June 5, 1981 is the day most commonly recognized as the beginning of the AIDS pandemic.
On this date, the Centers for Disease Control and Prevention reported five cases of a "rare form of pneumonia" in gay Los Angeles, California residents. The new illness, named Human Immunodeficiency Virus or HIV, weakened the immune system and could develop into it's most advanced state- AIDS or Acquired Immune Deficiency Syndrome.
Twenty-five years later, an international scientific team traced the origin of HIV to wild chimpanzees in a remote area of Cameroon, Africa. There is still no cure for HIV or AIDS.