'Surgical vaccine': Delegates at the International AIDS Conference 2008 in Mexico City.

Credit: International AIDS Society/Mondaphoto

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MEXICO CITY: Circumcision appears to offer men even greater protection against HIV than thought, according to two studies presented at a major AIDS conference.

U.S. researcher Robert Bailey of the University of Illinois at Chicago put forward long-term data from a trial in Kisumu, Kenya, that in its initial phase enrolled 2,784 uncircumcised, uninfected men.

Half of the group were circumcised, and the others were circumcised at a later date and they were subsequently tested for HIV.

Astonishing results

Previously published research from this trial found that, after two years, circumcised men were 59 per cent less likely to contract the human immunodeficiency virus (HIV) than uncircumcised counterparts.

The benefit was so astonishing that at this 24-month mark, the uncircumcised men were offered circumcision, as it would have been unethical not to do so.

In a presentation on Thursday at the 17^th International AIDS Conference, Bailey said the estimate of protectiveness at 24 months had been adjusted to 60 per cent in the light of refined lab tests from blood specimens. And he also reported that at the 42-month mark, circumcision offered a protectiveness of 65 percent.

This extension of the study, conducted among 1,739 of the original 2,784 volunteers, will run until December 2009.

"The 60 per cent protective effect against HIV acquisition ... over the first 24 months of the study, we now find to be sustained and possibly strengthened to approximately 65 per cent over three and a half years of follow-up," Bailey said.

"These results further support the addition of male circumcision to our limited armamentarium of HIV prevention," he said

Defence against HPV

Meanwhile, South African researcher Dirk Taljaard reported on a new aspect of a now-famous circumcision trial at Orange Farm, South Africa.

This French-led trial was the first to show that surgical removal of the foreskin offered protection against HIV, also around 60 per cent.

Taljaard said that analysis of other data from the Orange Farm trial showed that circumcision offered no shield to the man against gonorrhoea. It offered only "borderline" protection against trichomonal vaginitis, a parasite that dwells in the male and female sexual organs and is transmitted through vaginal intercourse.

But it did provide protection of 36 per cent against the human papilloma virus (HPV), a pathogen that can cause genital warts and is linked to cancer of the cervix and penis, he said.