No symptoms are required. Most hepatitis C virus (HCV)-infected persons are asymptomatic; however, many have chronic liver disease, which can range from mild to severe.
One or more of the following four criteria:
A case that is anti-HCV positive (repeat reactive) by EIA and has alanine aminotransferase (ALT or serum glutamic pyruvic transaminase [SGPT]) values above the upper limit of normal, but the anti-HCV EIA result has not been verified by an additional more specific assay or the signal to cut-off ratio is unknown.
A case that is laboratory confirmed and does not meet the case definition for acute hepatitis C.