Delta infection in the Naples area. Epidemiologic and clinical significance.

To define the epidemiologic and clinical significance of delta infection in the Naples area, we sought anti-delta antibodies in all cases of HBV-associated liver diseases, hospitalized in our department during 1983 (234 acute hepatitis, 9 of which fulminant; 51 chronic hepatitis; 32 cirrhosis; 19 hepatocarcinomas) and in randomly selected acute hepatitis over the previous 6 years. Delta agent in acute forms and IgM anti-HBc in delta-positive acute forms were also tested. The acute cases were controlled for at least 9 months after dismissal. Delta infection showed a high prevalence in the Naples area (20% of all acute cases in 1983; similar prevalences in previous years; high rate of coinfections, 81%; no peculiar modalities of circulation) and a high pathogenicity, as proved by the greater prevalence in fulminant cases (66.7%) and severe chronic forms. Moreover superinfection appears a more dangerous event than coinfection as regards the diseases becoming chronic (77.8% vs 2.5%).