AIDS was first reported June 5, 198

AIDS was first reported June 5, 1981, when the U.S. Centers for Disease Control (CDC) recorded a cluster of Pneumocystis carinii pneumonia (now still classified as PCP but known to be caused by Pneumocystis jirovecii) in five homosexual men in Los Angeles.^[154] In the beginning, the CDC did not have an official name for the disease, often referring to it by way of the diseases that were associated with it, for example, lymphadenopathy, the disease after which the discoverers of HIV originally named the virus.^[76][77] They also used Kaposi's Sarcoma and Opportunistic Infections, the name by which a task force had been set up in 1981.^[155]

In the general press, the term GRID, which stood for Gay-related immune deficiency, had been coined.^[156] The CDC, in search of a name, and looking at the infected communities coined “the 4H disease,” as it seemed to single out Haitians, homosexuals, hemophiliacs, and heroin users.^[157] However, after determining that AIDS was not isolated to the homosexual community,^[155] the term GRID became misleading and AIDS was introduced at a meeting in July 1982.^[158] By September 1982 the CDC started using the name AIDS, and properly defined the illness.^[159]

The earliest known positive identification of the HIV-1 virus comes from the Congo in 1959 and 1960 though genetic studies indicate that it passed into the human population from chimpanzees around fifty years earlier.^[10] A recent study states that a strain of HIV-1 probably moved from Africa to Haiti and then entered the United States around 1969.^[160]

The HIV virus descends from the related simian immunodeficiency virus (SIV), which infects apes and monkeys in Africa. There is evidence that humans who participate in bushmeat activities, either as hunters or as bushmeat vendors, commonly acquire SIV.^[161] However, only a few of these infections were able to cause epidemics in humans, and all did so in the late 19^th—early 20^th century. To explain why HIV became epidemic only by that time, there are several theories, each invoking specific driving factors that may have promoted SIV adaptation to humans, or initial spread: social changes following colonialism,^[162] rapid transmission of SIV through unsafe or unsterile injections (that is, injections in which the needle is reused without being sterilised),^[163] colonial abuses and unsafe smallpox vaccinations or injections,^[164] or prostitution and the concomitant high frequency of genital ulcer diseases (such as syphilis) in nascent colonial cities.^[165][166] See the main article Origin of AIDS.