The health of wildlife is inseparable from our own: Joe Roman
My daughter and I helped a few leopard and wood frogs cross the road toward a pond. We thought it could be a good year for amphibians, since there was almost no one on the road, except for a few young biologists on foot (not social distancing as far as I could tell).
Moving frogs out of danger gives me a sense of purpose. As I walked the slick dark roads, I thought about how diseases spread among animals and people, and how we respond.
Pathogens and the pet trade
An American toad on a Vermont road. (Credit: Jayson Benoit)
In the past few decades, millions of frogs have disappeared across the globe. The most deadly pathogen known to science is the chytrid fungus Batrachochytrium dendrobatidis or Bd. It strikes the young and the old, with frogs appearing lethargic. As the disease spreads through the skin, essential for respiration, frogs struggle to breathe. Chytridiomycosis kills in about two weeks, which helps spread the pathogen as sick individuals move between ponds, streams, and forests.
The disease caused the extinction of more than 90 frog species, including several harlequin frogs of Central and South America. Many others, such as the Wyoming toad, are extinct in the wild, surviving thanks to the efforts of conservationists who have sheltered them in place to ride out the disease in captivity. Five hundred species have gone into steep decline. Most have not recovered.
The following morning, I called up Karen Lips, a professor at the University of Maryland who helped break the story in the 1990s. As a result of the coronavirus pandemic, she told me, "people understand more about the role of density, epidemic curves, and social distancing."
"We've heard a lot about wildlife markets in Asia," said Lips, "but the U.S. can do something important, too." Amphibians are shipped in containers with no regard to species or home range. The pet trade is where these amphibians meet up and swap diseases.
And once they get to the U.S. or Europe, Lips said, "They escape, they are dumped out in the pond when they die, people pour the water out, and that's all infected." Humans spread the fungus from continent to continent.
Frogs are a sociable bunch for part of the year when they gather together to mate. Many species are highly susceptible to the disease and are at great risk of extinction, whereas some don't seem to show much impact at all. The most vulnerable need our help to quarantine. A few species have been moved to captive-breeding programs, to treat them for infections and keep them from contaminated habitats. For others, the reduction in frog density was like social distancing, limiting contact and disease transmission.
The age of extinction
Deforestation is a major driver of biodiversity loss. (Credit: CodiePie/flickr)
What is this new world? Just as we're in the midst of a sixth extinction event, we have created a new disease-scape, one that is tied to biodiversity loss.
The first disease transition occurred when people began domesticating animals. Diphtheria, influenza, smallpox, and tuberculosis are a few of the highly lethal diseases we got from cattle, ducks, pigs, and other animals that live near people. As human communities became larger and more connected, virulent forms of these pathogens evolved.
The second epidemiologic transition occurred during the Industrial Revolution. As life expectancy rose in the nineteenth century, in part because of lower childhood mortality, chronic diseases emerged as the greatest health challenge. Air and water pollution were linked to higher rates of cancer, birth defects, and neurological problems.
As some pollutants were curtailed in the late twentieth century and antibiotic use became widespread, it looked like we could defeat chronic and infectious disease. But then came the stark reality of the AIDS crisis. Some epidemiologists proposed that we had entered a new disease-scape.
This third transition affects humans, animals, and the ecosystems that surround us. Ecological disruptions such as overhunting, deforestation, and industrial agriculture have helped release zoonotic diseases into human populations, creating novel environments where they prevail.
The age of extinction goes hand-in-hand with this new disease-scape. Like the frogs before them, many North American bats are in the midst of a pandemic. Millions died overwintering in their caves after a fungal pathogen entered the northeast U.S. from Europe around 2006.
When I first moved to Vermont, a summer ritual was watching the bats forage for insects over our barn. The skies are mostly empty in the summer now, if you can ignore the mosquitoes.
Like bats and frogs, modern humans tend to form dense clusters that were once relatively isolated from each other: people in cities, bats in caves, and frogs in their breeding ponds. Such clusters are adaptive; they can provide warmth, breeding opportunities, and commerce. But in the age of global homogenization, they put us at risk.
With wildlife markets as generators for disease transmission between species, and humans moving about the world between dense locations, it is hard to see how we end this.
Now that we understand the consequences of globalization, what can we do?
Control disease, reduce markets, and bolster wildlife
Credit: Nik Anderson/vperemen.com
Control wildlife diseases. As is true for the spread of coronavirus, the transmission of wildlife diseases will not be curtailed by voluntary measures. "We're all about building walls these days," said Lips. "I hope if we learn anything from this coronavirus it's that unregulated wildlife trade is a problem for many reasons…the focus tends to be on rhinos and elephants, but the smaller stuff is important, too,"—especially for quelling introduced pathogens.
We have learned to shelter in place in a few short weeks—and very long days. We can change how we relate to wildlife, putting their health, and our own, before commercial interests.
New York Senator Kirsten Gillibrand has presented strong legislation to Congress to reduce disease transmission. The Invasive Fish and Wildlife Prevention Act would establish stringent quarantine measures for imported species.
Reduce wildlife markets. The commercial use of wildlife is morally questionable, unsustainable, and unhealthy for humans, wildlife, and ecosystems. After the outbreak of the coronavirus, China announced a temporary ban on wildlife trade and permanent closure of wildlife food markets. With powerful constituencies aligned against those closures, there are signs that the decree could lapse, much as it did after the SARS epidemic in 2003. The trade ban should be permanent, with help going to farmers and other workers affected by the ban. Vietnam, one of the largest traders in wildlife, has committed to stopping illegal trade. Enforcement will be key here, since poaching and the black market have operated for years, with profits rivaling the illegal drug trade.
Given the widespread support for controls on native mammals and birds, we should also protect reptiles, fish, and amphibians. In the U.S., the commercial pet trade continues to grow: 82 percent of states allow some form of commercial use of native amphibians or reptiles. This trade should be limited, and no animals should be shipped with other species and populations, where they can spread disease.
Increase wildlife. We should consider wild populations and native ecosystems as life support, rather than a larder for us to exploit. Let's restore Earth's remaining wild places, and the wolves, whales, pangolins, and mountain lions, the bats, frogs, fish, and native insects, that we've driven close to extinction.
Vermont roads were eerily quiet for much of the spring, but as travel restrictions have been lifted, we've noticed more dead frogs and toads.
Before we humans come roaring back, let's slow down and let the coronavirus pandemic teach us what we have yet to learn: the health of wildlife is the same as our health.
Joe Roman is a conservation biologist and author based at the University of Vermont. His research and writing focus on the conservation and ecology of endangered species, and he has worked on the connections between biodiversity and human health for more than a decade.
His views do not necessarily represent those of Environmental Health News, The Daily Climate or publisher, Environmental Health Sciences.
Banner photo: A spring peeper in Maine. (Credit: Fyn Kynd/flickr)
