Around the world, the incidence of HIV in gay men is startlingly consistent, hovering between 2 and 5 percent. Although the U.S. transmission rate declined in the early years of the American epidemic, when activists were promoting condoms and HIV was constantly in the news, in recent years rates have begun to creep up again.
The sexual HIV transmission rate in men who have sex with men (MSM) is substantially higher than the rate seen in heterosexuals. This is due to a number of biological, behavioral, and social factors.
The average HIV transmission rate during anal sex is estimated to be 18 times higher than the rate during vaginal intercourse. The risk of acquiring HIV during an act of unprotected anal intercourse is estimated to be 1.4 percent.
The role variability of gay men increases transmission risk. Men who practice receptive, unprotected anal intercourse are at higher risk of contracting HIV. Men who practice insertive, unprotected anal intercourse are more likely to transmit HIV to their partners. This combination optimizes the spread of HIV between gay men in a way not seen in heterosexual couples.
Homophobia and other forms of legal and social discrimination against gay men make it more difficult for them to access health care. This may cause delays in diagnosis and treatment of HIV infection. Since people are often most infectious during acute infection, and treatment reduces infectivity, this further increases the HIV risk among MSM.
In addition, certain groups of gay men are at particularly high risk for not only the above reasons but also because a large percentage of their potential partners are infected with the virus. This issue is particularly problematic for Black MSM. They often date within very small, high-risk communities. As such, their HIV risk is often higher than that of other MSM, even when their behavioral and lifestyle choices are safer.
For example, Black MSM in the United States are three times as likely to have HIV as other MSM even though, on average, they are less likely to engage in risky behaviors-- such as using drugs during sex. However, it's not just the higher risk of their partner pool that causes this disparity. Black MSM with HIV are also less likely to have health insurance, be on successful cART regimens, or have a high CD4 count than other HIV positive MSM. This reflects systemic healthcare inequities related to race, whose effects are not limited to Black MSM.
The Extent of the Problem - Social and Biological Factors Affecting HIV Risk in MSM?
In an article published in the July 2012 special issue of The Lancet on "HIV in Men who have Sex with Men", Dr. Chris Beyrer and colleagues calculated that 80-90 percent of the HIV epidemic in gay men would disappear if the transmission rate during anal intercourse was the same as it is during vaginal intercourse. Role segregation alone could also drop the numbers by 20-50 percent, and putting those two things together might get rid of as many as 95 percent of HIV infections seen in gay men.
Increased access to non-judgmental healthcare would help as well. If gay men felt safe disclosing their sexual risk to their doctors, they might get tested more frequently, treated sooner, and reduce the risk of infecting their partners while also improving their health. Unfortunately, although the CDC recommends universal HIV testing (for everyone, not just gay men), very few doctors and clinics have actually been implementing such measures.
Fortunately, there are signs that things may be improving. After powerful data was released showing that reducing viral load reduces the likelihood of sexual transmission of HIV, both New York and San Francisco have recommended universal access to HIV treatment - removing restrictions related to CD4 count. This could be a great boon to serodiscordant gay couples, since reducing an infected partner's viral load is not only a form of treatment, it also helps keep their lover safe from infection.
Beyrer, C., Baral, S.D., vanGriensven, F. Goodreau, S.M., Chariyalerstak, S., Wirtz, A., & Brookmeyer, R. (2012) Global epidemiology of HIV infection in men who have sex with men. The Lancet. 380(9839):367-377
Millett, G.A., Peterson, J.L., Flores, S.A., Hart, T.A., Jeffries, W.L., Wilson, P.A., Rourke, S.B., Heilig, C.M., Elford, J., Fenton, K.A>, & Remis, R.S. (2012) Comparisons of disparities and risks of HIV infection in black and other men who have sex with men in Canada, UK, and USA: a meta-analysis. The Lancet. 380(9839):341-348