CHICAGO -- A stunning one-third of young gay black men in large U.S. cities are infected with HIV, another sign of the growing racial divide in the AIDS epidemic.
The findings, based on a study released Monday, show that HIV infections are disturbingly common among gay men of all races in their 20s, especially considering that they grew up knowing how AIDS spreads.
However, HIV is particularly rampant among young gay blacks, and experts worry that these men have missed the safe-sex message that has been a drumbeat among white homosexual men since the mid-1980s.
The study found that among young gay men, 3 percent of Asians, 7 percent of whites, 15 percent of Hispanics and 30 percent of blacks are infected with the virus.
"That 30 percent is an amazing statistic," said Dr. Helene Gayle, AIDS chief at the Centers for Disease Control and Prevention. "When people think `gay,' they think `white.' But the people still at greatest risk are sexually active gay men, and that cuts across all races and ethnicities."
The study, directed by the CDC's Linda Valleroy, was presented at the Eighth Annual Retrovirus Conference in Chicago.
Since the epidemic's start, when AIDS was primarily a disease of gay white men, the burden of HIV has increasingly shifted to blacks. Now, just over half of the estimated 40,000 new HIV infections annually occur among blacks. Among infected women, blacks outnumber whites almost 4 to 1.
Many worry that homosexual men have grown complacent about catching HIV because effective treatments can hold the disease in check. Some of these gay men may be more likely to have risky sex, such as anal intercourse without condoms.
The new study does not reveal whether dangerous sex practices are growing among the young, but it does show that such habits are common. Almost half of the men surveyed admitted they had had unprotected anal sex during the previous six months.
While the overall infection rate of 12 percent was alarming, the researchers said they were most surprised by the level of AIDS infection among the young black men. "It's really horrifying," Valleroy said.
The survey was based on testing of 2,401 gay men ages 23 to 29 between 1998 and 2000. They were tested at parks, bars, clubs and other gay meeting places in Baltimore, Dallas, Los Angeles, Miami, Seattle and New York City.
Except in Miami and Seattle, where few blacks were in the study, the infection rate for blacks was around 30 percent in all the cities.
In general, AIDS infections have become less common among gay men since the height of the epidemic in the 1980s. For instance, in New York, just over half of all gay men of all ages who were tested at venereal disease clinics in 1988 were infected, compared with 20 percent in 1997.
Valleroy said there is no easy explanation for why the disease is so much more prevalent among young gay blacks. But one reason may be that blacks are less likely to admit their homosexuality, so they miss the frequent exhortations for safe sex.
"Being gay is more hidden among African Americans," she said. "There is no Gay Men's Health Crisis for African Americans. They tend not to live in the gay neighborhoods."
Dr. Carlos del Rio of Emory University in Atlanta, who studies AIDS in inner cities, noted that the disease largely affects populations on the edges of the mainstream, including gay men and poor blacks.
"In African Americans, there is a much greater stigma about being homosexual than there is among whites," he said. "That makes them even more marginalized."
Less than one-third of those who had HIV in the survey knew about their infection.
An earlier study by the same group looked at AIDS infections among gay 15- to 22-year-olds. It found that 14 percent of blacks were infected.