Rise in Unprotected Sex by Gay Men Spurs H.I.V. Fears

The New York Times reports:

Federal health officials are reporting a sharp increase in unprotected sex among gay American men, a development that makes it harder to fight the AIDS epidemic.

The same trend has recently been documented among gay men in Canada, Britain, the Netherlands, France and Australia, heightening concerns among public health officials worldwide.

According to the Centers for Disease Control and Prevention, the number of men who told federal health investigators that they had had unprotected anal sex in the last year rose nearly 20 percent from 2005 to 2011. In the 2011 survey, unprotected sex was more than twice as common among men who said they did not know whether they were infected with H.I.V.

Being tested even once for H.I.V. is associated with men taking fewer risks, whether the test is positive or negative, health experts say. But the most recent survey found that a third of the men interviewed had not been tested in the past year.

The findings are worrying because “unprotected anal intercourse is in a league of its own as far as risk is concerned,” Dr. Thomas R. Frieden, director of the disease centers, said on Wednesday as the figures were released.

The data, published in the agency’s Morbidity and Mortality Weekly Report, do not explain why unprotected sex has risen so rapidly, but a leading hypothesis, Dr. Frieden said, is that more men are “sero-sorting” — that is, those who are uninfected (“H.I.V. seronegative” on lab reports) try to sleep only with other men who are uninfected, or who hope they are, or who merely promise they are.

“The problem with sero-sorting is that it’s really easy to get it wrong,” Dr. Frieden said. “When one-third of men aren’t even tested in the last year and a tenth of those who thought they were negative were actually positive, you don’t want to risk your life on a guess.”