It was a balmy Sunday evening in early 1999, and Dr. Kaw Bing Chua hadn't had lunch or dinner.
There wasn't time to eat. Chua was chasing a killer. And he thought maybe he had finally tracked it down.
He slid the slide under the microscope lens, turned on the scope's light and looked inside. "A chill went down my spine," Chua says. "The slide lit up bright green, like bright green lanterns."
Right there, in Chua's hands, was a virus the world had never seen before. And as he soon learned, it's also one of the most dangerous ones.
Now Chua had enough of the virus to kill everyone in the lab. Maybe worse.
The new virus — eventually called Nipah — is on the World Health Organization's list of viruses most likely to cause a global pandemic. It's the virus that inspired the 2011 movie Contagion. And just this past January, governments and philanthropists pledged hundreds of millions of dollars to develop a Nipah vaccine because it poses such a big threat.
Back in 1999, Nipah was spreading across Malaysia. And Chua was the only one who knew it.
But nobody believed him. Chua was still training in virology at the University of Malaya in Kuala Lumpur and didn't have clout or confidence.
"I called my department head at his home. I said, 'Prof, please come. I want to show you something,' " Chua says.
Chua's professor told him to throw away the experiments — that Chua was wasting time. But Chua didn't throw away the virus. Instead he packed it up and brought the samples to the U.S.
Living in a nightmare
An hour south of Chua's laboratory experiments, a mysterious disease was devastating a farming town called Nipah. The disease was as deadly as Ebola, but instead of attacking blood vessels, it attacked the brain.
It felt like living in a nightmare, says Thomas Wong, who was a pig farmer in Nipah at the time. "Every day we were seeing in the newspaper that people were dying," Wong says. "I lost many friends. Many friends."
The disease struck lightning fast.
Young men would be healthy one day. The next day their brains would swell up. They couldn't walk. Or talk.
"They'd become comatose, and some of them became paralyzed," says Dr. C.T. Tan, a neurologist at the University of Malaya, who took care of patients from Nipah.
Some people even had what looked like locked-in syndrome — they were conscious and awake but couldn't move or speak.
There was nothing Tan could do. No cure, no treatment. About half the patients died.
"We didn't know what it was," he says. "It was terrifying."
Nearly 1 in 3 families in Nipah had already lost someone. And the window of opportunity for keeping the disease contained was quickly closing. It had already spread to several states and hopped over the border into Singapore — where 4 million people lived.
Yet the Malaysian government told people not to worry. It said the disease was coming from mosquitoes. And it had it under control because it was spraying for mosquitoes.
Both Tan and Chua thought the government was wrong. And there was one big clue: "No Muslims were getting sick," Tan says.
Mosquitoes don't care which religion you practice. "So if the disease was coming from mosquitoes, you would have Muslims, Hindus and Christians getting sick," Tan says.
But only Chinese Malaysians were catching the disease — and even more specifically, only Chinese farmers raising pigs.
"As you know, Muslims don't handle pigs," Tan says.
Pigs were crying
At this point, Chua agreed with Tan: This disease wasn't coming from mosquitoes. "No, no I knew it was something else, and people were dying!" he exclaims.
"But no one would believe me," he says. "I was practically begging people to believe me."
So Chua had to get crafty.
He persuaded his professor to send him to a Centers for Disease Control and Prevention lab in Fort Collins, Colo. Scientists study mosquito-borne diseases there. They also have a powerful microscope that would show exactly what type of virus was causing the problem.
Chau wrapped up samples of the virus in special packaging, put them in his carry-on luggage and hopped on a plane.
"It was an emergency," Chua says. "I had to get the samples there very quickly."
When a scientist put the samples into the microscope, Chua says a sense of great fear rushed through him: "The moment I saw the screen, I said 'Goodness! It's a paramyxo!' "
The image revealed the telltale signs of a frightening group of viruses: paramyxoviruses.
These viruses come from livestock, not mosquitoes. And they often infect the lungs. So they can spread rapidly through the air. Measles is a type of paramyxovirus, and it's one of the most contagious viruses on Earth.
Chua quickly realized just how dangerous this virus could be. He rushed to a phone and called officials in Malaysia. "Stop fighting mosquitoes!" he told them. "It's coming from pigs."
The Malaysian government listened. And it did something very drastic.
"Malaysia's army moved in for the country's biggest-ever animal culling," Journeyman Pictures reported in a documentary back in 1999. "Almost 1 million pigs, shoved into pits and shot."
Awali Muniandy helped with the pig culling. He says it was a horrific scene.
"The pigs were screaming, and you could see some tears on their faces," says Muniandy, who's with the Department of Veterinary Services Malaysia. "It was pitiful."
But the culling worked. The outbreak completely stopped. The new killer virus appeared to have vanished.
And the world was left with a mystery: Where did the pigs get the virus?
Huge pig farms turned into virus factories
It took more than a decade to figure all out, but eventually scientists realized that pigs had been getting Nipah virus for years. Maybe more. They very likely picked it up from bats.
But the outbreaks were small. And no one really noticed because the farms were small.
"In the olden days, the pigs were running and the family would look after a few pigs," neurologist Tan says.
Then in the '80s and '90s, Malaysia went through a massive economic boom. Families were entering the middle class. They could afford to eat pork several times a week.
So farmers changed the way they raised pigs. They started packing the pigs into tight quarters and industrializing the farms. They could produce more meat with fewer resources. But the productivity bump came with a cost: "When a virus got into the pigs, it could multiply very quickly," Tan says.
When you have thousands and thousands of pigs on one farm, there's a seemingly endless supply of new piglets to infect. The pig factory becomes a virus factory. The virus spreads like wildfire through the whole farm. Hops to another farm. And eventually jumps into farmers.
"The way people grow their food has changed; so has the way diseases spread," Tan says. "Agricultural industrialization was part of what triggered the outbreak."
This pattern has occurred throughout human history. When we change the way we interact with animals, we unleash new diseases.
For example, when people first started raising cows and farming, thousands of years ago, we very likely started catching something like the measles from cows.
Now we're in a new phase of agriculture: factory farming. From it, we've gotten a new strain of the flesh-eating bacteria disease MRSA, a slew of bird flus, swine flu and Nipah.
In Malaysia, pig farms have gotten cleaner. Farmers break large farms into smaller ones and keep pigs isolated from other animals and people. As a result, Nipah has stayed away.
But across Asia, there have been at least 16 outbreaks of Nipah since 1999 — in India, Bangladesh and the Philippines.
And there are signs the virus is becoming more dangerous. In the Malaysian outbreak, the fatality rate was about 40 percent, and the virus didn't seem to spread between people. But more recently, Nipah has killed up to 70 percent of those infected — and can spread not only from animals to people but also between people.
"The world is changing so fast," says Tan. And sometimes the only way to keep up is when a scientist like Chua isn't afraid to challenge the status quo.
What do you want to know about pandemics? Share your questions by submitting them in our special tool here. Our global health team will answer some of them in an upcoming story.
SCOTT SIMON, HOST:
When you talk to disease experts about what might alarm them, it's not Ebola or Zika. It's Nipah. It's as deadly as Ebola but attacks the brain, and it has the potential to spread by mere cough. As NPR's Michaeleen Doucleff reports, Nipah originated in Malaysia - the unintended consequence of that country's efforts to lift itself from poverty. A warning, this story includes some graphic descriptions.
MICHAELEEN DOUCLEFF, BYLINE: This story begins in a small farming town called, Nipah. It's where the virus gets its name. It's about an hour drive south of Malaysia's capital, Kuala Lumpur.
So I'm riding with Thomas Wong who was a pig farmer here 20 years ago.
THOMAS WONG: (Foreign Language Spoken).
DOUCLEFF: He says everyone in Nipah was a pig farmer because Nipah was at the center of Asia's booming pork industry. The region was going through a huge economic surge. Families now had enough money to buy pork for lunch and dinner. So pig farmers were getting rich.
How many pigs were in this area?
WONG: About half a million.
DOUCLEFF: Half a million pigs - wow.
WONG: Yes. Very densely populated.
DOUCLEFF: Very densely populated. And they're all gone now?
WONG: Oh, no. All buried.
DOUCLEFF: All buried, all underground because back in 1998 something went terribly wrong here. Wong pulls up to an abandoned farm.
So maybe you can take us through what happened? So the disease came to this farm here?
WONG: Yeah. The pigs...
DOUCLEFF: He says, first, baby pigs started getting sick. They'd get a cough, couldn't walk. Then they'd died. There were so many dead piglets that their bodies piled up around the town, and the town smelled like death.
WONG: Oh, the smell - dead like dead rats.
DOUCLEFF: Then the situation got worse. People started dying.
WONG: Every day we'd see the newspaper that people dying.
DOUCLEFF: Did you lose any family or friends?
WONG: Friends, yes - lots of friends.
DOUCLEFF: The disease struck lightning fast. Dr. C. T. Tan is a neurologist who took care of patients from Nipah. He said farmers were healthy one day, and then their brain swelled up. They couldn't walk or talk.
TAN CHONG TIN: They'd become comatose. And some of them become paralyzed.
DOUCLEFF: And then...
TAN: After two, three days, they'd die.
DOUCLEFF: There was nothing Tan could do - no cure, no treatment.
TAN: We thought it was some unusual infection, but we didn't know what it was.
DOUCLEFF: And time was running out. Dozens of people had already died in Malaysia, and the disease had spread to Singapore.
WONG: That was frightening.
DOUCLEFF: Yet the Malaysian government told people not to worry - that the disease was coming from mosquitoes, and they were taking care of it by spraying. But one young scientist - he thought the government was wrong.
OK. We're here.
His name is Kaw Bing Chua. I met him at the farm where the outbreak began. He was ordered to test blood samples for the mosquito virus. Those samples kept coming back negative.
KAW BING CHUA: No, no. I know it was something different, and people dying.
DOUCLEFF: Chua thought it might be a new virus, one that the world had never seen before. But to prove it, he had to do something very dangerous. He had to grow the virus in his lab without proper safety measures. Putting himself and his lab at risk so he could study it. He worked late into the night for weeks, said a little prayer before each experiment. Then one Friday evening, he opened up one of his petri dishes, and there it was.
CHUA: I actually saw initially the cell membranes thickening.
DOUCLEFF: You could see the virus actually coming out of the cell.
DOUCLEFF: And that means you had found what was making them sick.
CHUA: Yes, yes.
DOUCLEFF: What did you feel like?
CHUA: Of course, very fearful.
DOUCLEFF: Very fearful?
DOUCLEFF: The virus looked ruthless, destroying every human cell he tested. It grew like gang busters. In just a few weeks, he had grown enough to wipe out a whole town. He called his boss over to show him.
CHUA: I said, please come. I want to show you something. When he looked under the microscope...
DOUCLEFF: He didn't believe the results. He told Chua to throw away the experiment. But Chua didn't throw it away. Instead, he took it to the U.S.
CHUA: It was an emergency, actually.
DOUCLEFF: It's an emergency. You had to get it there quickly.
DOUCLEFF: Did you just carry it with you?
CHUA: Yes. Of course, with special packing.
DOUCLEFF: That's right. Wrapped the samples carefully, put them in his carry-on luggage and boarded a plane to the U.S. Centers for Disease Control and Prevention. The CDC had a special microscope that they could identify exactly what the virus was. Chua will never forget what he saw.
CHUA: The moment I saw the thing, I said, goodness.
DOUCLEFF: You said, goodness?
CHUA: Yes. It's paramyxo.
DOUCLEFF: A paramyxo virus. These viruses come from livestock, not mosquitoes. Scientists think the next pandemic will be caused by a virus like this - highly lethal and the potential to be super contagious.
Chua rushed to a phone, called up officials in Malaysia and told them, stop fighting mosquitoes. It's coming from the pigs. Finally, the Malaysian government listened and did something very drastic.
(SOUNDBITE OF ARCHIVED RECORDING)
TIM LESTER: Malaysia's army moved in for the country's biggest-ever animal culling.
(SOUNDBITE OF PIGS SQUEALING)
LESTER: Almost one million pigs.
(SOUNDBITE OF GUNSHOTS)
DOUCLEFF: That's tape from Journeyman Pictures which reported on the outbreak back in 1999. The results of the culling were dramatic. The outbreak stopped - dead stopped. As Chua is telling me all this, he starts to choke up.
CHUA: No one believed me. Practically begging people to believe - nobody believed me.
DOUCLEFF: It's an amazing story, Dr. Chua. I mean, it's amazing. Your persistence is why this outbreak stopped.
CHUA: (Crying) Let me cool down.
Chua had saved many lives, but the world was still stuck with a mystery. Why did the pigs get sick? It turned out that the pigs had been getting the disease for years undetected. Dr. Tan, the doctor treating Nipah patients, was studying this.
TAN: In the old days, the pigs were running around, and the family would look after a few pigs.
DOUCLEFF: A few pigs would get sick, but no one was bothered. It just looked like the flu. But in the past few decades, farmers in Asia had changed the way they raised pigs. They were packing more pigs into farms, starting to industrialize them.
TAN: So it also means that when the virus get to the pigs, it can also multiply very quickly.
DOUCLEFF: When you have thousands and thousands of pigs, not 10, there's a seemingly endless supply of new piglets to infect. The pig factory becomes a virus factory. The virus was spreading through coughs from one farm to the next and eventually into farmers.
TAN: The way we grow our food - it changes.
DOUCLEFF: So agricultural intensification was part of the trigger?
DOUCLEFF: And that's something we don't think about. As people get richer, there could be this devastating consequence. In this case, factory farming, which feeds more people, inadvertently created the Nipah outbreak. And you see this around the world. With cows in the U.S., you get new types of MRSA, a flesh-eating bacteria. With chickens in China - a whole slew of bird flu.
TAN: The world is changing so fast.
DOUCLEFF: In Malaysia, pig farms have gotten cleaner, and Nipah has stayed away. But across Asia, there have been more than 16 other outbreaks. And there are signs the virus is evolving, becoming more contagious in people. Michaeleen Doucleff, NPR News. Transcript provided by NPR, Copyright NPR.