New CDC Studies Shed Light on Factors Underlying High HIV Infection Rates Among Gay and Bisexual Men

New Data Show High Rates of Infection

Continuing Among Gay Men

Most Young Gay and Bisexual Men With HIV

Unaware They are Infected

Psychosocial Problems and Age of Partners Tied to HIV Risk

BARCELONA, Spain - New Centers for Disease Control and Prevention (CDC) research presented at the XIV International AIDS Conference provides further evidence of high rates of new HIV infection among gay and bisexual men in the United States and sheds light on factors underlying high-risk behavior among these men. The new data, summarized at a press briefing today at the conference, offer insight into steps needed to tailor HIV prevention to meet the challenges currently facing gay and bisexual men in the United States and other industrialized nations.

In a large CDC study, conducted in sexually transmitted disease (STD) clinics in five major U.S. cities, researchers found the rate of new HIV infections among men who have sex with men (MSM) to be nine times higher than among women and heterosexual men. According to other CDC research, a number of factors contribute to high rates of infection among MSM, including psychosocial problems like depression and illicit drug use, age of sexual partners, and low rates of HIV testing among young MSM, particularly African Americans.

"This research helps us understand some of the factors contributing to risky behavior and HIV infection," said Ronald Valdiserri, M.D., M.P.H., deputy director of CDC's HIV, STD, and TB prevention programs. "As we work to renew HIV prevention among gay men and others at high risk, this knowledge is critical to forging solutions that address the current realities of gay and bisexual men's lives."

New Data Show Continuing High Infection Rates Among Gay and Bisexual Men

In one of the largest studies on HIV incidence in the U.S., CDC researchers provided further evidence of high rates of HIV infection among gay and bisexual men.

HIV infection rate nine times higher for gay men. CDC epidemiologist Laurie Linley and colleagues found the rate of new HIV infections for MSM to be nine times higher than for women and heterosexual men. The researchers examined anonymous blood samples from more than 40,000 high-risk patients of all ages at sexually transmitted disease (STD) clinics in Los Angeles, Denver, Miami, and Newark, N.J. for the period 1997-1999. To estimate HIV incidence, they used the Serologic Testing Algorithm for Recent HIV Seroconversion (STARHS), a testing method that uses two HIV antibody tests of different sensitivities to detect recent infections. The researchers estimated that 4.8 percent of MSM were infected annually, compared to 0.4 percent of heterosexual men and 0.5 percent of women. The researchers also found significant differences in infection rates between MSM of different racial groups. Among the 2,665 MSM in the sample, estimated annual infection rates for African Americans and Latinos were 6.2 percent and 6.1 percent, respectively - more than twice the 3 percent incidence for white MSM. Abstract TuPeC4865, "Using STARHS to estimate HIV-1 incidence among patients attending STD clinics in selected U.S. cities, 1997-1999," Poster, Tuesday,

9 July 2002, 8:00 (2:00 AM EDT)

Other research has also shown higher infection rates among MSM of color compared to white MSM. For example, a CDC study of young MSM, ages 23 to 29 in six U.S. cities, found that African-American MSM had an annual infection rate of 14.7 percent, compared to 2.5 percent among whites. While the findings from these studies are not directly comparable due to differences in the study settings, the cities included, and the time periods, both studies suggest that HIV infection rates are high among MSM of color.

CDC Research Offers New Insight Into Factors Behind Gay Men's HIV Risk

Several CDC studies summarized at the press conference shed new light on the possible causes of high HIV risk among gay and bisexual men. One study revealed that the majority of young African-American MSM with HIV were unaware of their infection, likely a factor underlying especially high rates of infection in this community. CDC's research also reveals that psychosocial health problems such as depression, drug use, and partner violence are linked to high-risk behavior and HIV infections, and that gay men are more likely to engage in high-risk sex with younger partners than with partners of the same age or older.

"New strategies are needed to reach young gay and bisexual men with counseling and testing services - particularly African-American men," said Valdiserri. "These findings also point to the need for a more comprehensive approach to gay men's health which addresses the multiple health and social issues influencing HIV risk."

Large majority of young gay men with HIV unaware of infection, especially young African-American men. More than three-fourths of young gay and bisexual men infected with HIV were unaware of their status - including 91 percent of African-American MSM - and may have unknowingly transmitted the virus to their partners, according to a study led by CDC's Duncan MacKellar. Researchers surveyed 5,719 MSM between the ages of 15 and 29 in six major U.S. cities, of whom 573 tested positive for HIV; 440 men (77 percent) were unaware of their infection. While HIV-infected African-American MSM were the most likely to be unaware of their HIV status, 60 percent of white MSM and 70 percent of Hispanic MSM also did not know they were infected. Of the 440 men who were unaware of their infection, 59 percent perceived themselves to be at low or very low risk of being infected. Abstract MoPeC3427, "Unrecognized HIV infection, risk behavior, and misperception of risk among young MSM - 6 U.S. cities, 1994-2000," Poster, Monday, 8 July 2002, 8:00 (2:00 AM EDT)

Psychosocial health factors increase HIV risk. Psychosocial health problems - including multiple drug use, partner violence, history of childhood sexual abuse, and depression - interact to increase sexual risk behavior and HIV infection rates among gay and bisexual men in the United States, according to research led by CDC's Ron Stall, Ph.D. In a household-based survey of 2,881 MSM in New York City, Chicago, Los Angeles, and San Francisco, the researchers found that rates of HIV infection and high-risk sex were sharply higher in the presence of these psychosocial problems. The percentage of men reporting high-risk sex increased steadily from 7.1 percent among those with none of the four health problems to 33.3 percent for those suffering from all four. Similarly, of those with none of the psychosocial health problems, 13 percent indicated they are HIV infected, compared to 25 percent of those with all four health problems. According to Dr. Stall, HIV prevention and other health promotion efforts may be more effective if prevention programs, mental health agencies, substance abuse programs, and other public health agencies improve efforts to address the interrelationships between HIV and the psychosocial health problems facing gay and bisexual men in urban settings. Abstract MoPeC3433, "Co-occurring psychosocial health problems among urban American men who have sex with men (MSM) are interacting to increase vulnerability to HIV transmission," Poster, Monday, 8 July 2002, 8:00 (2:00 AM EDT)

Age of partner may influence risk behavior among MSM. New CDC research indicates that gay and bisexual men are more likely to engage in high-risk sexual behavior if their partners are younger. The study, by CDC behavioral scientist Gordon Mansergh, Ph.D., and colleagues, defined "high-risk" behavior as unprotected anal intercourse with partners of unknown or different HIV status. The San Francisco study examined sexual patterns among a diverse sample of MSM in four age categories: 20s, 30s, 40s, and 50 and older. Of the 376 sexually active MSM surveyed, 52 percent reported having high-risk sex during their most recent encounter. Analysis by age of partners found that 56 percent of men with younger partners engaged in high-risk sex, compared to 43 percent of those with partners in a similar or older age group. Study authors stress the need to better understand this elevated level of risk with younger partners in order to guide ongoing prevention efforts. Abstract WePeE6409, "Toward understanding why younger men who have sex with men (MSM) are at high risk for HIV infection through examination of sexual mixing characteristics," Poster, Wednesday, 10 July 2002, 8:00 (2:00 AM EDT)

Update on Nonoxynol-9

CDC also released a study on nonoxynol-9 (N-9) use which suggests that many MSM are using the product even though CDC has recommended against N-9 use as an HIV prevention tool.

Use of N-9 continues despite potentially increased HIV risk. Following the discovery that the N-9 may increase risk of HIV transmission, CDC recommended in 2000 that N-9 not be used for protection against HIV during intercourse. However, a 2001 CDC survey of MSM in San Francisco found that 41 percent of those who had used N-9 during anal sex in the past year did so without a condom because they thought or hoped it would be protective against HIV, underscoring the need for better education on the risks of N-9 use. Abstract MoPeD3535, "Continued use of Nonoxynol-9 in a diverse sample of men who have sex with men (MSM) and a potentially effective prevention message to reduce N-9 use," Poster, Monday, 8 July 2002, 8:00 (2:00 AM EDT).