Adult male circumcision could prevent millions of new HIV infections in sub-Saharan Africa, but circumcised men should not cease practising safe sex, researchers told the International AIDS Conference in Toronto on Thursday.

The protective benefits of male circumcision could save lives immediately, since microbicides and vaccines likely won't be available for years. 

A trial comparing HIV infection rates among circumcised and uncircumcised men in South Africa was stopped early last year after researchers found the practice appeared to reduce the risk of female-to-male HIV transmission by 60 per cent.

"Even if further trials show a lower risk of HIV infection in circumcised men, male circumcision will not provide complete protection against HIV infection," cautioned Catherine Hankins, chief scientific advisor for UNAIDS.

"Circumcised men can still contract HIV and pass it on to their partners."

If the benefit of male circumcision is proven, Hankins said it must be part of HIV prevention strategies that include:

• Correct and consistent use of condoms.
• Reductions in the number of sexual partners.
• Delaying onset of sexual relations.
• Voluntary and confidential counselling and HIV testing.

Men in the trial who were circumcised had the procedure performed under anesthesia by a doctor or trained nurse. It took about 30 minutes and cost about $50 US per person.

Based on the trial findings, a mathematical simulation of 823,000 sexually active men and women suggested that targeting just 10 per cent of men could avert 32,000 infections, according to Dr. Kyeen Mesesan of Yale University in New Haven, Conn.

Why it helps

Health officials are hoping the protective findings will be confirmed by two other clinical trials, underway in Uganda and Kenya, before they would consider recommending countries add adult male circumcision to their HIV prevention programs, said Dr. Kevin de Cock, director of WHO's HIV-AIDS department.

In circumcision, the foreskin on the penis is removed. The procedure appears to help reduce the risk of infection with HIV because the skin layer is thinner, allowing an easier way for the virus to enter, de Cock said.

The foreskin is also easily damaged, and its cells include those targeted by the virus.

If African countries add adult male circumcision to their prevention programs, it needs to be simple, safe and cost-effective, while also respecting local cultural and religious practices, scientists stressed.

The results of another trial examining how male circumcision affects the risk of transmitting HIV to female partners is expected in late 2007. The effects for men who have sex with men hasn't been tested in a trial.