Male circumcision definitely reduces the risk of HIV infection, researchers at the South African Cochrane Centre announced on Wednesday.

The center had previously held that there was not enough evidence to recommend circumcision as an intervention.

"Research on the effectiveness of male circumcision for preventing HIV in heterosexual men is conclusive," said lead researcher Nandi Siegfried, co-director of the center, which is located at the South African Medical Research Council.

"No further trials are required to establish that HIV infection rates are reduced in heterosexual men for at least the first two years after circumcision."

She said policy makers could now consider using circumcision as an additional tool in HIV prevention programs.

The Cochrane Collaboration is a highly-respected international network of researchers that seeks to improve healthcare decision-making through systematic reviews of the effects of healthcare interventions such as circumcision.

Siegfried said three recent African trials supported the conclusion that circumcision reduced HIV risk.

"After including new data from these trials in their review, Cochrane researchers have changed their previous conclusions that there was insufficient evidence to recommend circumcision as an intervention to prevent HIV infection in heterosexual men."

Previous studies had investigated the association between circumcision and HIV, but until now, Cochrane researchers had been unable to strongly recommend circumcision because of the lack of high quality evidence.

Siegfried said circumcision might help to protect against HIV by removing cells in the foreskin to which the virus was specifically attracted. These Langerhans cells had receptors that enabled the virus to enter them.

The new clinical trials included in the review took place in South Africa, Uganda and Kenya between 2002 and 2006, and included a total of 11,054 men.

The results show that circumcision in heterosexual men reduced their risk of acquiring HIV by an average 54 percent over a two year period, compared with uncircumcised men.

Further research was needed to establish whether male circumcision offered any benefit to women partners of those circumcised men, or to homosexual men.

She warned that policy makers also needed to think about the culture and environment in which circumcision was carried out.

(Xinhua News Agency April 16, 2009)