[Non-A, non-B Hepatitis. A progress report].

The present state of the art in non-A, non-B hepatitis is reviewed. Eight years of world-wide efforts in research have not yielded a definite characterization of agent(s) and markers of this viral infection. Diagnosis is therefore established mainly by exclusion of the hepatitis viruses A and B, Epstein-Barr virus and cytomegalovirus, and drug-induced liver disease. Currently available serological, electron microscopic, immune electron microscopic and clinical information on non-A, non-B hepatitis in chimpanzee and man is briefly reviewed. Some light microscopic features provisionally regarded as suggestive of non-A, non-B hepatitis in man are presented. In daily practice the diagnostic tools in the near future will largely depend upon progress in the elaboration of suitable serological test systems and on further confirmation of microscopic findings, unless an unexpected breakthrough occurs through identification and characterization of the virus(es) in non-A, non-B infection.