Friday, September 30, 2022

Where Did Aids Originate From

How The Aids Epidemic Really Began

Where did Aids come from?

In Randy Shilts history of AIDS, And the Band Played On, he tells the story of an Air Canada steward named Gaëtan Dugas, who suffered from what Dugas called gay cancer and infected 40 people or more with HIV.

He was, Shilts wrote, Patient Zero.

Dugas, through his extensive travels and unrepentant, unprotected sex even after he was diagnosed, undoubtedly helped spread AIDS. But was he the man who brought the disease to America?

In the new book The Chimp and the River: How AIDS Emerged from an African Rain Forest , author David Quammen says no.

Dugas himself was infected by some other human, presumably during a sexual encounter and not in Africa … somewhere closer to home, Quammen writes. As evidence now shows, HIV had already arrived in North America when Gaëtan Dugas was a virginal adolescent.

Using molecular genetics, researchers have now traced the exact strain of HIV that became a pandemic HIV-1, Group M, Subtype B to its original source.

Amazingly, through examination of genetic samples from humans and chimps, Quammen reveals scientists have found exactly when and where AIDS started even a probable theory as to how.

They are the first warnings of what is happening.

Tracing The Origin Of The Aids Pandemic

Beatrice H. Hahn, MDProfessor of Medicine and MicrobiologyUniversity of Alabama at BirminghamBirmingham, AlabamaSummary by Tim HornEdited by Lucia Torian, PhD

Reprinted from The PRN Notebook® | September 2005 | Dr. James F. Braun, Editor-in-Chief, Tim Horn, Executive Editor. | Published in New York City by the Physicians Research Network, Inc.® | John Graham Brown, Executive Director | All rights reserved. ©September 2005

For those lucky enough to be in attendance, the keynote lecture delivered at the 6th Conference on Retroviruses and Opportunistic Infections at the end of January 1999 was nothing short of a jaw-dropping experience. Dr. Beatrice Hahn of the University of Alabama at Birmingham presented the first concrete evidence of the primate origin of HIV-1, the much more prevalent of the HIV types responsible for the AIDS pandemic. The official report of her teams findings, published in a February 1999 issue of Science, was a no less captivating example of seminal scientific research .

The Aids Epidemic Arises

Though HIV arrived in the United States around 1970, it didnt come to the publics attention until the early 1980s.

In 1981, the Centers for Disease Control and Prevention published a report about five previously healthy homosexual men becoming infected with Pneumocystis pneumonia, which is caused by the normally harmless fungus Pneumocystis jirovecii. This type of pneumonia, the CDC noted, almost never affects people with uncompromised immune systems.

The following year, The New York Times published an alarming article about the new immune system disorder, which, by that time, had affected 335 people, killing 136 of them. Because the disease appeared to affect mostly homosexual men, officials initially called it gay-related immune deficiency, or GRID.

Though the CDC discovered all major routes of the diseases transmissionas well as that female partners of AIDS-positive men could be infectedin 1983, the public considered AIDS a gay disease. It was even called the gay plague for many years after.

In September of 1982, the CDC used the term AIDS to describe the disease for the first time. By the end of the year, AIDS cases were also reported in a number of European countries.

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Why Is Haiti Significant

In the 1960s, the ‘B’ subtype of HIV-1 made its way to Haiti. This is thought to have happened because many Haitians had been working in the Democratic Republic of Congo and had then returned to Haiti. Initially, Haitians were blamed for starting the HIV epidemic, and suffered severe racism, stigma and discrimination as a result.

Case Definition For Epidemiological Surveillance

Where Did HIV Come From

According to a study published in the Proceedings of the National Academy of Sciences in 2008, a team led by Robert Shafer at Stanford University School of Medicine discovered that the gray mouse lemur has an endogenouslentivirus in its genetic makeup. This suggests that lentiviruses have existed for at least 14 million years, much longer than the currently known existence of HIV. In addition, the time frame falls in the period when Madagascar was still connected to what is now the African continent the said lemurs later developed immunity to the virus strain and survived an era when the lentivirus was widespread among other mammals. The study was hailed as crucial, as it fills the blanks in the origin of the virus, as well as in its evolution, and could be important in the development of new antiviral drugs.

In 2010, researchers reported that SIV had infected monkeys in Bioko for at least 32,000 years. Previous to this time, it was thought that SIV infection in monkeys had happened over the past few hundred years. Scientists estimated that it would take a similar amount of time before humans adapted naturally to HIV infection in the way monkeys in Africa have adapted to SIV and not suffer any harm from the infection.

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The Origin Of Hiv: Pan Troglodytes Top Of Page

Chimpanzees can be divided into two species: the common chimpanzee and the bonobo . Pan troglodytes can be divided into four subspecies: Pan troglodytes schweinfurthii , also known as the eastern common chimpanzee Pan troglodytes troglodytes , or the central common chimpanzee Pan troglodytes verus , or the western common chimpanzee and Pan troglodytes vellerosus , or the Nigeria chimpanzee. The geographic locations of the four Pan troglodytes subspecies in sub-Saharan Africa are detailed in Figure 2.

Figure 2.Pan Troglodytes Subspecies

Chimpanzees can be divided into two species: the common chimpanzee and the bonobo . Pan troglodytes can be divided into four subspecies: Pan troglodytes schweinfurthii , also known as the eastern common chimpanzee Pan troglodytes troglodytes , or the central common chimpanzee Pan troglodytes verus , or the western common chimpanzee and Pan troglodytes vellerosus , or the Nigeria chimpanzee.

Prior to 1999, only three wild-born Pan troglodytes tested in laboratories had been found to harbor SIV . Two of the chimpanzees , caught wild in Gabon, had viruses with similar genotypes. The third chimpanzee , confiscated in Antwerp after having been illegally imported from Zaire , had a variant of SIVcpz that differed genotypically from the SIVcpz variants found in GAB1 and GAB2 .

Figure 3.Evolutionary Relationships of SIVcpz and HIV-1 Strains

Figure 4.Bushmeat in Pointe Noire, Democratic Republic of Congo

Beyond Gombe Top Of Page

After the completion of data collection and analysis in Gombe, Dr. Hahns team ventured to forested areas in the vicinity of Kisangani on the Congo River, home to other communities of P. t. schweinfurthii. While Gombe National Park represents the eastern range of Pan troglodytes, the Kisangani forests are more centrally located. Here, Dr. Hahns group documented the presence of SIVcpz infection in two of three field sites.

Additional field surveys have been conducted . They included the habituated communities in Kanyawara and Ngogo, both in Kibale National Park in Western Uganda habituated chimpanzees in the Budongo Forest, in northern Uganda habituated members of the M group in Mahale Mountain National Park in southern Tanzania and nonhabituated chimps in the Nyungwe Forest Reserve in western Uganda. We got multiples samples from known individuals and, surprisingly, did not find a single shred of virus, Dr. Hahn said. Its possible that the virus was in these communities once, but has gone extinct. Alternatively, she explained, the eastward spread of SIVcpz may have been influenced by biogeographical barriers, such that certain communities were never exposed to this virus.

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Unresolved Questions About Hiv Origins And Emergence

The discovery of the main HIV/SIV phylogenetic relationships permits explaining broad HIV biogeography: the early centres of the HIV-1 groups were in Central Africa, where the primate reservoirs of the related SIVcpz and SIVgor viruses exist similarly, the HIV-2 groups had their centres in West Africa, where sooty mangabeys, which harbour the related SIVsmm virus, exist. However, these relationships do not explain more detailed patterns of biogeography, such as why epidemic HIV-2 groups only evolved in the Ivory Coast, which is one of only six countries harbouring the sooty mangabey. It is also unclear why the SIVcpz endemic in the chimpanzee subspecies Pan troglodytes schweinfurthii did not spawn an epidemic HIV-1 strain to humans, while the Democratic Republic of Congo was the main centre of HIV-1 group M, a virus descended from SIVcpz strains of a subspecies that does not exist in this country. It is clear that the several HIV-1 and HIV-2 strains descend from SIVcpz, SIVgor, and SIVsmm viruses, and that bushmeat practice provides the most plausible cause of cross-species transfer to humans. However, some loose ends remain.

It is not yet explained why only four HIV groups spread considerably in human populations, despite bushmeat practices being widespread in Central and West Africa, and the resulting human SIV infections being common.

Natural History Of Sivcpz Infection

The Origins of AIDS

Initially, SIVcpz was thought to be harmless for its natural host. This was because none of the few captive apes that were naturally SIVcpz infected suffered from overt immunodeficiency, although in retrospect this conclusion was based on the immunological and virological analyses of only a single naturally infected chimpanzee . In addition, SIV-infected sooty mangabeys and African green monkeys showed no sign of disease despite high viral loads in blood and lymphatic tissues , leading to the belief that all naturally occurring SIV infections are nonpathogenic. However, the sporadic prevalence of SIVcpz, along with its more recent monkey origin, suggested that its natural history might differ from that of other primate lentiviruses. To address this, a prospective study was initiated in Gombe National Park, Tanzania, the only field site where SIVcpz infected chimpanzees are habituated and so can be observed in their natural habitat.

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What Is The Evidence That Hiv Causes Aids

The epidemic of HIV and AIDS has attracted much attention both within and outside the medical and scientific communities. Much of this attention comes from the many social issues related to this disease such as sexuality, drug use, and poverty. Although the scientific evidence is overwhelming and compelling that HIV is the cause of AIDS, the disease process is still not completely understood. This incomplete understanding has led some persons to make statements that AIDS is not caused by an infectious agent or is caused by a virus that is not HIV. This is not only misleading, but may have dangerous consequences. Before the discovery of HIV, evidence from epidemiologic studies involving tracing of patients sex partners and cases occurring in persons receiving transfusions of blood or blood clotting products had clearly indicated that the underlying cause of the condition was an infectious agent. Infection with HIV has been the sole common factor shared by AIDS cases throughout the world among men who have sex with men, transfusion recipients, persons with hemophilia, sex partners of infected persons, children born to infected women, and occupationally exposed health care workers.

The conclusion after more than 28 years of scientific research is that people, if exposed to HIV through sexual contact or injecting drug use for example, may become infected with HIV. If they become infected, most will eventually develop AIDS.

Why Do Scientists Look At Recent Samples Of Hiv To Determine The Virus’ Overall Age Wouldn’t It Be Better To Use Older Samples That Haven’t Had As Much Time To Mutate

It would, but scientists don’t have that luxury. Other than the 1959 sample, there are very few preserved specimens of HIV-infected tissue that predate the early ’80s, when the virus was first recognized by health authorities. Researchers still hope there are forgotten samples in African freezers. “There has to be some serum or plasma somewhere, and given modern technology we could fish out the virus,” says Dr. David Ho, director of the Aaron Diamond AIDS Research Center and one of the world’s leading authorities on HIV.

But even if those samples are found someday, they won’t necessarily yield definite answers about the virus’ age, says Korber: “Often, you can’t get anything out of samples like that.” Most African samples are made of blood serum, and serum samples contain viral RNA, which degrades much faster than the DNA found in tissue samples. In fact, says Ho, the 1959 sample, which was sequenced by his laboratory, was kept in a freezer but still didn’t survive the ravages of time. “It was completely dried up,” he says. “We were only able to get small pieces , and we had to stitch them together.”

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Origin Of Hiv And Aids

The origin of theâ¯Human Immunodeficiency Virus has been a subject of scientific research and debate since the virus was identified in the 1980s. There is now a wealth of evidence on how, when and where HIV first began to cause illness in humans.

Find out more in our interactive timeline of the HIV epidemic.

  • Want to know more about the history of HIV?
  • Aids: Origin Of Pandemic ‘was 1920s Kinshasa’

    PPT

    Health editor, BBC News website

    The origin of the Aids pandemic has been traced to the 1920s in the city of Kinshasa, in what is now the Democratic Republic of Congo, scientists say.

    An international team of scientists say a “perfect storm” of population growth, sex and railways allowed HIV to spread.

    A feat of viral archaeology was used to find the pandemic’s origin, the team report in the journal Science.

    They used archived samples of HIV’s genetic code to trace its source, with evidence pointing to 1920s Kinshasa.

    Their report says a roaring sex trade, rapid population growth and unsterilised needles used in health clinics probably spread the virus.

    Meanwhile Belgium-backed railways had one million people flowing through the city each year, taking the virus to neighbouring regions.

    Experts said it was a fascinating insight into the start of the pandemic.

    HIV came to global attention in the 1980s and has infected nearly 75 million people.

    It has a much longer history in Africa, but where the pandemic started has remained the source of considerable debate.

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    Primate Lentiviruses Top Of Page

    HIV is an RNA virus that codes for the enzyme reverse transcriptase, which is needed to transcribe the viral RNA into a DNA copy that is capable of integrating itself into the host cell genome. Within the retrovirus family, HIV is classified as a lentivirus. It has morphologic and genetic similarities to animal lentiviruses, including those infecting cats , sheep , goats , and non-human primates . “When we compare the sequences of these lentiviruses, phylogenetic analysis yields clusters revealing common ancestors,” Dr. Hahn explained. “The human viruses cluster with SIV they do not cluster with the lentiviruses in other animals. However, the cluster that we do see indicates that the human viruses have to be the result of cross-species transmission, meaning that they clearly came from primates.”

    One limitation of the research conducted thus far is the fact that most SIVs are derived from primates studied in captivity. This, Dr. Hahn argued, does not provide information concerning the prevalence, genetic diversity, and geographic distribution in the wild. “What we’re left with are questions concerning the magnitude of the existing SIV reservoirs and the associated human zoonotic risk,” she said.

    Where Did Hiv Come From

    HIV/AIDS

    Disease Diction

    A zoonosis is an infection or infectious disease that is transmissible from vertebrate animals to people.

    The best accepted theory about the origin of HIV is that it is a descendant of a closely related virus, simian immunodeficiency virus , which infects monkeys. Researchers have known for a long time that certain viruses can pass from animals to humans, a process that is called zoonosis. HIV may have crossed over from chimpanzees as a result of a human killing a chimp and eating it for food.

    In 1999, researchers confirmed that tissue from a chimpanzee carried a form of SIV that was nearly identical to an aggressive form of HIV, HIV-1. It appears highly likely chimpanzees were the source of HIV-1, and that the virus at some point crossed species from chimpanzees to humans. We cannot say for sure when the virus first emerged, but it is clear that HIV started to infect humans and became epidemic in the middle of the twentieth century.

    Potent Fact

    Why don’t mosquitoes transmit AIDS? The HIV virus does not multiply in mosquitoes. If a mosquito feeds on an HIV-infected human, the virus is treated like food and digested along with the blood meal. If the mosquito resumes feeding on a non-HIV-infected individual, too few particles are transferred to initiate a new infection.

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    New Class Of Antiretrovirals

    In 1995, the FDA approved saquinavir, the first in a different anti-HIV drug class called protease inhibitors. Like NRTIs, protease inhibitors stop the virus from copying itself, but at a different stage during the infection.

    A year later came yet another class of antiretrovirals, called non-nucleoside reverse transcriptase inhibitor , including nevirapine . Similar to AZT, NNRTIs shut down HIV by targeting the enzymes it needs to multiply.

    These drugs paved the way to a new era of combination therapy for HIV/AIDS. Doctors began prescribing saquinavir plus AZT or other antiretrovirals. This combination therapy was dubbed highly active antiretroviral therapy . That approach became the new standard of care for HIV in 1996. HAART greatly lengthened the life span of people with AIDS.

    Gombe National Park Top Of Page

    New documentary explores the truth behind the origin and rise of HIV/AIDS | Your Morning

    With the noninvasive screening assays at the ready, Dr. Hahns team headed to Gombe National Park in Tanzania. Its probably the most famous chimp colony in the world, Dr. Hahn explained. This is where Dr. Jane Goodall started her work over forty years ago. Gombe is wonderful because many of the chimps are habituated to the presence of human observers. They go about their business and they arent bothered when someone follows them and records what they do on a daily basis.

    Dr. Hahn explained how her study team collects urine from wild chimps. Trees in the forest contain nests, she said. The chimps sleep in the nests, in order to avoid being attacked by leopards during the night. We would wake up in the morning before the chimps and stand under the trees with collection baskets. Basically, they do the same thing we do in the morning. Wed capture the urine in the baskets and collect the necessary sample amount. As for feces, wed collect it off the jungle floor and preserve it for testing.

    Gombe National Park is a very small national park, approximately 675 kilometers by 70 kilometers, located on the shores of Lake Tanganyika. Its pretty much an island of forest in Tanzania, Dr. Hahn explained. Everything to the north, south, and east of Gombe National Park has been deforested, meaning that theres no place for the chimpanzees to go. This is bad, because the chimps cant get out and there is concern of inbreeding.

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