The most important epidemiologic characteristic of AIDS is that virtually all asymptomatic infected persons are infectious and will remain so indefinitely. To combat the AIDS infection, efforts in the United States should focus on preventing transmission from the estimated 1.5 million persons already infected. Existing tools should be used effectively. These include public information, health education, counseling and serologic testing of persons at high risk, treatment and prevention of intravenous drug abuse, and serologic screening of organ and tissue donors. Adequate confidentiality of test results should be ensured to promote voluntary testing as an important means of achieving behavioral change among persons most likely to have been exposed to the infection. Persons whose sexual or drug abuse behavior puts them at higher risk of infection are the highest priority target group. 6 references. (Author abstract modified)