AIDS origin

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AIDS is thought to have originated in sub-Saharan Africa during the 20th century. It was transferred to humans by a similar route as some classic Old World infectious diseases. The ancient Old World was the incubator of many diseases like smallpox because it had large human populations in close association with large animal populations, especially those that lived in herds or social groups.

Contents 1 Possible spread from animal to human populations 2 History of known cases and spread 3 Identification of the virus 4 See Also 5 Further reading 6 Notes

[edit] Possible spread from animal to human populations

HIV originated in non-human primates as far as is known.

Researchers announced in May 2006 that the HIV virus most likely originated in wild chimpanzees in the southeastern rain forests of Cameroon (modern East Province) rather than in Kinshasa, Democratic Republic of Congo (formerly Zaire), as had previously been believed. Seven years of research and 1,300 chimpanzee genetic samples led Dr. Beatrice Hahn of the University of Alabama, Birmingham, to identify chimpanzee communities near Cameroon's Sanaga River as the most likely originators. The researchers say that transference from chimp to human most likely occurred when a human was bitten by a chimp or was cut while butchering one, and the human became infected.[1] Calculating based on a fixed mutation rate, the jump from chimpanzee to human likely occurred during the French colonial period (1919–1960). Comparative primatologist Jim Moore suggests that this may have been the result of colonial practices of forced labour, which could have suppressed the immune system of the initial hunter enough to allow the virus to infect and take hold. Likewise, forced immunisations (using one needle on many patients) may have sped the virus's spread through Cameroon and beyond.[2]

A more controversial theory known as the OPV AIDS hypothesis suggests that the AIDS epidemic was inadvertently started in the Belgian Congo by Hilary Koprowski's 1950s research into a polio vaccine prepared from tissue cultures using locally captured non-human primates.^[1][2] Edward Hooper rejects the dates calculated using a fixed mutation rate on the basis that phylogenetic dating of "the most recombinogenic organisms known to medical science", immunodeficiency viruses, is "inherently incapable of making any allowance for recombination". ^[3] However, in February 2000 one of the original developers of the polio vaccine, Philadelphia based Wistar Institute found in its stores a phial of the original vaccine used in the vaccination program. It was analysed in April 2001 and no traces of either HIV-1 or SIV were found in the sample.^[4] A second analysis showed that only macaque monkey kindney cells,which cannot be infected with SIV or HIV, were used to produce the vaccine.^[5] While the analysis was done on only one phial of vaccine, most scientists have concluded that the polio vaccine theory of the origins of HIV is not possible.^[6]

Both species of the virus (HIV-1 and HIV-2) are believed to have originated in West-Central Africa and jumped species (zoonosis) from a non-human primate to humans. HIV-1 evolved from a Simian Immunodeficiency Virus (SIV_cpz) found in the chimpanzee subspecies Pan troglodytes troglodytes.^[7] DNA sequencing indicates that HIV-1 (group M) entered the human population in the early 20th century, probably sometime between 1915 and 1941.^[8][9] HIV-2 crossed species from a different strain of SIV, this one found in sooty mangabeys (an Old World monkey) of Guinea-Bissau.^[10]

SIVs in non-human primates tend to cause non-fatal disease. Comparison of the gene sequence of SIV with HIV should therefore give us information about the factors necessary to cause disease in humans. The factors that determine the virulence of HIV as compared to most SIVs are only now being elucidated. Non-human SIVs contain a nef gene that down-regulates CD3, CD4, and MHC class I expression; most non-human SIV's therefore do not induce immunodeficiency; the HIV nef gene however has lost its ability to down-regulate CD3, which results in the immune activation and apoptosis that is characteristic of chronic HIV infection.^[11]

[edit] History of known cases and spread

One of the earliest documented HIV-1 infection dates from 1959, and was discovered in the preserved blood sample of a man from Leopoldville, Belgian Congo (now Kinshasa, Democratic Republic of the Congo).^[12] However, it is unknown whether this anonymous person ever developed AIDS and died of its complications. The oldest documented case of the then-unknown syndrome was detected that same year, when a 25-year-old British sailor who had traveled in the navy between 1955 and 1957 (but apparently not to Africa), sought help at the Royal Infirmary of Manchester, England. He reported to have been suffering from puzzling symptoms, among them purplish skin lesions, for nearly two years. His condition had taken a turn for worse during Christmas 1958, when he started suffering from shortness of breath, extreme fatigue, rapid weight loss, night sweats and high fever. The doctors thought he might be suffering from tuberculosis and, even though they found no evidence of bacterial infection, they treated him for tuberculosis just to be safe, to no avail. The sailor continued to weaken and he died shortly after in August 1959. His autopsy revealed evidence of two unusual infections, cytomegalovirus and Pneumocystis carinii pneumonia (PCP, renamed Pneumocystis jiroveci pneumonia), very rare at the time but now commonly associated with AIDS patients. His case had puzzled his doctors, who preserved tissue samples from him and for years retained some interest in solving the mystery. Sir Robert Platt, then president of the Royal College of Physicians, wrote in the sailor's hospital chart that he wondered "if we are in for a new wave of virus disease now that the bacterial illnesses are so nearly conquered". It was only 31 years later, after the AIDS pandemic had become well-known and widespread, that they decided to perform HIV-tests on the preserved tissues of the sailor, which eventually turned out a positive result. The case was reported in the July 7, 1990 issue of the British medical journal The Lancet; their claim was retracted in a letter in the January 20, 1996 issue where they admitted that the tissue sample was contaminated in the laboratory (Corbitt G, Bailey A, Williams G. HIV infection in Manchester, 1959 . Lancet 1990; ii: 51.)^[13][14] Another early case was probably detected that same year, 1959, in a 48-year-old Haitian, who 30 years before had immigrated to the United States and at the time was working as a shipping clerk for a garment manufacturer in Manhattan. He developed similar symptoms to those just described for the British sailor, and died the same year, apparently of the same very rare kind of pneumonia. Many years later, Dr. Gordon R. Hennigar, who had performed this man's autopsy, was asked whether he thought his patient had died of AIDS; he replied "You bet" and added "It was so unusual at the time. Lord knows how many cases of AIDS have been autopsied that we didn't even know had AIDS. I think it's such a strong possibility that I've often thought about getting them to send me the tissue samples."^[15]

In 1969, a 15-year-old African-American male died at the St. Louis City Hospital from aggressive Kaposi's sarcoma. AIDS was suspected as early as 1984, and in 1987, researchers at Tulane University School of Medicine confirmed this, finding HIV-1 in his preserved blood and tissues. The doctors who worked on his case at the time suspected he was a prostitute, though the patient did not discuss his sexual history with them in detail.^{[16][17][18][19][20]}

In 1976, a Norwegian sailor named Arvid Noe, his wife, and his nine-year-old daughter died of AIDS. The sailor had first presented symptoms in 1969, four years after he had spent time in ports along the West African coastline. Tissue samples from the sailor and his wife were tested in 1988 and found to contain the HIV-1 virus (Group O).^[21][22] The next documented western death from AIDS was that of Dr. Grethe Rask in 1977. Rask, a Danish surgeon, had worked in the Congo in the early 1970s.

It thus appears that either HIV existed in very low levels in the United States in periods prior to 1981, or it may have gone extinct in the United States at times, with the present infection established in the USA about 1976. HIV in Africa likewise was at first at levels too low to be noticed. In the United States and Africa HIV was at first mostly found only in residents of large cities. The infection is now more widespread in rural areas, and has appeared in regions such as China and India, where it was previously not evident.

Author Randy Shilts mentioned that what was later called AIDS became evident in the gay community in the Fire Island, New York area in the four years after the 1976 Bicentennial celebrations. The infection tended to double in numbers about every nine to ten months. It therefore took a couple of years before a new disease was suspected because there were at first not enough symptomatic individuals to be noticed.

The official date for the beginning of the AIDS epidemic is marked as June 5, 1981, when the US Centers for Disease Control and Prevention reported in its Morbidity and Mortality Weekly Report newsletter that unusual clusters of Pneumocystis carinii pneumonia had been discovered in gay men in Los Angeles in the early 1980s.^[23] Over the next eighteen months, more PCP clusters were discovered among otherwise healthy men in cities throughout the country, along with other opportunistic diseases (such as Kaposi's sarcoma^[24] and persistent, generalized lymphadenopathy ^[25]), common in immunosuppressed patients.

In June 1982, a report of a group of cases amongst gay men in Southern California suggested that a sexually transmitted infectious agent might be the etiological agent,^[26] and the syndrome was initially termed 'GRID' (Gay-Related Immune Deficiency^[27]). However, the same opportunistic infections also began to be reported among hemophiliacs,^[28] heterosexual intravenous drug users, and Haitian immigrants.^[29] By August 1982, the disease was being referred to by its new name: Acquired Immune Deficiency Syndrome (AIDS).^[30] An anagram of AIDS, SIDA, was then coined for use in Portuguese (Síndrome da Imunodeficiência Adquirida) in French (Syndrome d'Immuno-Déficience Acquise) and Spanish (Síndrome de Inmunodeficiencia Adquirida).^[31] In Russian it got the name SPID (Sindrom Priobretyonnoy Immunitetnoy Defitsitnosti)

[edit] Identification of the virus

In May 1983, doctors from Dr. Luc Montagnier's team at the Pasteur Institute in France, reported that they had isolated a new retrovirus from lymphoid ganglions that they believed was the cause of AIDS.^[32] The virus was later named lymphadenopathy-associated virus (LAV) and a sample was sent to the U.S. Centers for Disease Control, which was later passed to the National Cancer Institute (NCI).^[33] In May 1984, Dr Robert Gallo of the NCI also isolated a virus that caused AIDS, and named it Human T-cell Lymphotropic Virus-III (HTLV-III).^[34] In January 1985 a number of more detailed reports were published concerning LAV and HTLV-III, and by March it was clear that the viruses were the same, from the same source, and was the etiological agent of AIDS.^[35][36] In May 1986, the International Committee on the Taxonomy of Viruses ruled that both names should be dropped and a new name, HIV (Human Immunodeficiency Virus), be used.^[37]

[edit] See Also

• AIDS conspiracy theories

[edit] Further reading

• Edward Hooper, The River, Little Brown and Company, 1999, ISBN 0-316-37261-7.
• AIDS, 1981: Mystery of an Emerging Epidemic by Brenda Wilson. All Things Considered, June 5, 2006. National Public Radio. Audio, 13 min. (Early cases in New York City.)
• Robert Searles Walker, AIDS: TODAY, TOMORROW - An Introduction to the HIV Epidemic in America (Humanities Press, NJ 1994, 2nd Ed.), ISBN 0-391-03859-1.

[edit] Notes

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