Outstanding in the Field (Ep 3): Chronic Wasting Disease - Oh, Deer

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Welcome, and thanks for tuning in to this episode of Outstanding in the Field, brought to you by the USGS Ecosystems Mission Area. We’ve been highlighting the USGS’ critical and quirky research on animals and ecosystems across the country. I’m Marisa Lubeck.

In this episode we’ll be talking about chronic wasting disease, or CWD, a fatal and contagious wildlife disease that’s of great concern in North America. It’s as ominous as it sounds, causing brain damage that leads to its victims slowly wasting away to death. Discovered in 1967, CWD affects both free-ranging and captive animals in the deer family, including white-tailed deer, mule deer, elk, and moose. The disease is spreading across the landscape and within affected populations; it’s been detected in over half the U.S. states as well as Canada, South Korea, and Norway, Finland, and Sweden. There’s currently no treatment or vaccine.

As far as we know, CWD does not affect humans or livestock – there’s a sort of species barrier preventing this. So why are scientists and wildlife managers so concerned? Bryan Richards works at the USGS National Wildlife Health Center in Madison, Wisconsin. Bryan is an expert on CWD – he’s practically dedicated his career to it – and he has some thoughts.

[Bryan speaking] “I regularly hear from folks that, well, CWD doesn’t matter, there’s still lots of deer out there, people don’t get it, why should we care? And the refrain to that is that we have these characteristics – increasing geographic footprint, increasing prevalence, and population-level impacts – can you name any disease of humans, of domestic livestock, of wildlife where we would have these characteristics and say, ‘Eh, that’s no big deal’?”

Animals in the deer family are also valuable, both environmentally and economically. They’re critical to biodiversity, serving as a middle link in the food chain between the plants they consume and the predators that prey on them. Deer and elk are valued by people for food, they’re culturally important to Tribal communities and hunters in North America, and they contribute to the economy through hunting licenses and hunting expenditures.

So, what do we know about CWD? What is science telling us? What is this thing? Here’s Dr. Camille Hopkins, the Wildlife Disease Coordinator for the USGS Ecosystems Mission Area:

[Camille speaking] “CWD is the only prion disease that’s affecting free-ranging wildlife.”

A what disease?

[Camille speaking] “A prion is an abnormally folded protein. Prions are able to spread or infect other proteins in the brain to switch from a normal protein to an abnormally folded protein. This takes time, and that’s why it’s called chronic.” 

CWD is similar to another well-known prion disease – mad cow disease - and, for affected animals, it’s always fatal.

In order for wildlife managers to make the best policy decisions possible, they need access to the best CWD science available. That’s where the USGS comes in. Right now, the main method for managing CWD once it’s detected is reducing the animal population size. New and ongoing USGS research can help managers refine this approach or even help develop additional, innovative strategies. Our experts conduct research to support early detection and risk assessments, they do both laboratory and field studies to better understand the disease, and they maintain an online map of CWD occurrence. Also, right now, the only reasonable way to detect CWD is when an animal has died, collecting tissue to look for the prions. But, the USGS is testing ways to look for prions from living animals:

[Camille speaking] “An exciting new effort is that USGS scientists are looking into developing live animal tests to look for prions in biological samples as well as samples from the environment.” 

And, as Bryan explains, the USGS is using science to help predict the spread of CWD:

[Bryan speaking] “Some of the most innovative work that’s been accomplished by USGS has been in the modeling realm. Our scientists have been able to better articulate and predict how CWD is advancing, moving geographically across the landscape, and how it might move in the future. And also there’s a tremendous body of work about disease dynamics or transmission within individual herds where CWD has been detected.”

Tackling a massive wildlife health issue like CWD is a mighty task, so the USGS is doing it with a little help from our friends. Actually, a lot of help from a lot of friends. Since CWD outbreaks can occur in captive animals in, for example, deer farms, the U.S. Department of Agriculture works with the Department of the Interior to study and manage the disease. The USGS also works with the National Park Service, the Fish and Wildlife Service, state wildlife agencies, universities, and even the medical industry.

Remember when I said that CWD doesn’t affect humans? That there’s a species barrier keeping CWD within the deer family? That’s true, I wasn’t lying, and science suggests that the barrier is robust, but…

[Bryan speaking] “…that science also suggests that that barrier is not absolute. So in response to the science that’s been done, the World Health Organization and our own Centers for Disease Control have come out with some guidance. Out of an abundance of caution, they suggest that no part of any animal with CWD be consumed by humans.”

So, hunters, if you’re in an area where CWD may occur, contact your state wildlife agency for more information on the potential risk.

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There’s so much more to learn more about USGS research on chronic wasting disease. Keep learning on our website at usgs.gov.

This podcast is a product of the U.S. Geological Survey, Department of the Interior. Our original artwork is by Jeffrey Kemp, and our theme music is by USGS scientist Marty Fitzpatrick. A big thanks to the rest of the Outstanding in the Field team, Suzanna Soileau, Hannah Hamilton, Sue Kemp, and Catherine Puckett. I’m Marisa Lubeck. Thanks for listening.

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