Positive findings in research results due to be reported next year could lead the World Health Organization to suggest the procedure, said Kevin De Cock, director of the agency's HIV and AIDS programs. Circumcision prevented 6 of 10 potential infections with HIV, the virus that causes AIDS, among 3,300 men in South Africa, a study found last year.

Circumcision might stop as many as 2 million infections with HIV over 10 years in sub-Saharan Africa, according to a WHO analysis. While such evidence helped researchers in Kenya enroll more than 2,000 participants in their study, widespread adoption may not be easy in all parts of Africa, said Lovemore Gwanzura, a professor at the University of Zimbabwe who studies AIDS.

``There are strong traditional beliefs that don't tie up with circumcision,'' Gwanzura said in an interview at the 16th International AIDS Conference in Toronto. ``It's going to be an uphill task.''

Circumcision may be one of the most effective short-term solutions to prevent the spread of HIV, said health officials and celebrity advocates who spoke at the conference, including former U.S. President Bill Clinton and Microsoft Corp. founder Bill Gates. It would cost about $50 per adult male.

An HIV vaccine still remains as much as a decade away and public-health officials are seeking new prevention methods in the meantime, especially for Africa, where 24.5 million people are infected with the virus. Almost 40 million people worldwide have HIV or AIDS.

Risks

While circumcision might reduce the risk of infection, the procedure won't provide 100 percent protection, researchers emphasized today at a media briefing during the conference.

``Whatever gains might be made through male circumcision could be wiped out by people letting down their guard,'' said Catherine Hankins, chief scientific officer for the United Nations' UNAIDS program. ``A circumcised man might think he no longer needs to use condoms. A women might think, `Oh well, he's circumcised, I don't need to raise the issues of condoms.'''

Circumcision, a tradition for Jews and Muslims, has been performed for more than 4,000 years. The earliest evidence of the practice was found in drawings in tombs in ancient Egypt depicting a man being circumcised, according to the researchers who conducted the study in South Africa.

Common Method

The most common method of circumcision in the U.S. involves pushing the foreskin away from the head of the penis and clamping it with a metal or plastic ring. The foreskin is then snipped off and the remaining skin is stitched back onto the penis. In older boys and adults, it takes up to 10 days to heal.

There are basic biological explanations for how circumcision may help prevent HIV, said WHO's De Cock, who is a physician. One reason is that the cells on the surface of the foreskin are easier for the virus to invade than those on the tip of the penis, he said.

The two studies under way, like the research in South Africa, are testing whether circumcision prevents a man from becoming infected with the virus. A fourth study, which is receiving money from the Bill & Melinda Gates Foundation, is assessing whether circumcising men who already have HIV helps prevents them from passing it on to their female partners.

Performing the procedure on adult men in Africa would raise several logistical and practical issues. Physicians would need to be trained to perform the procedures in developing countries, where the WHO already estimates that $7.2 billion will need to be spent over the next five years to solve shortages of health- care workers.

Safety

Pain, safety and deeply held cultural values such as perceptions of masculinity will be the biggest obstacles in persuading men to get circumcised, researchers said today during a media briefing at the conference.

While scientific evidence is incomplete on the effectiveness of circumcision in preventing HIV infection, countries need to be ready for positive results, Clinton said during a media briefing at the conference.

``We all need to be prepared for a green light that could have a staggering impact,'' Clinton said. ``It is going to be a total headache figuring out how to sell people on it and do it in a safe way.''

The key in persuading men to get circumcised will be strong education programs, said Michael Munywoki, an AIDS policy adviser for the United Nations Mission in Sudan.

Sudan

In the northern part of Sudan, where the population is mostly Muslim, boys are traditionally circumcised. In contrast, there's a strong bias against the procedure in the non-Muslim south, Munywoki said. Peer-to-peer education may be the most effective way to mobilize men and gain acceptance for such a significant cultural change.

``Circumcision is very difficult to remove from the cultural context it grew up in,'' said Carolyn Williams, head of AIDS epidemiology at the National Institutes of Health, which is funding the ongoing research. ``You're going to have difficultly going into an area of mixed cultures and telling non-Muslims that they should now look like Muslim men.''

Receptiveness to the concept probably will vary from region to region, De Cock said.

``It's a pretty radical thing to suggest,'' De Cock said. ``The gravity of the AIDS epidemic and its recalcitrance in the face of other interventions certainly strengthened the debate.''

To contact the reporter on this story: Marni Leff Kottle in Toronto at mkottle@bloomberg.net ; Carey Sargent in Toronto at Csargent3@bloomberg.net .