So, why the higher HIV risk for gay men? "A couple of different things could give gay men an overall higher risk for HIV than heterosexuals," Goodreau said.
One reason HIV remains epidemic among gay men is that anal sex is much more conducive to the transmission of HIV transmission than is vaginal sex, the researcher said.
"That puts gay men at much higher risk overall," he said.
In addition, HIV transmission is more easily transmitted through the penis than via the vagina or the anus, Goodreau said. Heterosexuals tend to maintain the same role (insertive vs. receptive), while gay men can switch roles -- making the transmission of HIV more likely, he noted.
So, for gay men and straight men who have the same number of partners and have unprotected sex, gay men are more likely to transmit and receive HIV, Goodreau said. "That's why you can get huge epidemics among gay men and virtually none among heterosexual men," he said.
To end the HIV epidemic, gay men would need to have significantly lower rates of unprotected sex than those seen among the straight men, Goodreau believes.
One expert believes the study does have its flaws, however.
"The information here is mostly based on people's reports of their own behavior," said Philip Alcabes, an associate professor at the School of Health Sciences of Hunter College/City University of New York. "When trying to make use of information on self-reported sexual behavior, we have to remember that it isn't clear that anybody tells the truth," he said.
For more on HIV, visit the U.S. Department of Health and Human Services.
SOURCES: Steven Goodreau, assistant professor, anthropology, University of Washington, Seattle; Philip Alcabes, Ph.D.,
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