Are bisexually identified men in San Francisco a common vector for spreading HIV infection to women?

This article examines sexual risk taking among self-identified bisexual men in San Francisco and whether risk reduction has occurred, with respect to both homosexual and heterosexual behaviors, among human immunodeficiency virus (HIV) antibody-positive and HIV antibody-negative men. It also examines psychosocial correlates of unprotected anal and vaginal intercourse.

The participants were members of a population-based longitudinal cohort of 1034 single men aged 25 through 54 years recruited from the 19 census tracts in San Francisco that had the greatest prevalence of the acquired immunodeficiency syndrome in 1984. Of the total sample, 140 subjects initially identified themselves as bisexual; 85% of these men remained in the study.

The participants reported dramatic reductions in sexual risk taking. Prevalences of unprotected anal sex with men were similar among HIV-positive bisexual men (89% in 1984-1985 and 18% in 1988-1989) and those who were HIV negative (65% and 20%). The prevalence of unprotected vaginal sex was much lower for HIV-positive men (16% in 1984-1985 and 2% in 1988-1989) than for HIV-negative men (35% and 20%). Unprotected intercourse was associated primarily with situational and interpersonal factors.

Striking reductions in risk behaviors were reported. This subgroup of single, bisexually identified men appears unlikely to be a common vector for spreading HIV infection to women.