in a remote province of Zaire.

[music playing]

Belgian nuns tending to the sick described horrific symptoms

followed by agonizing deaths.

REID WILSON: It attacks tissue around the body.

It basically attacks everything in the human body

except for your bones.

NARRATOR: Doctors from Zaire, Europe, and America

traveled to the epicenter to investigate.

REID WILSON: When responders got there,

they had no idea what they were looking at.

But they did know that they were looking

at this deadly new virus.

NARRATOR: The researchers might not

have known what this new virus was,

but they learned how it spread so quickly.

[whoosh]

Medical supplies were so scarce here

that the Belgian nurses had resorted

to reusing hypodermic needles.

[music playing]

This virus had an astounding mortality rate of nearly 90%.

In less than two months, it claimed some 300 lives.

[whoosh]

Then suddenly, the nightmare ended, and no one knew why.

NANCY JAAX: They just knew the virus popped out of nowhere,

and it disappeared just as quickly.

NARRATOR: Epidemiologists named Ebola Zaire

after the nearby Ebola river and dreaded its return,

which it did in just a few relatively contained

outbreaks over the next decade.

But the greatest fear was that someday the virus

would emerge in a densely populated

region, which it also did.

[music playing]

REID WILSON: So back in 1989, in the Washington suburb

of Reston, all of a sudden, a bunch of monkeys at a warehouse

started dying.

NARRATOR: Hazleton Laboratories, Reston,

Virginia, one of the largest animal testing

companies in the country.

A shipment of 100 long-tailed macaques

came in from the Philippines.

Two were dead on arrival.

The illness quickly spread to dozens of monkeys.

Desperate for a diagnosis, the company

sent samples to a high security lab run by the military, a US

Army Medical Research Institute of Infectious Diseases,

or USAMRID.

[whoosh]

Lieutenant Colonel Nancy Jaax examined the tissues.

NANCY JAAX: What we found then was really pretty alarming.

I was seeing a section of liver.

I saw all these very large cells--

which are called macrophages--

and they were full of material which

is very typical in a filovirus infection.

[whoosh]

NARRATOR: A filovirus, a tiny spaghetti-like strand

that replicates at lightning speed

and causes devastating diseases.

Dr. Jaax was very familiar with them.

She worked behind layers of bomb resistant walls

where the army stored an archive of frozen killers.

[whoosh] Marburg--

[whoosh]

--Ebola Sudan--

[whoosh]

--and the most lethal of all, Ebola Zaire.

Dr. Jaax used her stash of filoviruses

to compare it to the monkey sample, and to her surprise,

the one that matched was the virus

that struck Zaire in 1976.

We're thinking, well, that's not possible we

need to check it again.

And they checked it three times, and every time,

there was no mix up.

It was showing positive for Ebola Zaire.

JERRY JAAX: I think Nancy came to my office and said--

NANCY JAAX: I did go to his office.

JERRY JAAX: --you're not going to believe what just happened.

You know, it looks like we've got Ebola virus

in these monkeys in Virginia.

There was a lot of confusion and going, oh, wow.

This is really crazy.

What are we going to do?

NANCY JAAX: We immediately had to kick into high gear.

NARRATOR: The army formed the battle plan.

The first order, euthanize the monkeys to prevent an epidemic.

Nancy's husband, Colonel Jerry Jaax, led the team.

JERRY JAAX: Nobody likes killing monkeys,

but we were in an emergency situation.

It was something that we had to do to make sure

that we didn't have a significant outbreak

within the human population.

NARRATOR: They dodged a bullet.

And they soon realized this strain of Ebola

wasn't harmful to humans, but they

knew it was only a matter of time

before they'd have to face the unimaginable.

NANCY JAAX: The question, of course,

is are you going to get a mutation

that then makes it more airborne or makes it more contagious.

JERRY JAAX: What we did in a contained building

was pretty dramatic, but imagine if it was a city.

REID WILSON: The nightmare scenario

for global public health officials

is something that combines the transmissibility of something

like the Spanish flu--

which infected probably about a billion people a century ago--

and the mortality of Ebola.

NAHID BHADELIA: What keeps me up at night

is that we'll have a disease that's transmitted by droplets.

ANTHONY FAUCI: Something that is respiratory-borne

that is a virus like influenza, likely influenza, that has

both high degree of transmissibility and high

degree of morbidity and mortality.

REID WILSON: If something like that spreads around the world,

we're just not ready to fight it.

[whoosh]

[whoosh]