<p>The most chilling moment of my medical career occurred in 1985, when I led a program to test incoming U.S. Army recruits for HIV, the virus that causes AIDS. At the time, little was known about the emerging HIV virus or AIDS. As I began to analyze blood samples from the first 600,000 recruits, I discovered that HIV had silently infected a large cross section of apparently healthy young adults. At that moment I realized that we were already losing the race to control the virus, and that the human species was destined to be afflicted with HIV as a fact of life -- and death -- for decades to come.</p>