Male circumcision may lower the risk of heterosexual men contracting HIV by as much as 60 percent, according to major studies released in February.
But the procedure may not reduce the transmission rate of HIV among men who have sex with men, some researchers say.
Three studies in Africa have shown that circumcision lowered the rate of HIV infection in straight men by about half. One of the two published in February looked at 2,784 men in Africa, the other almost 5,000 men in Africa. They found a protective effect of 53 percent and 51 percent respectively in men who were circumcised, compared to those who were not. The trials were stopped early because of the dramatic results.
On Mar 28, UNAIDS and the World Health Organization recommended that heterosexual men undergo circumcision to reduce their chances of infection.
But the studies looked primarily at heterosexual transmission. Researchers say that anal sex, considered to be the highest risk factor for men who have sex with men (MSM), is not necessarily part of the circumcision equation. Sharif Sawires, senior public analyst at the UCLA program in Global Health and the David Geffen School Of Medicine, says unprotected anal sex is risky because the surface layer of the anus is considerably thinner than vaginal tissue, making it more susceptible to infection; circumcision is therefore considered less likely to make a difference.
“The highest risk for MSM is not to the insertive partner, but to the receptive partner,” writes Sawires in an e-mail. “MC [male circumcision] will likely have little or no benefit in transmission rates from insertive to receptive partner, but that is only preliminary. There are a lot of investigators interested in MSM population and MC — so yes, there will likely be a lot of folks looking specifically at the MSM population.”
The studies have been done in regions — mostly sub-Saharan Africa — where heterosexual transmission is considered to be the main cause of infection, says John Maxwell, director of special projects at the AIDS Committee Of Toronto.
“So it’s men who are engaging in vaginal intercourse with women and it’s their risk of contracting HIV from their female partners,” says Maxwell. “Nothing has been done in terms of the context of how does it reduce the risk for men engaging in anal sex.”
The inner surface of the foreskin has a high density of HIV target cells; researchers believe that removing it would give HIV fewer cells to target. The inner surface of the foreskin also has less keratin than the rest of the surface of the penis; keratin is a protein substance on the shaft of the penis that provides a protective barrier from HIV infection.
Maxwell says there are other reasons why the study results may not be directly applicable to Canada.
“It’s also happening within the context of largely resource-poor countries where issues such as access to healthcare and regular checkups for STIs [sexually transmitted infections] may be very different from high-income countries like Canada and the US. So we don’t really know what the impact is going to be in terms of this sort of call for circumcision for men in terms of what that may do for gay men,” says Maxwell.
Maxwell also questions the practicality of a global push to circumcise men. Factors such as cost and physical impact must be taken into consideration. It’s one thing to circumcise infants, another to circumcise men in the 20s and 30s, as some have suggested.
“When we look at where we’re at in terms of HIV prevention, vaccines are a long time away,” he says. “When we’re looking at prevention we need to be careful not to look at one thing as the magic bullet and the fear right now is sort of this mass push for circumcision is almost seen as though that will be the be-all and the end-all. In reality, it isn’t.”
There’s an ongoing study in Uganda looking at HIV transmission rates from male to female partners, says Sawires. In this case, though still preliminary, circumcision doesn’t appear to be reducing transmission to women.
Some people wonder if infant circumcision, which has been declining in Canada for the past decade, will become more popular again in the wake of these studies — why leave your son at a higher risk? But Maxwell says it’s easy for people to make the wrong assumption about such studies. There are other factors that need to be considered. Increased promotion of circumcision might create a false sense of security in some people.
“You’re not getting any protection for the women if their male partners, for example, are already HIV-positive but don’t know it,” he says. “Even in Canada where we like to think that people go regularly for testing, on average it’s assumed that about 30 percent of people who are HIV-positive don’t know their HIV status because your HIV status is only as good as the time where you got your last test.”
Maxwell wonders if there are other things that could be done, such as making condoms more accessible and supporting the development of vaginal microbicides — which would give women greater independence instead of relying on their male partners to use condoms.
“Men should also be supporting the development of microbicides that could be used anally,” he says. “That would certainly be of benefit to gay men, but it would also be a benefit to heterosexual couples who engage in anal sex, too.”