CDC: Gay and Bisexual Men Comprise 61% of New HIV Infections

Sandra Yin

August 05, 2011

August 5, 2011 — More than 30 years into the HIV epidemic, an average of approximately 50,000 people in the United States still become infected each year, according to the US Centers for Disease Control and Prevention’s (CDC's) first multiyear estimates from its national HIV incidence surveillance. The estimates were published August 3 in PLoS ONE.

"While we’re glad it’s not increasing, it’s not good enough," said CDC director Thomas Frieden, MD, during a press conference this week. "The number of HIV infections remains far too high."

The number of new HIV infections in the United States hit a high of 56,000 and a low of 47,800 between 2006 and 2009. The incidence estimates are based on direct measurement of new HIV infections with a laboratory test that can distinguish recent from long-standing HIV infections.

More needs to be done to prevent HIV, he said. Already an estimated 1.2 million people in this country are infected. Of those, about 1 in 5 don’t know they’re infected, he noted. "If you don’t know you’re positive," he said, "you can’t get treated."

Gay and bisexual men continue to account for a disproportionate share of new infections, according to the new estimates. While men who have sex with men (MSM) make up 2% of the US population, they represented the majority (61%) of all new HIV infections in 2009.

New Infections in Black MSM Surged

Young MSM (ages 13 to 29) were most affected, representing more than 1 in 4 (27%) of all new HIV infections nationally in 2009. Although young MSM of all races are affected, black MSM were the only group to see a statistically significant jump in new infections over the 4 years studied. Between 2006 and 2009, new HIV infections among young black MSM surged by half (48%), from 4400 infections to 6500 infections.

"CDC is very concerned about this increase," said lead author of the report Joseph Prejean, PhD, from the HIV Incidence and Case Surveillance Branch, CDC Division of HIV/AIDS Prevention. "While we don’t have all the answers about what might be driving this trend, we do know that individual risk behaviors alone do not account for it."

Previous CDC research has shown that black MSM have fewer sex partners, are less likely to use illegal drugs associated with HIV risk, and are no more likely to report unprotected anal intercourse than white MSM. Instead, CDC experts believe that more complex factors are at work. For example, young black men have higher rates of syphilis than their white peers, which can increase the risk of acquiring and transmitting HIV. Previous research has also shown that black MSM are more likely to have undiagnosed infection than MSM of other racial/ethnic groups. As a consequence, they are at greater risk of unknowingly spreading the virus to their partners, he said.

Structural factors including the following may also explain the trend:

  • The stigma of HIV and homosexuality, which may keep black MSM from using HIV prevention services;

  • Limited access to healthcare, HIV testing, and HIV treatment;

  • Increased probability of having older sexual partners, who are more likely to be infected with HIV than MSM of other racial/ethnic groups; and

  • Underestimated personal risk for HIV.

Racial and Ethnic Divide

The estimates also reflect a racial and ethnic divide. "Despite overall stability [in the number of new infections] among African Americans and Latinos, HIV remains one of the most glaring health disparities among African Americans and Latinos overall," Dr. Prejean said.

Blacks are disproportionately affected by the HIV/AIDS epidemic. Although they make up 14% of the total US population, they accounted for 44% of new HIV infections in 2009, according to the new estimates. The HIV infection rate among blacks in 2009 was nearly 8 times as high as that of whites. Black men have the highest HIV infection rates of any group by race and sex — more than 6 times that of white men. And black men represent about 70% of the new infections among blacks.

The new data also reveal that black women bear a much heavier burden of HIV than women of other races. Black women have a new HIV infection rate 15 times that of white women. However, the HIV incidence from 2006 to 2009 did not change significantly for black men or black women.

Latinos are another group that is disproportionately affected by HIV. Although Hispanics represent about 16% of the US population, they accounted for 20% of new HIV infections in 2009. Their infection rate was nearly 3 times that of whites. Hispanic men represented 79% of new HIV infections among Hispanics. Most are MSM. Hispanic women have an HIV infection rate that is more than 4 times that of white women.

When asked what physicians can do to help drive the HIV infection rate down, Dr. Prejean said they could ensure that HIV testing is routine. "When testing is done as a routine, rates of testing go way up," he said. Physicians also need to help patients gain access to care. Approximately one third of people who test positive do not enter into care promptly after testing positive.

PLoS ONE. Published online August 3, 2011. Full text

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