Non-A, non-B hepatitis: a contemporary assessment.

The current status of non-A, non-B (NANB) hepatitis is reviewed with respect to: (i) epidemiology and incidence of posttransfusion and sporadic NANB hepatitis; (ii) experimental transmission of NANB hepatitis; (iii) serologic tests and the evidence for virus-like NANB agents; (iv) clinical features of NANB hepatitis as compared to hepatitis B; (v) indication and impact of therapeutic and preventive measures against NANB hepatitis. Without specific markers for NANB infection, non-A, non-B hepatitis continues to be a diagnosis by exclusion of infection with hepatitis A, hepatitis B or other viruses. Recent observations suggest that NANB hepatitis may in fact be caused by a group of viruses immunologically different from but genetically similar to the hepatitis B virus.