July 23, 2012
A study published in the Lancet on Friday warns that despite "decades of research and community, medical and public health efforts," "HIV remains uncontrolled in MSM [men who have sex with men] in 2012." The authors wrote, "This reality demands reinvigorated effort, new approaches grounded in biology and epidemiology, and concerted effort to reduce the structural risks that aid and abet" HIV's spread among MSM.
HIV prevalence among MSM is 15 percent or higher in the United States, Spain, Chile, Thailand, Malaysia, South Africa, and several other nations in Africa and the Caribbean, the researchers reported.
Central to HIV's disproportionate impact on MSM is the greater transmission risk associated with unprotected receptive anal sex -- a 1.4 percent probability, which the authors said is 18 times higher than for penile-vaginal intercourse. Amphetamines and deliberate avoidance of condoms also may play a role, the authors said.
"If the transmission probability of receptive anal sex was similar to that associated with unprotected vaginal sex ... cumulative HIV incidence in MSM would be reduced by 80-98 percent" within five years, the team wrote.
Warning that "Casual partnerships are ... a substantial driver of the epidemic in MSM," the authors continued: "If unprotected anal intercourse in casual partnerships instead happened within long-term main partnerships, HIV prevalences would be reduced by 29-51 percent."
The team called for increased use of antiretrovirals, both to reduce the infectiousness of HIV-positive men and to lower the risk for those uninfected (pre-exposure prophylaxis). A rectal microbicide to kill the virus in infected semen could also play a role someday.
[PNU editor's note: The study, "Global Epidemiology of HIV Infection in Men Who Have Sex With Men," was published in the Lancet (2012;doi:10.1016/S0140-6736(12)60821-6) as part of a series of articles called "HIV in Men Who Have Sex with Men."]