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Public Radio's Environmental News Magazine (follow us on Google News)

Saving Forests Could Save Us from Diseases

Air Date: Week of

Preventing deforestation is a crucial step in the fight to prevent outbreaks of diseases humans can catch from wildlife. (Photo: Kate Evans, CIFOR, Flickr, CC BY-NC-ND 2.0)

COVID-19 is just one in a line of numerous diseases that have spilled over from animals to the human population, often thanks to deforestation and the wildlife trade bringing infected wildlife close to humans. With the COVID-19 pandemic alone estimated to cost several trillions of U.S. dollars, a new study suggests that spending just a tiny fraction of that to curb deforestation and the wildlife trade could prevent another costly pandemic. Coauthor Aaron Bernstein MD of the Harvard T.H. Chan School of Public Health joins Living on Earth's Bobby Bascomb to talk about the costs and benefits of preventing future so-called zoonotic disease outbreaks.


CURWOOD: From PRX and the Jennifer and Ted Stanley Studios at the University of Massachusetts Boston, this is Living on Earth. I’m Steve Curwood.

Many human diseases actually originate in animals. Think of HIV, malaria, Lyme disease and of course Covid19, scientists call them zoonotic disease. This Coronavirus got its start in the wet markets of Wuhan, China, likely from a bat or pangolin being sold there. More than 660,000 people have died from Covid19 costing trillions of dollars worldwide and we’re still not out of the woods but the answer to preventing future outbreaks may very well lie in the woods. Forests are the source of animals that can carry these diseases. A new study published in Science suggests we could avoid the next pandemic and save trillions of dollars by spending tiny fraction of that to curb deforestation and the wildlife trade. Living on Earth’s Bobby Bascomb is here now. Hi Bobby, now you spoke with one of the co-authors of the report, right?

BASCOMB: Hi Steve, yes, I spoke with Dr. Ari Bernstein he is a pediatrician with the Harvard T.H. Chan School of Public Health. And I started my conversation with Dr. Bernstein by asking him about zoonotic diseases that move from animals to people.

BERNSTEIN: We see the emergence of new diseases, the appearance of new diseases like COVID, overwhelmingly coming from wild animals and to a lesser extent, domesticated animals. And that reflects increasing contact between people and wildlife in particular. And of course, the reality that we live in a highly connected world, with many densely populated cities, that those two things together really amplify. When a disease moves into a person, the chances that it spreads to lots of other people are much higher.

BASCOMB: And zoonotic diseases are actually very common. I've read that something like six out of 10 diseases in humans actually originate in animals. Can you give us some examples that people are familiar with?

BERNSTEIN: Sure, the reality is that we swim in a common germ pool with all other animals. And so there are some diseases like COVID-19 that have come directly from an animal to person. There are other diseases which you know, are in people, but they're sort of a first cousin in other species. A good example of that is something like chicken pox. There are similar viruses. There's monkey pox, there's camel pox. And you can actually have some transmission of those other pox virus into people, but these viruses shared a common ancestor. And of the diseases that people commonly get, you know, there are lots of these zoonotic diseases. You know, there's plenty of examples around the world, whether it's rabies, or Lyme disease, West Nile virus in the United States. And so it's really more the rule, as you point out, than the exception. And so we shouldn't be terribly surprised that when we're changing life on Earth at such a rapid rate today, that we're sort of stirring the pot of the common germ pool, so to speak, and that these diseases, particularly viruses, tend to pop out into people.

BASCOMB: And in your paper, you list several ways to help prevent future zoonotic outbreaks like COVID-19. What are some of those suggestions?

COVID-19 is believed to have started in one of China’s wet markets, likely through consumption of a bat or pangolin. (Photo: Whiz-Ka, Flickr, CC BY 2.0)

BERNSTEIN: You know, the paper came about because a group of folks were bewildered by how much was being spent to deal with one emerging zoonotic virus. And the question was, well, how much would we have to spend to do what we know we need to do to prevent these viruses from spilling over into people. A good chunk of these emerging diseases come from deforestation, and not necessarily the cutting down of trees, per se, but all the activities that come with that. So building of roads, the establishment of settlements in forests, the likelihood that people are going into the forest, not just to chop down trees, but perhaps to gather wildlife. And so we looked at how much it would cost to reduce deforestation in places that are particularly high risk. We know another chunk of emerging infections come from wildlife trade, we see this with, you know, the pet trade, where people import pets from various corners of the Earth and the places and the pets are carrying pathogens. The part of the wildlife trade that we were most concerned with is actually not at the buyer end, it's at the procurer end. It's that there are people who are going out into wilderness and harvesting animals, for pets, for medicines, for furs, for all kinds of stuff. And those contexts are the high risk ones. And we know that because what little work we've done to understand what viruses in particular may be in wildlife shows that there are lots of viruses. And in the case of, for example, coronaviruses like SARS-CoV-2, the virus that causes COVID-19, or the past SARS virus, their natural host is bats and you look in bats, there are lots of coronaviruses in bats. And so as people go into the wilderness, you know, bats are often captured as food, but they're also captured for other reasons. So we focus on what it would take to really address the risks. And the third big area we try and tackle is surveillance. So you know, it's not, I think practical to stop the wildlife trade, it's not going to, we think it's impractical to end all tropical deforestation, as much as I think many people would like to see that. So what we need to do is we need to have much better surveillance of wildlife and people who are at high risk for spillover. And so we try and think through which organizations and what the budget would be to do that, and those are the three big areas.

BASCOMB: So really, what you're calling for then is to limit the human wildlife interaction. What evidence is there that any of these methods, though, that you suggested would actually help prevent the spread of disease?

Deforestation and the side ventures that go along with it, such as roadbuilding and logging, increase the likelihood of animal contact resulting in zoonotic disease spillover. (Photo: Jan van der Ploeg, CIFOR, Flickr, CC BY-NC-ND 2.0)

BERNSTEIN: What we have at this point is proof of concept. So there have been very small scale interventions along the lines we described that have definitely prevented us spillover. A good example of this is Nipah virus in Bangladesh. Nipah virus first emerged in Malaysia in the 90s. And there have been subsequent outbreaks in Bangladesh. And in Bangladesh, the virus is transmitted from bats to people, it turns out through date palm sap. In Bangladesh, palm trees are tapped like maple trees are tapped here in New England for their sap, and there are buckets put on the trees. And the bats like the syrup, so they would defecate into the palm sap. And a very easy way of dealing with that is by covering the buckets. That's a pretty low-cost, low-tech, highly-effective way to prevent spillover. There is also the PREDICT program, which has been much in the news. That was a 10 year program funded by the United States Agency for International Development that works to do viral discovery in bats. It is the reason why we know what we know about the prevalence of coronaviruses in bats in Asia. And looking into those viruses, it gives us a sense of what may be out there. Now, we don't know whether any of those viruses are going to be big problems for people. We don't have the science to know that yet. But it is certainly helpful. And you know, there's a proposal to do that at a much bigger scale called the Global Virome Project that would seek to identify 70% of the viruses that are in wildlife in high-risk areas. And then of course, with the wildlife trade, we've seen bits and pieces of this. I think one of the challenges of the wildlife trade is there's really no entity in the world that's charged with monitoring wildlife for diseases. There's also by the way, work on deforestation showing that protecting forests protects outbreaks, certainly with vector borne diseases, and also other diseases that may come in the forest like Ebola. So we're really calling for a scaling up of this. And we've talked about in this paper how important it is to really do good science around the efficacy of these interventions as they scale up.

BASCOMB: And obviously if we were able to dramatically reduce deforestation and the wildlife trade, that would have many other knockoff benefits as well. You know, tropical forests, of course, are a crucial carbon sink, and it would protect biodiversity, which is in crisis. Can you tell me more about that, please, if you've looked into it?

BERNSTEIN: Sure, yeah, no, it's a critical part of our argument. You know, I think many people would rightly be a bit skeptical of how effective the interventions we propose are going to be. I think we are pretty clear that while we know preventing deforestation and addressing the wildlife trade, and really doing better surveillance, carry the potential to reduce risks of spillover, we can't say with great certainty what the return on investment there is, because we haven't really done it at scale. And so we need to really understand that. But at the same time, if we have your point, which is that we have a bunch of reasons to be doing these things anyway, particularly preventing deforestation is the clearest example. You know, we not only have the carbon value that you alluded to, there's huge water value, so, particularly tropical forests are hugely important to local water resources. There's indigenous rights. But there are other things that protecting forests do, they prevent fires. And so you see, you know, compounding value that occurs when you protect forests. And now we add another dimension, which is prevention of disease spread.

It is estimated that the Covid-19 pandemic will cost the world around $6 trillion in lost GDP in 2020 alone. (Photo: Don Harder, Flickr, CC BY-NC 2.0)

BASCOMB: Well, how much might these strategies cost to implement? And how does that compare to the cost of dealing with the COVID pandemic to begin with?

BERNSTEIN: The COVID pandemic has cost roughly $6 trillion in lost GDP. Governments have spent huge sums of money to try and prop up economies. And on the other side of it, you can put a dollar value to the deaths that have occurred. Economists assign what's called a value of a statistical life. And you come up with a dollar figure, you multiply that by the number of people who have died, and you're talking another several trillion dollars in value there. So the cost of doing what we recommend, so that's substantially increasing the budget for addressing the wildlife trade, putting in measures to reduce deforestation by half, dealing with wildlife trade and surveillance, we estimate those costs to be somewhere around $20 to $30 billion for those. And so when you do the math, you look at $20 to $30 billion versus, you know, $6 trillion in GDP loss, and many more trillion in other expenditures. And it becomes clear that salvation comes cheaply. And even if you spent that $20 to $30 billion, every year for a decade, you'd still only be on the order of 1% to 2% of the costs of this one pandemic. And it's very easy to forget that there's nothing written that this can't happen again. And there's also nothing written that this is the worst pathogen that might spill over into people. So, you know, I think certainly as a clinician, as a doctor, if I had any capacity to prevent the kind of, you know, disease and suffering that this kind of thing did for essentially the cost difference we see here between the prevention actions we're talking about, and the cost of this one disease, I would be committing malpractice not to use it.

BASCOMB: Well, you know, that sounds like a really good investment, but a tall order, with many world economies struggling because of the pandemic. Where would this money come from, and where should it go?

Aaron Bernstein is the Interim Director of the Center for Climate, Health, and the Global Environment at the Harvard T.H. Chan School of Public Health, a pediatrician at Boston Children's Hospital, and an Assistant Professor of Pediatrics at Harvard Medical School. (Photo: Courtesy of Harvard School for Public Health)

BERNSTEIN: Part of the answer to that is easy. The money needs to come from richer countries, and it needs to come from them out of self-interest, because, you know, we can clearly see in the United States that we have a huge problem in this country from a virus that emerged somewhere else. And so we have a direct interest for our own people, for our own economy, in doing things that would prevent the spillover diseases that happen in other parts of the world. And the money would go to places that we know spillover is more likely. And I think, you know, pretty clearly, we can't afford not to do these things. I can't even imagine a situation in which another virus like a COVID emerged in the coming year. And so to not make an investment, which is a rounding error of the massive sums of money that are being spent right now to try and prop up economies, and deal with the virus that's emerged itself is crazy. We would really be foolish to not spend a few percent of the price tag of this one virus to do anything we can to prevent another pandemic like this one.

CURWOOD: Dr. Ari Bernstein, with the Harvard Center for Climate, Health, and the Global Environment. So, Bobby, you’ve spent a lot of time in tropical rainforests, specifically Brazil reporting on deforestation. So, what’s going on in Brazil today?

BASCOMB: Well, not only do they have one of the biggest outbreaks of Covid 19 but after years of protecting the Amazon deforestation is on the rise there again.

CURWOOD: What’s going on?

BASCOMB: Well, Jair Bolsonaro was elected president in January of 2019. He has called climate change a hoax. While much of the world see the Amazon as the lungs of the world, an international treasure, he sees it as a commodity to be exploited for Brazil’s economic gain. He favors more mining on indigenous land, which is constitutionally protected. He’s reduced the amount and number of fines imposed on people who illegally mine, farm and log in the Amazon.

CURWOOD: For years Brazil has worked with the international community to curb deforestation. How have they responded to the new president and his approach to the Amazon?

BASCOMB: Right, the Amazon fund started in 2008 and raised more than a billion dollars to help halt deforestation. The lion’s share of that money came from Norway. Norway has suspended donations and Germany had planned to donate about 39 million dollars to the fund but Mr. Bolsonaro told them to keep their money, Brazil doesn’t want it.

CURWOOD: Wow. That really leaves us in a tough spot. Brazil has the world’s largest rainforest and is so important in terms of sequestering carbon and stopping run away climate change. And now we have yet another reason to curb deforestation to prevent future outbreaks of diseases like Covid19 as Dr. Bernstein told you earlier.

BASCOMB: Yes, exactly. The idea has been to pay for the ecosystem services that rainforests provide and now we see a standing forest provides yet another service, housing the animals that can transmit deadly diseases if they come in contact with people. But Mr. Bolsonaro’s track record doesn’t suggest that he’s going to be open to that. Although, after downplaying the seriousness of Covid19 he did actually contract it himself so maybe there’s hope.

CURWOOD: Thanks, Bobby. That’s Living on Earth’s Bobby Bascomb.

NOTE & CORRECTION: Dr. Bernstein reached out to us on August 2nd with the following correction: "In the interview I said that chicken pox was a human variety of a pox virus with analogues in other animals (eg camel pox). I should have said small pox, not chicken pox. Chicken pox is a kind of herpes virus (which, for the record, are closely related to the pox viruses, and we treat these with the same medications, eg)."



Read “Ecology and Economics for Pandemic Prevention” in Science

Harvard T.H. Chan School of Public Health | “Solutions for Preventing the Next Pandemic”

Read a Q&A with Dr. Aaron Bernstein on the connections between climate change and COVID-19

The Harvard Center for Climate, Health and the Global Environment (C-CHANGE)

About Aaron Bernstein, MD


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