Fewer people in all U.S. groups tested positive for human immunodeficiency virus except for gay and bisexual men ages 13 to 24 and over 45, they wrote in a special issue of the Journal of the American Medical Association.
The diagnosis rate fell to 16.1 per 100,000 people in 2011 from 24.1 in 2002, the researchers wrote in the issue, published to coincide with an international AIDS meeting in Melbourne, Australia.
The U.S. drop is in line with a global downturn in the epidemic of AIDS, or Acquired Immune Deficiency Syndrome. The United Nations said on Wednesday that there were 2.1 million new HIV infections worldwide in 2013, down 38 percent from 2001.
The U.S. decline followed increased emphasis on care and treatment for people with HIV, including use of antiretroviral therapy, the report said.