More than 1 million people in the United States were living with the human immunodeficiency virus (HIV) that causes AIDS, in 2006, up 11 percent from 2003, the U.S. Centers for Disease Control and Prevention revealed Thursday.

The CDC previously estimated that 994,000 Americans were living with the deadly virus in 2003. According to the new federal estimate, the HIV prevalence has increased by 11 percent, or 112,000 people, since 2003.

"These data really show the continued impact that the epidemic is having on Americans, and they really reinforce the severe toll that is experienced in multiple communities," said acting director of CDC's Division of HIV/AIDS Prevention, Richard Wolitski.

The human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS) by infecting helper T cells of the immune system.

According to the fact sheet prepared by the CDC, HIV spreads by sexual contact with an infected person, by sharing needles and/or syringes (primarily for drug injection) with someone who is infected, or, less commonly (and now very rarely in countries where blood is screened for HIV antibodies), through transfusions of infected blood or blood clotting factors.

The new federal report says, although, the population living with HIV is growing as people become newly infected, still the good news is that better treatments have prolonged the lives of HIV-infected people than ever before, and the percentage of people who don't know they're infected with the virus is decreasing.

According to the CDC study, published Friday (Oct. 3) in the agency's Morbidity and Mortality Weekly Report, one in five people or 232,700 of the 1.1 million HIV-infected people, are unaware of their infections, and new infection rates have been stable at about 56,000 new infections a year, giving a clear indication that state-of-the-art HIV testing and prevention efforts are having an effect.

The Atlanta-based agency estimated that blacks were the hardest hit racial group. The figures show that 46 percent of all HIV/AIDS cases diagnosed in 2006 occurred in black Americans, for a rate of about 68 cases per 100,000. Hispanics also had high rates of newly diagnosed disease, accounting for 18% of HIV cases, for a rate of 26 cases per 100,000.

“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.''

In August, a CDC study had reported that the number of HIV infected cases in the United States is greater than previously estimated. The study, CDC presented on the eve of the 17th International AIDS Conference, in Mexico City, revealed that at least 56,300 cases of new HIV infections are occurring nationally each year, which is 40 percent more than the government has long estimated.

The study also reported that the deadly virus has its greatest effect among gay and bisexual men of all races and among African-American men and women.
The global pandemic, HIV AIDS is spreading like forest fire around the world, affecting an estimated 33 million people globally. According to a July 29 report by UNAIDS, the New York-based agency that coordinates the United Nations response to the disease, 2.7 million new infections occurred last year. The infection has engulfed nearly 25 million lives since mid-1980s, when the HIV was first isolated.