Aids first appeared in 1959. Its definition states that its any of a group of retroviruses and esp. HIV-1 that infect and destroy helper T cells of the immune system causing the marked reduction in their numbers that is diagnostic of AIDS -- called also AIDS virus, human immunodeficiency virus. A retrovirus is any of a group of RNA-containing viruses (as HIV) that produce reverse transcriptase by means of which DNA is produced using their RNA as a template and incorporated into the genome of infected cells and that include numerous tumorigenic viruses. During the 2000 year 5.3 million people were newly infected with HIV/AIDS. At the end of the 2000 year 36.1 million people will be living with HIV/AIDS
Where did it come from? Scientists have different theories about the origin of HIV, but none have been proven. The earliest known case of HIV was from a blood sample collected in 1959 from a man in Kinshasha, Democratic Republic of Congo.
(How he became infected is not known.) Genetic analysis of this blood sample suggests that HIV-1 may have stemmed from a single virus in the late 1940s or early 1950s.
We do know that the virus has existed in the United States since at least the mid- to late 1970s. From 1979-1981 rare types of pneumonia, cancer, and other illnesses were being reported by doctors in Los Angeles and New York among a number of gay male patients. These were conditions not usually found in people with healthy immune systems.
In 1982 public health officials began to use the term "acquired immunodeficiency syndrome," or AIDS, to describe the occurrences of opportunistic infections, Kaposi's sarcoma, and Pneumocystis carinii pneumonia in previously healthy men. Formal tracking (surveillance) of AIDS cases began that year in the United States.