While the annual number of new HIV infections in the United States remained stable at about 50,000 between 2006 and 2009, between those years HIV infections increased among young, black gay and bisexual men, a new report shows.

The Centers for Disease Control and Prevention released its first multi-year estimates on the national HIV incidence surveillance on Wednesday. It is published in the journal PLoS ONE. The multi-year incidence estimates allow for an examination of trends over time.

The CDC said the estimates are based on direct measurement of new HIV infections with a laboratory test that can distinguish recent from long-standing HIV infections.

The new estimates show that there were 48,600 new HIV infections in the U.S. in 2006 and some 56,000 in 2007. In 2008, there were 47,800 such infections and 48,100 in 2009, data show.

"More than 30 years into the HIV epidemic, about 50,000 people in this country still become infected each year," said CDC Director Dr. Thomas Frieden. "Not only do men who have sex with men continue to account for most new infections, young gay and bisexual men are the only group in which infections are increasing, and this increase is particularly concerning among young African American (men who have sex with men.) HIV infections can be prevented.  By getting tested, reducing risky behaviors, and getting treatment, people can protect themselves and their loved ones."

The CDC found that in 2009, the largest number of new infections was among white men who have sex with men (11,400), and that group was followed closely by black men who have sex with men (10,800).  There were 6,000 Hispanic men who have sex with men affected and so were some 5,400 black women.

"While we're encouraged that prevention efforts have helped avoid overall increases in HIV infections in the United States, and have significantly reduced new infections from the peak in the mid-1980s, we have plateaued at an unacceptably high level," said Dr. Kevin Fenton, director of CDC's National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention.  "Without intensified HIV prevention efforts, we are likely to face an era of rising infection rates and higher health care costs for a preventable condition that already affects more than one million people in this country."

The CDC estimates that men who have sex with men make up only 2 percent of the U.S. population, but they are a part of the groups that bear the greatest burden.

Men who have sex with men accounted for the majority, 61 percent or 29,300, of all new HIV infections in 2009, according to the report.

Young men who have sex with men, especially those between 13 and 29 years, were most severely affected, according to the CCDC, and that figure represented more than one quarter of all new HIV infections nationally i.e. 27 percent in 2009. 

The CDC said that young men who have sex with men of all races are heavily affected, but by race/risk, young black men of such were the only group to see a statistically significant increase in new infections over the four-year time period of the study.

CDC estimates that new HIV infections among young, black men who have sex with men increased 48 percent during that period, from 4,400 HIV infections in 2006 to 6,500 infections in 2009.  

It unclear as yet why this is so, but the study suggests that there could be several factors for this. The CDC said this could be because:

  • A higher proportions of young, black men who have sex with men are unaware of their infection than those of other racial/ethnic groups;
  • There's a stigma of HIV and homosexuality, which can decrease the use of HIV prevention services;
  • There's limited access to health care, HIV testing and treatment;
  • The increased likelihood of having older sexual partners (who are more likely to be HIV infected), compared to men who have sex with men of other racial/ethnic groups;
  • Of higher rates of some sexually transmitted diseases among young black men, which can facilitate HIV transmission; and
  • Of under-estimating personal risk for HIV.

"We are deeply concerned by the alarming rise in new HIV infections in young, black gay and bisexual men and the continued impact of HIV among young gay and bisexual men of all races," said Dr. Jonathan Mermin, director of CDC's Division of HIV/AIDS Prevention. "We cannot allow the health of a new generation of gay men to be lost to a preventable disease. It's time to renew the focus on HIV among gay men and confront the homophobia and stigma that all too often accompany this disease."

Communities of color are also disproportionally affected by the HIV infection.

While blacks represent 14 percent of the total U.S. population, the CDC's new estimates find that they accounted for 44 percent of new HIV infections in 2009, and the rate that year was almost eight times as high as that of whites.

The HIV infection rate among black men was the highest of any group by race and sex. It was more than six times that of white men, and the rate among black women was 15 times that of white women, according to the CDC.

Hispanics, who represent approximately 16 percent of the total U.S. population, accounted for 20 percent of new HIV infections in 2009.  That year, the HIV infection rate among them was nearly three times as high as that of whites, and the rate among Hispanic women was more than four times that of white women.

"HIV remains one of the most glaring health disparities in this country," Fenton said. "While we all have individual responsibility to protect ourselves from HIV infection, the research clearly shows that individual risk behavior alone doesn't account for the significant racial disparities in HIV.  It is essential to understand the underlying factors that contribute to these disparities, such as poverty, discrimination and lack of access to health care."