The current status of non-A, non-B viral hepatitis.

It is probable that two or more different viruses account for non-A, non-B hepatitis throughout the world, with a third agent causing epidemic hepatitis in India and neighboring countries. NANB virus(es) is the major cause of transfusion-associated hepatitis, and is responsible for roughly 20% of sporadic hepatitis cases. NANB postransfusion hepatitis progresses to chronic hepatitis in half or more of cases. This form of chronic hepatitis, while usually minimally symptomatic, causes progressive liver destruction and eventual cirrhosis in a significant proportion of cases. To date, the NANB virus(es) has not been specifically identified, either serologically or by electron microscopy. When developed, serologic assays will find their most immediate application in the identification of NANB virus carriers among blood donors, thereby being applied to the prevention of post-transfusion hepatitis. No specific therapy is available for NANB virus infection. Gamma globulin is of uncertain prophylactic efficacy.