The finding, reported at the CDC's 2007 National HIV Prevention Conference, points to a big hole in what CDC AIDS chief Kevin Fenton, MD, PhD, calls "the key element of our HIV prevention strategy" -- HIV testing.
"Research shows that those who do not know they are infected are more likely to engage in HIV risk behavior," Fenton said at a conference news briefing, noting that 20% of HIV-infected Americans don't know they're carrying the AIDS virus.
Nearly two-thirds of men who have sex with men -- MSM -- do change their behavior. But as researchers finally begin to get a closer focus on the exact risk behaviors of HIV-positive men, troubling findings are emerging.
"Recent data suggest only one in five MSM have been reached by intensive HIV programs. This is 26 years into the epidemic, so we do have some way to go in targeting preventions," Fenton said.
"The scale of HIV prevention efforts is not at the critical mass to make the impact that is needed," Robert Janssen, MD, director of the CDC's division of HIV/AIDS prevention, said at the news conference. "My understanding is that state and federal budgets [for preventing sexually transmitted diseases] are stable, which means they are eroding over time. What we can do is provide the best data on the gaps that need to be covered."
That gap became apparent in several conference reports highlighted at the news briefing.
35% of HIV+ MSM Have Unsafe Sex
Fenton pointed to a study by CDC researcher Nicole Crepaz, PhD and colleagues, which analyzed data from 27 studies including more than 10,000 MSM who knew they carried HIV.
More than one in three of these men -- 35% -- reported recent unsafe sex (anal or vaginal intercourse without a condom).
That's very close to the 37% of Boston-area HIV positive MSM who reported unprotected anal intercourse in a conference report by Kenneth Mayer, MD, medical director of Boston's Fenway Community Health.
This behavior was not entirely irresponsible. More than 30% of these men in the Crepaz study and more than 41% in the Mayer study had unprotected sex only with partners already infected with HIV.
This practice, called serosorting, is not truly safe. While it does prevent infection of uninfected partners, the practice spreads sexually transmitted diseases such as syphilis and gonorrhea. And even though a person already has HIV, that person can still catch a second, potentially more dangerous HIV strain.
One in 10 HIV-positive men in the Crepaz study and 23% of the HIV-positive men in the Mayer study reported unsafe sex with partners they knew to be HIV-negative. This suggests that men who know they carry HIV are less likely to have unprotected sex with uninfected partners if these partners have had a recent HIV test.
On the other hand, men seem to behave badly with men they meet on the Internet than they do when they meet at bars or gay-oriented events. Nearly two-thirds of MSM recruited online reported recent unsafe sex in the Crepaz study.
"This study really underscores the continued need for positive protection methods for men," Fenton said.
Fenton also called attention to a troubling study by CDC researcher Kate Buchacz, PhD, MPH, and colleagues.
The Buchacz study showed that half of MSM diagnosed with syphilis at STD clinics in three major cities -- Atlanta, San Francisco, and Los Angeles -- were also infected with HIV.
Each year, studies suggest, 3% to 4% of U.S. MSM get HIV. But Buchacz and colleagues found that more than 10% of men with syphilis infections had recent HIV infections, too.
"Syphilis in the U.S. is overwhelmingly concentrated in MSM," Fenton said. "This demonstrates the need for routine HIV testing and investigation of HIV-positive men for syphilis infection."
African-American MSM: Surprising New Data
The U.S. HIV epidemic first appeared among MSM -- and almost half of U.S. HIV infections are among MSM.
But America's HIV epidemic is vastly worse for African Americans than for any other racial or ethnic group. Half of U.S. HIV infections are among African Americans. And African-American men are seven times more likely to have HIV than white men are.
Nearly half of African-American MSM -- 46% -- are HIV positive, CDC researcher Gregorio Millett noted at the news conference. Millett's team conducted a painstaking analysis of data on African-American MSM collected in 53 studies conducted from 1980 through 2006.
The study showed that:
- African-American MSM are no more likely than white MSM to report unsafe sexual activity. During the 1980s -- but not from 1990-2006 -- African-American MSM were 60% more likely than white MSM to report unprotected anal intercourse. Millett suggests that HIV "seeding" during the 1980s may have shaped the current epidemic.
- African-American MSM tend to have fewer sex partners than white MSM.
- African-American MSM were 36% less likely than white MSM to report use of drugs linked to HIV infection -- that is, injection drugs, crack or cocaine, opiates, and amphetamines.
- African-American MSM are no more likely than white MSM to report commercial sex work or sex with known HIV-positive partners.
- HIV-positive African-American MSM are only half as likely as white MSM to be taking anti-HIV drugs. Lack of treatment could play a role in increased HIV transmission.
- African-American MSM are 71% less likely than white MSM to think of themselves as gay and 58% less likely to disclose their same-sex behavior to others. Both of these factors are linked to higher risk of HIV infection.
Millett's team is now investigating social network factors that may affect HIV transmission among African-American MSM.