A Tiny Twisted Protein, A Big Problem For Wildlife
This segment is part of The State of Science, a series featuring science stories from public radio stations across the United States. This story, by Rae Ellen Bichell, originally appeared on the Mountain West News Bureau and KUNC.
You may be familiar with bovine spongiform encephalopathy, better known as mad cow disease. Did you know there’s a lesser-known—but similar—illness that affects deer, moose, and elk? It’s called chronic wasting disease, and like mad cow, it is also a brain disease, thought to be caused by a malformed, twisted protein called a prion. CWD leads to unusual behavior, and often results in the animals becoming gruesomely thin before they die. First discovered in 1967, CWD now has been detected in at least 26 states, three Canadian provinces, Norway, Sweden, and South Korea.
Rae Ellen Bichell, a reporter with the Mountain West News Bureau and KUNC, explored chronic wasting disease in a multipart series titled “Bent Out Of Shape.” She joins Ira to talk about the disease, research into its origin and spread, and what’s known about the possible effects of human exposure to CWD.
Check out the full series.
Rae Ellen Bichell is a reporter for the Mountain West News Bureau and KUNC. She’s based in Greeley, Colorado.
IRA FLATOW: This is Science Friday. I’m Ira Flatow, coming to you today from the beautiful studios of KUNC in Greeley, Colorado. And later in the hour, we’re going to be talking about some of our favorite science books to enjoy during your summer downtime. And we want your suggestions. What science book is on your summer reading list this year that you would suggest that we read also? Give us a call. Our number– 844-724-8255. Also, you can reach us at 844-SCI-TALK, or tweet us @scifri. But, first–
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IRA FLATOW: It’s time to check in on the state of science, and we mean by that local science stories with national importance. Now, you may be familiar with what’s called mad cow disease, more technically known as bovine spongiform encephalopathy. But you may not be aware that there’s a similar disease that affects deer, moose, and elk. It is also a brain disease that leads to unusual behavior, and the animals become gruesomely thin before they die. It’s called chronic wasting disease.
It was first discovered in 1967. But it is spreading. It has been detected in at least 26 states, three Canadian provinces, and South Korea. And it’s a topic of concern right here in the Mountain West. Rae Ellen Bichell is a reporter with the Mountain West news bureau and with KUNC, and you’ll find links to her stories on chronic wasting disease at Bent Out Of Shape on our website at sciencefriday.com. Welcome to Science Friday.
RAE ELLEN BICHELL: Yeah, thanks for having me.
IRA FLATOW: Let’s talk about this. Set the scene for us. What is this illness like? How do you recognize it? What does it do?
RAE ELLEN BICHELL: Yeah, so like you said, it’s a brain disease– neurodegenerative. It actually leaves holes in the brain. And, like you mentioned, it’s in this group of diseases called transmissible spongiform encephalopathies, which basically just means contagious spongy brain. So that gives you a pretty clear picture.
That ends up impacting behavior. It’s weird for a lot of reasons, including that it can take a really long time, sometimes years, before an infected animal actually starts to look sick. I went out with Heather Swanson, who’s a wildlife biologist with the city of Boulder. She was checking on some deer that she’s monitoring. And a lot of the ones that they are pretty sure are infected actually looked really healthy. But she and some other researchers have been studying which animals get eaten by mountain lions. And she said this.
HEATHER SWANSON: The mountain lions were definitely preferentially selecting deer that had chronic wasting disease over those that were negative. And for most of the ones that they had killed, we had not detected any chronic wasting disease symptoms yet. So, certainly the lions were able to key in on far more subtle cues than we were.
IRA FLATOW: Wow, that is interesting. And it was originally discovered here in Colorado.
RAE ELLEN BICHELL: It was, yeah. Back in the 1960s, there were some researchers up in Fort Collins, which is just a little bit west of us. They were studying deer, trying to answer some questions about winter nutrition, but the research animals kept getting sick and dying. And they eventually looked at samples of their brains and saw these holes and realized this was something trickier than they expected.
IRA FLATOW: And they found the cause of what was causing that?
RAE ELLEN BICHELL: Yes, it was a prion. So we’re talking about this class of diseases. It’s not your typical pathogen. Usually, we think about things that make you sick– that’s viruses, bacteria, maybe fungi. This is none of those. It’s just a protein.
So, basically, all healthy mammals have this protein in our healthy bodies. It’s not really known why we have them. Researchers are looking into that question. But we all have them. And the problem arises when– it’s all about the shape of the protein. So problems happen when your healthy prion proteins come in contact with a misshapen bad version, essentially.
IRA FLATOW: So, as you mentioned before, it’s very similar to mad cow or other kinds of misfolded protein diseases.
RAE ELLEN BICHELL: Yeah, it is, in that they’re all caused by prions. There’s been some discussion, especially in the last year or so, it seems, about whether this prion disease could become like mad cow disease in its ability to jump between species.
IRA FLATOW: And that’s the thing. You said it’s not like the flu. It’s not a virus. It’s a misfolded protein, but it is contagious. Right? It can spread from animal to animal.
RAE ELLEN BICHELL: It is. And that’s one of the things that distinguishes chronic wasting disease from other prion diseases. So, in the case of mad cow disease, or other prion diseases, often the infectious material– those misshapen proteins that we were talking about– stay pretty contained in the brain and the central nervous system.
So to pick two examples, in mad cow disease, the general thought is that cows spread it to each other, or obtain the disease by eating feed that was contaminated with other cow brains. And, then, a really crazy example in people, actually, was found years ago in Papua New Guinea. A prion disease was being passed in these groups of people who were, as part of their funerary practices, eating the brains of the deceased.
So, usually contained in the brain, but in this case with chronic wasting disease, it’s not contained in the central nervous system. It spreads in a lot of ways. So infected animals, we talked about deer and elk, moose. They shed the infectious material in pee, poop, blood, saliva. It’s a lot more opportunity to expose other animals.
IRA FLATOW: Well, if you’re a hunter and you’re hunting some of these deer, and you don’t know that they’re infected with the wasting disease, can you eat them– an infected animal– and also get sick yourself?
RAE ELLEN BICHELL: There’s a lot of questions about that right now. And it’s something that public health departments in this region are monitoring pretty closely. There so far haven’t been any cases of human prion disease that could be linked to eating wild meat. But researchers really have not ruled that out as a possibility. It’s under active investigation. I can go into more detail on that if you’re interested.
IRA FLATOW: Yeah,
RAE ELLEN BICHELL: Yeah, so there’s a big study right now going on in Canada that’s looking at macaque monkeys. And the question there– it’s a decade-long study. It’s supposed to wrap up in less than a year or so. Should have some answers on that.
They infected these macaque monkeys, which are pretty similar to people in terms of genetic makeup. They infected them with chronic wasting disease prions in a number of different ways, including through their stomachs, and straight into the brain. And the researchers there say that they, so far, in preliminary findings, have found some evidence that the monkeys did get chronic wasting disease.
But there’s a lot of things that make that study really complicated. For one, these are all preliminary findings. They have not been published in peer-reviewed journals.
And then, also, there’s this issue that came up in talking to those researchers that a lot of the monkeys also have diabetes. And that could also cause some of these symptoms that they were seeing.
IRA FLATOW: But we don’t know how– have the researchers you’ve talked to talked about the dangers of people thinking how it might spread?
RAE ELLEN BICHELL: Oh, yes. So how it might spread is a big question, because it can be spread in so many different ways. It’s not clear which one of those routes– saliva or blood or something else– actually leads to infection.
What is really complicating the matter is that there’s evidence that, in addition to it being spread in a bunch of different ways that people could come into contact with, that there might also be a number of different versions of this illness. That it might not all be one thing.
IRA FLATOW: Now, you talked to reindeer farmers in Norway and Sweden. Is this a problem that they’re talking about, also?
RAE ELLEN BICHELL: Yeah, so chronic wasting disease was identified in the Nordic countries pretty recently– Finland and Norway, and then just a few months ago in Sweden. There is concern there among reindeer herders and reindeer farmers. I lived in Finland for a number of years, so I know firsthand that reindeer herding is really big in that region. It’s a huge part of their culture. And a member of the Sami reindeer herders association of Norway told me that if CWD spreads to their semi-domesticated animals, that quote “it could easily wipe out the entire Sami reindeer husbandry culture.”
IRA FLATOW: No kidding.
RAE ELLEN BICHELL: So a lot of concern there about that.
IRA FLATOW: Wow. What are wildlife officials doing to try to contain the spread of CWD? Can they do anything?
RAE ELLEN BICHELL: Yeah, there’s not a lot you can do, or at least not a lot you can do easily and seemingly effectively. So here in Colorado, where we’ve got about 57% of the deer herds that are infected–
IRA FLATOW: We have that many?
RAE ELLEN BICHELL: Pretty high number, yeah. The gist of the plan here in Colorado is monitor the infected herds for a long time. Do a lot of trial and error to see before and after what works. And a lot of that has to do with letting hunters hunt more in certain areas, or hunt more of a certain kind of animal. There’s also this move to reduce anything that would concentrate a lot of animals in one place. So feeding wildlife in the winter or providing salt licks.
But then there’s also some effort to get the word out more about this disease to people who handle meat and bodies, so hunters, taxidermists, meat processors.
IRA FLATOW: Is there any way if you suspect that something may be contaminated– I guess, the first thing to do is just don’t touch it. But if you’re not sure, can you disinfect it? You know, we use disinfectant on other kinds of pathogens. Can you use it on prions to try to disinfect the meat?
RAE ELLEN BICHELL: Prions are really hard to destroy. An example that’s really stuck with me from past reporting, not on this particular prion disease, but sometimes in cases where surgical teams were operating on people realized that that patient has a prion disease, they often just get rid of– they landfill all the equipment they used during the surgery.
IRA FLATOW: It’s like nuclear waste.
RAE ELLEN BICHELL: It’s really tricky to disinfect it. The normal routes don’t work.
IRA FLATOW: What happens next? Is there legislation? I mean, we always get down to following the money. Is there any legislation to try to research this, to try to find a better fix for it?
RAE ELLEN BICHELL: Well, I should say there is already a lot of people who are researching this, who have been researching this, who will continue to research it. But there are a bunch of bills about chronic wasting disease that have been introduced in this session, including three in the Senate. They’re basically about giving more money to research the disease, especially to figure out how to keep it from spreading.
IRA FLATOW: Well, thank you very much Rae Ellen.
RAE ELLEN BICHELL: Yeah, thanks for having me.
IRA FLATOW: Rae Ellen Bichell is a reporter with Mountain West news bureau and with KUNC. And, as I said before, you’ll find links to her series on chronic wasting disease, Bent Out Of Shape. It’s on our website at sciencefriday.com.