How a Sick Chimp Led to a Global Pandemic: The Rise of HIV


Here at SciShow, we talk a lot about the fascinating,
complicated, and often very weird stories of discovery and collaboration that led to
the science we know today. But one of the strangest is something we haven’t
covered in much detail before, and it’s a biggie: the decades it took to figure out
exactly what HIV and AIDS were, and how to prevent and treat them. Since the start of the AIDS crisis, some 70
million people have been infected with HIV, and 35 million of those people have died. Both those numbers are staggering in their
own way, and together, they tell the story of a disease that has led to an incredible
amount of loss, but also one that — if you’re lucky enough to have access to the right medicines
— is no longer a death sentence. So, in honor of World AIDS Day on December
1, we want to tell you that story. There’s a lot to cover, so we’ll do it
in two parts. This episode, we’ll go over how we figured
out what HIV is, when the infection morphs into AIDS, and where we think the virus came
from. Next time, we’ll look back to the earliest
treatments, the arrival of antiretroviral drugs, which were complete game-changers,
and go over the creative ways scientists are now thinking about prevention and possibly
even a cure. But first, the basics. HIV, or human immunodeficiency virus, is a
retrovirus that infects immune cells, most notably what are known as CD4 T cells. The “retrovirus” part just means that
the virus uses RNA — DNA’s more wily, less stable cousin — as its genetic material,
and that once HIV infects a cell, it makes a DNA version of its genome with a special
enzyme, then inserts that DNA into the host genome. If that sounds sneaky — well, it is. And it’s part of why HIV has been so difficult
to treat, which we’ll talk about more next time. Now, those CD4 T cells that HIV infects and
ultimately kills are a kind of white blood cell known as ‘helper’ T cells. When they recognize a threat, they pump out
proteins that help coordinate a bunch of different immune responses. You definitely want them around. HIV is spread by bodily fluids, including
blood, semen, vaginal fluid, and breast milk. That’s why HIV can be transmitted through
sex, dirty needles, breastfeeding, and any other swapping of fluids you might do — with
a major exception: saliva isn’t one of those fluids. Saliva is full of other stuff that prevents
HIV from being infectious, like antibodies and a bunch of antimicrobial proteins. So unless there’s a lot of blood in your
saliva for some reason, it can’t transmit HIV. When someone is first infected, they might
feel like they have a bout of the flu, with a fever, headache, rash, sore throat, and
muscle and joint pain. That’s because the virus is infecting lots
of cells and the immune system is trying to fight it off. But within a few weeks those symptoms pass
because by then the person has specific antibodies that can keep the virus from running totally
rampant. After that, they usually feel fine for a long
time — in many cases, a really long time, like several decades. Until, one day, they don’t, because the
virus has finally killed off too many T cells, leaving the body unable to properly defend
itself against pathogens — anything that might be dangerous or infectious. That’s when someone is said to have AIDS,
or acquired immune deficiency syndrome. Usually AIDS is diagnosed once the person’s
T cell count falls below 200 cells per microliter of blood, which is well below the normal 500-1500,
or if they develop what’s called an opportunistic infection. These are infections that anyone with a reasonably
strong immune system would be able to fight off, easy-peasy. But because HIV has obliterated most of their
T cells, AIDS patients get sick. And, they can die. Most of the time it’s an opportunistic infection
that killed them. So, some of that was probably familiar to
you, but pretend for a moment that you’ve never heard of HIV or anything else I just
mentioned. Because back in the ‘80s, we didn’t know
these basic facts. All doctors knew was that suddenly, healthy
young gay men were developing extremely rare infections and cancers — and, it was killing
them. One of the first people to notice the pattern
was an immunologist at UCLA. Between the fall of 1980 and the following
spring, he saw a string of five patients, all gay men in their 20s or 30s, with an unusual
kind of pneumonia. There was a fungus growing inside their lungs. Normally, the fungus was totally harmless
and would never infect the lungs, but in these men it had, and it was making it hard for
them to breathe. The patients also had oral thrush — basically
yeast infections in their mouths — and few CD4 T cells. By June, when the immunologist wrote up the
results for the CDC’s weekly Mortality and Morbidity report, two patients had died. A month later, a dermatologist in New York
chimed in with a similarly disturbing report, this time with Kaposi’s sarcoma, a rare
cancer where patients develop blotchy purple lesions on their skin. In two and a half years, 26 young gay men
in New York and LA had been diagnosed with Kaposi’s. Some also had the weird fungal pneumonia,
and 8 had died. It’s hard to imagine now, but at this point,
scientists had no idea what was making people sick. They didn’t know if it was some sort of
toxin or a pathogen. And if it was an infection of some kind, they
didn’t know how it was spreading. That meant they couldn’t warn people about
how to protect themselves. The association with gay men, though, was
certainly striking, and early on, many called the mystery disease GRID, for gay-related
immune deficiency. Lots of people would talk about it as the
“gay cancer” or “gay plague.” But the disease wasn’t limited to gay men. It was turning up in hemophiliacs — people
whose blood doesn’t clot properly and are treated with clotting factors taken from other
people’s blood. Doctors were also seeing cases in IV drug
users, women, infants, and heterosexual men. In particular, 20 recent immigrants from Haiti
had gotten sick, and none said they were gay. Those clues were important, because they told
scientists the disease — which had finally been given the name AIDS — was probably
infectious, and probably transmitted by blood. There were other diseases that spread in similar
ways, like hepatitis B. So in March of 1983, the CDC issued a warning
that doctors needed to be careful about blood transfusions, and that the disease seemed
to spread through both gay and straight sex. Debates about the specifics, including whether
it could spread through saliva, would happen later. But what was the infectious agent? The race was on for scientists to figure out
what was causing the disease. French molecular biologist Luc Montagnier
suspected a virus because at the time, the blood products hemophiliacs used were filtered
for things like bacteria and fungi. But viruses were too small to catch. So along with his colleague Françoise Barré-Sinoussi,
he searched cells taken from AIDS patients and found a retrovirus. Around the same time, Robert Gallo at the
NIH in the US also identified a retrovirus in samples from AIDS patients. Both groups published their work in May 1983,
and shortly afterward another team found yet another retrovirus. All the viruses had been given different names,
and at first, it’s wasn’t totally obvious that they were the same thing. But they were, and in 1986, the cause of AIDS
had been given an official name: HIV. So, HIV was the problem, but where had it
come from, and why had the epidemic struck now, in the decade of big hair and Michael
Jackson? While some researchers were scrambling to
identify whatever it was that made AIDS infectious, others noticed that macaque monkeys also seemed
to suffer from an AIDS-like disease. One group decided to take some blood samples
from these sick monkeys, and in 1985 they found a virus that was similar to HIV. It was eventually called SIV, for simian immunodeficiency
virus. Researchers started to think that HIV might
have come from our primate relatives, jumping the species barrier. After a lot of work, they figured out that
the virus behind the epidemic was very similar to the chimpanzee version of SIV, and they
were the ones who had passed it to us. But how exactly? There’s no real way to put this delicately,
but most scientists agree that the reason why SIV made the leap into humans — what’s
called a spillover — is because we had a taste for bushmeat, or wild game. In this case, monkeys and chimps. This is known as the cut-hunter hypothesis. In the course of butchering a chimpanzee,
some SIV-infected chimp blood enters a small cut on the hunter’s hand. Or, a bit of blood splatters in their mouth. The virus is close enough to human biology
to infect the hunter, and over time, if the hunter passes the virus along to enough people,
it evolves into the HIV we know today. Spillovers like these happened many times
— we can tell because the virus mutates quickly, and by looking at genetic differences,
we can identify multiple lineages of the virus, each one corresponding to a spillover. We’ve traced the current epidemic to just
one of these, called ‘M’ for main. By analyzing chimpanzee pee and poop, researchers
think the chimps who passed that version of the virus to us lived in southwestern Cameroon,
in the forests near the Congo. And based on the oldest blood samples we can
find that we now know have HIV in them, which are from 1959 and 1960, scientists estimate
that HIV-1 first infected humans around 1908. If that seems like a long time ago, well,
it takes a while for a virus to take off. By the 1920s, it’s thought that the virus
traveled downriver — in a person, of course — to the burgeoning city of Kinshasa, then
known as the Belgian colonial city of Leopoldville. There weren’t many women around other than
prostitutes, so experts think HIV spread that way, and possibly through injectable drugs
the colonists used to treat some tropical and venereal diseases. This was before disposable syringes, and nurses
were trying to treat lots of people with just a few of them, so the syringes may have only
been rinsed with alcohol before being used on the next patient. So the very methods meant to stop the spread
of disease may have actually been
encouraging it. With time, infected people in Kinshasa left
to go to other places, and they did the unavoidable: they brought the virus with them. Because the virus mutates so quickly, we can
group the viruses into 9 different subtypes and get a sense of how HIV traveled around
the world from Central Africa. Several subtypes spread to other parts of
Africa. Subtype C went south and then landed in India. Subtype B went to Haiti — and then, through
several quirks of history, came to the US. First, in 1960, when the Belgians left the
Congo, French-speaking Haitians started to arrive in the Congo to work as doctors, lawyers,
and other professionals. But with the creation of Zaire in 1965, the
immigrants felt unwelcome, so they went back to Haiti, bringing HIV with them. There, HIV expanded especially quickly, possibly
because of a plasmapheresis center where people could get paid to donate their blood plasma. The center used a machine that mixed the blood
of different donors, allowing viruses to transfer. By 1982, nearly 8 percent of a group of young
mothers in a Port-au-Prince slum were HIV-positive — an astoundingly high number. HIV is thought to have entered the US around
1969, with just one infected person or unit of plasma from Haiti. It took about a decade for anyone to notice,
but by then it was too late. The epidemic had begun, and HIV was not only
in the Americas, but Europe and Asia, too. And now that it was here, we needed to figure
out how to fight it. But we’ll get to that in the next episode
of this mini-series. In the meantime, thanks for watching this
episode of SciShow, and if you want to learn more about HIV and all kinds of other science,
you can go to youtube.com/scishow and subscribe.

100 thoughts on “How a Sick Chimp Led to a Global Pandemic: The Rise of HIV”

  1. So you are saying that after THOUSANDS of years of hunting chimps, we managed to get infected only in 1908??

  2. I was diagnosed HIV positive in 2008 and take no antiretroviral drugs. I've been HIV undetectable since 2011.

  3. why does this dude have emo ear piercings if he's hosting a science show? its very undisciplined, also its hard to believe or trust him because of his dressing. not to say he should be a nerd but atleast somewhat formal and presentable.

  4. Here in South africa some white people deliberately injected a lot of people with HIV posing as medical doctors.

  5. I remember hearing a story about a pilot who had sex with a chimp in the 1970s and it spread from him to other partners. Anyone ever heard this?

  6. HIV and aids came around when polio was cured the cure for polio was the cause of aids look it up government accidents again

  7. And with the huge rise of human body part trade and people eating each other out of superstitions beliefs in places like Congo, Malawi,and surprisingly now South Africa we will surely something even worse than aids come out of Wakanda. Here is a link
    https://youtu.be/_njz8-FHhAo

  8. Please do better research ,there were scientists across the western world who needed monkeys for experiments as well as blood for research and they were responsible for the spillover as well as a failure to take action on prevention and spread ,they actually destroyed the labs and buried all reports and even traces of the labs .IDK the if actual investigative documentary is still available but if anyone comes across it please add a link .

  9. What concerns me these days is a lot of people are careless again b case it’s no longer viewed as fatal. HIV rates are rising again. The retro virus is notorious for continuous mutations so the treatments make be become ineffective. The prep drug prevention also has a lot of long term consequences on the liver and kidney that can lead to health consequences with prolonged use.

  10. I just read someone claiming it started in europe because some of us cant contract HIV or AIDs. No not how it works. We lack the protein on the blood cell or the antigen for the disease to enter or attach. Im 0 negitive. Meaning there is no protein on the surface. There are many diseases that enter your blood this way. So immunity to this does not mean it started in Europe. I do appriciate being called albino and a supremacists thank you. Thats very telling about how you feel about your skin. If my skin color was a defect it would be less attractive to others. A defect is less attractive because you dont want your children to be unhealthy. This is why we think certain people are more attractive than others. You are a hateful stupid person. The type that would lie about king tut and all the white red haired mummies around the world. Not admitting we have a history. My people give you credit fir things you never did and yours steal my history. Who has the problem here? Does it sound like the problem is me? Of course you will want to and have exterminated my people. Its the same reason certain people pick on little blonde hairs girls. The reason is obvious to everyone. Just know everyone sees why. Sickening. Hope you figure out how to breed it out when we are all attached to big nordic men.

  11. I saw a documentary explaining that HIV was accidently created in a lab. A group of researchers in Congo were developing a cure for polio using various animal tissue, including monkey kindneys. They didn't know what SIV was, so they didn't think to do further testing. All they knew is that vaccine worked for polio, without knowing it would give people HIV.

    They didn't release it to the public that they did a mistake because they didn't want to have their lab shut down. Imagine the lawsuits and outrage if the public found out about this.

  12. Also, back in the 70’s the hepatitis vaccine was made with plasma, so people getting the vaccine were sometimes infected with HIV.

  13. Also, people in the inner city, often people that were homeless, or people trying to pay for their drug habit, were being paid for their blood donations, which contributed to the spread of this disease.

  14. No, HIV is from anal sex, not from monkeys. Doctors and researchers are too scared to disclose this information.

  15. 1908, for the first time it made the jump from some poor chimp that got chomped…. well, there go 99.9% of all the conspiracy theories associated with where HIV came from!!!

  16. Is All of This is Fact, Then What is GRID, And who had it, How did they get it, Where is it Today????

  17. We should be thankful that this is a disease that's 100% preventable. Education makes this the end of this disease's transmission. Hopefully

  18. If anyone has seen Forrest Gump I believe JENNY was infected with HIV. They never went into detail but she did shoot up dope a lot and was a hoe lol

  19. This is inaccurate. Tainted Chimpanzee tissue was used by Dr.Hilary Krowpowski in order to create a Polio vaccine.

    An investigation was done in regards to that. And one of te biologist investigating was murdered in the Congo where it all began.

    They tested the tainted polio vaccine on innocent Africans “Congo”. This information is out there for all to search.

  20. Quite informative. Can you also do a video on human genes resistant to HIV.. You can start your research with me.

  21. This guy doesn't blink ehh? Is he extraterrestrial of some kind or what? Nicely done vids, welldone dude!!!

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  23. 6:36 "why now in the decade of [..] Micheal Jackson". Well, in hindsight he shouldn't have named that specific persons, seeing MJ is now accused of being a sex addict.

  24. Don't be deceived, HIV was invented in a lab in USA. It has a patented cure as well. Look for tetrasilver tetroxide

  25. This may be the most informative video I’ve ever watched on YouTube. I just got finish watching Pose & wanted to know how this outbreak started.

  26. Some of this spread has got to be humans humping any and everything around without a condom because it don't feel as as good and still today.

  27. This was already confirmed in the documentary The origin of Aids. When scientists were experimenting vaccines for polio and sent one vaccine to Russia voluntarily and one to Congo Africa forced.

  28. Why do we get told of a death sentence disease, warn you, lecture you, but when discover cures, drugs medicine that works slow down or cure, it's not really mention, highlight, …..negative news and catastrophe, but don't say the positive, the cures, help that's working….?

  29. it dont take years to detect, you will know within weeks unless your ignorant. DR. Robert Gallo has a patent on AID, it is man made. Gallo is known as the father of aids. Dr Gary Davis ( black dr ) found the cure and of course the US government knocked him off ( killed him ).
    https://www.youtube.com/watch?v=t7gqVZIoz0w

  30. I watched a video saying its a hoax..But a old friend of mine supposedly has it..And he tells people he has it…

  31. The Polio vaccine trials causing cross-contamination still controversial, seems undue influence from pharmaceuticals et al trying to revise history …
    https://www.ncbi.nlm.nih.gov/m/pubmed/7935079/

  32. Given how segregated American communities are I still find it hard to believe that HIV entered and the then spread through out the US via a Haitian. What I can believe is the sex tourism of foreigners, namely Americans and Europeans going to Haiti for their so to speak enjoyments. How we don't it wasn't spread by such means or even introduced to Haiti or the rest of the West Indies similarly?

  33. Is it weird that I thought for a long time that HIV was first transmitted by a person having unprotected sex with a chimpanzee

  34. This was either an experiment gone wrong or sent out into the world by our own government, the monkey just didn't get HIV and just passed it on to humans,if you people believe that you need to wake up. Some people would even believe it's a form of population control, we will never know will we.

  35. 1908? But those chimpanzees existed way before then. Why would it all of a sudden become a problem?

  36. Also, I read that HIV was actually created in the lab by growing something on chimpanzees liver to cure polio. The scientists screwed everyone over.

  37. You left out the alleged unintentional contamination of the vaccines that were contaminated because the scientists didn't follow lab protocol and used a chimpanzee that hadn't cleared quarantine.

  38. This reminds me of an Ebola virus documentary. One woman cut herself while in the process of cooking a chimp's arm. She wore no gloves, the environment was unsanitary, all while, was ignorant and cared less about contracting anything. "Ebola doesn't exist here"

  39. Let me sum this up in a few words there was and had never been a case of HIV in Africa pre second world war…this was a time when biological warfare was in its prime and was tested and developed further on "rural Africans" by the West…This was developed as a population control mechanism…unfortunately for the powers that be its effects are too slow in affecting population growth and hence theyve developed Ebola as an alternative to speed up the death rates….FACT!!

  40. House In Virginia aka H.I.V. All in death ish aka AIDS.

    Stop being nasty, and digging your graves with your mouth and private parts.

  41. Jep, that chimp lived in a US laboratory, next to the one who had ebola… send it to his brothers in Africa with the vaccine for smallpox….

  42. Scientist created HIV. Man made, United nation government did this to the people. the government force immunization on the people. they were test rats .

  43. I had this video on in the background, sat down and expected to see John Green, you sound so alike to each other.

  44. Nobody wants to admit or tell the truth. AIDs became an epidemic due to sexual immorality. That’s it!! Don’t even try to argue with me.

  45. Hmmm ever think the polio vaccination that was made from monkeys and given to about 5 million Africans has something to do with it?

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