"HIV infection through receptive oral sex is a very rare event--statistically our study showed a probability of zero--and is rarer than HIV infection through receptive anal intercourse using a condom," said the study's lead author Kimberly Page Shafer, PhD, MPH, assistant professor of medicine at UCSF's CAPS. The findings are being published in the November 22, 2002 issue of AIDS.

The study enrolled 239 men who have sex with men starting in 1999 from anonymous testing and counseling sites in San Francisco. The participants reported no anal or vaginal sex and no injection drug use in the six months prior to entering the study. The participants reported a median of three partners with whom they had been the receptive partner for oral intercourse and ninety-eight percent reported unprotected receptive oral intercourse. Twenty-eight percent knew their partner was HIV-infected and of those, thirty-nine percent swallowed ejaculate.

"If you compare our group, which practiced oral sex exclusively, with men who engaged in receptive anal intercourse from the same testing sites during a similar time period--and considering both those who reported using protection and those who did not--you find significant HIV transmission even among those who used protection during receptive anal intercourse," said Shafer.

The participants were screened for HIV infection and also for recent HIV infection using both the standard test for HIV and a test for HIV that is "detuned" to detect only those HIV infections that have occurred within the six months prior to taking the test.

"Although this study is the first to try to systematically define the risk, case reports exist of HI
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Contact: Jeff Sheehy
jsheehy@psg.ucsf.edu
415 597 8165
University of California - San Francisco
21-Nov-2002