The U.S. Centers for Disease Control and Prevention said on Thursday that more than 1 million people in the United States had HIV in 2006, and one in five are unaware of their being infected.

The new federal estimate based on 2006 data has shown that the number of people who are living with the deadly virus is growing and has increased by 11 % or 112,000 people since 2003. 

This increase is largely attributed to the fact that while there are new people getting infected the earlier infected patients are surviving thanks to the new anti-retroviral treatment. There has been a decrease in people who are unaware of their infection from 25 % in 2003 to 21 % in 2006.

The CDC has used different methods than the past to collect data on the number of people. In the new statistical method called "back-calculation". The report feels that past estimates of the number of Americans with HIV could have been overstated at the time. Earlier estimates had put the figure at 1 million for the year 2003 and using the new methods the CDC says possibly the figures were 994,000 who were infected with HIV.

Richard Wolitski acting chief of the CDC's HIV/AIDS prevention division said, in a telephone interview, "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." 

Of all the racial groups blacks, who make up 12 % of the overall population were the hardest hit accounting for 46 % of the cases in 2006 with 1.7 % of U.S. blacks infected compared to 0.6 % Hispanics and 0.2 % whites. Gay and bisexual men were also those who figured on the higher numbers with gay men representing 48 % of the HIV infected number. In 18 % of the cases the person contracted the infection through the use of an infected needle said the CDC Atlanta based study. Men represented three quarters of the infected people.

Wolitski said as the number of infected people increases so does the cost of providing medical services and the pressure on the U.S. health care system. The report says that one out of five people or 232,700 people out of the 1.1 million HIV infected people are unaware that they carry the infection. "We're not going to be able to treat our way out of this epidemic. We need to have strong prevention programs so we can prevent these infections from occurring in the first place," said Wolitski.

New HIV infection rates have been stable at 56,000 new infections a year, and in 2006 14,000 Americans died of AIDS with the total death toll reaching 546,000 since it was first noticed in early 1980, s. Globally HIV infects 33 million people and 25 million have already died from it.

The study recommends increasing the reach of testing, treatment and prevention services in order to reduce the impact of the deadly virus.