Hepatitis C is liver inflammation (hepatitis) that is caused by the hepatitis C virus (HCV). The HCV causes acute and chronic viral hepatitis C. Unlike hepatitis B, however, hepatitis C is infrequently transmitted sexually, so that it is an unusual STD. It is primarily spread by exposure to infected blood, such as from sharing needles for drug use, piercing, tattooing, and occasionally sharing nasal straws for cocaine use. About 5% of babies born to women infected with HCV will also become infected with the virus. Sometimes there is no method of spread identifiable.

Most infected people have no symptoms, so a delayed or missed diagnosis is common. In contrast to HBV, with which chronic infection is uncommon, the majority (75-85%) of people infected with hepatitis C develop chronic (long-term) infection. However, as is the case with hepatitis B, chronically infected individuals are infectious to others and are at an increased risk of developing severe liver disease and its complications, even if they have no symptoms.

How is hepatitis C infection diagnosed?

Hepatitis C infection is diagnosed by using a standard antibody blood test. The antibody indicates an exposure to the virus at some time. Thus, the hepatitis C antibody is found in the blood during acute hepatitis C, after recovery from the acute hepatitis, and during chronic hepatitis C. Individuals with a positive antibody test can then be tested for evidence of virus in the blood by a test that detects the genetic material of the virus (called the polymerase chain reaction, or PCR). The PCR test rarely is needed to diagnose acute hepatitis C but sometimes can be helpful to confirm the diagnosis of chronic hepatitis C.