The HIV-infected population in the U.S. rose to 1.1 million in 2006 from an estimated 994,000 in 2003, scientists at the government´s Centers for Disease Control and Prevention stated in a study to be published in the agency´s Morbidity and Mortality Weekly Report.

The government researchers also say that since better treatments have been introduced, these have significantly prolonged lives.

Scientists had stated in the medical journal Lancet in July that since combinations of powerful drugs were introduced in 1996, the average life expectancy of 20-year-old HIV patients has risen about 13 years, and this estimate also reflects CDC´s recent study that raised its count of annual new infections by about 40 percent to more than 56,000.

Richard Wolitski, acting director of Atlanta-based CDC´s Division of HIV/AIDS Prevention, said they expect HIV cases “to keep on increasing over time as treatment prolongs the lives of infected people and new infections outpace deaths.''

Blacks were the hardest hit racial group, accounting for about 46 percent of cases in 2006. About 1.7 percent of U.S. blacks are infected, compared with 0.6 percent of Hispanics and 0.2 percent of whites.

“CDC has recognized and reported data on the disproportionate impact of the disease on blacks in the U.S. since the early years of the epidemic,'' Wolitski said. “This disparity is not one that is new, but it´s one that remains and requires a heightened level of response.''

About half of all patients were men having sex with men, or MSM, the study said, and about 18 percent of people contracted the virus by injecting drugs with contaminated needles. About half of new infections originate from people who have the virus and don´t know it, according to the CDC.

“Expanding the number and reach of effective HIV prevention services for at-risk populations, including blacks, Hispanics, and MSM of all races, can contribute to reducing the disproportionate numbers of infections in these groups,'' the authors concluded.

About 33 million people are infected with HIV worldwide, with 2.7 million new infections last year, according to a July 29 report by UNAIDS, the New York-based agency that coordinates the United Nations response to the disease.

The number of deaths dropped about 10 percent to 2 million in 2007 because of increased availability of drugs, the report said.