1Raffaella Romeo, Riccardo Perbellini, 1 Division of Gastroenterology, IRCCS Fondazione Cà Granda Ospedale Maggiore Policlinico, University of Milan, 20122 Milano, Italy.
Chronic infection with hepatitis delta virus (HDV) has lately regained clinical importance because of the recent evidence of increasing prevalence in several European countries, due to immigration from highly endemic areas. HDV requires the mandatory presence of hepatitis B virus (HBV) for propagation to hepatocytes. It is transmitted by the same routes of HBV and it can be acquired either by co-infection (simultaneous transmission of the two viruses) or super-infection (acquisition of HDV by an already chronic carrier of HBV). As a consequence, every HBV carrier is potentially at risk for HDV superinfection. Since the clinical course of super-infection can be severe, early diagnosis of HDV infection is necessary.