Twenty-five years of HIV/AIDS--United States, 1981-2006.

On June 5, 1981, MMWR published a report of Pneumocystis carinii pneumonia in five previously healthy young men in Los Angeles, California. These cases were later recognized as the first reported cases of acquired immunodeficiency syndrome (AIDS) in the United States. Since that time, this disease has become one of the greatest public health challenges both nationally and globally. Human immunodeficiency virus (HIV) and AIDS have claimed the lives of more than 22 million persons worldwide, including more than 500,000 persons in the United States.