Delta Hepatitis: Forgotten, but Not Gone

Following the discovery of the hepatitis D virus (HDV) in the late 1970s and the development of assays to diagnose its infection, epidemiologic studies indicated that hepatitis D was endemic worldwide, with its prevalence varying in different countries. In most patients, chronic hepatitis D ran a severe and progressive course; the clinical profile of the disease was characterized by the presence of hepatitis B surface antigen (HBsAg) in blood, elevated alanine transaminase (ALT), an aggressive hepatitis on histology, and markers of HDV replication with absent markers of HBV replication in serum. With reduction of adult-acquired HBV infection in the past 20 years, the prevalence of HDV has also declined significantly in Europe and the industrialized world, because of reduction in the number of HBsAg-carriers necessary to HDV to persist. This has led to the less frequent diagnosis of hepatitis D. However, HDV infection has not disappeared. Europe still has a reservoir of the virus, sustained by two different pools of HDV-infected patients: the residual aging domestic pool that survived the brunt of the hepatitis D epidemic in the 1970s and 1980s, and the population of young patients with recent HDV infections migrating to Europe from areas where HDV remains endemic. The predominant clinical pattern is advanced cirrhosis in most domestic patients with long-standing disease, and a florid disease resembling the prototype pattern of HDV disease described in the 1980s, in the emigrants.