Salud

Discovery
AIDS was first clinically observed in 1981 in the United States.[21] The initial cases were a cluster of injecting drug users and homosexual men with no known cause of impaired immunity who showed symptoms of Pneumocystis carinii pneumonia (PCP), a rare opportunistic infection that was known to occur in people with very compromised immune systems.[163] Soon thereafter, an unexpectednumber of gay men developed a previously rare skin cancer called Kaposi's sarcoma (KS).[164][165] Many more cases of PCP and KS emerged, alerting U.S. Centers for Disease Control and Prevention (CDC) and a CDC task force was formed to monitor the outbreak.[166]
In the early days, the CDC did not have an official name for the disease, often referring to it by way of the diseases that were associatedwith it, for example, lymphadenopathy, the disease after which the discoverers of HIV originally named the virus.[167][168] They also used Kaposi's Sarcoma and Opportunistic Infections, the name by which a task force had been set up in 1981.[169] At one point, the CDC coined the phrase "the 4H disease", since the syndrome seemed to affect Haitians, homosexuals, hemophiliacs, and heroinusers.[170] In the general press, the term "GRID", which stood for gay-related immune deficiency, had been coined.[171] However, after determining that AIDS was not isolated to the gay community,[169] it was realized that the term GRID was misleading and the term AIDS was introduced at a meeting in July 1982.[172] By September 1982 the CDC started referring to the disease as AIDS.[173]

Robert Gallo,co-discoverer of HIV in the early eighties among (from left to right) Sandra Eva, Sandra Colombini, and Ersell Richardson.
In 1983, two separate research groups led by Robert Gallo and Luc Montagnier independently declared that a novel retrovirus may have been infecting AIDS patients, and published their findings in the same issue of the journal Science.[174][175] Gallo claimed that a virus his grouphad isolated from an AIDS patient was strikingly similar in shape to other human T-lymphotropic viruses (HTLVs) his group had been the first to isolate. Gallo's group called their newly isolated virus HTLV-III. At the same time, Montagnier's group isolated a virus from a patient presenting with swelling of the lymph nodes of the neck and physical weakness, two characteristic symptoms of AIDS.Contradicting the report from Gallo's group, Montagnier and his colleagues showed that core proteins of this virus were immunologically different from those of HTLV-I. Montagnier's group named their isolated virus lymphadenopathy-associated virus (LAV).[166] As these two viruses turned out to be the same, in 1986, LAV and HTLV-III were renamed HIV.[176]
Origins
Both HIV-1 and HIV-2 are believed tohave originated in non-human primates in West-central Africa and were transferred to humans in the early 20th century.[4] HIV-1 appears to have originated in southern Cameroon through the evolution of SIV(cpz), a simian immunodeficiency virus (SIV) that infects wild chimpanzees (HIV-1 descends from the SIVcpz endemic in the chimpanzee subspecies Pan troglodytes troglodytes).[177][178] The closestrelative of HIV-2 is SIV(smm), a virus of the sooty mangabey (Cercocebus atys atys), an Old World monkey living in litoral West Africa (from southern Senegalto western Ivory Coast).[60] New World monkeys such as the owl monkey are resistant to HIV-1 infection, possibly because of a genomic fusion of two viral resistance genes.[179] HIV-1 is thought to have jumped the species barrier on at leastthree separate occasions, giving rise to the three groups of the virus, M, N, and O.[180]
There is evidence that humans who participate in bushmeat activities, either as hunters or as bushmeat vendors, commonly acquire SIV.[181] However, SIV is a weak virus, it is typically suppressed by the human immune system within weeks of infection. It is thought that several transmissions of the virus from...