A program of the Centers for Disease Control and Prevention screened 2.8 million Americans for HIV and diagnosed about 18,000 with the virus, officials said. A report from agency, published in the Morbidity and Mortality Weekly Report, said the CDC began a three-year program in 2007 in the top 25 areas most affected by the human immunodeficiency virus. The study cost more than $102 million, with the CDC funding health departments in the designated areas to increase HIV testing and facilitate linkages to care for disproportionately affected populations -- particularly African-Americans, who bear a greater burden of HIV than other races or ethnicities, the report said. The Expanded HIV Testing Initiative calls for HIV testing to become a standard part of healthcare for all Americans, officials said. "Between September 2007 and October 2010, 2,786,739 tests were conducted, 18,432 persons were newly diagnosed with HIV and 75 percent of these cases, for whom follow up data was available, were linked to care," the report said. CDC officials estimate 20 percent of the 1.2 million people living with HIV in the United States don't know they are infected, so expanding testing is critical to helping people receive life-extending treatment and protecting the health of their partners, the report said.