Original subtitles

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.