In developed countries it is relatively uncommon, with a prevalence of 1 per 550 population in the United Kingdom and United States. In low endemicity countries, the virus is mainly spread by sexual or blood contact among people at high risk, including intravenous drug users, patients receiving haemodialysis, homosexual men, and people living in institutions, especially those with learning disabilities. Men are more likely then women to develop chronic infection, although the reasons for this are unclear. Up to 300 million people have chronic hepatitis C infection mainly worldwide. The virus is spread almost exclusively by blood contact.
Vertical transmission is also unusual.
Presentation Chronic viral liver disease may be detected as a result of finding abnormal liver biochemistry during serological testing of asymptomatic patients in high risk groups or as a result of the complications of cirrhosis. Patients with chronic viral hepatitis usually have a sustained increase in alanine transaminase activity. The rise is lower than in acute infection, usually only two or three times the upper limit of normal. In hepatitis C infection, the -glutamyltransferase activity is also often raised. The degree of the rise in transaminase activity has little relevance to the extent of underlying hepatic inflammation.