[Delta hepatitis].

Abstract

Hepatitis delta virus is a small defective RNA virus that replicates only in the presence of hepatitis B virus. Delta infections occur in two circumstances: co-infections where both viruses are acquired simultaneously, and superinfections where delta virus infects a patient who is already a chronic carrier of hepatitis B virus. In both cases, delta virus may induce a more severe outcome of the disease. Diagnostic tests of delta infection have recently become available and should be used in all cases of acute hepatitis B occurring in populations at risk of delta infection such as intravenous-drug addicts. Prevention of delta infection is essentially based on immunization against hepatitis B of populations exposed to both viruses.