Epidemiology of viral hepatitis and HIV co-infection.

Worldwide, hepatitis B virus (HBV) accounts for an estimated 370 million chronic infections, hepatitis C virus (HCV) for an estimated 130 million, and HIV for an estimated 40 million. In HIV-infected persons, an estimated 2-4 million have chronic HBV co-infection and 4-5 million have HCV co-infection. HBV, HCV and HIV share common routes of transmission, but they differ in their prevalence by geographic region and the efficiency by which certain types of exposures transmit them. Among HIV-positive persons studied from Western Europe and the USA, chronic HBV infection has been found in 6-14% overall, including 4-6% of heterosexuals, 9-17% of men who have sex with men (MSM), and 7-10% of injection drug users. HCV infection has been found in 25-30% of HIV-positive persons overall; 72-95% of injection drug users, 1-12% of MSM and 9-27% of heterosexuals. The characteristics of HIV infected persons differ according to the co-infecting hepatitis virus, their epidemiologic patterns may change over time, and surveillance systems are needed to monitor their infection patterns in order to ensure that prevention measures are targeted appropriately.