Although the risk is low, the frequen cy of exposure to invasive procedures among hospitalized patients justifies the strict application of standard precautions and disinfection procedures . Sexual and mother to child transmission is very low as well as non sexual horizontal transmission. To evaluate preventive measures and the impact of patient management, HCV surveillance must rely on the monitoring of newly diagnosed hepatitis C patients, HCV seroconversions, and of chronic liver d iseases including cirrhosis and hepato-cellular carcinoma. (C) 1999 Elsevie r; Paris.