EPIDEMIOLOGY OF HBV-ASSOCIATED DELTA AGENT: GEOGRAPHICAL DISTRIBUTION OF ANTI-DELTA AND PREVALENCE IN POLYTRANSFUSED HBsAg CARRIERS

Abstract

The epidemiology of infection with the hepatis-B-virus (HBV)-associated δ agent was assessed from the prevalence of antibody to δ in 1206 HBsAg-seropositive subjects from various parts of the world. Anti-8 was prevalent in unselected HBsAg-positive Italians, whether residents in Italy or elsewhere, and in drug addicts and polytransfused HBsAg carriers throughout the world, suggesting that δ-associated infection is spread through contact in Italy and parenterally in other countries. Parenteral transmission of the δ agent was confirmed by a separate survey of the prevalence of anti-δ in 648 polytransfused patients with chronic blood disorders, which showed a higher prevalence of anti-δ in HBsAg-positive hæmophiliacs than in the general HBsAg-positive population of Italy, Germany, and the U.S.A. In view of the failure to detect δ in the absence of markers of HBV, the prevalence of anti-δ among polytransfused HBsAg carriers suggests that the δ-associated agent is transmitted by superinfection or coinfection of HBsAg carriers, the HBsAg carrier state possibly providing a rescue function to the superinfecting agent.