Johns Hopkins Gazette | February 2, 2009
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The newspaper of The Johns Hopkins University February 2, 2009 | Vol. 38 No. 20
HIV Transmission Rate Declines in United States, Study Finds

By Tim Parsons
Bloomberg School of Public Health

Although the number of people living with HIV has increased in the United States over time, the rate at which an infected person passes the virus on to an uninfected person has dropped significantly since the peak of the epidemic, according to a study by researchers at the Johns Hopkins Bloomberg School of Public Health and the Centers for Disease Control and Prevention.

Researchers found the rate of transmission has dropped 88 percent since 1984 and 33 percent since 1997. The study will be published in JAIDS: Journal of Acquired Immune Deficiency Syndromes and is available on the journal's Web site in advance of publication.

"For every 100 persons living with HIV today, five or fewer will transmit the virus to an uninfected person in a given year," said David Holtgrave, lead author of the study and chair of the Bloomberg School's Department of Health, Behavior and Society. "In other words, 95 percent or more of those living with HIV do not transmit the virus to others, which indicates that prevention efforts are having a real impact."

Holtgrave and his colleagues based their analysis on the CDC's latest HIV incidence data. According to the study, the annual transmission rate in 1984 was 44 per 100 persons with HIV. The annual rate dropped to 6.6 per 100 persons by the early 1990s. The transmission rate rose slightly to 7.5 per 100 persons in 1997, when new antiretroviral therapies were first introduced; researchers said these therapies might have led some persons at risk for HIV to disregard prevention measures. By 2006, the transmission rate dropped to just below five per 100.

"The declines reflect the success of prevention efforts across the nation," said Richard Wolitski, study co-author and acting director of the CDC's Division of HIV/AIDS Prevention. "However, despite this success, we cannot forget that new HIV infections are increasing among gay and bisexual men and that African-Americans and Hispanics continue to experience disproportionate and unacceptably high rates of HIV and AIDS. The fight against HIV is far from over."

The research was not funded by a specific grant.


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