November 4, 2009

Many HIV-Positive Swiss MSM Have Chlamydia—and Don’t Know It

More than 10 percent of Swiss HIV-positive men who have sex with men (MSM) were infected with rectal Chlamydia trachomatis—many without knowing it—according to a study published November 15 in Clinical Infectious Diseases and reported by aidsmap.com.

A previous study had found that Swiss MSM infected with chlamydia, a common sexually transmitted infection (STI), often were infected rectally. But rectal infection doesn’t always cause symptoms, so men might be unaware that they are carrying the bacterium. When people are unaware they are infected with an STI, they can be more likely to transmit or become infected with HIV.

To determine the rate of rectal chlamydia infection in HIV-positive MSM in Switzerland, Thanh Dang, MD, from the University Hospital Center in Lausanne, Switzerland, and his colleagues surveyed MSM enrolled in the Swiss HIV Cohort Study (SHCS). Dang’s team offered rectal chlamydia testing to all MSM in the Swiss study who reported one or more episodes of unprotected receptive anal intercourse in the previous two years or had symptoms of proctitis—which can include rectal pain or discharge, cramps and bloody stools. In all, 147 men were tested.

Dang and his colleagues found that 16 men (10.9 percent) had rectal chlamydia infection. An additional four men had rectal gonorrhea. One of the men with chlamydia was infected with a strain that causes lymphogranuloma venereum (LGV), an STI that can cause painful genital ulcers. What’s most notable however is that of the 16 men infected with chlamydia, only three had symptoms. Most had no reason to suspect that they were infected.

The authors found that the greater the number of times that a man had unprotected receptive anal intercourse, the greater his chances of being infected with chlamydia. Given the results of their study—especially the fact that so many infected men had no symptoms—the authors are recommending that MSM with a history of unprotected receptive anal intercourse be screened for rectal chlamydia and that they be counseled about reducing sexual risks to themselves and others.

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