Specifically, male circumcision reduced by 30 percent the likelihood that the female partner would become infected with the virus that causes AIDS, with 299 women contracting HIV from uncircumcised partners and only 44 women becoming infected by circumcised men. Similar reductions in risk were observed for the other two kinds of infection, but not for other common STDs, including human papillomavirus, syphilis, gonorrhea and Chlamydia.
According to the Hopkins researchers who led the study, Ronald Gray, M.D., and Steven Reynolds, M.D., M.P.H., the findings support efforts to assess male circumcision as an effective means of preventing HIV infection. Circumcision is a practice common in North America and among Jews and Muslims, but not generally in Eastern and Southern Africa, Europe or Asia.
The couples in the study come from the Rakai cohort, a population of roughly 12,000 in Uganda whom researchers are monitoring to see how HIV infection spreads. The researches based their findings on extensive interviews with each participant and annual check-ups and blood tests.
The findings confirm what has been noticed anecdotally in Africa, where regions in which circumcision is common have lower rates of HIV infection than those without. And, the results confirm what was first reported in summer 2005 from a clinical trial conducted in South Africa about the protective effects of circumcision on HIV-negative men who have sex with HIV-positive women.
According to researchers, circumcision's effects come from the nature of the foreskin's inner lining, or mucosa, whose cells bind to the virus more easily and have roughly nine times more virus in them than the outer layer of the foreskin. Removal of the foreskin, they say, may simply reduce the susceptibility factor, or degree of exposure to HIV, for the sexual partner.
Thomas C. Quinn, M.D., professor of infectious diseases at Hopkins and a senior investigator at the National Institute of Allergy and Infectious Disease, will present an overview of this trial, plus two others presently under way, as part of a plenary discussion at CROI on circumcision and HIV. But, he says, "We will have to wait for the ongoing two trials before drawing conclusive recommendations about circumcision for all men, and whether or not the benefits apply to transmission from females to males only, or to females from men as well. However, early indications are dramatic and, if proven, one case of HIV disease could be prevented through circumcising anywhere from 15 to 60 males."
Male Circumcision and the Risks of Female HIV and STI Acquisition in Rakai, Uganda, by Ronald Gray, Marie Thoma, Oliver Laeyendecker, David Serwadda, Fred Nalugoda, Godfrey Kigozi, Noah Kiwanuka, Nelson Sewankambo, Steven Reynolds, Maria Wawer, and Thomas Quinn. And, Circumcision and HIV Transmission:The Cutting Edge, by Thomas Quinn.
2006 Conference on Retroviruses and Opportunistic Infections, Feb. 5 - Feb. 9, Denver, Colo.
(Embargoed for release at 11:15 a.m. MT/1:15 p.m. ET, Wednesday, Feb. 8; oral presentation #127, Session 33, Ballrooms 1 and 2; preceded by plenary discussion at 8:30 a.m. MT, Main Lecture Hall, Colorado Convention Center)