Sexually Transmitted Infections and Male Circumcision: A Systematic Review and Meta-Analysis
Robert S. Van Howe
Received 12 December 2012; Accepted 22 January 2013
The claim that circumcision reduces the risk of sexually transmitted infections has been repeated so frequently that many believe it is true. A systematic review and meta-analyses were performed on studies of genital discharge syndrome versus genital ulcerative disease, genital discharge syndrome, nonspecific urethritis, gonorrhea, chlamydia, genital ulcerative disease, chancroid, syphilis, herpes simplex virus, human papillomavirus, and contracting a sexually transmitted infection of any type. Chlamydia, gonorrhea, genital herpes, and human papillomavirus are not significantly impacted by circumcision. Syphilis showed mixed results with studies of prevalence suggesting intact men were at great risk and studies of incidence suggesting the opposite. Intact men appear to be of greater risk for genital ulcerative disease while at lower risk for genital discharge syndrome, nonspecific urethritis, genital warts, and the overall risk of any sexually transmitted infection. In studies of general populations, there is no clear or consistent positive impact of circumcision on the risk of individual sexually transmitted infections. Consequently, the prevention of sexually transmitted infections cannot rationally be interpreted as a benefit of circumcision, and any policy of circumcision for the general population to prevent sexually transmitted infections is not supported by the evidence in the medical literature.
Male Circumcision Significantly Reduces Prevalence and Load of Genital Anaerobic Bacteria
Cindy M. Liu, Bruce A. Hungate, Aaron A. R. Tobian, David Serwadda, Jacques Ravel, Richard Lester, Godfrey Kigozi, Maliha Aziz, Ronald M. Galiwango, Fred Nalugoda, Tania L. Contente-Cuomo, Maria J. Wawer, Paul Keim, Ronald H. Gray, Lance B. Price [Familiar names behind an endless stream of studies promoting circumcision]
Male circumcision reduces female-to-male HIV transmission. [They always have to get that in, even though this is about bacteria, not viruses.] Hypothesized mechanisms for this protective effect include decreased HIV target cell recruitment and activation due to changes in the penis microbiome. We compared the coronal sulcus microbiota of men from a group of uncircumcised controls (n=77) and from a circumcised intervention group (n=79) at enrollment and year 1 follow-up in a randomized circumcision trial in Rakai, Uganda. [This must be one of the most over-studied group of subjects ever - relatively few, all volunteers for circumcision so hardly a random population sample, recruited by snowball techniques and hence over-likely to know each other and have sexual partners in common.] We characterized microbiota using, 16S rRNA gene-based quantitative PCR (qPCR) and pyrosequencing, log response ratio (LRR), Bayesian classification, nonmetric multidimensional scaling (nMDS), and permutational multivariate analysis of variance (PerMANOVA). At baseline, men in both study arms had comparable coronal sulcus microbiota; however, by year 1, circumcision decreased the total bacterial load and reduced microbiota biodiversity. Specifically, the prevalence and absolute abundance of 12 anaerobic bacterial taxa decreased significantly in the circumcised men. While aerobic bacterial taxa also increased postcircumcision, these gains were minor. The reduction in anaerobes may partly account for the effects of circumcision on reduced HIV acquisition [or may not, even partly - pure speculation].
The bacterial changes identified in this study may play an important role in the HIV risk reduction conferred by male circumcision. Decreasing the load of specific anaerobes could reduce HIV target cell recruitment to the foreskin. [Speculation piled on speculation.] Understanding the mechanisms that underlie the benefits of male circumcision could help to identify new intervention strategies for decreasing HIV transmission, applicable to populations with high HIV prevalence where male circumcision is culturally less acceptable. [This is new and somewhat mysterious. Have they finally noticed that men aren't all keen to have (the best) part of their penises cut off?]
[This study seems intended to frighten. No prize for guessing which study got plastered all over the media!]