Original subtitles

From the plagues of egypt

to the black death,

smallpox,

cholera,

and the spanish flu,

humans have repeatedly faced contagious diseases

that have the power to change the course of history.

We like to think that modern medicine

can protect us against almost everything, but...

Is that really true?

Or are we destined to face a future

of ever more potent illnesses

that attack without warning

and can bring civilization to its knees?

Well...

...That is what we'll try and find out.

News reports surface that a new,

highly contagious disease first discovered in wuhan, china,

is spreading like wildfire.

In a matter of weeks, the lethal virus...

Known as "coronavirus" or "covid-19"...

Sweeps the globe.

On March 11,

as the number of infections and deaths

continue to climb,

the world health organization declares

that the outbreak has become a worldwide pandemic.

What separates, clinically,

coronavirus from other common viruses such as influenza

is that it knows how to hide itself.

It has what we call a period where you could be asymptomatic.

That means without symptoms.

That's a chance to pass that virus to other people,

keeping the disease going on and spreading.

Most of the time, when you wait for these symptoms,

you've already missed it.

In the wake of the harrowing effects

of the coronavirus outbreak,

scientists have been compelled to reexamine

the nature of viruses themselves.

Viruses are very mysterious,

because you can't see them.

You need a very powerful microscope

to be able to see them.

And we didn't even know that they were around

until relatively recently.

A virus is essentially a bit of nucleic acid,

either dna or rna,

encapsulated in some sort of coating. Right?

So it needs to... it needs to get into another organism

and then essentially hijack that organism's cellular machinery

to make more copies of itself.

It needs to

actually take over another living cell.

And whether that's the living cell of a human,

animal,

plant or even a bacteria,

it needs that.

It's making more and more viruses

till that cell is not needed anymore.

A virus relies on either

direct transmission through sneezing or coughing

or touching, um, a viral particle

from a person who's expelled it.

Or they rely on a mosquito or some other organism

to be transmitted between people.

And so the density of people

will facilitate quicker spread of viruses,

especially if it's, um, relatively contagious

and-and easy to-to transfer from one person to another.

According to experts,

the origins of many viruses

remain shrouded in mystery.

It's so difficult

to determine the origin of viruses because,

when you want to study that virus,

you have to separate what is the natural history of that cell.

So one of the important things

that epidemiologists are looking at right now is,

what did we learn from the past?

What should we be looking at?

Where should we be looking?

Some of the earliest records of plagues

are found in ancient india,

china, the middle east,

and they talk about plagues occurring

before the very first civilization,

around 3200 bc.

Throughout human history,

there have been accounts of devastating afflictions

that defied understanding at the time they happened.

But perhaps a closer examination of these plagues

will provide some lessons about infectious diseases

and how they begin.

Emperor justinian sits atop a powerful throne.

But lurking in the shadows is a hidden enemy

about to consume his kingdom.

A plague

started by a bacteria

comes out of the east

and infects.

This simple bacteria

ended up killing

almost one half the population of the entire old empire.

With that type of death toll,

the economic and social ramifications

were catastrophic.

Everything that justinian had tried

was now collapsing.

His military collapsed, his economy collapsed.

And everything that he tried to do

was of no avail.

Justinian plague is caused by a bacterium,

yersinia pestis.

It can either enter humans directly, um, through...

From saliva or-or coughing.

It usually manifests itself

in terms of swelling of the lymph nodes.

The skin turns black and basically dies.

And then there's a progression of fever

and chills and eventual death.

As justinian's empire was collapsing and breaking

and his military strength was waning...

Because the science of medicine in those days

was far more primitive than we have today.

People cry out, "why?

Why is this happening?"

The plague of justinian, as it became known,

ultimately killed an estimated 50 million people.

The vast byzantine empire was crippled

not by an invading army

but by an enemy they could not see and did not understand.

At the time,

since the existence of bacteria and viruses

had not yet been discovered,

many believed that the invisible force that caused the plague

was god himself.

It was a belief that was widely accepted,

because people would read in the bible

about how pestilence from the past

had been created by the hand of god.

Whenever humanity is infected

by something greater and beyond human understanding,

it has always been psychologically understood

to be an expression of the wrath of god.

We have in the book of exodus

the famous ten plagues of egypt.

Moses had come back after seeing god on the mountain

to free the hebrews from slavery.

He went before the pharaoh and asked to let his people go.

Of course, the pharaoh said no.

Therefore, the hebrew god sent a number of plagues through egypt.

The bible stories are clear.

The order of the plagues are well-documented in the bible.

We know, of course,

that there was the turning of the nile into blood.

There were the frogs, the lice,

the pestilence and, of course,

the great plagues of the three days of darkness

and, of course, the death of the firstborn.

The biblical writer who is writing what happens

and is inspired by god

does say that the plague stopped

after the hebrews were finally free.

So, perhaps there was some divine intervention from god.

But we'll never know,

because miracles are very difficult to prove.

Was there a higher power involved

that both started and ended the plagues of egypt

and the plague of justinian?

Perhaps more clues as to what causes devastating plagues

can be found by examining the disease responsible

for claiming more lives than any other.

Officials from the california odepartment of public health

alert residents that a woman has tested positive

for a dangerous and quite unexpected disease.

The bubonic plague,

otherwise known as the black death.

Does the bubonic plague still exist?

The answer is... Yes.

And it's amazing

how, many centuries later,

you could say this with a calm voice.

What is the difference?

The answer is antibiotics.

We know that if you have symptoms early

that antibiotics can save your life.

While it's not as prevalent anymore,

the plague is certainly still in circulation.

In the united states, right, in more rural areas,

where people come into contact with-with rodents

that might be infected with it,

it's still known to, like, crop up here and there.

The worst case of the bubonic plague that there was

was known as the black death,

in the middle of the 1300s.

And that wiped out

60% of all of europe's population.

12 trade ships arrive

from the black sea

and drift into the port of messina to unload freight.

As dockworkers

approach the vessels,

they discover a disturbing scene.

The port master goes on board

to see the crew, and, to their surprise,

it was almost like there were zombies on the ship.

Gangrene fingers.

Big boils.

And if I saw

a crew that had black fingers

and boils, let's be honest:

It sounds like a zombie apocalypse.

The black death seemed to have been introduced

via the silk road,

which is a major trading route

in the early medieval period from central asia

where the bubonic plague regularly pops up.

Europe seems to have been largely unprepared

for this devastating event.

This is in the 1300s.

It went for quite a few years,

and whole villages and areas were wiped out.

And like many plagues, uh, people wondered why.

These cities would get the plague,

and no one knew why.

And then we always have the advantage

of looking back on history and tracing.

Historians could look back and say, "wait a minute.

"all the cities with ports

"that do a lot of trading were infected.

And what were going to all these ports? Ships."

The black death

was spread by fleas that lived on rats.

And wherever these rats went, the fleas went,

and they bit people. That's what made them ill.

The flea would actually vomit the bacteria

onto the person's skin while biting them.

The disease spreads to the body's lymph nodes

and causes buboes,

which are infected sores

which get to be about the size of an egg.

And they eventually burst and expel bloody pus.

The body goes through

such horrific and gruesome transformations

that from the time you contract the bubonic plague until death

can sometimes only be a matter of days.

During the middle ages, many believed

that demons were responsible for the black death.

- - and people who were deemed

to be wicked or unworthy

were punished

in hopes of driving the demons away.

Many people believed

that the source of this plague

was caused by evil spirits,

witchcraft and the like.

The powers of the occult.

And this led many people

to seek out any type of expressions

of the occult, witchcraft and the like...

...And to root it out

in the attempt to placate god.

Some were so convinced that the black death

was a scourge brought by evil spirits,

they were willing to scourge themselves.

One common occurrence during the time of the black death

was to see, uh, people that were called flagellants, which...

They were under the belief that they were being punished

by god for their sins, so they would publicly atone,

and they would March through the town square,

flogging themselves in the name of god.

This flagellation movement really exploded.

Whole towns flagellating themselves.

Those that didn't were accused of being with the devil.

Something else that came from the black death was

the practice of selling holy relics.

When the black death was decimating europe,

the church were saying,

"come to us,

and we can cure you."

the bones of a saint

or something that had once belonged to a saint

kept in these churches. They were called relics.

And people believed that if they went there

or close to such relics,

prayed, that god may intervene

and protect them from the plague.

Now, they weren't curing anyone,

but people were still flocking to the churches

just on the hope that they could be cured.

So, when we talk about the many lives

that were lost during the black death,

I think about a horror movie.

Historians estimate that the black death

wiped out anywhere from 50 to 200 million people,

at least a third of europe's population.

So it's little wonder

that most people thought that something so destructive

must have been some kind of punishment from god.

But today, we have a much different understanding

of this disease.

We call it the black death,

but it's-it's a bacteria called yersinia pestis.

But it's not as dangerous as it was then.

Now we have antibiotics.

We can detect it.

You know, you can treat it.

In any case,

yersinia pestis is still around today,

which begs the question,

is it possible

to actually kill off a fatal disease

once and for all?

Perhaps the answer can be found

by examining a deadly plague

that, believe it or not,

has been infecting humankind

for more than 10,000 years.

The valley of mexico.

Spanish conquistadors led by hernán cortés

arrive at tenochtitlán, the capital of the aztec empire,

bearing dreams of conquest

and an insatiable desire for gold.

But they also brought with them a lethal, infectious disease.

Smallpox is introduced

into the americas very dramatically

at a specific point in time

and alongside the european invasion.

This is a tremendous sort of clash of civilizations,

the likes of which the world had never seen before

and will never see again.

The single most deciding factor

as to why native american civilizations fell so rapidly

was the introduction of smallpox.

So, smallpox is a virus.

It causes these sort of irregularly spaced,

pustule-y skin lesions

and had a devastating effect

on-on native americans, um, in the new world.

In europe, most people had experienced smallpox.

They had the scars,

or they had it as children.

But there was no immunity in the new world.

There was no immunity among kids.

There was no immunity among adults.

And so, when this new disease came,

everybody was vulnerable.

And so it spread like wildfire.

Although the exact numbers will never be known,

many experts estimate

that a staggering 95% of the indigenous population

would eventually die from smallpox.

But what's even more chilling

is the fact that smallpox ran rampant

for thousands of years.

I am astounded

by how far back smallpox goes.

For most of human recorded history,

we believe it's the same strain

that was infecting one person after another,

this human chain of infection.

The egyptian pharaoh ramses v had scarring on his face

that's consistent with smallpox.

It is estimated that smallpox has killed

between 300 and 500 million people

in its more than 10,000-year existence.

How did we finally beat it?

Well, it just so happens that the cure for smallpox

was discovered in a small english village in the 1790s.

In the late 1700s, doctors were noticing

that milkmaids did not seem to be affected by smallpox,

and their complexions remained unscarred.

And people were starting to make that connection

that there might be immunity from catching

a different kind of pox virus, cow pox.

So milkmaids were exposed to the cow pox virus,

probably got infected,

and were then immune to smallpox.

Edward jenner was an english physician,

and decided to test this observation,

and took a piece of an ulcer from a cow

that was infected by cow pox,

and gave it to an eight-year-old boy.

And then, a little bit later,

gave this little boy a dose of smallpox.

Fortunately, the eight-year-old boy did not develop smallpox

and was actually protected.

Because it wasn't, like, a direct viral intake,

you would get, like, a slightly lesser version of the disease.

But because you had been exposed to it,

you would, of course, then have immunity.

So it was probably the first instance

of a crude version of vaccination.

As it turns out, edward jenner's revolutionary experiment

is remembered today for its inspiration,

its sheer audacity

and because it provided a new defense

against infectious disease,

which we now refer to as "the vaccine."

the word "vaccine" comes from the virus name "vaccinia,"

which was the virus that was the cow pox-derived virus

that left people immune to smallpox.

Vaccines prevent disease,

and some vaccines can last for decades,

and some vaccines need to be given every year.

For smallpox, people had to get vaccinated every ten years.

Vaccines are humanity's single greatest weapon

against plagues.

Rooted in science and not superstition,

they provide a powerful way to fight outbreaks.

The last naturally occurring case of smallpox

was identified in 1979, and in 1980,

the world health organization declared

that smallpox was eradicated.

So no longer spreading from person to person.

Eradicating smallpox was the biggest public health victory

in the history of the human race.

The eradication of smallpox is the most famous use

of a highly-effective vaccine,

but there are some diseases that are harder to cure.

There are viruses

for which we have no vaccines at all,

because they mutate too rapidly.

And so, because viruses mutate,

there's a certain limitation to what you can do with vaccines.

The minute you get too confident,

and you think that we defeated mother nature,

somehow, it always finds a way to come back.

Vaccines are one of mankind's

greatest scientific triumphs.

But not all medical recoveries

can be easily explained by science.

Sometimes, the body's reaction

to an infection is so bizarre and so inexplicable

that it can only be described as...

Miraculous.

July 4, 1863.

Gettysburg, pennsylvania.

On the morning after the bloodiest battle

of the civil war,

thousands of dead soldiers lay strewn

across the blood-soaked farmland.

But while the brutality of the civil war is well-documented,

approximately two-thirds of the more

than 600,000 deaths in the war

weren't caused by injuries sustained on the battlefield,

but rather... By disease.

The civil war represents

the last major conflict that, um, that humans experienced

um, before the, sort of, the inception

or the origins of germ theory.

You can imagine the conditions

that soldiers live in, crowded together,

substandard sanitation.

In some cases,

open wounds that aren't being treated correctly.

It's really gross.

Everything smells terrible.

Uh, these doctors aren't washing their aprons.

They can't explain where they're getting these diseases from,

how they may be spreading it.

As uncontrollable infections ravaged

both union and confederate encampments,

soldiers and their doctors debated the cause

of their afflictions.

Many came to believe that the air itself was poisoned.

When we talk about

some of the deadliest viruses that we know,

some of them get transmitted by respiratory droplets, the air.

When you cough, when you sneeze, just by talking.

So maybe they weren't too off by saying the air is bad.

In the mid-nineteenth century,

little was known about disease control

or preventing the spread of germs.

But as the scope of the war widened

and the ferocity of infectious outbreaks resulted

in even more horrific causalities,

doctors were forced to expand their knowledge of diseases

and how to contain them.

They realize that

maybe a barn isn't the best place to be doing

amputations and open surgeries.

So, as the war goes on,

there's beginning to be an understanding

of what medicine should be.

Things like triage,

things like an ambulance system, hospitals...

These are all established during the civil war

in the united states for the first time.

In many ways, the civil war marked the beginning

of medical science as we know it

and the end of mankind's

superstitious attitude towards disease.

But there is one event on the battlefield

that medical historians still struggle to explain to this day,

because it simply defies understanding.

April 7, 1862, hardin county, tennessee.

Union and confederate forces square off

in one of the bloodiest confrontations

of the civil war... The battle of shiloh.

After two days of vicious fighting...

...More than 20,000 men lie dead or dying.

So, ulysses s. Grant is the commander

of the union army at this battle.

He went out, and looked over the battlefield,

and he could see that there were so many soldiers who had been

wounded and killed that he could have walked across one side

of the battlefield to the other

without ever touching the ground,

walking from body to body to body.

As night falls over the battlefield,

many injured soldiers lie helpless,

hoping to be rescued before their wounds become infected.

What happens next is one of the enduring mysteries

of the civil war.

Soldiers are out between the lines,

wounded during the course of the battle.

It's cold at night. They're out there shivering.

And they happen to look down at their shattered arm or leg,

and they notice this soft, faint, bluish-greenish glow

seeming to come off their wounds in the darkness.

There was a connection that was being made amongst the soldiers

that those who experienced this glowing wound effect

seemed to have better outcomes

when they went back to the field hospital, and it seemed

as though their wounds may not have been as infected.

They termed this bluish-green glow

angel's glow. Why?

Because, to them, it looked like a halo.

Mystical light surrounding them.

So, it was a way of them thinking that god

or the angels were protecting these particular soldiers.

Was the so-called angel's glow

a type of divine intervention

that somehow protected certain soldiers from deadly infections?

Perhaps. But recently, a new theory has surfaced...

One that suggests this phenomenon

may have had a more conventional explanation.

It wasn't until many years, like 150 years later,

that a 17-year-old high school student visited shiloh,

and he decided for his science project

to research bacterium that glows.

And they were able to find out that there was a bacteria

that would emit some sort of parasitic worm.

It would get into the veins, and then it would glow.

Could the angel's glow

really have been a sign of a type of bacteria,

rather than guardian angels?

And if so, could this bacteria have actually been responsible

for saving the lives of the wounded soldiers?

Presumably, what happened with those soldiers

with the angel's glow

is that those bacteria were actually infecting their wounds.

And because those bacteria exude a lot of antibacterial

and antimicrobial compounds, they actually reduce the level

of infection in the soldiers

that they, that they, uh, colonized.

The bacteria theory

is the best scientific explanation we have

for what caused the angel's glow.

If this incredible theory is true,

then it seems that some forms of bacteria

can actually help us in the fight against disease.

But the soldiers whose lives were saved

at the battle of shiloh believed that what healed them

could only have been sent from heaven.

We can't know what those soldiers experienced

out there on the battlefield between the lines.

They're in the dark, they're suffering from shock.

Who's to say that they didn't experience that

or that they did experience that?

Guardian angels, reaching down to comfort

and even cure dying soldiers during the american civil war?

To some it sounds like pure fantasy.

But to others, especially those

who've had their own close calls with death,

there's no doubt that such a notion is entirely plausible.

When dealing with deadly diseases,

it's hard to be certain of pretty much anything.

Not only do we often know very little

about how to cure an illness,

we know even less about where an illness comes from.

For instance, what if I told you

that what we commonly refer to as the spanish flu

didn't come from Spain at all, but from a remote army base...

...In kansas?

At the height of world war I,

more than 50 years after the end of the american civil war,

soldiers from more than 30 nations are engaged

in trench warfare all over europe...

...And a new, unexpected enemy emerges...

...The spanish flu.

Europe is awash

in the influenza virus.

They had a massive outbreak of influenza,

and these soldiers serving at the front lines

are directly impacted on both sides of the conflict.

- -the symptoms were pretty horrific,

and so these soldiers were not capable of performing

their duties, and many of them actually die of the disease.

We're used to the flu, but the 1918 flu

had more severe symptoms and lingering effects.

When the flu first started spreading,

their skin turned blue.

They just had no oxygen in their blood.

It was not uncommon for people to lose all their hair.

It was not uncommon to have neurological side effects.

The 1918 influenza strain

caused an incredibly high fever, it caused coughing.

In many cases, patients' lungs would fill with fluid

as this virus is taking over their body.

That would cause an immune system overreaction

and they would essentially drown.

Medics on the front lines,

prepared for the ravages of war,

look on in horror as young, healthy soldiers

begin to die within days,

or even hours of showing symptoms.

The spanish flu was caused by, um, an h1n1 influenza virus.

And the particular strain of the h1n1 virus

was a little unusual amongst influenza viruses

in that it was much more contagious, it was much easier

to expel and spread between people.

In 1918, we still really were

sort of incapable of stopping its spread.

This was right at the end of world war I,

and so soldiers were, of course, kept in close quarters

and barracks together.

And then, also, people were sort of moving around the world

more than they probably normally would have been

sort of traveling.

Um, and so those were some of the factors

that caused it to spread really rapidly.

Since finding a cure for a mysterious virus

in the midst of a world war is a difficult,

if not impossible undertaking,

both the central powers and the allied powers

decided the best course of action

was to downplay the threat posed by the disease.

In fact, the 1918 flu is called the spanish flu

not because it came from Spain, but because,

initially, Spain was the only country willing

to acknowledge its existence.

The reason we think of it as the spanish flu

is because Spain had a free press at that time,

and the rest of the world did not.

Spain was not involved in world war I,

and their king ended up getting the 1918 flu.

So it was a matter of national interest,

and most americans learned of the flu

from the spanish papers.

The so-called spanish flu is estimated to have infected

one third of the world's population at the time,

roughly 500 million people.

But while the press created a lasting nickname

for the 1918 flu,

some researchers have suggested that it actually originated

in the heartland of the united states.

March 4, 1918.

Fort riley, kansas.

Before the so-called spanish flu outbreak was reported in europe,

a private at this remote army base in the united states

starts to feel ill.

In March of 1918, an army private named albert gitchell...

He's a cook with the army...

He reports symptoms, so he goes to the hospital.

Uh, he's sick, he's-he's not feeling well.

He's got a bit of a cough, bit of a fever.

In the end, he ultimately goes in to work,

feeding all of these soldiers in this army camp.

In the weeks that follow, the members of this camp

come down with a pretty nasty flu strain.

And there are no other outbreaks similar to this at this point,

which suggests that this outbreak is starting

at that camp, and potentially with that soldier.

There were 1,127 cases just at fort riley itself,

and 46 people died.

So all these soldiers at fort riley are thinking

they just had a bad cold, or maybe even a mild flu.

They were eventually all put on trains,

which spread all over the country

going to various ports.

And then they were all shipped off to europe

to fight in the war.

Many scientist now believe that army private albert gitchell

was the first man to contract the 1918 flu.

Gitchell spread it to his fellow servicemen

when he served them food.

And soldiers then were sent overseas

to fight in the war, and they unwittingly

spread the disease around the globe.

But of course that explanation is only a theory.

The situation fits the epidemiology,

the number of people who got sick afterwards.

But whether we will ever know for sure

who patient zero was,

or whether it absolutely came from kansas,

it's hard to be absolutely sure.

It's really hard to learn where any virus starts,

where any pandemic starts, because you're not recording

everywhere all the time,

and having the scientific tools in place

to be able to detect it.

The great mystery of any of these pandemics

or public health crises is where did it start?

And, ultimately, why did it start?

And what were the circumstances that allowed that to happen?

It's the story of how we interact with one another,

and how we spread diseases amongst each other.

If you track that and you find that out,

we could prevent it happening again in the future.

The spanish flu outbreak lasted for three long years

and killed an estimated 50 million people

before society finally developed enough collective immunity

for the virus to die out.

History shows us that no matter how lethal a disease may be,

humankind has always found a way to endure it,

whether by employing medical breakthroughs

or sheer patience.

But what kind of illnesses will we have to face in the future?

Could they be different than

what we've experienced in the past?

And might they come to our planet from another world?

British astronomer sir fred hoyle

publishes a book titled astronomical origins of life:

Steps towards panspermia.

In it, hoyle investigates the controversial theory

of panspermia, which suggests that

life on earth did not originate here

but rather in space,

and that asteroids carried the microbial

building blocks of dna to our planet.

You cannot dismiss the possibility

that maybe life came from outer space.

That we were seeded. Seeded by asteroids or comets

that then put their organic materials

onto the planet earth.

And so there's a new theory in astronomy that says that

the solar system is like a ping-pong game

with meteorites carrying microbial lifeforms,

going back and forth between venus, mars,

the earth and the moon.

This has given momentum to the panspermia theory.

Some scientists have suggested that if the theory

of panspermia is true,

then it's possible that extraterrestrial viruses

could also travel here, bringing with them diseases

that would be much different

from the ones that exist on earth.

When you think about the core elements

of viral plagues... those are the four genetic codes,

dna or rna within a protein shell...

That's something that's easier to imagine being stable

deep inside an asteroid, and safe.

And so any sort of virus or plague,

you can imagine them starting from

one of these asteroid events.

A space plague is a leap into the unknown.

We have no way of knowing what kinds of dna,

or maybe a modified dna version exists in outer space.

We have never seen other kinds of viruses from outer space

that can infect earthlings.

So right now we simply don't know the answer.

I think if a plague came from outer space,

just like the way some of the plagues we know

jump from animals to humans, suddenly,

any sudden change in the viruses

or bacteria that are attacking you as a human,

your immune system will not have a defense to, most likely.

These dramatic events, whether it's from space

or a sudden jumping from animals to humans,

are the reason these plagues can be so devastating.

A plague from outer space?

While that may seem like a far-fetched notion,

it's a possibility that science must be prepared for.

There are always these viruses out there,

these things that we can't explain.

It's important for us to always be vigilant, to be aware

and to have our public health authorities

always on the lookout.

So we can never put our guard down.

Hopefully, the faster we are

and the better we are at bioengineering,

the faster we can make vaccines and countermeasures.

It's key to have them so that we can make ways

to protect ourselves.

Preparing for any disease is complex,

and it requires a lot of, um, mobilization of government,

public health, and the science to be able to figure out

what happened, and to prevent it from happening again.

To be able to halt transmission of this disease, whatever it is.

It becomes a detective story as well.

You need to figure out where it came from

and how to attribute the disease.

It's a mystery that our lives depend on,

and we need people to be working on that

and thinking about that.

Perhaps what makes deadly diseases so frightening

is that we never know when they're going to strike next.

And that uncertainty is also what forces us

to ask ourselves are we really safe?

Well, the truth is that only time will tell.

Which means that, at least for now,

these questions will remain unexplained.

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