HETEROSEXUAL TRANSMISSION OF HUMAN-IMMUNODEFICIENCY-VIRUS (HIV) IN NORTHERN CALIFORNIA - RESULTS FROM A 10-YEAR STUDY

To examine rates of and risk factors for heterosexual transmission of human immunodeficiency virus (HIV), the authors conducted a prospectiv e study of infected individuals and their heterosexual partners who ha ve been recruited since 1985, Participants were recruited from health care providers, research studies, and health departments throughout No rthern California, and they were interviewed and examined at various s tudy clinic sites, A total of 82 infected women and their male partner s and 360 infected men and their female partners were enrolled. Over 9 0% of the couples were monogamous for the year prior to entry into the study; <3% had a current sexually transmitted disease (STD). The medi an age of participants was 34 years, and the majority were white. Over 3,000 couple-months of data were available for the follow-up study, O verall, 68 (19%) of the 360 female partners of HIV-infected men (95% c onfidence interval (CI) 15.0-23.3%) and two (2.4%) of the 82 male part ners of HIV-infected women (95% CI 0.3-8.5%) were infected, History of sexually transmitted diseases was most strongly associated with trans mission. Male-to-female transmission was approximately eight times mor e efficient than female-to-male transmission and male-to-female per co ntact infectivity was estimated to be 0.0009 (95% CI 0.0005-0.001). Ov er time, the authors observed increased condom use (p < 0.001) and no new infections. infectivity for HIV through heterosexual transmission is low, and STDs may be the most important cofactor for transmission, Significant behavior change over time in serodiscordant couples was ob served.