Blacks and Hispanics continue to be disproportionately affected by increasing rates of HIV infection, the U.S. Centers for Disease Control and Prevention reported today, with minority women and men who have sex with men at particularly high risk.

Last month, the CDC reported that at 56,300 new cases in 2006, the rate of new HIV infections was roughly 40-percent higher than earlier estimates had indicated. At that time, they found that 75 percent of new infections that year were among men.

In the Morbidity and Mortality Weekly Report, the CDC reports more detailed analysis of data from the HIV Incidence Surveillance System. Dr. Kevin Fenton and Dr. Richard Wolitski, at the CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, discussed the findings in a telebriefing.

“For the first time we’re able to provide new HIV incidence estimates for specific subpopulations, with further breakdowns of new infections among various races, transmission categories, age groups, and gender,” Fenton said. “These data will allow us to target HIV prevention efforts and evaluate their impact with much more precision than ever before.”

According to Fenton, the data show a “strikingly high incidence of new HIV infections among young (ages 13 to 29) black males who are gay or bisexual; the heavy impact among white men who have sex with men in their 30s and 40s; and that, compared with other women, black women bear the heaviest burden of HIV.”

Dr. Wolitski pointed out that “individual differences in rates of risk behavior and substance use do not account for the disparity in infection rates in young black men who have sex with men, which means that factors outside the individual are increasing the risk associated with any risky sexual encounter.”

Such factors include higher background prevalence of HIV among African Americans, he said, the risk is increased because the infection rate among African Americans is already higher than in other groups.

Another factor is the “different patterns of age mixing, in which younger black men who have sex with men may be more likely to have slightly older partners compared with other races or ethnicities.”

Other factors likely include stigma, lack of access to effective prevention services, and underestimation of personal risk.

Responding to a question from Reuters Health, Fenton said that the HIV prevalence (overall number of individuals already infected) is driving the disproportionate disease incidence (the rate of new infections) among black women, as well as “patterns of sexual mixing in which they are having intercourse with men who are themselves at high risk, such as bisexual men or men who inject drugs or who were exposed while in prison.”

Also at issue among black women, he added, are “power imbalances with men in sexual relationships that limit their ability to protect themselves.”

Summing up, Fenton said, “Today’s analysis serves as a powerful reminder that the U.S. epidemic of HIV is far from over, and we all need to do more.”

He concluded: “The U.S. epidemic will end only when all of us - federal, state, and local governments; politicians, communities, and businesses; social and civic organizations; schools, families, and individuals across the nation - realize that ending AIDS is possible, and then collectively committing to make that happen.”

“Together we can realize the goal of ending this epidemic in our lifetime.”

SOURCE: Morbidity and Mortality Weekly Report, September 12, 2008.