Circumcision found to lower HIV risk

Circumcision reduces the risk of HIV infection by half, according to a new study conducted among nearly 8,000 adult males in Kenya and Uganda, researchers reported Wednesday.

Circumcision proved so effective that the study was halted a year early and the procedure was offered to all study participants.

Previous research has suggested that circumcision is beneficial, but the new trial is “definitive,” according to Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, which cosponsored the study with the Canadian Institutes of Health Research.

“It’s not a magic bullet,” said Dr. Kevin De Cock, director of the World Health Organization’s department of HIV/AIDS, but it has the potential to prevent “many hundreds of thousands and perhaps millions of infections over coming years.”

The findings, which apply only to heterosexual transmission of HIV from women to men, will have less impact in the United States, where nearly 80% of males are circumcised and homosexual contact between men still plays a major role in transmission of the virus.

But they could have a major effect in the rest of the world, where heterosexual contact is the major form of transmission.

Nonetheless, experts cautioned that circumcision does not eliminate risk. The procedure “has to be integrated with all the other things that we do to prevent new HIV infections,” said epidemiologist Robert Bailey of the University of Illinois at Chicago, who led the Kenya study.

Circumcision rates vary widely in Africa. The average is just over 60% for the entire continent, but less than 20% in South Africa, where the AIDS epidemic is most severe.

Early small trials of circumcision had shown a beneficial effect from the procedure, in which the foreskin is removed from the penis, but experts feared that the benefits might be related to cultural biases rather than the procedure itself.

Even a 2005 study of more than 3,000 men in South Africa, which showed that circumcision reduced HIV transmission by 60%, failed to move funding agencies, which feared that the findings could not be reproduced at other sites.

The new results appear to have tipped the balance. UNAIDS and the WHO said Tuesday that they would rapidly convene a panel of experts to determine how to implement the findings.

The Ugandan trial in Rakai enrolled 4,996 men ages 15 to 49, half of whom underwent circumcision. All the men in both studies also received counseling on HIV risk reduction and were advised to wear condoms.

But because condom usage is not 100%, the researchers expected to see infections in both groups.

A U.S. National Institutes of Health board reviewed the data Tuesday and found 43 cases of HIV infection among the uncircumcised men, compared with 22 among the circumcised -- a 48% reduction in risk.

The Kenyan trial in Kisumu enrolled 2,784 men ages 18 to 24. The monitoring board found 47 cases among the uncircumcised men, compared with 22 among the circumcised -- a 53% reduction in risk.

Faced with those results, the board said the trial should be terminated immediately.

“Circumcision is now a proven, effective prevention strategy to reduce HIV infections in men,” Bailey said.

An ongoing trial in Africa is also studying whether circumcision of men will reduce the HIV infection rate among women.

Fauci said during a Wednesday teleconference that cells of the foreskin appeared to be more fragile than those on the rest of the penis, and thus more susceptible to invasion by HIV.

The folds of the uncircumcised penis can also trap the virus, holding it against the penis in a warm, moist environment that promotes infection.

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thomas.maugh@latimes.com