AIDS avoidance: more studies find that circumcision deters HIV.

Two large clinical trials in East Africa show that being circumcised halves a man's risk of contracting HIV infection. The finding mirrors the results of a recent South African study (SN: 10/29/05, p. 275).

Combined, the reports offer definitive evidence that circumcision confers strong-though not complete--protection against infection by the virus, says Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases in Bethesda, Md.

The spotlight now moves to policy makers in Africa, some of whom are already investigating strategies to make safe circumcision available to men and boys who want the operation.

The fragile foreskin around the penis harbors immune cells that are easily infected with HIV (SN: 4/3/04, p. 212). After the foreskin is removed in circumcision, the remaining outer layer becomes tough and more difficult for HIV to penetrate.

The new findings come from areas in which few men are circumcised. In one study, researchers in Uganda enrolled 4,996 male volunteers between the ages of 15 and 49. In the other study, in Kenya, 2,784 men between 18 and 24 agreed to participate. The scientists randomly assigned half the men in each trial to get circumcised upon enrollment and the other half to wait 2 years for the procedure.

Scientists halted both trials earlier this month when it became clear that the circumcised men were contracting fewer HIV infections, Fanci announced last week.

Among the circumcised men, 22 in each trial became infected with HIV. Among uncircumcised men, 42 in Uganda and 47 in Kenya became infected.

Widespread male circumcision in Africa could have a potent impact on AIDS there (SN: 7/29/06,p. 77). "If decisions are made to scale up [circumcision programs] in different countries, it does have the potential to prevent many thousands ... or even millions of infections over the coming years," says Kevin M. De Cock, director of the HIV/AIDS department at the World Health Organization in Geneva. "A once-only intervention that confers a 50 percent efficacy is obviously a very important development."

Among tribes in Africa that don't routinely practice circumcision, there are often no specific taboos against it, says Robert C. Bailey of the University of Illinois in Chicago, who worked on the Kenya trial. "Cost is the biggest barrier," he says.

In Swaziland, which has a high HIV-infection rate, some clinics are promoting "Circumcision Sundays" as an anti-HIV measure, charging as little as $40 for the operation. And in Zambia, international doctors are working with local authorities to develop a surgical manual for circumcision, says Catherine Hankins of the Joint United Nations Program on HIV/AIDS.

So far, no African country has adopted a formal policy promoting or subsidizing circumcision, says Jeckoniah Ndinya-Achola, a physician at the University of Nairobi in Kenya. But Zambia, Swaziland, Tanzania, Lesotho, and Kenya have held talks about such programs.

Meanwhile, researchers in Uganda are investigating whether circumcision limits HIV transmission from men to women. Results are expected in 2008.