Studies made in African countries point that circumcision can decrease the rate of HIV infection in heterosexual men by 50%.

But circumcision can not replace standard methods of preventing infections, as the condom does, warn the specialists. 8,000 men from Uganda and Kenya entered the studies due to finish in July and September 2007, respectively. But US National Institutes of Health Data and Safety Monitoring Board stopped the trials as it was unethical not to offer circumcision in the men who were acting as controls. The study found a 53% reduction in new HIV infections in heterosexual men who were circumcised in Kenya and of 48% in Uganda. A 2005 study in 3,280 heterosexual men in South Africa showed a 60% decrease in the incidence of new infections in circumcised men.

Scientists believe specific cells in the foreskin may be potential targets for HIV infection and also the skin under the foreskin turns less sensitive and bleeds less, decreasing the risk of infection following circumcision.

Researchers had already noted that circumcised men appeared to be less at risk of infection, but it was unclear whether this was due to differences in sexual behavior. Statistic modeling pointed that male circumcision could avoid about six million HIV infections and three million deaths in sub-Saharan Africa.

A further study in Uganda to investigate the risk of HIV transmission to female partners is due to report in 2008, but the effect among homosexual men has not yet been studied.

Dr Kevin De Cock, director of the HIV/AIDS department of the World Health Organization said the results were a "significant scientific advance", but warned that circumcision would never replace existing prevention strategies. "We will have to convene a meeting which we hope will happen quite soon to review the data in more detail and have discussions about the implications."

"This is an intervention that must be embedded with all the other interventions and precautions we have. Men must not consider themselves protected. It's a very important intervention to add to our prevention armamentarium."

"This is about as good epidemiological data as we can request. There will be many other research questions about implementation but this is very persuasive."

"Male circumcision performed safely in a medical environment complements other HIV prevention strategies and could lessen the burden of HIV/AIDS, especially in countries in sub-Saharan Africa where, according to the 2006 estimates from UNAIDS, 2.8 million new infections occurred in a single year." said NIH director Dr Elias Zerhouni.

"The Ministry of Health of the Kenyan government is already holding discussions about how this can be made available. It will need a certain amount of improvement to existing facilities." said Dr Jeckoniah Ndinya-Achola, co-principal investigator at the University of Nairobi, Kenya.

But Tom Elkins, Senior Policy Officer at the National AIDS Trust warned: "There is a real danger in sending out a message that circumcision can protect against HIV. This is not the case and could lead to an increase in unprotected sex."

"There is still a long way to go in providing comprehensive prevention programs in many countries, and resources should go into normalizing the use of condoms, which are the most effective method currently available for preventing HIV."