MONDAY, June 17 (HealthDay News) -- The younger you are, the less likely you are to realize you are infected with HIV or receive treatment for it, a new study finds.

Early diagnosis, prompt and continued care, and antiretroviral drug therapy are key to lowering the risk of illness and death among patients, and reducing transmission of HIV, the virus that causes AIDS.

However, this study of 2009 data from the National HIV Surveillance System found that people under the age of 45 who are infected with the virus are much less likely than their older peers to know they are infected or to be getting proper care.

The study also revealed that more than 200,000 of the more than 1.1 million Americans who are infected are unaware they carry the virus. The investigators also found that only about 37 percent of infected people received regular care, only one-third were prescribed HIV-suppressing medicines, and 25 percent had achieved a "suppressed viral load," meaning HIV was being kept to very low levels.

These results varied widely by age. For example, among HIV-infected people aged 13 to 24, only about 40 percent had received a diagnosis of HIV infection and only 30 percent had been referred for care.

Lower percentages of people aged 25 to 44 received regular care, were prescribed drug therapy and had a suppressed viral load, compared with those aged 55 to 64, the study found. For example, 28 percent of young adults with HIV were receiving treatment, compared with 46 percent of those aged 55 to 64.

The study was published online June 17 in the journal JAMA Internal Medicine.

Overall, more than 850,000 Americans with HIV had not achieved the treatment goal of viral suppression. This included 75 percent of men with HIV, 79 percent of blacks, 74 percent of Hispanics, and 70 percent of whites.

"Individuals, health care providers, health departments and government agencies must all work together to increase the numbers of people living with HIV who are aware of their status, linked to and retained in care, receiving treatment and adherent to treatment," concluded researchers led by H. Irene Hall of the U.S. Centers for Disease Control and Prevention.

"In 2011, the HIV field was shocked to learn that only about a quarter of individuals living with HIV were successfully receiving HIV treatment," Drs. Katerina Christopoulos and Diane Havlir, of the University of California, San Francisco, wrote in an accompanying commentary.

"The sobering numbers of those missing out on effective treatment because they did not know they were infected and those who knew their status but did not seek care spurred collaboration between the HIV treatment and prevention movements, two areas with different funding streams that often operated independently of one another," they noted.

"Already the HIV community has mobilized to further develop and study interventions that address bottlenecks in the cascade. Achieving an AIDS-free generation will be within reach if, and only if, these efforts succeed," Christopoulos and Havlir concluded.

More information

The U.S. National Institute of Allergy and Infectious Diseases has more about HIV/AIDS.