Female-to-Male Transmission of HIV To the Editor.\p=m-\Padianet al1 studied 379 heterosexual couples for evidence of human immunodeficiency virus (HIV) transmission and found that male-to-female transmission is much greater than female-to-male. In the single case offemale\x=req-\ to-male transmission, the index case had multiple sexual contacts and reported vaginal bleeding during sex, and her regular male partner who seroconverted also reported penile
bleeding during sex. Are the results of this study consistent
with the results of other such studies? We reviewed the literature searching for HIV serologic studies of heterosexual couples with both male and female index cases.1-8 Studies were excluded if only female-to-male or male-to-female transmission was studied. We started with all studies referenced in the Padian et al article and reviewed the abstracts of the Seventh International Conference on AIDS. We identified 16 studies meeting the study definition. The designs of the 16 studies were similar. Heterosexual individuals (index cases) were identified with HIV infection (AIDS, AIDS-related complex, or through testing). Sexual partners who had no other risk factors for HIV were re¬ cruited, questioned about sexual and other behaviors, tested for HIV, counseled about "safe-sex" practices, followed up, and retested for HIV at later times if negative on initial
testing. All investigators compared the male-to-female and femaleto-male transmission rates. Most investigators also compared risk behaviors of couples where HIV transmission had oc¬ curred (both members were positive) with couples in whom HIV transmission had not
yet occurred.
In this second
com¬
parison, couples were generally aggregated independent of the sex of the index case. The second comparison was per¬ formed to identify risk factors for transmission, but also to identify potential confounding variables for interpreting the female-to-male and male-to-female transmission comparisons. Transmission rates varied widely among the studies (Table [see 1856]). Overall, 732 infections were noted among nonindex partners in 2413 couples. Rates were generally higher in couples recruited in Africa or Haiti (female-to-male trans¬ mission, 58% [83/143]; male-to-female transmission, 53% [171/ 324]) than couples recruited in the United States or Europe (female-to-male transmission, 15% [67/461]; male-to-female transmission, 28% [411/1485]). Transmission rates were sta¬ tistically greater for couples in whom the male was the index case (P
bleeding during sex. Are the results of this study consistent
with the results of other such studies? We reviewed the literature searching for HIV serologic studies of heterosexual couples with both male and female index cases.1-8 Studies were excluded if only female-to-male or male-to-female transmission was studied. We started with all studies referenced in the Padian et al article and reviewed the abstracts of the Seventh International Conference on AIDS. We identified 16 studies meeting the study definition. The designs of the 16 studies were similar. Heterosexual individuals (index cases) were identified with HIV infection (AIDS, AIDS-related complex, or through testing). Sexual partners who had no other risk factors for HIV were re¬ cruited, questioned about sexual and other behaviors, tested for HIV, counseled about "safe-sex" practices, followed up, and retested for HIV at later times if negative on initial
testing. All investigators compared the male-to-female and femaleto-male transmission rates. Most investigators also compared risk behaviors of couples where HIV transmission had oc¬ curred (both members were positive) with couples in whom HIV transmission had not
yet occurred.
In this second
com¬
parison, couples were generally aggregated independent of the sex of the index case. The second comparison was per¬ formed to identify risk factors for transmission, but also to identify potential confounding variables for interpreting the female-to-male and male-to-female transmission comparisons. Transmission rates varied widely among the studies (Table [see 1856]). Overall, 732 infections were noted among nonindex partners in 2413 couples. Rates were generally higher in couples recruited in Africa or Haiti (female-to-male trans¬ mission, 58% [83/143]; male-to-female transmission, 53% [171/ 324]) than couples recruited in the United States or Europe (female-to-male transmission, 15% [67/461]; male-to-female transmission, 28% [411/1485]). Transmission rates were sta¬ tistically greater for couples in whom the male was the index case (P
