HIV has a hugely disproportionate impact on gay and other men who have sex with men in the US, according to new figures released by the US Centers for Disease Control and Surveillance (CDC).
Investigators calculated that the rate of new HIV infections amongst gay and bisexual men is 44 times that seen in other men, and some 40 times greater than women.
Newly analysed figures also showed that rates of syphilis diagnosis are up to 71 times higher amongst gay and bisexual men than other populations.
“It is clear that we will not be able to stop the US HIV epidemic until every affected community, along with health officials worldwide, prioritise the needs of gay and bisexual men with HIV prevention efforts”, commented Dr Kevin Fenton of the CDC.
Gay men account for 48% of the US’s 1 million HIV infections. The only group in which new HIV diagnoses are increasing is men who have sex with men, who in 2006 comprised 53% of all HIV cases in the country.
CDC data presented to the 2010 National STD Prevention Conference showed that there were between 522 to 989 new HIV diagnoses per 100,000 gay and bisexual men each year compared to twelve per 100,000 amongst other men and 13 per 100,000 amongst women.
This meant that the rate of new HIV diagnoses was up to 44 times higher amongst gay and bisexual men than other groups.
Syphilis rates were calculated to be between 91 to 73 cases per 100,000 in gay and bisexual men, some 46 times the rate of two per 100,000 seen in other men, and 71 times greater than the one per 100,000 observed in women.
The CDC’s data also showed the uneven impact of HIV on different populations of gay and bisexual men.
The greatest number new HIV infections amongst gay men in 2006 involved white gay men (13,230), closely followed by black gay men (10,130).
Amongst white gay men, most new infections were seen in those in their 30s (4,670), followed by those aged between 40 and 49 (3,740).
A somewhat different age profile was observed for black gay men. New infections were disproportionately located amongst those aged between 13 and 29 (5,200).
The investigators found that HIV prevalence amongst gay men in some urban centres was as high as 25%. Moreover, approximately 50% of men were unaware of their HIV infection, this figure increasing to nearly 80% amongst some populations of younger gay men.
A complex interaction of several factors is increasing the HIV for gay men, the CDC believes.
Most important of these is the high HIV prevalence amongst gay men. This means that each sexual encounter increases the risk of exposure to HIV. Investigators also believe that younger black gay men partnering with older black gay men, amongst whom HIV prevalence is high, may also lead to increased risk.
The large number of undiagnosed infections amongst gay men are also believed to be contributing to the continued spread of HIV.
Complacency is also suggested as explanation. The CDC states that this is especially the case for younger gay men who did not “personally experience the severity of the early AIDS epidemic.”
However, such reasoning cannot explain the large number of new HIV infections amongst men aged between 30 and 50.
Advances in HIV treatment have, the CDC believe, have lead some gay men to develop the “false belief” that “HIV is no longer a serious health issue.”
Difficulty maintaining a lifetime of safer sex is also suggested as another contributory factor.
Homophobia and other forms of discrimination, which can prevent men from accessing health care and prevention services, are also in the CDC’s belief fuelling the spread of HIV amongst gay men, as are high levels of drug use.
“The risk of HIV transmission through receptive anal sex is much greater than the risk of transmission via other sexual activities, and some gay and bisexual men are relying on prevention strategies that may be less effective than consistent condom use”, comment the CDC.
They highlight that many syphilis infections in gay men are probably acquired through oral sex.
“There is no single or simple solution for reducing HIV and syphilis rates among gay and bisexual men”, said Fenton. “We need intensified prevention efforts that are as diverse as the gay community itself. Solutions for young gay and bisexual men are especially critical, so that HIV does not inadvertently become a rite of passage for each new generation of gay men.”