US CDC finds 19 percent HIV prevalence among MSM in 21-city survey

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Almost one in five participants in a 2008 survey of US men who have sex with men (MSM) were found to be HIV-positive, and almost half of the HIV-positive MSM were not aware of their status.

The US Centers for Disease Control and Prevention (CDC) has announced these and other findings from its periodic cross-sectional survey of urban MSM in the September 24th Morbidity and Mortality Weekly Report (MMWR). The survey collected information and biological specimens from 8,153 sexually active MSM in 21 major cities.

While an overall HIV prevalence rate of 19% was observed (95% confidence interval [CI], 18% – 20%), African-American survey respondents had a significantly higher rate of 28% (95% CI, 26% – 31%).


representative sample

Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).


Social attitudes that suggest that having a particular illness or being in a particular situation is something to be ashamed of. Stigma can be questioned and challenged.



sexually transmitted diseases (STDs)

Although HIV can be sexually transmitted, the term is most often used to refer to chlamydia, gonorrhoea, syphilis, herpes, scabies, trichomonas vaginalis, etc.

community setting

In the language of healthcare, something that happens in a “community setting” or in “the community” occurs outside of a hospital.

HIV prevalence ranged from 6% in Atlanta to 38% in Baltimore. Six other cities had HIV prevalence rates above 20%: Dallas, Houston, Miami, New Orleans, New York and San Francisco.

Among the 1562 men found to be HIV-positive, 44% either said that they did not know their HIV status or said that their last HIV test yielded a negative result (95% CI, 41% – 46%).

Further racial disparities were observed, with only 26% of HIV-positive white MSM unaware of their status (95% CI, 22% – 29%), but 59% of HIV-positive black MSM unaware of their status (95% CI, 55% – 63%). Hispanics and other non-whites also surpassed whites in this regard.

Higher rates of young HIV-positive MSM were unaware of their status as well. Seventy-five percent of HIV-positive MSM aged 18 – 19 fell into that category (95% CI, 55% – 89%), and 68% of those aged 20 – 24 did so (95% CI, 61% – 75%).

It is important to note that survey respondents were recruited from urban social venues identified by health department staff, and that two-thirds of those venues were bars and nightclubs. The findings therefore are not representative of the entire US population of MSM.

Nonetheless, the MMWR article raises concern about the HIV epidemic’s persistence in US MSM populations in the face of intensive targeted HIV prevention campaigns.

Five cities that were included in both the most recent survey and the preceding survey (2004/2005) were compared to each other in the MMWR article. While trends for individual cities varied, there were no major overall differences in relation to either HIV prevalence or awareness of having HIV.

The MMWR article also called attention to current efforts to encourage HIV testing, noting that 55% of HIV-positive MSM who did not know their status had not taken an HIV test within the preceding twelve months. The CDC recommends HIV testing on an annual basis or more frequently for sexually active MSM.

“This finding suggests that increased efforts to educate MSM and health-care providers about HIV testing guidelines and to reduce barriers to HIV testing for MSM are necessary,” the authors concluded. They also observed that since 45% of HIV-positive MSM who did not know their status had fulfilled the CDC testing recommendation, shorter testing intervals may be advisable for some MSM.

The CDC has estimated that nearly half of the more than one million HIV-positive people in the United States are MSM. CDC surveillance also suggests that MSM are the only major HIV risk group still continuing to experience an increasing number of infections.

In a statement about the MMWR update, Gay Men’s Health Crisis (GMHC), one of the largest community-based AIDS organizations in the United States, called for new HIV prevention approaches that address homophobia as a driver of the MSM epidemic.

“We should recognize anti-gay prejudice as a public health threat that has public health effects,” said GMHC representative Sean Cahill. “The CDC and state and local health departments must challenge anti-gay stigma and promote acceptance of gay people, including encouraging parents to accept and love their gay sons. Expanded [HIV] testing campaigns are not enough.”

GMHC also emphasized the link between high HIV prevalence among young MSM and young people’s sexual health more generally.

“Nearly 20 million Americans got a sexually transmitted disease last year, and half of them are 15 to 24 years old,” Cahill said. “We must get real about providing age-appropriate sexual health education in schools.”


Smith A et al. Prevalence and awareness of HIV infection among men who have sex with men — 21 cities, United States, 2008. MMWR Morb Mortal Wkly Rep 59: 1201 – 1207, 2010.