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Serosorting May Decrease HIV Spread


 

WASHINGTON — Serosorting—the selection of sex practices based on a partner's known or perceived HIV status—is becoming more popular among men who have sex with men, Dr. Robert M. Grant said at the Ryan White CARE Act clinical meeting on HIV treatment.

Increased serosorting may reduce the spread of new HIV infections in this population. “This trend suggests that we need to think of sexual risk in a new way,” said Dr. Grant of the University of California, San Francisco.

HIV patients' choices of partners with the same HIV status for high-risk sex may explain a plateau in HIV among men who have sex with men (MSM) in recent years, Dr. Grant said. He cited the 2003 HIV/AIDS Epidemiology Annual Report from the San Francisco Department of Public Health, which showed a tapering off of annual HIV incidence in MSM locally from 4% in 1999 to 2.9% in 2003.

The San Francisco report also noted that receptive unprotected anal intercourse (UAI) among MSM decreased from 1999 to 2003, which suggests that HIV-negative MSM are selectively using condoms or taking other precautions if they know their partners are HIV positive.

“We suspect it is a harm-reduction strategy that is better than not serosorting,” Dr. Grant said.

Results from several studies of MSM in San Francisco presented at the Conference on Retroviruses and Opportunistic Infections earlier this year support an increase in serosorting behavior. A total of 32% of 310 MSM who were randomly surveyed reported no UAI, but 27% reported UAI with partners with the same HIV status. Another 21% reported no anal sex, while 19% reported UAI with partners who had a different HIV status. Data were not available for the remaining 1%.

In addition, the rate of newly diagnosed HIV-positive infections among MSM who were tested in an STD clinic between 2001 and 2005 was 2.6% among HIV-positive patients who reported serosorting, vs. 4.1% among those who reported no serosorting, based on data from more than 6,000 HIV tests.

Serosorting as a risk reduction strategy is probably more effective than not serosorting but less effective than adhering to other safe sex practices such as condom use, Dr. Grant said. Serosorting does not protect against other STDs, he added; additional data from the San Francisco clinic study showed that serosorters had about the same risk of developing STDs as those who were not serosorting (27% vs. 29%).

Although there is nothing wrong with serosorting, Dr. Grant recommends that clinicians continue to promote HIV testing to patients, as well as disclosure of HIV status to prospective sex partners.

Whether serosorting can increase the risk of infection with a second HIV strain (superinfection) remains to be seen. Data on superinfection are limited, but recently infected patients may be the most vulnerable. If there is a risk of superinfection, it may decline over time.

Of the 20 documented cases of HIV superinfection in the medical literature, 90% occurred during the first 3 years of infection, and no evidence of superinfection has been documented among HIV patients with long-term infections, Dr. Grant said.

That doesn't mean superinfection can't occur later on. But the possible risk of superinfection from serosorting should not be overstated, he added, and more research is needed to define the period of possible susceptibility to a second infection.

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