Non-A, non-B hepatitis: dead ends or new horizons?

Researchers who work on hepatitis may sometimes think that they have come to a dead end with non-A, non-B hepatitis, but in recent years there has been gradual progress in knowledge about these diseases. A hepatitis A like agent that causes epidemic waterborne non-A, non-B hepatitis has been characterized, and the epidemiology of the different forms of non-A, non-B hepatitis has been clarified. The diagnosis of non-A, non-B hepatitis, which may be a problem in routine clinical work, is usually based in scientific reports on serum alanine transferase activity being raised to at least twice the upper normal limit on at least two occasions one or more weeks apart. Other causes of raised serum alanine transferase activity, such as drug reactions and infections with cytomegalovirus and Epstein-Barr virus, have also to be excluded.