2 Clinical need and practice
2.1 Hepatitis C is a disease of the liver caused by the hepatitis C virus (HCV). The presence of HCV RNA (ribonucleic acid) in serum indicates infection. There are 2 main phases of infection: acute and chronic. Acute hepatitis C refers to the period immediately after infection, whereas chronic hepatitis C is defined as infection that lasts for more than 6 months. In the UK, there are 2 major routes of HCV transmission: sharing needles in intravenous drug misuse and receiving transfusions of infected blood or blood products. However, children acquire the virus primarily from their mothers at birth. Breast feeding does not appear to increase the risk of HCV transmission.
2.2 Six main genetic types of HCV, known as genotypes 1 to 6, with further subtyping (a–j) have been found. In England and Wales genotypes 1 and 3 account for more than 90% of all diagnosed infections. The effectiveness of antiviral treatment depends on the viral genotype; the response is generally better in people infected with genotypes 2 or 3 than in those infected with genotypes 1, 4, 5 or 6.
2.3 Infection with HCV can lead to complications, including hepatic dysfunction, hepatic cirrhosis, hepatocellular carcinoma and death. Progression to severe hepatitis or cirrhosis during childhood is rare (less than 5%) and the mean time to development of cirrhosis in people infected as infants is estimated to be 28 years.
2.4 Estimates from the Health Protection Agency in 2011 show that HCV was newly diagnosed in 26 people aged 1 year or younger and 21 people aged 1–14 years in England in 2010. Estimates for chronic infection in children and young people in the UK are not available.
2.5 The aim of treatment is to clear the virus from the blood. Sustained virological response, defined as undetectable serum HCV RNA 6 months after the end of treatment, usually indicates resolved infection, although relapse occurs in approximately 5% of people after 5 years.