CDC Updates Estimates of HIV Prevalence in the United States

By Liz Highleyman

In recent months, the U.S. Centers for Disease Control and Prevention (CDC) has released data showing that the annual rate of new HIV infections is 40% higher than previously estimated and provided a detailed breakdown of HIV incidence according to sex, age, race, and risk category.

Most recently, in the October 3, 2008 issue of Morbidity and Mortality Weekly Report, investigators with the CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention provided the latest data on HIV prevalence in the U.S.

While incidence figures tell how many people are newly infected during a given period, prevalence refers to the total number of HIV positive people, including both newly infected individuals and those with long-standing infection.

The new data reflect reported new infections from 40 states with long-term name-based reporting, as well as AIDS diagnoses and deaths from all 50 states and Washington, DC. AIDS cases, unlike HIV infections, have consistently been reported by name, which helps ensure more complete data and rule out duplications. The new prevalence estimates take into account the aforementioned updated incidence numbers, which were derived using a new testing method.

Summary of Findings

• An estimated 1,106,400 (range 1,056,400-1,156,400) adults and adolescents in the U.S. were living with HIV at the end of 2006.

• This represents a prevalence rate of 447.8 cases per 100,000 persons.

• Using back calculation, the researchers estimated that there were 994,000 people living with HIV in 2003 (slightly lower than previously thought).

• As with the recent incidence figures, the new prevalence data show that a disproportionate number of people living with HIV are men who have sex with men (MSM) and African Americans.

• 74.8% of all people with HIV in 2006 were men.

• 48.1% of all cases were attributed to male-to-male sexual contact.

• Overall, 27.6% of HIV cases were attributed to heterosexual sex.
Among women, however, 72.4% of HIV cases were presumably due to heterosexual sex.

• 18.5% of all HIV cases were linked to injection drug use.

• 46.1% of all people living with HIV in 2006 were African American.

• 34.6% were white.

• 17.5% were Latino/Hispanic.

• 1.4% were Asian/Pacific Islanders.

• 0.4% were American Indians and Alaska Natives.

• The HIV prevalence rate among black women was nearly 18 times higher than that of white women.

• The HIV prevalence rate among black men was about 6 times higher than that of white men.

• The HIV prevalence rate among Latina/Hispanic women was about 4 times higher than that of white women.

• The HIV prevalence rate among Latino/Hispanic black men was more than twice that of white men.

• An estimated 232,700 people with HIV -- or about 1 in 5 -- are unaware that they are infected (down from a previous estimate of 1 in 4).

While an increase in HIV incidence is discouraging, higher prevalence is not all bad news, since a growing number of people living with HIV reflects the fact that fewer people are dying of AIDS thanks to effective antiretroviral therapy.

"With more HIV-infected individuals living longer, and the expectation that HIV prevalence will continue to increase over time as treatments continue to prolong the lives of people living with HIV, it is critical that we reach those living with HIV with testing, medical care, and prevention services," said Richard Wolitski, acting director of the CDC's Division of HIV/AIDS Prevention. "Growing HIV prevalence also means increased opportunities for transmission to HIV-negative individuals. Efforts to reduce the number of new infections must therefore be designed to meet the needs of both infected and uninfected populations."

10/07/08

Reference
ML Campsmith, P Rhodes, HI Hall, and others. HIV Prevalence Estimates -- United States, 2006. Morbidity and Mortality Weekly Report. 57(39):1073-1076. October 3, 2008.


Other sources
Centers for Disease Control and Prevention. Questions and Answers: HIV Prevalence Estimates -- United States, 2006. October 2, 2008.

RJ Wolitski. Dear Colleague letter. National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention. October 2, 2008.