Offering circumcision would have a very small effect on reducing HIV transmission rates among gay and bisexual men in the United States, according to researchers presenting findings at the XVIII International AIDS Conference held this week in Vienna, Austria.
Three key studies in Africa in 2005 and 2007 showed that HIV transmission rates were decreased in men who were circumcised. These clinical trials were conducted on heterosexual males in Uganda, Kenya and areas of sub-Saharan South Africa. All three random trials showed that circumcision reduced the risk of female-to-male HIV transmission by 50 to 60 percent.
The success of these trials offered hope that similar trials for homosexual men in the U.S. would reveal similar results.
"Circumcision protects HIV-negative heterosexual men from acquiring HIV from their female partners," said Chongyi Wei, an author of the new study and a post-doctoral researcher at the University of Pittsburgh. However, study results were not the same for homosexual men.
In the new study, researchers from the University of Pittsburgh surveyed 521 gay and bisexual men in San Francisco.
They found that 115 men (21 percent) were HIV-positive and 327 (63 percent) had been circumcised. Of the remaining 69 men (13 percent), only three (0.5 percent) said they would be willing to participate in a clinical trial of circumcision and HIV prevention.
The researchers extrapolated their findings to the entire gay and bisexual male population of San Francisco, an estimated 65,700 people, and determined that only 500 men would potentially benefit from circumcision.
Of that group, "few would be willing to be circumcised even if circumcision is found to be an effective HIV prevention strategy among gay and bisexual men," said Wei. In fact, only four (0.7 percent) of the study participants said they would be willing to get circumcised if this were the case.
Differences in HIV transmission
The difference between the results of the clinical trials in Africa and the U.S. study is that the main cause of HIV infection in Africa is heterosexual sex, while homosexual sex is the leading cause of transmission in the Unites States, Wei said.
"Our study's main conclusion is that circumcision would have very limited impact on the HIV epidemic among gay/bisexual men in San Francisco because most of them are already circumcised, Wei told LifesLittleMysteries.
And, Wei said, the majority of gay/bisexual men participate in both the receptive role (the partner who is penetrated) and the insertive role (the partner who penetrates the other). Because circumcision only increases the protection for the man in the insertive role, it would not be likely to protect a man in all acts in which he is likely to engage.
Circumcision is thought to reduce the risk of HIV transmission by removing parts of the foreskin that are most susceptible to infection by the virus, according to the American Urological Association (AUA).
"Circumcision in the U.S. already is very common, making it applicable to a limited number of men as a potential HIV prevention strategy in adulthood," Wei said. "Our study indicates that any potential benefit may likely be too small to justify implementing circumcision programs as an intervention for HIV prevention."
A once uncommon practice in Africa, circumcision is now being promoted by several countries there.
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This article was provided by LifesLittleMysteries, a sister site to LiveScience.