A campaign to encourage African men to get circumcised to prevent infection by HIV gained a powerful boost Wednesday by three new studies unveiled at the world AIDS forum in Rome.
New cases of HIV among men fell by an astonishing 76 percent after a circumcision programme was launched in a South African township, researchers reported.
Had no circumcisions been carried out, the tally of new infections among the overall population, men and women combined, would have been 58 percent higher.
"This study is a fantastic result for a simple intervention which costs 40 euros (56 dollars), takes 20 minutes and has to be done only once in a lifetime," said David Lewis, of the Society for Family Health in Johannesburg and the University of the Witwatersrand, South Africa.
In 2006, trials in Kenya, Uganda and South Africa found foreskin removal more than halved men's risk of infection by the human immunodeficiency virus (HIV).
Longer-term analysis found the benefit to be even greater than thought, with a risk reduction of around 60 percent.
After pondering risks and benefits, health watchdogs set in motion circumcision campaigns in 13 sub-Saharan countries that have been badly hit by the AIDS virus.
Advocates call it "surgical vaccine", describing it as a cheap yet effective form of prevention.
Sub-Saharan Africa is home to two-thirds of the 33 million people living with HIV. As of mid-2010, around 175,000 circumcisions had been carried out in the 13 countries considered priorities, according to UNAIDS.
The new study was conducted between 2007 and 2010 in Orange Farm, a township of 110,000 adults, where more than 20,000 circumcisons had been performed, especially in the 15-24 age group which is most sexually active.
Two other studies released in Rome added to the good news about circumcision:
-- Circumcised men say they experience greater sexual pleasure after surgery, a finding that should help overcome unease about the operation.
Investigators at the University of Makerere interviewed 316 men, average age 22, who had been circumcised between February and September 2009.
A year after the operation, 220 of the volunteers said they were sexually active, of whom a quarter said they used condoms.
A total of 87.7 percent said they found it easier to reach an orgasm after being circumcised, and 92.3 percent said they experienced more sexual pleasure.
-- Newly-circumcised men are just as likely as uncircumcised men to practice safe sex, according to interviews conducted among 2,207 men in western Kenya, six months after they had had the operation.
This helps ease concerns that circumcised men are tempted to abandon condom use in the belief they are completely shielded from HIV.
France's 2008 Nobel laureate Francoise Barre-Sinoussi, who in 1983 co-identified HIV as the source of AIDS, said over-confidence in circumcision was a major anxiety.
"Nothing provides 100-percent protection, not even a vaccine," she told AFP. "Let's stop thinking that one preventative tool is enough. Circumcision has to be part of a combined approach."
The theory behind the benefits of circumcision is that the inner foreskin is an easy entry point for HIV. It is rich in so-called Langerhans cells, tissue that the AIDS virus easily latches on to and penetrates.
On the downside, male circumcision does not reduce the risk for women who have intercourse with an HIV-infected man, and the protective benefit does not seem to apply to homosexual intercourse.
There is an indirect advantage, though. The fewer men who are infected with HIV, the smaller the risk of infection for others.
"Science is proving that we are at the tipping point of the epidemic," said Michel Sidibe, executive director of UNAIDS.
Scaling up voluntary circumcision to young men in places with HIV prevalence will help reach the UN's 2015 goal of halving sexual transmission of the disease, he said.