Although it has been recognized for some time that regions with greater prevalence of male circumcision tend to have lower HIV infection rates than regions where most men are uncircumcised, until recently no study had specifically tested the efficacy of adult male circumcision in preventing the acquisition of HIV. 

In 2005, the results of an 18-month study in Orange Farm, South Africa suggested that circumcision reduced men’s risk of contracting HIV during sexual intercourse by over 60% during the study period. 

Although there is no conclusive explanation of the relationship, research suggests male circumcision may reduce transmission by removing cells in the inner foreskin that serve as entry points for the virus. 

Despite the encouraging results of the study in South Africa, there is a need for more studies to confirm these findings. 

In July 2005, UNFPA, UNICEF, WHO and UNAIDS advised that these results should be confirmed before male circumcision is broadly promoted as a standard measure within comprehensive HIV prevention programmes. 

Two other trials were conducted in Kenya and Uganda.

The results were available in 2007 and supported the findings of the South Africa Orange Farm Intervention Trial, which demonstrated at least a 60% reduction in HIV infection among circumcised men.

A further trial to assess the impact of male circumcision on the risk of HIV transmission to female partners from HIV-infected men, led by researchers at Johns Hopkins University, is currently under way in Uganda, with results expected later in 2008.

Whatever the results of these trials, it is important to emphasize that male circumcision is not a perfect solution. 

Circumcised males are not immune to HIV, but rather have a reduced risk of transmission. 

A circumcised male could still become infected with the virus after just one contact with an HIV-positive sexual partner. 

The implications for women are also not yet clear.

Condoms are still the most effective prevention method.