The failure of gay men younger than 30 to protect themselves against HIV -- particularly during anal intercourse -- has led to a 17.4 percent rate of HIV infection, which is substantially lower than rates first seen in young gay men in the early 1980s but unacceptably high, according to findings of a study supported by the National Institute of Allergy and Infectious Diseases (NIAID).
In 1992, investigators for the study, the San Francisco Young Men's Health Study (SFYMHS), screened for HIV infection among 425 gay and bisexual men aged 18 to 29 randomly selected using sampling methods from 21 census tracts of the city.
Overall, 74 men or 17.4 percent had HIV. By age group, the infection rates climbed from 4.5 percent among men aged 18 to 23 to 10.7 percent among the 23 to 26 year-olds and to 28.4 percent among those aged 27 to 29, reports Dennis Osmond, Ph.D., investigator in SFMHS at the University of California at Berkeley and San Francisco. Dr Osmond plans to discuss the data during an oral presentation June 8, at the IX International Conference on AIDS in Berlin.
Most of the men aged 26 or younger have been sexually active since 1985 or later -- after awareness of AIDS had become widespread in the homosexual community of San Francisco," explains Dr. Osmond. "Although these young gay men have grown up during a decade of increased public awareness of how the AIDS virus is transmitted, they have not fully adopted behaviors that would lower their risk for infection."
For example, Dr. Osmond reports that the number of sexual partners the SFYMHS participants had during the previous 12 months related to their risk of infection: a 2.4 percent rate among those without partners, 12.1 to 17.3 percent among those with one to nine partners and 30.8 percent of those with 10 or more partners.
Specifically, the association between HIV infection and the number of partners during the past year was even stronger among men who acted as the receptive partner during anal intercourse (RAIs), a behavior that puts one at very high risk for becoming infected with HIV, explains Warren Winkelstein, Jr., M.D., M.P.H., principal investigator of SFYMHS, and professor of epidemiology at the University of California at Berkeley.
While the 151 men who were not RAIs had an HIV infection rate of 8.6 percent, RAIs who had one partner had a rate of 16.7, those with two to four partners, 14 percent, five to nine partners, 34.5 percent and those with 10 or more partners, 55.9 percent.
These alarmingly rates of high risk activities show that these men, unlike older gay men, have failed to take preventive messages to heart," says Lewis K. Schrager, M.D., SFYMHS project officer and chief of the epidemiology section of the Vaccine and Trials and Epidemiology Branch in NIAID's Division of AIDS.
By analyzing the study data, the SFYMHS investigators estimate that an annual rate of new HIV infections at 2.9 percent overall among gay men aged 18 to 29 in the city. While men, aged 27 to 29 had the highest estimated annual rates of new infections, 3.6 percent, the researchers calculated lower rates for younger men: a 1.5 percent rate among those aged 18 to 23 and a 1.9 percent rate for those aged 24 to 26. Other studies have estimated infection rates of 0.8 to 0.9 percent among gay men older than 30 in the San Francisco area, Dr. Osmond reports.
These findings suggest, Dr. Winkelstein explains, that as the young men begin sexual activity, they do not strongly identify with the epidemic nor do they personalize the sense of risk of their activities.
"Because of their youth and the long period of disease-free state before full-blown AIDS occurs, these younger people have not yet gone through the loss to AIDS of friends and loved ones that older gay men have experienced," says Dr. Winkelstein.
NIAID, a component of the National Institutes of Health (NIH), supports investigators and scientific studies at universities, medical schools, hospitals and research institutions in the United States and abroad aimed at preventing, diagnosing and treating such illnesses as AIDS, tuberculosis, allergies and asthma. NIH is an agency of the U.S. Department of Health and Human Services.
Drs. Osmond, Winkelstein and Shrager's coinvestigators include James A. Wiley, Ph.D., Thomas Coates, M.D., Haynes W. Sheppard, Ph.D., Kim Page, M.P.G., Michael Ascher, M.D., Andrew Moss, Ph.D., Karen Garrett, Thomas Piazza, Ph.D., Edwin Charelbois, M.P.H., Michael Samuel, Dr.P.H., William Lang, M.D., and Robert Hays at the University of California, Berkeley and San Francisco and at NIAID.
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