Scientists Link Increased Deforestation To Zoonotic Disease Outbreaks : Short Wave There's evidence deforestation has gotten worse under the pandemic. It's especially troubling news. Scientists are discovering a strong correlation between deforestation and disease outbreaks. NPR correspondent Nathan Rott talks to Short Wave reporter Emily Kwong.

The Link Between Deforestation and Disease

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MADDIE SOFIA, BYLINE: You're listening to SHORT WAVE from NPR.



Hey, everybody. SHORT WAVE reporter Emily Kwong here with NPR national correspondent Nate Rott. Howdy, Nate.

NATE ROTT, BYLINE: Hey, Emily. I know it's not the holiday season, but I want to start today by paying a visit to a ghost of an epidemic past.


ROTT: So not the present, not the coronavirus...

KWONG: Am I going to have to be Scrooge in this scenario?

ROTT: Emily, I think that's going to depend on your attitude.

KWONG: All right. I see how it is.

ROTT: OK. So we're not going to go too far back in time. And the reason that we're going back in time is not great.


UNIDENTIFIED REPORTER #1: The World Health Organization is sounding the alarm

UNIDENTIFIED REPORTER #2: With a painful and grotesque set of symptoms...

UNIDENTIFIED REPORTER #3: Dozens of deaths are reported in Guinea in West Africa.

UNIDENTIFIED REPORTER #4: Spread of this Ebola virus...

UNIDENTIFIED REPORTER #5: The Ebola virus is back.

KWONG: Ah, this was the Ebola outbreak that started in 2013 in West Africa.

ROTT: Exactly. It was and still is the largest Ebola outbreak in history. It lasted for years, killing more than 11,000 people. And the reason I want to talk about it right now is because a couple of years after it all started, the World Health Organization put out a report on the outbreak. And it said something that was a little surprising - that the outbreak may have been caused by deforestation - by foreign mining and timber operations.

KWONG: Tracing a disease to mining itself - that's really interesting. So how did they come to that conclusion?

ROTT: So at that point, epidemiologists had determined that the outbreak started in a small village in Guinea. And they believe the first person to get it was a little boy. He was 18 months old, and he got sick after playing near a hollow tree behind his home. And that tree was filled with fruit bats.

KWONG: And bats, I know, are known to carry the Ebola virus and all sorts of other diseases.

ROTT: Right. But this is not the fault of, you know, the big bad bat. Scientists believe those bats were there because more than 80% of their natural habitat, the surrounding forests, had been destroyed by logging and mining.

KWONG: Ah - so they had nowhere else to go.

ROTT: Yeah. Deforestation pushes bat and boy into close contact. Close contact means it's easier for pathogens - viruses, bacteria, you name it - to jump from animal to human or vice versa. And this plays out all of the time.

KWONG: What we call a zoonotic spillover - I've reported on this and talked about it in the podcast before. But I'm glad we're revisiting it because, considering that three out of four emerging infectious diseases are zoonotic, meaning they come from animals, we have to talk about how humans are kind of responsible for that because it's behind the current coronavirus we're all dealing with.

ROTT: Totally - and I'm going to make you a Scrooge 'cause I've got more bad news.

KWONG: For real?

ROTT: (Laughter) There are concerns that the current coronavirus pandemic is making deforestation worse right now.

KWONG: Well, bah! Humbug!

ROTT: (Laughter).

KWONG: Today on the show - the relationship between deforestation and disease...

ROTT: And how both can make the other worse...


KWONG: OK. Nate Rott, you said that the current pandemic may be making deforestation worse. But isn't the coronavirus kind of a net positive for the environment - because we know that greenhouse gases are slightly down, less road kill because of less traffic?

ROTT: #WeAreTheVirus.

KWONG: (Laughter) Yes.

ROTT: Yeah, I thought the exact same thing, too, Emily. And it is true to an extent. But then I talked to Edward Barbier, an economist with Colorado State University who co-wrote a paper for the World Economic Forum with the environment minister of Costa Rica and a leading conservationist in Columbia on this very topic. And he sort of popped my bubble.

EDWARD BARBIER: The perception that you're getting through the media is that nature's getting a break from the virus. However, what's happening in tropical forests in particular is basically a field day for illegal activities.

KWONG: So how is that - that it's a field day for illegal activities?

ROTT: So what's top of mind for just about everyone in the world right now? The coronavirus - it's leading news coverage. It's closed down economies. It's forced millions of people into unemployment. It's drawing tons of government resources. So governments are preoccupied dealing with this virus, Barbier says, which means there's less enforcement and less attention...

BARBIER: For agriculture, mining, logging - you name it.

ROTT: So there have been stories about more poaching in Africa and Asia since the outbreak started. There have been reports of increased deforestation in Southeast Asia, Africa and South America. In the first four months of this year alone, there was a 55% increase in illegal logging in the Amazon compared to last year.

KWONG: I mean, deforestation was already a really big problem in all of these places. Right? I mean, I remember the fires in Australia and the Amazon just a few months ago.

ROTT: Yeah. I mean, it's been a terrible couple of years for tropical forests. But Emily - so do me a favor really quick - OK? - and count to six.

KWONG: OK - one, two, three, four, five, six.

ROTT: In the time that it took you to do that - in those six seconds it took you to count, the world likely lost about a soccer field-sized area of tropical forest. That's how fast tropical deforestation happened last year.

KWONG: That is just an environmental nightmare. And it's tough 'cause it's tied up with different ' economies.

ROTT: Totally. And you know, to add another layer to this sort of distressing and depressing cake I'm baking for you right now...


ROTT: ...It's those tropical forests that are believed to hold most of the world's pathogens, whether those be viruses, bacteria, fungi - you name it - because those places are so rich in biodiversity.

KWONG: Honestly, I'm going to need some cake after hearing these facts and figures.

ROTT: Don't let me stop you.

KWONG: Well, it's just that these areas that are rich in biodiversity - rich in pathogens like the coronavirus, you're saying, are seeing more deforestation. And I'm thinking how more deforestation could lead to an increased risk of a pathogen jumping from an animal to a human.

ROTT: Yeah, yeah. I mean, unfortunately, that's what epidemiologists and ecologists that I've talked to have said - that it increases the likelihood of a zoonotic spillover. Here's Amy Vittor, who's with the Emerging Pathogens Institute at the University of Florida.

AMY VITTOR: I mean, to think of it as - you know, as we destroy natural habitats, it's kind of like poking a beehive. You know? Stuff will change, and stuff will shake out.

KWONG: And it sounds like some of that stuff will sting.

ROTT: Yeah. There are tons of zoonoses, many that a lot of us are familiar with. You know, we have Lyme disease, rabies, lots of flus - just to name a handful. Most of Vittor's research has been on malaria, which I think is one that most people have heard about. She's documented malaria outbreaks around the world that follow recent deforestation.

KWONG: That makes sense, actually, because if you clear forests, you might have more ponds or places for mosquitoes to make babies.

ROTT: Yeah. I mean, there's a reason the Great Lakes have so many stinking mosquitoes, right?

KWONG: Right - but how does deforestation increase the risk of people getting something like Ebola exactly? Is it just because of proximity?

ROTT: So proximity is definitely a factor, and we'll get into that in a minute. But there's another theory that scientists are looking at, too, that I love because it involves the idea of a bat sneezing, which I really wish we had a sound for right now (laughter).

KWONG: Well, Nate, today is your lucky day.

ROTT: Oh, my.


ROTT: That little puff is what it is?

KWONG: Mmm hmm.


ROTT: I want to say thank you to all of the producers at SHORT WAVE for bringing me the sound of a bat sneezing.


ROTT: So...


ROTT: ...This theory is basically one about dilution.


ROTT: So think of it like this. Every species - you, me, bats, dogs, wombats - we all carry around a bunch of pathogens. And there's an idea that all of the biodiversity that exists in the world - and particularly in tropical rainforests - helps to dilute all of those pathogens. So here's Christina Faust, an infectious disease ecologist at the Center for Infectious Disease Dynamics at Penn State University.

CHRISTINA FAUST: So if a bat sneezes, it's more likely to sneeze on another animal than a human. But when it's low diversity, there's not much else out there to help pick up that pathogen.

ROTT: Except us...

KWONG: Yeah.

ROTT: And so that's the worrisome part because the world is in the middle of an extinction crisis right now. There's a million species at risk of disappearing, many within decades, because of human activities.

KWONG: So if a bat sneezes, it's becoming more and more likely that adorable virus-filled little sneeze lands on a person.

ROTT: Exactly. And Faust says it's not entirely clear how much of a role that plays in zoonotic spillover compared to physical proximity, the thing you mentioned just a little bit earlier.

KWONG: Yeah. I mean, there's a reason we're all being told to stand 6 feet apart. Viruses need close distance.

ROTT: No doubt, you know? So a bat sneezes and you're a hundred miles away, you're probably good, right? Bats sneezes and you're, like, chilling in your hammock below it...

KWONG: Mmm hmm.

ROTT: ...Maybe not. So that closeness can happen in two ways - right? - human gets close to animal, which happens most of the time, or animal gets close to human. Laura Bloomfield, a Ph.D. candidate at Stanford University, looked at this issue in Uganda near Kibale National Park, where the human population is exploding. And she says that's stressing out the ecosystem, causing animals to venture into human areas more often. And it's causing more forest fragmentation - you know, roads, trails, buildings - each of which increases the edges...

LAURA BLOOMFIELD: Between human landscapes and forested landscapes - so you can kind of think of, like, each those edges as providing a potential opportunity for human-animal interaction.

ROTT: Bloomfield recently had a paper published on this that essentially quantified how much more likely those types of interactions are when that kind of fragmentation occurs.

KWONG: OK. So to summarize, deforestation can lead to more disease in two ways - by killing more species that can dilute pathogens and by creating more places where humans and animals can interact.

ROTT: Yeah. Those are the two leading theories that I heard talking to different epidemiologists about this.

KWONG: OK, Nate. So, what can we do to address that? Did the epidemiologists have any solutions for this?

ROTT: So they said there's a bunch of stuff we can do right now that would help to make a difference. So we can invest more money into research and monitoring different hot spots.


ROTT: We could protect more forests. We could stop illegal logging. We could create buffer zones around forests. We could give targeted aid to hot spots in developing countries to sort of lessen people's dependence on natural resources.

KWONG: OK. So basically changing our global economy (laughter) - easy as pie...

ROTT: Yeah, easy as cake, you know. It's not going to be easy, Emily. I think we all know that. But it is urgent because, as we're learning, the pandemic is speeding up deforestation in different parts of the world. And we now have more evidence that deforestation could lead to future outbreaks.

KWONG: A vicious cycle...

ROTT: It totally is. And Bloomfield says the current pandemic should make clear to people everywhere that even though deforestation and some of these issues that we've been talking about may seem far away, they're really not.

BLOOMFIELD: It gives us the opportunity to really think of these problems globally because what we have seen is that human-animal interaction in one place and the spillover of an animal infection to people can have global devastation.

KWONG: Nate Rott, thank you so much for this reporting.

ROTT: Yeah. I appreciate you taking the time to let me talk about it.


KWONG: This episode was produced by Abby Wendle, edited by Viet Le and fact-checked by me, Emily Kwong. You're listening to SHORT WAVE, the daily science podcast from NPR.


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