Background:  Observational data and a recent randomized trial suggest that circumcision reduces male HIV acquisition. However, little is known about the effects of male circumcision on HIV and sexually transmitted infections acquisition in female partners.

Methods:  We identified men linked to wives or consensual partners in a large community cohort in Rakai District, Uganda. Men were interviewed to ascertain circumcision status. Female HIV acquisition was assessed in 44 HIV^­ women with circumcised male HIV⁺ partners and 299 HIV^­ women with uncircumcised HIV⁺ males. Female syphilis (n = 4617) and herpes simplex virus (HSV)-2 (n = 184) were detected by serology, and human papilloma virus (HPV) (n = 400), gonorrhea/chlamydia (n = 2086), trichomonas, and bacterial vaginosis (n = 4205) were detected from self-collected vaginal swabs. Multivariate Poisson regression was used to assess the incident rate ratio (IRR)of female acquisition in HIV^­ women with a male HIV⁺ discordant partner. Multivariate log-binomial regression was used to assess the prevalent rate ratios (PRR) of sexually transmitted infections in female partners of circumcised and uncircumcised men, after adjustment for sociodemographic and behavioral characteristics.

Results:  The incidence of female HIV acquisition was 6.6/100 person-years in wives of circumcised HIV⁺ men versus 10.3/100 person-years in wives of HIV⁺ uncircumcised men (IRR = 0.064, CI 0.27-1.32, p = 0.22).  The risks of sexually transmitted infections in female partners of circumcised versus uncircumcised men were:  HSV-2 (PRR = 0.75, CI 0.54 to 1.03), HPV (PRR = 0.66, CI 0.46 to 1.12), trichomonas (PRR = 0.65, CI 055 to 0.77), and bacterial vaginosis (PRR = 0.86, CI 0.80 to 0.93). The risk of female genital ulcer disease was also reduced in wives of circumcised men (PRR = 0.73, CI 0.53 to 0.98). Circumcision did not affect the risks of syphilis (PRR = 0.93, CI 0.76 to 1.13), chlamydia (PRR = 1.06, CI 0.61 to 1.84), or gonorrhea (PRR = 1.19, CI 0.51 to 2.79).

Conclusions:  In these observational data, male circumcision was associated with reduced risk of female HIV acquisition and lower risks of selected sexually transmitted infections. Circumcision may affect male HIV infectivity by removal of the foreskin mucosa thus reducing female HIV exposure, and/or an indirect effect via reduction of female sexually transmitted co-infections and genital ulcer disease. Depending on the results of an on ongoing randomized trial, male circumcision may have an important role for HIV and sexually transmitted infections prevention in women.