Will Mass Adult Male Circumcision Bring an End to the HIV Pandemic?

Western organizations have big, big plans for the penises of millions of African men. They are to be clipped, and in short order. In Tanzania alone there is a plan to circumcise 2.8 million men in the next five years. What those men decide to do with their newly trimmed penises, after the mobile circumcision unit is just a painful memory, will ultimately determine whether or not these campaigns are effective at reducing HIV/AIDs rates in Africa.  

In response to a scientific finding that the female-to-male HIV transmission rate is as much as 76% lower for men who are circumcised, the World Health Organization is advocating for a mass adult male circumcision in Africa. Governments and NGOs have jumped onboard, including The Bill and Melinda Gates Foundation that has promised $50 million, making 650,000 circumcisions possible in Swaziland and Zambia in the next few years.

One possible problem with this plan is that people will change their sexual behavior in response to the now lower risk of having unprotected sex with multiple sexual partners. If the scale of this behavioral effect is large enough then these programs will not only be ineffective, they could actually increase the HIV transmission rate.

This is the same argument that is used to explain why access to contraceptives increased accidental pregnancy rates over the past century.

Think of this in terms of a cost benefit analysis. A man will either wear a condom, or abstain from sex altogether, if the expected cost of unprotected sex (the risk of sexually transmitted infection) exceeds the benefit of unprotected sex (the pleasure of having sex without a condom). Following circumcision, the expected cost of unprotected sex for men is lower because the probability of being infected with HIV has fallen. Presuming the benefit to sex without a condom is unchanged (which may or may not be true) lowering the expected costs should encourage more men to be willing to engage in risky sex.

The same cost benefit approach also predicts that women will also be more willing to engage in unprotected sex if women believe that men who are circumcised are less likely to have HIV.

There is an alternative approach, however, that applies a long run approach to this same argument. If, in an area where HIV/AIDs rates are very high, men and women believe that no matter how careful they are today, infection in the future is inevitable, then they will chose to reap the benefit of unprotected sex today even when the cost is high (we have talked about this problem before). This approach takes into consideration the possibility that men who are uncircumcised have a fatalistic approach to infection, leading to risky sexual behavior, and that men who are circumcised might actually decrease risky sexual behavior today because they have reason to hope that they never will become infected.

What this boils down to is a belief in the ability of circumcision to protect them from infection.

New, yet unpublished, research finds that circumcised men who believe in this protection have fewer sexual partners than do other men (circumcised or uncircumcised) and that circumcised men who do not believe in this protection have more.

Circumcised “believers” are 10 to 20 percentage points less likely to have had multiple sexual partners (post-circumcision) than were circumcised “non-believers” and, in the long run, have a much higher likelihood of using a condom.

Circumcision is voluntary, in theory, so in the real world it is likely that the majority of men who opt for the procedure will be believers. So while this study finds that, on balance, there is no effect on risky-sexual behavior in the long-run, circumcision might lead to safer sex in general.

Good news for those who believe in the power of these programs to help bring about change in some of the world’s hardest hit regions.

I do have one more comment on the paper. The authors argue that one possible explanation for why circumcised non-believers have more sexual partners is because women find the circumcised penis more “aesthetically pleasing”. Personal preferences aside (after all, they call it a “Canadian” for a reason), I have a hard time imagining how aesthetic preferences actually translate into more sexual partners. For example, since when is the answer to the question “Why did you have sex with him” ever “Because his penis was so lovely”? Maybe for repeat performances this sort of thing matters, but for first time sexual encounter I am pretty skeptical.

Mattson, Christine, Nicholas Wilson, and Wentao Xiong. (2012) “Is Sex Like Driving? Risk Compensation Associated with Male Circumcision in Kisumu, Kenya.”