Circumcision: Effect on Heterosexual HIV Transmission

BETHESDA, Md., Dec. 14 -- Two U.S.-led trials of men in sub-Saharan Africa were halted early when interim analyses of results confirmed that circumcision can significantly reduce heterosexual transmission of HIV.

A trial of 2,784 HIV-negative men in Kisumu, Kenya, found a 53% reduction in HIV acquisition in circumcised versus non-circumcised men.

In the second trial, a study of 4,996 HIV-negative men in Rakai, Uganda, circumcision was associated with a 48% reduction in HIV infection.

The trials, both sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), were originally scheduled to continue until mid-2007, but the significant benefit identified in the preliminary analyses prompted NIAID to stop the studies on the basis of the clear clinical benefit of circumcision.

Anthony S. Fauci, M.D., the NIAID director, acknowledged that a number of earlier studies have reported similar findings but he said the new studies provided "confirmation from large, carefully controlled, randomized trials showing definitely that medically performed circumcision can significantly lower the risk of adult males contracting HIV through heterosexual intercourse."

In sub-Saharan Africa HIV is usually spread by heterosexual intercourse and most men are not circumcised.

The findings, however, are unlikely to affect clinical practice in the United States, where a large proportion of males are circumcised at birth and many HIV infections occur among men who have sex with men. It is not known whether circumcision has a similar protective effect for homosexual men.

Observational studies had suggested that HIV prevalence closely tracked circumcision practices in countries where circumcision was common HIV prevalence was lower, while in countries where circumcision was uncommon, HIV prevalence was higher.

Those observations first led a team of French and South African researchers to investigate the relationship between circumcision and HIV acquisition. In 2005 they reported that circumcision reduced heterosexual transmission of HIV by 60%.