All language subtitles for Virus.Hunting.Cave.to.COVID.2021.1080p.WEB_Eng

more than 38 million cases

Of covid-19
have been confirmed worldwide.

Authorities are still
trying to zero in

On the starting point
for this virus.

covid-19 is just
a latest example of a deadly

Viral disease jumping
from animals to people.

today,
more and more wild viruses

Are spilling into humans.

If we don't find a way to stop them,

Our very survival could be at stake.

with covid,

We've seen how
devastating this virus is,

If we wanna prevent
a pandemic from happening,

We really need to figure out
how this virus came about

So we can prevent these
things in the future.

[narrator] covid-19's origin
is still a mystery.

But one animal has emerged
as the prime suspect.

It's almost certain
that it evolved in a bat.

[linfa wang]

[jonna mazet] a lot of
characteristics of bats

Make them kind of
the perfect spreader.

[narrator]
time is of the essence,

So teams are racing
to understand

How bats trigger
deadly pandemics.

A global health problem
calls for nothing short

Than a united global response.

[murray]
there's a realization that

Health needs to be interpreted
on a global level.

It's not
someone else's problem,

It's all of our problem,
and we all need to step up.

The urgency is here
is not just covid,

But it's the next one,
and the next one

Because we do know
that it's coming.

[dramatic music]

[car honking]

[narrator] as covid-19 rages
throughout the summer of 2020,

Scientists globally
are mobilizing

To find the source of the virus.

It's too late to
stop this outbreak,

But learning from it could
help prevent the next one.

Emerging infectious diseases
is a really critical field

Of study that has
come into its own

In particular this
last year with covid.

[mazet] covid is deadly
and devastating

And we need to use it
as a clarion call

To be ready

So that we don't let anything
worse happen the next time.

[narrator] the first big goal
is to establish

Where this virus came from.

When we're looking at
something like covid-19,

Or any other emerging virus,

One of the things
that we really wanna do

Is find out
who is the reservoir.

Which is the species
that holds this virus?

[narrator] a major clue
to the pandemic's source

Is found inside
the virus itself.

Sars-cov-2, the virus
that causes covid-19,

Closely resembles
several other viruses

Found in bats across asia.

These bats had one
thing in common,

They were all horseshoe bats.

One of those close matches
was collected ten years ago

Here in northern cambodia.

The same team is now returning

To look for more
related viruses.

[soft music]

[vibol hul]

[narrator]
working as a virologist

For the
institute pasteur cambodia,

Vibol hul has spent years

Searching for
undiscovered viruses.

His mission is to find them

Before they have a
chance to infect humans.

Scientific studies
have shown that so far,

We have uncovered approximately

One percent of all the viruses

That that have the
opportunity to kill mammals

And human beings.

That's leaving us obviously,

With 99% more viruses
out there.

I think it's a really important
thing for us to be doing,

Identifying as many of
the viruses out there

That we possibly can

So the next time
that there is an eruption

We can say, "right,
these people are dying

In this area.

Be careful 'cause there's
this species here,

There's this virus here.
This is how we isolate it."

[narrator]
the team has just a few days

To catch hundreds
of horseshoe bats,

In the hope they will
provide enough virus data.

[wang]

[mazet] it's important to work
together across disciplines

To solve these huge problems.

[narrator]
virologists like vibol,

Are now joining forces with
bat experts, like neil furey.

With over 20 years
experience studying bats

In south east asia,

He's here to help vibol catch as
many horseshoe bats as possible.

What we have here is
a limestone karst hill,

Which are effectively like
a block of swiss-cheese,

They are full of holes.

And so they have quite abundant
cave dwelling bat populations.

An important member of that
group is the horseshoe bats,

Which have been
linked to covid-19.

With covid,
there's a realization that,

Like the economy,
health needs to be interpreted

On a global level

And for us to be thinking
of global health as an issue.

Human health, animal health
and environmental health

Are all inextricably linked

And therefore dependent
on each other.

And if we wanna
keep one healthy,

We need to keep
the other healthy as well.

[narrator] as the sun goes down,
bats begin to appear.

Since any one of them could
be carrying deadly viruses,

The team takes precautions.

[hul]

[narrator]
despite all this effort,

The odds are against
the team.

Only 5% of horseshoe bats
carry coronaviruses.

So vibol must catch hundreds
to improve his sample size.

[hul]

[neil furey]

The net as a whole
is a lot more visible

Because of all
the rain we've had.

That's acting against us.

Shake off any excess water.

Sophia can you check
the net down there?

Please.

Ooh, got one?

No, there he is,
there's one.

[narrator] but it's not
the bat they're looking for.

[furey] it's the
intermediate leaf nosed bat

[narrator] vibol decides
to sample it anyway

Since it roosts in the
same caves as horseshoe bats,

And may contain similar viruses.

[furey] that's a horseshoe bat.

[hul]

[furey]

If you're quick...

It's better for the bat.

The structure of
the face of the nose leaf,

Is absolutely unmistakable
for this species.

Okay, guys, we're going
to close up now.

Can I get everybody
out of here please?

[narrator] the team
has caught and bagged

Over 160 bats for sampling,

90% are horseshoe bats.

But their night
is far from over.

Now they must work quickly
to collect oral,

Rectal and blood samples
from every bat,

Then release them
back into the wild.

[hul]

[narrator] it may take vibol
months of analysis,

But data like this
is revealing

Potential virus hotspots
around the world,

Helping us avoid
future outbreaks.

[hul]

[narrator] huge efforts are
going into uncovering the role

That bats play in pandemics.

A key piece of that puzzle

Is figuring out why bats
seem less affected

By deadly viruses than humans.

[narrator] welcome to
the inside of your airway,

From the point of view
of a coronavirus.

All viruses are
microscopic parasites,

Whose sole purpose
is to infect cells,

Replicate and spread
to new hosts.

Killing the hosts
is never part of the plan.

But sometimes,
an invading virus can set off

A dangerous chain reaction.

The host's infected cells
release chemical signals

To alert the immune system.

Immune cells arrive
on the scene.

They attempt to kill the virus

By sacrificing
the infected cells.

Which triggers other defenses

Like raising
the body's temperature.

But sometimes healthy cells
are also killed

By the immune system

Leading to a run-away cycle
of destruction.

For covid-19 patients,

The body tries to kill the virus
with high fevers.

While the lungs fill with
the debris of dead cells

Leading to potentially lethal
breathing problems.

[narrator] singapore.

Inside a secured facility,

Linfa wang is continuing

His long battle to protect
humanity from future pandemics.

[narrator] what do these
outbreaks have in common?

They're all linked to bats.

[narrator] in 2003,
the outbreak of sars,

Or severe acute
respiratory syndrome,

Began in a hotel elevator
in hong kong.

[narrator] much like covid-19,

Sars was caused by
a deadly novel coronavirus

That attacked the airways.

Linfa became part of the
world health organization team

Tasked with tracing its source.

After 18 months of field work,

They tracked the virus
to a bat cave

In yunnan, china.

[narrator]
this colony of cave nectar bats

Provides linfa's team

With controlled
healthy bat samples.

Which are destined for
an entirely

Different kind of facility.

Where linfa can
study what happens

When they are exposed
to notorious killers.

[narrator] bsl3 labs contain
the viruses behind rabies,

Sars, covid-19 and mers,

Or middle east
respiratory syndrome.

[wang]

[narrator] when linfa
infected bat and humans cells

With the mers virus,

He discovered
special genes in bats

That reduced inflammation.

It seems bats evolved ways
to calm their immune system,

Preventing dangerous
over-reactions to viruses.

[narrator] it's a
hotly debated topic,

But these changes
may have done more

Than just help bats
tolerate viruses.

They may also
have led to viruses

That are more deadly to humans.

It takes a huge amount
of energy for a mammal

To be able to fly.

So a bat's metabolism

Or the process of
turning food into fuel

Has to be up
to five times faster

Than other mammals their size.

From the moment that
the bat takes off,

The cells need to pump out
a lot more power.

But ramping up the metabolism
also generates more heat.

During flight,

A bat's body temperature
can sky rocket

To 129 degrees fahrenheit.

Most viruses breakdown
at high temperatures.

But some manage
to adapt and survive

The punishing conditions
inside a bat during flight.

If these heat-adapted
viruses find their way

Into human hosts,

It's possible they're already

A big step ahead
of our defenses.

The highest fever most
of us can generate

Without killing ourselves

Is only 107 degrees fahrenheit

Giving the viruses
a better chance of surviving

And making us sick.

Bats can fly,

And that's super unusual
for mammals.

They live in lots of ecosystems

And they can move
across vast distances.

But these abilities

Also make them able
to spread viruses.

[murray]
over the last five years

We have been identifying
and evaluating bats

In locations that
which we would consider

A high-risk interface.

The areas in which
people and animals

Are coming into contact
more and more.

In 2017, we had
several projects

Going on in myanmar
at the same time.

[narrator] the smithsonian's
global health program,

Led by suzan murray,

Sent a team to rural myanmar

To study the movement of
flying foxes, or fruit bats.

[jen kishbaugh]
fruit bats are amazing

In terms of seed dispersal.

They've been very,
well-documented about helping

With the biodiversity,
helping with agriculture.

[narrator] these bats
prefer to roost in trees,

Rather than caves.

Which means, they're often
found living closer

To human settlements.

We wanted to understand,
do they migrate or not?

Where do they go?

Do they cross boundaries?

Do they come in contact
with different human villages?

[narrator] the team uses
gps tracking collars,

Combined with
biological sampling,

To figure out where
the bats are going.

[kishbaugh] like most animals,

Bats don't recognize
international boundaries.

These guys will go
thousands of kilometers

Across their range.

And by knowing where
the bats are moving,

That will tie into where
the disease is moving.

[narrator]
the gps collared bats

Are released back into
the night,

With jen and her team
tracking their every move.

[kishbaugh] the good thing
that came out of this study

Is we were able to
identify additional sites.

So there's a lot of different
types of exposure pathways.

There's a second area that we
would like to work in as well,

That has a very large
bat colony

Roosting over a pig farm.

That pig farm is directly
in the backyard

Of people that are
living in this community.

[narrator] viruses inside bats
aren't necessarily a threat,

It's when they leave the bat
that they can become a problem.

Zoonotic spillover

Is a term that
we use to describe

What happens when a virus
within the animal population

Moves over to the
human population.

And the real problem here
is not just the jumping,

That happens all the time,

It's when it gets to
the human population,

And then it starts spreading
from human to human,

That's the real problem.

If there's an outbreak
in the future,

We'll be able to tie that to

These are the animals
that live in this area.

These are the villages that
they come into contact with.

That's the sort of thing
that we would expect

To learn in the future.

[narrator] and there's
another factor at play.

Scientists are discovering
that bats release

Even more viruses

When they are under stress.

[narrator]
the island of singapore,

Home to over
five and 1/2 million people

And tens of thousands of bats.

In such close quarters,
scientists are working

To monitor the risk
of viral spill over.

Ecosystems are really complex
and it's really a challenge

To understand how and why spill
over might happen from bats.

What we want is to better
understand the when,

The how and the why
so we can mitigate risk.

[narrator] for the past
ten years, ian mendenhall

Has been working with
long-time friend,

Collaborator and bat expert,
ben lee.

They've been trying
to uncover what causes

Singapore's bats to release
more viruses into the ecosystem.

[mendenhall] oh yeah,
there's a lot of calls.

-[lee] yeah.
-There must be a

Lot of bats inside.

-And, you smell them too, right?
-[lee] oh, absolutely.

[narrator] today,

They're sampling a newly
discovered roost

Beneath a busy highway overpass.

[lee] come over here.
Take a look.

[mendenhall] oh yeah that looks
like a healthy colony.

[lee] this is definitely
cave nectar bats.

When we look at virus shedding,

We're looking at
the number of viruses,

Either in a drop of urine
or in guano.

We wanna know when
those virus levels are high

And that may correlate to risk

For other animals
to encounter these viruses

In the environment.

[mendenhall] lets go unpack
our gear and put our ppe on.

[lee] sure.

[narrator]
inside this bat roost,

It rains with potentially
virus-laden guano.

So full ppe is ben and ian's
best protection.

[mendenhall] you can hear
their alarm calls.

[lee] yeah.

Oh, its already collecting.

[mendenhall]
once we're inside the roost,

It's really an
intense experience

Because the bats
are flying around

'cause they're a bit alarmed
and you can feel

The urine and feces
hitting your tivex suit.

[narrator] while their
board collects samples,

They use a thermal camera to
gauge the status of the colony.

[lee]

[narrator] normally, viruses are
safely contained within the bat,

But under certain circumstances,

They are released
into the world.

We know that bats
can shed viruses

At different amounts
and at different times.

Some things it can
be in relation to

Is the time of the year,

The availability
of food resources

Or cutting down a forest

And other stressors
such as giving birth.

Those are physiological
stressful events

That can lead to
increased viral shedding.

That's when we need to
take notice and step back

And not be around bats.

[lee] should we take this out?

[mendenhall] yeah,
I think its time.

Looks like a
jackson pollock painting.

[narrator] each drop of
excrement provides a window

Into the viral ecosystem
of these bats.

[mendenhall] during the course
of our research,

Almost nine years
here in singapore,

We found the bats have
a wide diversity of viruses.

So we've seen astrovirses,
herpesviruses and poxviruses.

We found adenoviruses

We have also found
a really diverse pool

Of bat coronaviruses.

[narrator] studies like this
take years of hard work,

But these discoveries
could help reduce the risk

Of future zoonotic outbreaks.

[mendenhall] really when
they're shedding highest,

That's when the risk
may be highest

For spill over to humans
and the other animals.

And it's really
important to understand

When we should be putting
most of our resources

Into surveillance to try
and minimize spill over.

Lets put these in a safe place.

[narrator]
we know viruses are shed

When bats are
stressed or disturbed.

And there's one force of nature
more stress-inducing

Than any other.

We are the ones,

That cause this unique
set of circumstances

That allows diseases
to spill over.

The bad news is
we're putting ourselves

Into high-risk situations.

[narrator]
these risks are increasing

As humanity pushes
further into the wild

And becomes ever more connected.

[murray] the research has shown
that spill over events

Are becoming more
and more frequent.

But there are
a huge number of factors

That need to fall
into place just so

In order for
a spill over to

Become an epidemic
or a pandemic.

[narrator] back in 2017,

The team from smithsonian's
global health program,

Carried out another
project in myanmar.

This time at a set of caves
where humans and wild bats

Were interfacing
on a daily basis.

The smithsonian had been
working and operating

In myanmar for
the last 20 years.

In linno caves,
one of the big issues

Is the increased interaction
with animals in the wild.

We have identified this location

Because there's a number
of cave systems here.

There's well over
500 thousand bats,

Roosting every day.

At each cave site,
there's usually

A family that lives there.

Part of their livelihood,
is based on guano collection

From the bats for fertilizers.

This is a concern for us,

Because there is
so much potential

For people that are
interacting with the bats

To be exposed to
communicable diseases.

[narrator] this isn't
just a risk for one individual,

Bringing a virus
out of this cave

Could pose a threat
to the community,

If not the world.

The team is here
to find out if any viruses

Are spilling over
from bats into the people

Or their livestock.

[valitutto] there's a large
chance that these species

Will be sharing viruses
with the people

That come and interact
with these various wildlife.

We are evaluating for
the first time in this country

The viruses that
originate in these species

And how they may transfer
to livestock and humans.

We can take the information
that we're discovered and say,

"hey maybe we shouldn't be
collecting guano anymore,

At least from this cave site.

Maybe we should have stronger
rules about poaching.

Maybe we should have
rangers in the parks

To help prevent it."

[narrator] the smithsonian
global health team

Made some
interesting discoveries

But the results
also posed a new mystery.

In the caves in myanmar,
we did find new coronaviruses.

But, it doesn't mean that
all of those or any of them,

Will cause a problem.

[narrator]
six previously unknown

Coronaviruses were discovered,

However there was no sign of
outbreaks in the local people.

Something else must
be needed for viruses

To jump from bats to humans.

[narrator] deadly outbreaks
are on the rise

And all evidence points to bats
as major virus carriers.

Now experts are
racing to uncover

Why only certain bat viruses

Can jump species.

[narrator] for a virus,

Shedding from a bat
and coming into contact

With a new host is easy.

After that, things get tricky.

They need to infect
the new host's cells,

Replicate and spread
to other hosts.

[narrator] coronaviruses need
keys to unlock a host's cells.

These keys are spike proteins.

And different species
require different keys.

The genes to build
these spike proteins

Are contained in
the virus's rna.

Without the correct genes,

This bat-borne virus poses
little threat to other species.

However, viruses
are highly adaptive.

The genetic material
inside the virus

Can re-assort
and change around,

And come back as
a new variety that can

Transmit between species.

[narrator]
this process of acquiring

The right genes isn't easy,

But coronaviruses have
found a cunning shortcut.

Inside the bat cell,
the coronavirus releases

Its genetic material
to start replicating itself.

At this point,
the virus lacks the right genes

To infect humans.

But that is about to change.

In a moment of random chance,
a different coronavirus

Containing the missing genes
enters the same cell.

As the two viruses replicate,
their genes can swap around.

By themselves these
viruses can't create

The right spike proteins
to enter our cells.

But by combining their genes,
they've formed a new virus

With the power to infect humans.

Once this altered
virus replicates itself

And sheds from the bat,

It could be the start
of the next pandemic.

We really worry about these
viruses that are able to adapt

And change a bit more rapidly
than some other viruses.

And if that happens,
and it's the right mutation,

Or in this case,
the wrong mutation,

It can then start spreading
throughout the population.

[narrator] coronaviruses play
this genetic lottery

In a variety of animal hosts.

But some scientists believe

That one special feature in bats

Gives coronaviruses
more chances to mutate

In order to hit the jackpot.

[wang]

For example,

A seven gram bat
can live 43 years

And I always say, one bat year
is 20 to 30 human years.

So 43 times 30, you will be
a thousand-year-old human.

Imagine that.

[narrator]
bats living for decades

May make them natural incubators
for zoonotic viruses.

But for these viruses
to reach humans

They often need some
kind of stepping stone.

An ongoing study in rural
cambodia is revealing

That as our global need
for domestic animals grows,

So does the risk of
zoonotic outbreaks.

[erik karlsson] every single
human seasonal influenza virus,

Avian influenza virus,

Even human
seasonal coronaviruses.

So the things that came
before sars and sars-cov-2,

Those went through
domestic animals,

Before they got to humans.

[narrator]
for the past nine years,

Erik karlsson
has been tracking

How domestic birds
spread viruses,

Like avian influenza.

[karlsson] we're particularly
interested in how

The domestic animals

Are actually moving
around the country.

Because that's a really
important part of how the virus

Might be moving around
the country as well.

When we have
a virus that jumps

Into the domestic
animal population

From a bat or bird,

That can then amplify
in those domestic animals

And then become
a risk for humans.

[narrator] here,
wild and domestic animals

Often come into contact.

If a wild virus jumps into
the livestock population,

Erik needs to know all the
ways that virus could spread.

To do that he needs help
from industry insiders.

[karlsson] middlemen are the
ones that actually transport

The poultry either
from small farms

Or from other countries
even into the markets.

[narrator] today,
piseth and his wife pheaktra

Are taking the team to assess
a previously unknown bird farm.

[speaking in foreign language]

[karlsson] who knows
how many animals are here,

How many animals are
coming through these areas

And how much virus could
actually be circulating within.

Spillover events
are always occurring

Between wildlife
and domestic animals,

Humans and domestic animals,
humans and wildlife.

But it doesn't
really mushroom into

An epidemic
or a pandemic until

It can be amplified and spread
within human species.

[clucking]

[narrator] middlemen bouncing
between bird farms

Are pathways that
viruses can use to mix,

Spread and amplify.

But the bigger concern
is where all these paths

Eventually lead.

The nearest bat might be
over a 100 miles away.

But thanks to our
livestock networks,

There are zoonotic viruses
ending up in places

Where they can amplify
and infect humans.

[murray] whether it's
a pig or a chicken,

People tend to bring live
animals into the market.

And then you can have
a mixing bowl right there.

[narrator] the high density
of potential hosts,

Stressful environment,

And less than
hygienic conditions

Make it a perfect place
for a super-spreader event.

[karlsson]
we do find a lot of viruses

In these ducks in takeo.

We do actually come
to this market

And take samples from the people

To see if they're exposed
to any avian influenza as well.

[narrator] domesticating and
selling animals

Is an ancient practice.

But now expanding
livestock populations

In an ever more connected world,

Could be giving rise
to more outbreaks.

Something erik is working
with local officials to prevent.

So we have a very
big baseline now,

We know things like avian
influenza are actually

More prevalent at times
like festival periods.

More people are buying birds
and that allows us to target

Our interventions
at that time of year.

We're actually working
with these sellers

To improve the market

To make it a more bio safe
and bio-secure area.

[narrator]
thanks to human activity,

Outbreaks that once stayed
local are now going global

With devastating consequences.

I don't want people
to be afraid,

But this is why
I think we can,

And need to learn
about all of these things

And help people manage

Their risk and their
communities' risk.

And now we know,

That's the world's risk.

[narrator]
the covid-19 pandemic

Brought the world to
a standstill.

But one team in lockdown
has come up with a way

To uncover how this
virus might have evolved.

[murray] people often say the
best way to predict the future

Is to understand the past.

[narrator]
at the smithsonian institution,

A bold experiment
devised during lockdown,

May now help researchers
discover new viruses

Without ever needing
to travel into the field.

Today, two scientists have
been given special permission

To sample the largest bat
collection on earth.

We have all of these bats

That might be holding
coronaviruses.

We have animals that span
from the late 1800s to 2020.

Each specimen has
its own unique story.

[narrator]
these long-dead bat specimens

Offer a rich source
of information about when,

How, and where
bat coronaviruses evolved.

These historical patterns
could one day help scientists

Build models that predict
future outbreaks.

-Hey, missy. Good morning.
-[missy] hey. Good morning.

It's good to see you.

Yeah it's been a long time.
I'd give you a hug normally,

But I guess we'll
stay far apart.

Not today, yeah.

[hawkins] this project is really
exciting because for one

It brings together
a lot of researchers

That have expertise
in different areas.

[narrator] this experiment needs
missy's knowledge of the past

And carly's ability
to wield state of the art

Genetic detection tools.

[hawkins] okay, carly,
welcome to the bat collections.

[muletz-wolz]
this is incredible.

[narrator]
with over 138,000 bats,

This collection
may well hold the secrets

Of coronavirus evolution.

Missy just has to figure out
where to start looking.

We had a lot of samples
that came back from myanmar,

Which shares quite
a long border with china.

So we figured they might
be a great place to start.

[narrator] if a bat contains
any viruses related to killers

Like sars-cov-2,

Then wherever it was collected

May be a high risk
for spill over.

[hawkins] did you find one?

[muletz-wolz] oh I think I did,
the rhinolophus from myanmar?

-Perfect.
-Okay, set it on the tray.

[narrator] while this method
might be easier and safer

Than catching bats in the wild,

Its much harder
to find the viruses.

If we think about all
if the 100 years

Sitting in a jar
and degradation,

Its more likely
that we'll need to sample

Up to a 100 samples
for us to get one positive.

Okay so the first
thing we're gonna do

Is get the bats out.

All right, going in,
they look kinda scary...

[hawkins chuckles]

He does they do look
a little fearsome I guess,

[muletz-wolz]
let the alcohol drip off?

Okay, hey buddy, do you
have a coronavirus in there?

[hawkins] they're just so cool.

So just grab by his torso,
not by the wing.

[muletz-wolz]
does that look good?

-[hawkins] yup.
-[muletz-wolz] okay.

So this is a hippodiderous.

[narrator] unravelling how
coronaviruses evolved

Over the course of a century,

Could help us predict
their evolution

In the years to come.

[hawkins] one of my favorite
things about bats is that

-This is their thumb.
-Wow.

So their wing is actually
all the same bones as your hand

So it's like their doing
jazz hands when they fly.

[narrator] it may have been
dead over 100 years,

But this bat could still
provide vital information.

What tissues are
we going to sample today?

We know that this causes
respiratory infections,

So we definitely want the lungs.

We just need 50 micrograms.

Oh, look at that!
Right on the money.

-Wow!
-Right on the money.

Perfect cut.

Thank you, bat.

Back in your jar you go.

[narrator] now it's over
to carly to spend months

Painstakingly trying to extract

Any coronaviruses
from the samples.

[murray]
no matter what they find,

It will add to the body
of scientific knowledge

And inform some of
our future studies.

We are well on our way
to gaining the information

That we need to prevent
to next pandemic.

[narrator] the more links we
find between bats and viruses,

The more the public's
fear of bats grows.

[mazet] with terrible
disease outbreaks,

It is human nature

To want to find
something to vilify.

I think it's really dangerous
that we do that.

[narrator] in the face
of a deadly pandemic,

It's easy to forget
why we need bats.

[fran hutchins] here in texas,

We manage
bracken cave preserve,

It's 1500-acre
preserve protecting

The largest colony
of bats in the world.

Just that one colony of bats

Is eating 147 tons
of bugs a night.

That's worth about $800,000
a season in pesticides

That the farmer doesn't have
to buy to spray on their crops.

[narrator] the human race faces
an interesting dilemma.

We can't lose bats

Because it will do us
more harm than good.

We can't stress them because
they may shed more viruses.

And we can't avoid them

Because we're building deeper
into their habitats.

It's not as simple as saying
"what species did it come from?

Let's get rid of that species"
it's quite the opposite.

It's to find out
what that animal is,

And in this case bats

And recognizing all
the great things that bats do

And how do we safely
learn to live with bats?

[narrator] one city
may have stumbled on a way

Of reducing the stress on bats
caused by habitat loss.

[hutchins] the biggest struggle
that bats have with humans

And humans have with bats

Is the interaction
that we're having with them

As we move into
where they live

Because we're destroying
their habitat.

We need the bats
as much as they need us.

And we really need to learn
how to live together.

Back in the early 80s,

Texas department
of transportation

Widened congress avenue

And when they were building
that new bridge structure

What they didn't realize
at that time was,

It was the perfect habitat

For the mexican free-tail bats.

You can see up here in
the expansion joints,

Where the bats are roosting,
between the beams.

We have about a million
and 1/2 mexican free tail bats

Right above our heads here.

[narrator]
this bridge houses

The largest urban bat colony
in the world.

[hutchins] they basically built
a penthouse over the river

With a great view
of the capital,

They use the river to get out
of town to forage for food.

Just to see the excitement
on people's faces

When they finally get
to see a bat fly,

This amazing
spectacle of nature.

[narrator] bats may be
the source of some

Zoonotic outbreaks,
but they're not the cause.

Finding ways to reduce
our impact on bats

Could be one way of
preventing future pandemics.

[narrator] covid-19's rising
death toll and estimated cost

Of nearly $30 trillion

Has rallied
scientific collaborations

On a global scale

And forever redefined
how we approach

Global health.

[wang]

Now we need to remember forever

That we have to be looking

Further out in the future

And all of the ways
we interact with the hosts

That might carry
the next pandemic

And some of those
are probably bats.

[murray] well, a lot of folks
have been studying bats

But now it's time
for us all together

To share the information
we're gathering.

So if anything,

The reason to study bats
is only ramping up.

There's so much more to learn.