Pygmy elephants. Monkeys with noses the size of beer cans. And a deer so small you could cradle it like a baby.

And right there, sitting on a leaf, is the strangest bug we've ever seen.

"Check out the size of it," says virus hunter Kevin Olival as he picks up a ginormous roly-poly. "It's the size of a ping-pong ball!"

We're in the middle of Malaysia's Borneo rain forest. Olival has brought us here because this is the type of place where pandemics are born. HIV came from a rain forest. So did Ebola. Yellow fever. And Zika.

The next troubling outbreak could come from a rain forest like this. And a big reason why: all the crazy animals that live here.

Rain forests are the world's secret laboratory — where evolution experiments with body shapes, sizes and colors. Maybe if a monkey gets a giant schnoz, he'll have a better time finding love?

The result is a biological bonanza. "It's a biodiversity hot spot," says Olival, an ecologist and evolutionary biologist with the U.S.-based nonprofit EcoHealth Alliance.

This rich diversity in the rain forest doesn't apply to just creatures we can see. It also applies to creatures we can't see. Microcreatures. Nanocreatures. You guessed it: viruses.

New world order

The world is now in uncharted territory when it comes to infectious diseases. We're facing a whole new era. Over the past century, the number of new infectious diseases cropping up each year has nearly quadrupled. The number of outbreaks per year has more than tripled.

In the U.S., we have seen more than a dozen new human diseases appear over the past 25 years. For instance, a killer tick-borne virus showed up in Kansas in 2014. A new type of leprosy dismembered a man in Arizona in 2002. And a new hemorrhagic fever jumped from rodents into people, killing three women in California in 1999 — to name just a few.

But it's the tropical rain forest that is the most worrisome to many scientists like Olival.

Wearing a headlamp and a khaki shirt with the words "Virus Hunter" embroidered on the back, Olival looks like Indiana Jones' nerdy brother. He is constantly talking about how much he loves bats and admits he picked up his future wife by wowing her with his bat knowledge. But at the end of day, he is a global treasure hunter. He flies around the world collecting undiscovered viruses — and he focuses his hunt on viruses with the potential to kill.

It's part of a $200 million project called PREDICT, sponsored by the U.S. government and led by University of California, Davis, School of Veterinary Medicine. The goal is to figure out the viruses that are lurking inside animals around the world. So we are ready when a new and potentially harmful virus jumps from animals into people and causes an outbreak. In other words, Olival wants to find the next pandemic virus before it finds us.

Little puppy face

Olival and his team are out here in Borneo setting up traps to catch animals. On the ground, they set up little metal boxes, each about the size of a Coke bottle, to catch rodents, shrews and those tiny rabbit-size deer. And they have strung thin nylon nets high in the trees, like giant spiderwebs.

"We've got one," yells Olival's colleague Jimmy Lee, a virologist with EcoHealth Alliance. We rush over to one of the nets. Dangling in the middle is one of the most beautiful sights to a virus hunter: a bat.

Lee puts on thick gloves and starts to untangle the bat from the net. "They can bite," he says, as he holds the little creature gently in his hands. It's not much bigger than a grapefruit.

One glimpse at the bat's face, and my heart melted. "He has a little puppy face, doesn't he?" Olival asks.

And it's true. The bat — a short-nose fruit bat — looks uncannily like a brown puppy. It is incredibly cute, especially as it wraps its wings around its body like a little blanket. But you wouldn't want to snuggle with this little guy.

Bats are arguably one of the most dangerous animals in the world. They carry a daunting list of killer viruses. They likely triggered the Ebola outbreak in West Africa. They very likely launched a pandemic of killer pneumonia back in 2003, called SARS. And they're behind one of the viruses scientists think could cause a nasty pandemic: Nipah.

Bats carry viruses all over their bodies. In their spit. Their blood. And their poop. Because they fly, bats can spread these viruses across huge distances. So when there are bats in the sky, there could be Ebola in the poop that lands on your shoulder.

So if bats are such a problem, why not kill the bats? "Not a good idea," Olival says bluntly. "Bats do a lot of good for the environment. A lot."

Without bats, the world wouldn't have rain forests. Bats are key pollinators for more than 500 species of flowers and trees. They disperse seeds for many other plants, and they keep insect populations in check with their arthropod-rich diets.

As we learn a bit later, bats really aren't the ones to blame when it comes to creating outbreaks. It's the intruders into their homes that are the problem.

Olival and Lee lay the bat on small table, gently spread its wings open and then prick it to get a few drops of blood. They also take a smidge of saliva and then do a quick rectal swab.

"That's the worse part," Olival chuckles. Then they let the bat go.

Lee puts the samples in test tubes and drops them into liquid nitrogen. He'll take them back to the lab, extract genetic material to see if any of it looks like something they haven't seen before.

So far, Olival and Lee's team, have trapped and sampled more than 1,300 animals in this region of Malaysia, in partnership with the Sabah Wildlife Department and Danau Girang Field Centre. Globally, the PREDICT team has sampled more than 74,000 animals.

Not everyone is a fan of the project. Some infectious disease scientists think creating a long list of viruses isn't very helpful. They say money could be better spent on diseases we actually have now instead of trying to guess which ones might become a problem someday.

And even if scientists could predict when an outbreak is likely to happen, it might not, says Michael Osterholm, who directs the Center for Infectious Disease Research and Policy in Minneapolis.

"I don't think the actual premise for the PREDICT project — that it will make us better prepared for a pandemic — holds water," Osterholm says.

For example, in 2012 scientists predicted that the deadly H5N1 flu was about to jump from birds into people. "Did we do anything to prepare, like make a new or better flu vaccine?" Osterholm asks. "No."

We're not even making vaccines for viruses that we know are threats, that are regularly killing people, he says. "How are we going to convince people to invest money into a virus from the remote jungle for which we have no evidence that it has caused any human illness?"

1,000 viruses found

The next morning, we meet up with Olival at a quiet spot on the edge of the rain forest. He is going to show us what his team has found in all these bats and other animals in Borneo. He opens up his laptop and pulls up data from Malaysia.

It's a bit eye-opening. "We've found 48 new viruses. And 16 that were already known," Olival says as he scrolls down a large spreadsheet. There's a new polio-like virus in orangutans. A bunch of new herpes viruses in monkeys, rodents and bats.

And that's just in this part of Malaysia.

Teams with PREDICT have been sampling in rain forests around the world for seven years and found nearly 1,000 new viruses in more than 20 countries, such as a new rabies-like virus in shrews. And many, many SARS-like viruses in bats across three continents.

And then Olival drops a bombshell.

"These viruses aren't 'new,' " he says. "They're just new to science. But not to the animals in the forest," he adds.

All these viruses have been circulating in bats, monkeys and rodents for tens of thousands of years, maybe longer, he says, and no one has cared. No one has noticed. They're just a natural part of the ecosystem of the rain forest, coexisting with the animals, who are generally not harmed by the viruses.

How do they become problems then?

"Well, they don't magically jump out of the forest," Olival says. "It's because we are getting in there. Getting into the forest."

To see what he means, we take a short walk from where we're sitting. There's a break in the forest and an overlook of the land below. And the view is incredible.

As far as the eye can see are palm trees, row after row of oil palm trees. Nothing else. The rain forest has been eaten away by plantations for palm oil — you know, that inexpensive vegetable oil that is used in crackers, pizza dough, ice cream, even lipstick.

Before the palm oil boom in the 1980s, this was all pristine forest. Filled with all these crazy animals and their viruses, Olival explains. But then people came along and started cutting down the forest. Destroying their homes.

It's like puncturing a balloon filled with viruses, says Barbara Han, a disease ecologist at the Cary Institute of Ecosystem Studies in New York. "Whatever survives, spills out. Deforestation is closely tied to disease emergence."

In the past 40 years, more than a third of the Borneo rain forest has been destroyed. About half of that land has turned into palm oil plantations.

A similar pattern is happening all over the world.

By 2050, more than half of the world's population is projected to live in the tropics and subtropics, Han says.

Right now, only 15 percent of the world's rain forests is still intact. The rest has been burned flat. Broken into pieces. Or converted into farms, ranges for cattle, metal mines — even shopping malls.

"It's soybeans in the Amazon. It's suburban development in the U.S. Every part of this planet has been modified by people in some way," Olival says. "We're changing the environment in ways that are really unprecedented in human history."

Wild animals are now refugees. They have no home. So they come live in our backyards. They pee on our crops. Share our parks and playgrounds. Giving their viruses a chance to jump into us and make us sick.

"So it's really the human impact on the environment that's causing these viruses to jump into people," Olival says.

And cause an outbreak? I ask. Or a pandemic, says Olival.

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.



Copyright 2018 NPR. To see more, visit http://www.npr.org/.

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.

OLIVAL: Yeah.

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.

OLIVAL: Yeah.

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.

(SOUNDBITE OF MONSTER RALLY SONG, "ORCHIDS")

SIEGEL: You can see an animation of how an animal virus transforms into a deadly human virus at npr.org/pandemic.

(SOUNDBITE OF MONSTER RALLY SONG, "ORCHIDS") Transcript provided by NPR, Copyright NPR.