Human immunodeficiency virus and hepatitis delta virus in homosexual men. A study of four cohorts.

The prevalence of hepatitis delta virus antibodies was determined in four cohorts of homosexual or bisexual men positive for hepatitis B surface antigen who were evaluated between April 1984 and April 1985. Antibodies to hepatitis delta virus were found in 16 of 106 men in Los Angeles (15.1%; 95% confidence interval [Cl], 8.3% to 21.9%); 6 of 64 men in San Francisco (9.4%; 95% Cl, 3.5% to 19.3%); 1 of 76 men in Pittsburgh (1.3%; 95% Cl, 0.03% to 7.1%); and 0 of 52 men in Chicago (0%; 95% Cl, 0% to 5.6%). From 44.0% to 65.4% of men negative for hepatitis delta virus and all men positive for hepatitis delta virus but one (P less than 0.0001) were positive for antibodies to human immunodeficiency virus (HIV). In multivariate analysis, infection with hepatitis delta virus was associated with intravenous drug use (adjusted odds ratio [OR] = 6.7, P less than 0.01), with sexual activity as measured by number of partners (adjusted OR = 8.4, p less than 0.01), and probably with rectal trauma (adjusted OR = 3.9, P = 0.17). As with HIV infection, prevalence of hepatitis delta virus infection in homosexual men differs by location and is most likely transmitted both sexually and parenterally.