Methods of transmission of hepatitis C.

The route of transmission of hepatitis C virus is still controversial. Parenteral exposure via blood or blood products leads to infection in the majority of cases, and the majority of intravenous drug users become infected by repetitive exposure to contaminated injection equipment. The risk of infection from a single needlestick injury is 5-15% and may depend on the size of the innoculum. Other parenteral routes of transmission may include traditional healing practices and the use of contaminated medical equipment. Transmission is less common within a family but the prevalence of hepatitis C viral antibodies is higher in family members and sexual partners of carriers than in the general population. There are some well-documented instances of acute hepatitis C occurring after a defined sexual exposure. Vertical transmission is rare unless the mother has high levels of circulating HCV RNA as may occur in those also infected with HIV. The detection of hepatitis C in saliva and the higher than expected prevalence of infection in dentists may point to the possibility of transmission by salivary contamination. There remain large numbers of hepatitis C carriers in whom no route of infection can be identified.