The first recognised cases of AIDS occurred in the USA in the early 1980s (see timeline) and the origin of Aids and HIV has puzzled scientists ever since the illness first came to light. For years it has been the subject of fierce debate and the cause of countless arguments.
A number of gay men in New York and California suddenly began to develop rare opportunistic infections and cancers that seemed stubbornly resistant to any treatment in 1981. At this time, AIDS did not yet have a name, but it quickly became obvious that all the men were suffering from a common syndrome. The discovery of HIV, the Human Immunodeficiency Virus, was made soon after. While some were initially resistant to acknowledge the connection (and indeed some remain so today), there is now clear evidence to prove that HIV causes AIDS. But, what was the source of the virus and when and where did HIV first begin to cause disease in humans?
There are several subtypes of HIV that are prevalent in different parts of the world. The earliest known case of any type of HIV in a human was from a blood sample analysed in 1998 but collected in 1959. This suggested that HIV/Aids might have been introduced to humans in the 1940s or early 1950s. However, in January 2000 (San Francisco, California) the results of a new study presented at the 7th Conference on Retroviruses and Opportunistic Infections, suggested that the first case of HIV infection occurred around 1930.
- The first case of HIV infection probably occurred around 1930 in West Africa.
- One form of the virus (HIV-2) that causes Aids made the jump from animals to people by 1940 during a war in the West African country of Guinea-Bissau .
- A plasma sample taken in 1959 from an adult male living in what is now the Democratic Republic of Congo proved that the man died of HIV/Aids.
- HIV was found in tissue samples from an African-American teenager who died in St. Louis in 1969. Therefore the virus began to exist in the USA from the 1960s/1970s.
- HIV was found in tissue samples from a Norwegian sailor who died around 1976.
- The first two official AIDS deaths in South Africa were recorded in 1982.
In 1999, an international team of researchers reported that a subspecies of chimpanzee, native to west equatorial Africa, was the original source of the virus. They believe that it passed to humans when hunters became exposed to infected blood.
- HIV-1 was identified as a simian (monkey) immunodeficiency virus that was known to infect chimpanzees (SIVcpz), but this virus had significant differences between it and HIV. A group of researchers from the University of Alabama had studied frozen tissue from a chimpanzee and found that the simian virus it carried (SIVcpz) was almost identical to HIV-1, which was once common in west-central Africa.
- HIV-2 corresponds to a simian immunodeficiency virus found in the sooty mangabey monkey (SIVsm), sometimes known as the green monkey, which is indigenous to western Africa