ROBERT SIEGEL, HOST:
And today, we go on a hunt in an ancient forest in Southeast Asia. It's where deadly viruses hide out, waiting for their chance to leap into a person and then spread around the world. Think Ebola, Zika, bird flu. There are more diseases like these than ever before. NPR is taking the next few weeks to explore why.
MICHAELEEN DOUCLEFF, BYLINE: We got something? We got something - great.
SIEGEL: That's NPR's Michaeleen Doucleff. She joined a team of scientists as they tried to catch the next killer virus before it catches us. Here's her story.
DOUCLEFF: We've got bug spray. We've got headlamps. We're going into the forest. And it's steep.
KEVIN OLIVAL: And it's steep.
DOUCLEFF: That's Kevin Olival. He's a virus hunter with EcoHealth Alliance, a U.S.-based group of scientists. They fly around the world, looking for killer viruses.
DOUCLEFF: Becomes dense right away.
OLIVAL: Oh, thorns.
DOUCLEFF: And he's brought me to a tropical rainforest. We're on the island of Borneo in Malaysia...
OLIVAL: This way.
DOUCLEFF: ...Because this is the type of place where outbreaks are born.
OLIVAL: This way is a little easier.
DOUCLEFF: HIV came from a rainforest. So did Ebola. The next one could come from here. A big reason why - all the crazy animals that live in the forest.
OLIVAL: See the size of this guy?
DOUCLEFF: Oh, wow. What is that?
OLIVAL: It's a roly poly bug.
DOUCLEFF: Whoa. It's huge.
OLIVAL: (Laughter) Yeah.
DOUCLEFF: It's like the size of a chestnut. That's awesome.
OLIVAL: A ping - almost a ping-pong ball.
DOUCLEFF: This is one of the richest places on Earth for life. In this Borneo rainforest, in an area about the size of a small farm, there can be more species of plants and animals than in the U.S. and Canada combined.
OLIVAL: It's a hotspot for biodiversity.
DOUCLEFF: There are pygmy elephants, monkeys with noses the size of beer cans and a deer that's as small as a rabbit. That's right - a deer that you could cradle like a baby. Here's the thing. Places that have lots of crazy animals like this have lots of crazy viruses. Olival is trying to find out what viruses are inside these animals. So he's trying to catch them.
OLIVAL: Ooh. That's what it'll sound like when an animal goes in there.
DOUCLEFF: Olival's team has set up metal traps on the ground and up in the trees.
OLIVAL: OK. Just don't step on that trap.
DOUCLEFF: These traps are set up to trap rodents and small mammals.
What he really wants to catch is a bat.
OLIVAL: Yeah. To the bat nets we go.
DOUCLEFF: There are a dozen nets strung like huge spider webs high in the trees.
OLIVAL: The nets are open. The traps are baited and open. The rain is coming, unfortunately. So...
DOUCLEFF: So now we just wait, huh?
OLIVAL: Now we wait.
DOUCLEFF: For the bats to go hunting and fly into one of these nets. Then we can take their blood and look for new viruses.
OLIVAL: Michaeleen, we got one.
DOUCLEFF: Oh, there it is. Wow. He's so cute. Oh, look at his wings.
OLIVAL: Little puppy face.
DOUCLEFF: Little puppy face.
OLIVAL: Short-nosed fruit bat.
DOUCLEFF: Short-nosed fruit bat. So he's going into a bag.
OLIVAL: Which he can breathe through.
DOUCLEFF: The bag helps keep the bat calm as we carry him to a makeshift lab near the trapping site.
OLIVAL: So we're going to take the bat out of the bag.
DOUCLEFF: He really does look like a puppy. And he wraps his wings around his body like a little blanket.
OLIVAL: Aw, there he is.
DOUCLEFF: But this bat isn't something you want to snuggle with.
OLIVAL: Just be careful.
DOUCLEFF: This little guy - these bats are arguably one of the most dangerous animals in the world.
OLIVAL: Take your time.
DOUCLEFF: They triggered the Ebola outbreak in West Africa, the pandemic of killer pneumonia back in 2003 - that was called SARS. And they're behind one of the viruses scientists think could cause the next big one, Nipah.
OLIVAL: We're about to collect specimens from this bat. Mask is on. Gloves are on.
DOUCLEFF: One reason why bats are so dangerous is they have this weird ability to carry a lot of deadly viruses...
OLIVAL: Watch your finger.
DOUCLEFF: ...In their spit, their pee, their poop. And because they fly, they can spread these viruses over huge distances. So when there are bats up in the sky, there could be Ebola in that poop that lands on your shoulder.
OLIVAL: Do you guys want a leather glove?
DOUCLEFF: What Olival is trying to do is figure out what other viruses are in these bats. It's part of a $200 million project sponsored by the U.S. government. The goal is to catch the next killer virus before it catches us by setting up an early alert system for outbreaks.
OLIVAL: Right now, he's collecting a throat swab.
DOUCLEFF: The team is taking samples from all over the bat.
OLIVAL: They just took the blood sample. And now they're putting a piece of cotton on it to stop the bleeding.
(SOUNDBITE OF BAT CHIRPING)
DOUCLEFF: He's starting not to like it.
(SOUNDBITE OF BAT CHIRPING)
DOUCLEFF: Now the bat is fighting on the paper towel and kicking. Oh they're giving him a treat. They're giving him fruit juice.
OLIVAL: A little reward for his hard efforts.
DOUCLEFF: It is really cute. He just sucked the fruit juice out of the pipette like a little bottle. Aw, he's hungry.
DOUCLEFF: They put the samples in test tubes and store them in liquid nitrogen. Then they let the bat go.
OLIVAL: OK. Good job.
(SOUNDBITE OF CAR DOOR CLOSING)
DOUCLEFF: The next morning, we meet up with Olival at a quiet spot. He's going to show us what his team has found in all these bats and animals in Borneo. He opens his laptop.
OLIVAL: I've just pulled up all our data from Malaysia today, all the viruses that we found.
DOUCLEFF: Wow. Look at them.
DOUCLEFF: Line after line of new viruses.
OLIVAL: We found 48 new viruses here in Sabah and about 16 that were already known.
DOUCLEFF: OK. Wow. It's kind of scary to be honest (laughter) - just seeing that giant list. It's like, whoa.
There's a new polio-like virus in orangutans, a bunch of new herpes viruses in monkeys, many, many SARS-like viruses in bats. And that's just in Malaysia. The project Olival works with has been sampling in rainforests around the world. And they found nearly a thousand new viruses in 20 countries. Now, we've been saying new viruses. But what we mean is new to us.
OLIVAL: They've been in the forest for thousands of years. But they're new to science.
DOUCLEFF: And that's key. All these viruses have been circulating in bats, monkeys, rodents for tens of thousands of years - maybe longer. And no one has cared. No one has noticed. A virus is just a natural part of the ecosystem of the rainforest, coexisting with the animals and not bothering us.
OLIVAL: Exactly. It's just sitting out there in the forest.
DOUCLEFF: So then how does it become a problem?
OLIVAL: Well, these things - they don't just magically jump out of the forest. It's because we are getting in there.
DOUCLEFF: Getting into the forest. To see what he means, we just take a short walk from where we're sitting.
It's incredible. We just came over this overlook. And as far as the eye can see are palm trees, row after row after row of palm trees and nothing else. And it just hits you right in the gut.
This forest is being eaten away by palm-oil plantations - you know, that vegetable oil we put in crackers, pizza dough, ice cream, even lipstick? Before the palm-oil boom in the '80s, this was all pristine forest filled with all these crazy animals and their viruses. But then people came along and started cutting down the forest, destroying their homes. The animals had no place to go.
So they come and live on the plantations, near the workers' homes, even in the schoolyard where the workers' kids play. If a kid gets too close, he could pick up a new virus. You can see this all over the world. Forests get cut down, and animals show up in our backyards, on our farms, pee on our crops, giving their viruses a chance to jump into us and infect us. And it's getting worse.
OLIVAL: We're changing the environment in ways that is really unprecedented in human history.
DOUCLEFF: And it's not just palm oil in Malaysia.
OLIVAL: Soybeans in the Amazon. It's suburban development the U.S. It's - every part of this planet has been modified by people in some way.
DOUCLEFF: And with all these changes has come a new era of infectious diseases. Over the past 60 years, the number of new viral diseases has quadrupled. Many have come from animals in forests that have been chopped up, logged, turned into shopping malls.
OLIVAL: And so it's really the human impact on the environment that's causing these things to jump.
DOUCLEFF: And cause outbreaks.
OLIVAL: Yeah - cause pandemics.
DOUCLEFF: A pandemic, a deadly disease that bursts through international borders and could hurt millions. Michaeleen Doucleff, NPR News.
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SIEGEL: You can see an animation of how an animal virus transforms into a deadly human virus at npr.org/pandemic.
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