[Hepatitis B and the delta agent].

The delta agent seems to be a defective RNA virus which is dependent on a helper function provided by hepatitis B-virus. Delta agent infection occurs by parenteral transmission either together with hepatitis B-virus, or superimposed on chronic HBV infection. In the first case biphasic hepatitis may result, whereas in the second case mostly an acute delta agent infection develops, which is often followed by chronic delta hepatitis. The delta agent is endemic to certain areas, and also in certain risk groups such as drug addicts, hemophiliacs and polytransfused patients. A delta agent infection should be suspected in case of acute hepatitis in a hitherto clinical inapparent chronic carrier, especially if he belongs to one of the above mentioned risk groups. There is no specific therapy for delta infection, the only prophylactic measure is vaccination against hepatitis B.