Incidence and risk factors of acute Delta hepatitis in Italy: results from a national surveillance system. SEIEVA Collaborating Group.

The incidence of hepatitis Delta virus in the general Italian population was estimated by a specific surveillance system for acute viral hepatitis over the period 1987-1992. The hepatitis Delta virus incidence rate declined from 3.1/1,000,000 inhabitants in 1987 to 1.2/1,000,000 in 1992. Males predominated (83.8% of cases); the sex ratio was 5.2. Only 2.5% of cases occurred in subjects younger than 15 years. There were 119 (49.4%) coinfections of Delta and B hepatitis and 122 (50.6%) Delta superinfections in chronic HBsAg carriers. Jaundice was present in 83.6% of cases. The hospitalization rate was 97.5%; median stay in hospital was 25 days (range 1-98 days). The results of multivariate analysis showed that a history of intravenous drug abuse (odds ratio 34.9; confidence interval 95% = 16.8-72.5), household contact with an HBsAg+ carrier (odds ratio 10.7; confidence interval 95% = 4.36-23.30) and a history of two or more sexual partners within the previous 6 months (odds ratio 2.44; confidence interval 95% = 1.34-4.43) were independent risk factors associated with Delta hepatitis. No association was found with the other risk factors considered, such as blood transfusion, surgical intervention, hospitalization, other percutaneous exposures, dental therapy, contact with an icteric case, and household contact with an i.v. drug abuser. These findings indicate that, in Italy, Delta hepatitis currently has a minor impact. In addition to intravenous drug abuse and household contact with an HBsAg+ carrier, heterosexual activity appears to be an efficient route of HDV transmission.