HETEROSEXUAL TRANSMISSION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 FROMTRANSFUSION RECIPIENTS TO THEIR SEX PARTNERS

Using lookback procedures and other methods, we identified and then pr ospectively followed human immunodeficiency virus type 1 (HIV-1)-infec ted transfusion recipients and their sex partners to determine AIDS in cidence and risks of heterosexual transmission of HIV-1. At enrollment , 7 of 32 (21.9%) female partners of male recipients were themselves i nfected with HIV-1, as compared with none of 14 male partners of femal e recipients (p = 0.08). No additional episodes of transmission were o bserved. The prevalence of advanced immunodeficiency at enrollment was similar in male and female recipients. Male recipients with advanced immunodeficiency (CD4+ lymphocyte count less than or equal to 0.20 x 1 0(9)/L or a history of clinical AIDS) at enrollment were more likely t o have infected their female partners (odds ratio = 7.9; p = 0.03) tha n men with neither condition. Similarly, AIDS-free survival, as estima ted by the product-limit method, was lower among male transmitters tha n among male nontransmitters (p = 0.01). Transmission was not associat ed with frequency of unprotected vaginal intercourse. Our data suggest that HIV-1-infected men who develop immunodeficiency rapidly are more likely to infect their sex partners and that the greater efficiency o f male-to-female HIV-1 transmission is not explained by a greater numb er of sexual contacts or more advanced immunodeficiency in index subje cts.