Transcript for Chronic Wasting Disease
What is CWD (chronic wasting disease)?
Mark Drew, Wildife Veterinarian: CWD is the acronym for chronic wasting disease, which is a prion disease that’s found in ungulates—in deer, elk, moose, and now caribou. A prion is basically a misfolded protein. We all have proteins in our body that are in a certain structure, and this particular protein that we call a prion is misfolded, so it’s almost backwards.
A close-up view of brain tissue of CWD-infected mule deer is shown through a microscope. Lesions give the tissue a spongy appearance.
Mark Drew: And that misfolded protein is the thing that seems to be associated with the disease that we call chronic wasting disease.
How is CWD (chronic wasting disease) spread or transmitted?
Mark Drew: We don’t know, and that’s one of the dilemmas. When the protein misfolds, it seems to be much more resistant to being destroyed than the normal protein. So, the transmission, then, is really something that we don’t understand. We don’t know how it goes from animal to animal. We know that animals that are affected with chronic wasting disease excrete prions in their saliva, in their urine, in their feces. It’s in their nervous tissue. It’s in their lymph tissue. It’s in their skeletal muscle. It’s in their blood.
So, the animals have lots of places that the prions can be and be released into the environment. But we don’t know how that protein goes, then, from the environmental contamination to another animal, because it’s not a living thing. It’s not a bacteria. It’s not a virus. It’s not a parasite. It’s not living, so how it goes from an animal to the ground to another animal or direct transmission from an animal to an animal—we don’t understand, because it’s not a living agent.
What is the cure for chronic wasting disease (CWD)?
Stacy Dauwalter, Wildlife Health Biologist: There is no cure for CWD.
Mark Drew: If an animal gets chronic wasting disease, it’s a uniformly fatal disease.
Stacy Dauwalter: This is a disease that will eventually kill the animal.
Mark Drew: It takes sometimes months to years for animals to die of chronic wasting disease, and they typically don’t die of chronic wasting disease. They die of starvation. They die of aspiration pneumonia, those kind of things that CWD seems that predispose them to. But if you get a prion disease as a deer or an elk, it is a fatal disease.
How can hunters help with the threat of chronic wasting disease (CWD)?
Matt Pieron, Wildlife Biologist: The biggest thing that hunters can do is—I mean, number one’s stopping at our check stations.
On screen: Mores Creek Check Station Near Boise
Matt Pieron: Hunters are an integral part of this. We need to get as many hunter-harvested animals as we can to test for chronic wasting disease.
At a sampling station, Stacy Dauwalter prepares to take a sample from a harvested quadruped.
Stacy Dauwalter: I’m going to take a sample from the throat.
Matt Pieron: In different years, we’ll be sampling in different locations. So, it really won’t be anything different as far as what hunters are used to, that we’ll have our check stations out there. And folks are just going to need to be patient. If we’re sampling in your area, we’re going to need to get as many lymph nodes from the animals that we can.
At the sampling station, Stacy Dauwalter uses a knife to cut into the neck of a harvested quadruped that is on the back of a hunter's truck. She points to the animal's exposed lymph node as she speaks.
Stacy Dauwalter: So, first lymph node is right here. The disease will show up in the lymph node first, and it will progress through deer in a way that it will then house itself in the obex, which is the brainstem. So that’s why we take all the information—his tag number, location, age of the animal, species—because we want to be able to find what location we detected it at in the state, and we also want to be able to tell the hunter that we found chronic wasting disease in his animal.
Matt Pieron: In the past, we’ve sampled for CWD statewide every year. What we’re switching to now is we’re going to sample in certain parts of the state, and we’ll rotate around the state. The reason we’re doing it this way is we need to get a lot of samples for a given population to be confident in our ability to detect the disease, and if we spread our samples out all over the state, it reduces our ability to do that.
Voiceover: However, check stations alone will not be enough to get the sample numbers needed. So, for those areas in the yearly rotation, Idaho Fish and Game asks hunters who do not pass through a check station to voluntarily bring in their adult deer heads to Fish and Game offices. The staff will then remove the lymph nodes.
Stacy Dauwalter: We need heads have a little bit of throat in them. So, if they’ll feel for the hard cartilage in the throat and cut just beneath it and then bring in the rest of the head, that would be perfect. They can bring it to any regional office. We are requesting samples from adults and yearlings. Fawns are a little too young to have detected it and for the prion to have been built up in the body.
Report sick-looking deer, elk, and moose.
Matt Pieron: Anytime a hunter—or not even a hunter, any citizen, for that matter—if they do see a sick animal, something doesn’t look right, they should call us immediately, and we’ll come out and assess the situation. But the probability of a sick animal having CWD is much higher than just animals randomly harvested, so those are going to be critically important moving forward to detect CWD.
Zach Lockyer, Wildlife Biologist: I want the public to know that it’s a very important topic, and that this disease could have impacts to their experiences, whether they’re hunters or wildlife watchers, and that being informed and engaged is going to be important and really help us manage the disease if it ever does show up in Idaho.
On screen: [Idaho Fish and Game logo] © Idaho Fish and Game