The 20th year of AIDS: a time to re-energize prevention.

Since the first acquired immunodeficiency syndrome (AIDS) cases were reported in 1981, human immunodeficiency virus (HIV) has caused approximately 22 million deaths worldwide. In the United States, approximately 400,000 persons have died, and approximately one million have been infected. However, numerous persons have avoided infection through prevention efforts, and many lives have been prolonged through advances in treatment.