Name: 病気のチンパンジーが世界的なパンデミックに至った経緯HIVの台頭 (How a Sick Chimp Led to a Global Pandemic: The Rise of HIV)
Uploaded: 2021-01-14T09:37:13.000Z
Duration: 10 min 20 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：新型コロナウイルス,新型肺炎,COVID-19

程度の副詞

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

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.

HIV, or human immunodeficiency virus, is a retrovirus that infects immune cells, most

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.

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

When they recognize a threat, they pump out proteins that help coordinate a bunch of different

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

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

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,

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

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

But because HIV has obliterated most of their T cells, AIDS patients get sick.

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

By June, when the immunologist wrote up the results for the CDC’s weekly Mortality and

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

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.

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.

So along with his colleague Françoise Barré-Sinoussi, he searched cells taken from AIDS patients