BACKGROUND

The hepatitis C virus (HCV) is a small, single-stranded, blood-borne RNA virus of the family Flaviviridae. It was first identified in 1989 as a major cause of parenterally transmitted non-A non-B hepatitis. Infection with HCV is a leading cause of chronic liver disease worldwide. A proportion of patients with chronic infection develop progressive liver damage with cirrhosis and complications of end-stage liver disease over 20–40 years. The mortality from chronic hepatitis C (CHC) is also rising and is expected to double or triple over the next two decades. HCV is now the leading indication for liver transplantation in developed countries and will continue to pose an important health and economic burden for at least the next 10–20 years.

EPIDEMIOLOGY AND TRANSMISSION

There are an estimated 180 million people with CHC infection worldwide, with 3–4 million new infections per year. Overall, the estimated global prevalence of infection is 1–3%. In Western countries the true prevalence of HCV is likely to be significantly underestimated. In the United States for example, an estimated 4 million people have been infected; however, important epidemiological surveys have excluded particular groups traditionally at high risk for infection, such as prisoners, the institutionalized, and the homeless.

Following a peak incidence in the 1980s, a sharp decline in the number of new cases of CHC infection has been subsequently observed. Consequently, the majority of patients seen with CHC infection today largely represent individuals first infected with the virus over a period extending from the 1960s to the 1980s.