Male circumcision
Male circumcision and risk of male-to-female HIV-1 transmission: a multinational prospective study in African HIV-1-serodiscordant couples.
Baeten JM, Donnell D, Kapiga SH, Ronald A, John-Stewart G, Inambao M, Manongi R, Vwalika B, Celum C; for the Partners in Prevention HSV/HIV Transmission Study Team. AIDS. 2009. Dec [Epub ahead of print].
Male circumcision reduces female-to-male HIV-1 transmission risk by approximately 60%. Data assessing the effect of circumcision on male-to-female HIV-1 transmission are conflicting, with one observational study among HIV-1-serodiscordant couples showing reduced transmission but a randomized trial suggesting no short-term benefit of circumcision. Data were collected as part of a prospective study among African HIV-1-serodiscordant couples were analyzed for the relationship between circumcision status of HIV-1-seropositive men and risk of HIV-1 acquisition among their female partners. Circumcision status was determined by physical examination. Cox proportional hazards analysis was used. A total of 1096 HIV-1-serodiscordant couples in which the male partner was HIV-1-infected were followed for a median of 18 months; 374 (34%) male partners were circumcised. Sixty-four female partners seroconverted to HIV-1 (incidence 3.8 per 100 person-years). Circumcision of the male partner was associated with a nonstatistically significant approximately 40% lower risk of HIV-1 acquisition by the female partner (hazard ratio 0.62, 95% confidence interval 0.35-1.10, P = 0.10). The magnitude of this effect was similar when restricted to the subset of HIV-1 transmission events confirmed by viral sequencing to have occurred within the partnership (n = 50, hazard ratio 0.57, P = 0.11), after adjustment for male partner plasma HIV-1 concentrations (hazard ratio 0.60, P = 0.13), and when excluding follow-up time for male partners who initiated antiretroviral therapy (hazard ratio 0.53, P = 0.07). Among HIV-1-serodiscordant couples in which the HIV-1-seropositive partner was male, the authors observed no increased risk and potentially decreased risk from circumcision on male-to-female transmission of HIV-1.
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Editors’ note: The trend seen here among 1096 couples toward a protective effect of male circumcision for HIV-negative women in discordant partnerships is intriguing. Sexual behaviours of couples with circumcised men were similar to those in which the man was not circumcised, only genetically-linked transmissions (i.e. transmissions within the couple) were considered (incidence 3.0 per 100 person years), and follow-up time after initiation of antiretroviral treatment (when viral loads presumably fell) was excluded. The result was a borderline statistically significant 47 per cent reduced risk of HIV-1 acquisition in women. Possible mechanisms that might explain lower risk for women are reduced risk of sexually transmitted infections in circumcised men or reduced likelihood of direct HIV transmission that would have otherwise occurred as a result of microtrauma or inflammation of the foreskin.
The effects of circumcision on the penis microbiome.
Price LB, Liu CM, Johnson KE, Aziz M, Lau MK, Bowers J, Ravel J, Keim PS, Serwadda D, Wawer MJ, Gray RH., PLoS One. 2010. 5:e8422.
Circumcision is associated with significant reductions in HIV, HSV-2, and HPV infections among men and significant reductions in bacterial vaginosis among their female partners. The authors assessed the penile (coronal sulci) microbiota in 12 HIV-negative Ugandan men before and after circumcision. Microbiota were characterized using sequence-tagged 16S rRNA gene pyrosequencing targeting the V3-V4 hypervariable regions. Taxonomic classification was performed using the RDP Naïve Bayesian Classifier. Among the 42 unique bacterial families identified, Pseudomonadaceae and Oxalobactericeae were the most abundant irrespective of circumcision status. Circumcision was associated with a significant change in the overall microbiota (PerMANOVA p = 0.007) and with a significantdecrease in putative anaerobic bacterial families (Wilcoxon Signed-Rank test p = 0.014). Specifically, two families-Clostridiales Family XI (p = 0.006) and Prevotellaceae (p = 0.006)-were uniquely abundant before circumcision. Within these families they identified a number of anaerobic genera previously associated with bacterial vaginosis including: Anaerococcus spp., Finegoldia spp., Peptoniphilus spp., and Prevotella spp. The anoxic microenvironment of the subpreputial space may support pro-inflammatory anaerobes that can activate Langerhans cells to present HIV to CD4 cells in draining lymph nodes. Thus, the reduction in putative anaerobic bacteria after circumcision may play a role in protection from HIV and other sexually transmitted diseases.
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October 25th, 2009 at 3:52 am