Hepatitis C virus infection: the new global epidemic.

Hepatitis C virus infects an estimated 170 million people worldwide. It is a major cause of liver cirrhosis, end-stage liver disease and hepatocellular carcinoma. It is also a leading cause of liver transplant in the USA. The virus is primarily transmitted parenterally, but there is significant mother-to-child transmission. Partly due to the virus's genetic diversity, it evades the host immune response and it has been difficult to identify candidate vaccines. However, significant advances have been made in the treatment of chronic hepatitis C virus infection. Currently, the combination of pegylated interferon-alpha and ribavirin is the standard treatment for chronic hepatitis C virus infection, and leads to long-term eradication of the virus in approximately 54% of people. Treatment response is dependent on the infecting genotype, with 76 to 80% of those with genotypes 2 and 3, but only approximately 40% with genotype 1 or 4 achieving a sustained virologic response. Since treatment is expensive and associated with significant adverse effects, more effective strategies for the prevention of transmission are needed, especially in resource-limited countries, where the burden of disease is the highest.