Antibodies to hepatitis delta virus in intravenous drug addicts and male homosexuals in Spain.

In a study to determine the incidence of infection with hepatitis delta virus (HDV) in high-risk groups in Spain, tests to detect serological markers of infection with hepatitis B virus (HBV) and total antibodies against HDV (anti-HDV) were performed in serum samples from 451 unselected intravenous drug addicts and 168 homosexual or bisexual men. Most samples were obtained from primary health care units in Madrid. In drug addicts 87.4% of samples were positive for HBV markers and 15.1% were positive for anti-HDV. However, the incidence of anti-HD was much higher in HBsAg carriers (70.7%) than in individuals positive for anti-HBs (10.4%). Ninety-two samples (54.8%) from homosexual men were positive for HBV markers, but all were negative for anti-HD. Thus, parenteral transmission seems to play a major role in the spread of HDV in Spain, the sexual route being of minor relevance.