There is a number of viruses which may cause acute or chronic liver damage. Only some of them belong into the group of hepatotropic viruses and only the latter are the cause of acute or chronic viral hepatitis. So far we know seven hepatotropic viruses. The virus of hepatitis A (HAV), virus of hepatitis B (HBV), virus of hepatitis C (HCV), virus of hepatitis D (HDV), virus of hepatitis E (HEV), virus of hepatitis G (HGV) and Transfusion-Transmitted-Virus (TTV). For HAV and HEV orofaecal transmission is typical, the others are transmitted by the parenteral route. All cause acute hepatitis. Only HAV and HEV infections develop into the chronic stage. The decisive finding for the dynamic development of the problem of viral hepatitis was the discovery of the Australian antigen (Au antigen) by B. Blumberg in 1965. The discovery made it possible to recognize viral hepatitis B and by the application of new biotechnologies the genes of other viruses were detected. Some of them were not visualized so far. A great advance was alpha interferon and lamivudine treatment in patients with chronic hepatitis B and alpha interferon treatment along with ribavirine in chronic hepatitis C.

Keywords: Hepatitis, Viral, Human /classification/; Humans