The headline of the June 21 article "AMA Urges Caution on AIDS Tests" is both misleading and incorrect. It reflects a basic misunderstanding between the terms "infection" and "disease."

AIDS is a disease caused by the human immunodeficiency virus (HIV). Everyone exposed to the HIV, however, does not develop AIDS, just as many who are exposed to the flu virus never get the sniffles.

It is estimated that there are now 1.5 to 2 million Americans who are HIV-antibody positive as a result of infection but who do not manifest the disease AIDS. Although at the present time we do not know the precise number of HIV-antibody-positive individuals who will subsequently develop AIDS, estimates have been made ranging anywhere from 10 percent to 100 percent. In fact, the National Academy of Sciences in one study projected that 50 percent to 70 percent of all persons with the HIV virus will not get AIDS.

This essential distinction is often overlooked by articles in the media that confuse HIV testing, which is a measure of exposure to the virus, with AIDS testing, which is a measure of disease expression. The HIV test is accomplished with a simple blood test to detect antibody to HIV. AIDS is diagnosed using more sophisticated medical measures together with the HIV test.

In the June 21 article the AMA report addresses the need for HIV testing, not AIDS testing. Confusing the HIV test with an AIDS test not only confuses the public but also engenders unnecessary fear in the minds of many who may never in fact develop the disease AIDS.

JOSEPH A. BELLANTI Director, International Center For Interdisciplinary Studies of Immunology

EDWARD E. BARTLETT Associate Adjunct Professor Community and Family Medicine Georgetown University School of Medicine Washington