The Deadly Proteins Stalking Deer
You’ve heard of viruses, bacteria, and fungal infections. But what happens when disease is caused by misfolded proteins? Prion diseases, as they’re called, infect the central nervous systems of animals all over the world, including sheep scrapie, Mad Cow Disease, and even a new one recently discovered in camels.
In deer, the prion that causes Chronic Wasting Disease will stay undetected for years before a deer suddenly stops eating and begins to waste away. Always fatal, the infection spreads from deer to deer, and even lurks in soil—and it’s reaching new parts of the U.S. and the world every year. Judd Aiken, a professor at the University of Alberta, explains how prions like those that cause CWD interact with different soil types to bind to minerals and become more infectious… or pass harmlessly through. He describes new research about how humic acid, a product of organic matter in soil, seems to degrade prions and reduce the infectivity of CWD.
And, as deer hunting season wraps up for the year, Wisconsin Public Radio reporter Rich Kremer takes a look at how the state of Wisconsin has been trying to manage the spread of the deadly disease in an unusual location: captive-bred deer farms.
Plus, a holiday treat from a piano-playing robot hand.
Rich Kremer is a reporter and talk show host at Wisconsin Public Radio in Eau Claire, Wisconsin.
Judd Aiken is a professor in the Center for Prions and Protein Folding Diseases at the Department of Agricultural, Food and Nutritional Sciences at the University of Alberta in Edmonton, Alberta, Canada.
IRA FLATOW: This is Science Friday. I’m Ira Flatow. Where does disease come from? Maybe you think the answer is a virus, bacteria, maybe fungi. Would you ever stop to think that a protein could make you sick? Well, that’s what’s happening in prion diseases like mad cow, sheep scrapie, Creutzfeldt-Jakob disease.
Misshapen proteins become infectious and eventually get into the brain, where they cause all kinds of degenerative symptoms. And in the world of prion diseases, one is really leaving its mark here in the US, chronic wasting disease, which has been found in deer. More than two dozen states now, three Canadian provinces, as well as Korea and Finland, and even reindeer are infected.
One line of attack into slowing the spread. Well, it’s the soil. Prions in soil are a key to chronic wasting disease, but not all soils are created equal. Here to explain more is Judd Aiken, professor in the Center of Prion and Protein Folding Diseases at the University of Alberta in Edmonton, Alberta. Welcome to Science Friday.
JUDD AIKEN: Very good to be here. Thank you.
IRA FLATOW: Nice to have you. It’s still so mysterious to me that something as simple as a protein can actually cause disease. Describe how pro– how prions actually work to infect the host.
JUDD AIKEN: Yeah, it’s not simple. But basically with regard to chronic wasting disease, the disease agent has taken up this abnormal form of the prion protein is taken up by the animal. It enters– we first detected in the lymph system. It eventually migrates into the brain.
The abnormal protein is neurotoxic to brain cells. Now this is a protein that all mammals have. The sequence varies from species to species.
It’s not an issue– the normal form of the protein. Where the problem comes in is if an animal or a human for that matter gets exposed to this abnormal form, which is structurally different. It’s an aggregate of a protein, and it is very difficult to degrade. And as I said, it is neurotoxic.
IRA FLATOW: Why then is the soil such a key component of chronic wasting disease?
JUDD AIKEN: Service deer, moose, elk shed– infected deer, moose, and elk shed infectivity into the environment. It’s released in saliva, urine, feces, and so it will interact with soils. And it binds to soils and can be a source of infection to other animals.
IRA FLATOW: And your group found that organic matter might help determine if prions become infectious or not?
JUDD AIKEN: Yeah. Well, what we’ve– we been working on this for many, many, many years, and some of our studies looked at soil minerals. This was looking– more recently we’ve looked at organic material, and what we found was that humic acid, a component of soil– organic material component of soil– has the ability to degrade the prion protein, reduce the amount of abnormal protein, and reduce infectivity. I want to stress that this does not completely eliminate infectivity, but it we certainly saw a reduction.
IRA FLATOW: So it’s not going to– it’s not the sole answer then is what you’re saying?
JUDD AIKEN: I think it’s a great starting point. It’s not easy to find something that effectively degrades the abnormal form of the protein. They’re very resistant to all sorts of treatments.
IRA FLATOW: The soil is not the only way that the deer get it. They all– the CWD, they also get it from each other correct?
JUDD AIKEN: Yeah. There’s clearly animal-to-animal transmission that can occur. The disease agent is in saliva for example. And then there’s animal environment to animal. A lot of debate in the scientific and CWD world about the ratio of those, but both certainly do occur.
IRA FLATOW: Going now with the origin of where it first started?
JUDD AIKEN: Well, I don’t really know the origin. We know the location it first started was in Colorado and Wyoming probably in the mid 1960s. But as you indicated in your initial comments, it is spread quite a bit since then.
IRA FLATOW: How do we know about getting back to treating this soil with humic acid? How do we know– how much do we know to prevent the spread of CWD?
JUDD AIKEN: Well, I’m not proposing treating the soil with humic acid. What I’m saying is that humic acid in the soil can degrade prion protein. We have really few options right now on controlling it. And this is always a fatal disease, I should emphasize.
IRA FLATOW: Yeah, and I guess then that’s a call out to Wisconsin people, people who are around deer, about being careful about eating in the hunting season.
JUDD AIKEN: Let me talk about the human risk because this is important. This disease gets lumped with mad cow disease, which is a known zoonotic, i.e. mad cow, bovine spongiform encephalopathy, does– has been documented to transmit to humans. There is no evidence chronic wasting disease transmits to humans.
That’s not to say it can’t happen or hasn’t happened, but we have no evidence it does. The disease– maybe putting a lot more positive– the disease appears to be more like sheep scrapie. And sheep scrapie has been around for a couple hundred years, and we’ve not seen a human case linked to that.
IRA FLATOW: That’s the good news.
JUDD AIKEN: We have no evidence– I’m sorry. We have no evidence that it transmits to humans, but there is uncertainty there.
IRA FLATOW: I’m going to zoom in for a second on the practical side of chronic wasting disease. Sick deer and how to manage them. In Wisconsin, CWD was first detected in 2002. And the state has been trying to manage the spread ever since. And one area where that gets complicated, the state has many captive breeding operations where deer are provided for hunters, and those deer, too, are getting sick. Wisconsin Public Radio reporter Rich Kramer is here to explain more. Welcome to Science Friday.
RICH KRAMER: Thanks for having me.
IRA FLATOW: Let’s talk about why our captive deer a disease management problem in Wisconsin. Aren’t they behind fences?
RICH KRAMER: They are. Wisconsin has, like many other states, has a number of deer farms, around 380, and those are broken down generally into two categories. You’ve got your breeding farms and then hunting preserves, where they sell hunts for trophy deer.
So there has long been a concern about these farms as a potential source of CWD because it’s a concentrated area. Deer are in contact with each other, close quarters. So the thought is that if it gets on these farms, it can spread quite quickly. And through some reporting, we found out that in 2013, our state’s Department of Agriculture, Trade, and Consumer Protection changed policy to allow some of these facilities to continue operating even though they’ve got the disease on the landscape.
IRA FLATOW: You also talked to a deer farmer whose deer seemed to just get sick out of thin air right?
RICH KRAMER: That’s right. I talked with Greg Flees. He’s considered one of the biggest names in deer farming not only in Wisconsin but also nationwide. He said that he had trouble believing that one of his animals tested positive, and he suspected that the disease was already on the land when he bought it, fenced it in, and turned it into a hunting preserve.
GREG FLEES: We never took a deer from anywhere else other than this farm that’s never had a positive. We put them on to that property, and once they were on that landscape for a while, obviously we started get some positives. And it was one the first year, a handful the second year, and it’s gotten to be more and more.
IRA FLATOW: So then the deer farmer, CWD is a problem for their businesses.
RICH KRAMER: Oh, absolutely. Wisconsin has rules that if you do contract CWD, you cannot move deer to other farms. And for a breeding facility that either sells animals to these hunting preserves or to other deer farms for genetic– to incorporate some new genetics into their lines, that’s a death sentence for that business. So they are concerned about it, but they also stress that they’re not the source. They try to distance themselves as much as possible from the accusations that they are just contributing.
IRA FLATOW: So what about then the wild deer? Did they need to be kept safe from the captive deer, or is it vise versa?
RICH KRAMER: Well that–
IRA FLATOW: That’s what the farmer– the deer herder seem to be saying.
RICH KRAMER: Absolutely. Yeah. That same concern about the CWD coming from the outside in, it’s the same concern from the– about the inside– going from the inside of the farm to the outside to the wild deer. And this is why a lot of talk has been happening in Wisconsin about requiring an additional fence, two fences that are 8 feet tall. But even that has been tough to get any action on. Right now there are rules in the works, but there’s a lot of pushback from the deer farmers because they say it’s very expensive and could put them out of business.
IRA FLATOW: I see that. I know that deer hunting season is wrapping up for the year, so let’s talk about what’s next for the CWD problem in Wisconsin. Can it be contained?
RICH KRAMER: Well, it is spread– as you mentioned, the first cases were in 2002. Right now we’ve got 55 counties across our state that have been listed as CWD affected. Just this year alone, there was a record number, I believe, it was 900 positives. And overall since 2002, there have been 5,000, so the disease is definitely spreading.
There have been efforts to try to contain it, and we’ve got new leadership in the governor’s office. And this new governor has been pledging to do more science– of a science-based approach to try to keep the disease from continuing its spread across the state.
IRA FLATOW: Thank you for enlightening us, Rich.
RICH KRAMER: Thanks for having me.
IRA FLATOW: Wisconsin Public Radio reporter Rich Kramer. Good reporting on what’s going on in Eau Claire, Wisconsin. I want to also bring back our guest Judd Aiken, professor in the Center of Prion and Protein Folding Diseases at the University of Alberta in Edmonton. We just heard from the management problems about them in Wisconsin. Are prion diseases easy to manage in general?
JUDD AIKEN: Oh, geez. They are a huge, huge challenge. First of all, we have no treatment. Second, the animals appear healthy for most of the disease, i.e. if you’re shooting an animal in area that has CWD, you can’t look at that animal and say whether it’s infected or uninfected unless it’s very far into the disease clinically. That’s a problem. The testing requires a laboratory. And generally you’ve got to be looking at a large number of animals– if it’s early in the disease in an area, you got to be looking at a large number of animals. And you get a detection system that is rather clunky at best because we have to be able to distinguish abnormal form of a protein from a protein that is already there, normal form of the protein. They’re just structured differently.
IRA FLATOW: What about– are there prion diseases that are threatening to people? You said this is very low chance of people getting infected from CWD. What about other prion diseases?
RICH KRAMER: I didn’t really mean to say low. I’m just– I just said that we really don’t know the risk. We’re cautiously optimistic that it might be low, but we certainly don’t know. Mad cow disease is clearly a zoonotic disease, i.e. it can transmit to humans. Sheep scrapie appears not to.
There’s a recent prion disease discovered in camels of all things last year in Algeria. We know very little about that. It was only a very, very recent discovery.
IRA FLATOW: I’m Ira Flatow. This is Science Friday from WNYC Studios. Is it possible then that there are health problems that prions could be causing that we have not identified yet? We have not attributed them or isolated them to prions.
JUDD AIKEN: Ooh, that’s an interesting question. And I’m not probably the one to answer that. They’re clearly neurodegenerative diseases. They’re not prion diseases, but there’s an argument that Alzheimer’s, beta amyloid, [INAUDIBLE], they can accumulate by a prion-like mechanism perhaps.
Regarding chronic wasting disease, if it moves into humans, we don’t know exactly what we’re– in humans what we would be looking for. I’m not sure I’m answering your question–
IRA FLATOW: No. No, you are. You’re basically–
JUDD AIKEN: The best you’re going to get right now.
IRA FLATOW: Well, you’re basically saying there’s no great news about it. And that’s– maybe there’s hopeful news. Is it possible that we might be able to get any closer to a vaccine for example?
JUDD AIKEN: That’s a very good point. There was a recent vaccine that failed miserably. I– for chronic wasting disease– I do know of a couple groups that are actively trying– they’re very innovative, very smart people hoping that something comes because we need something– we need something to deal with disease. Here in Alberta, the disease is moving north and moving west. As it’s moving both directions, it’s going to start overlapping caribou. Caribou are the same species as reindeer, and we know from Norway that reindeer can get the disease.
IRA FLATOW: So it’s in three provinces in Canada right now?
JUDD AIKEN: Yep. It is. Initially, it was in Saskatchewan. This was a game farm animal that was brought in– infected elk into Saskatchewan. Eventually it moved into wild service there. It spread into Alberta. It’s close to Manitoba, but it’s a disease that is just gradually spreading unless we’re moving the disease agent unintentionally vehicularly. And I do want to emphasize that the problem with this disease is the nature of this infectious agent, it’s difficult to detect, and the disease doesn’t show as a clinical disease until way toward the end of the infection process.
IRA FLATOW: So there’s no mass screening then for this in animals?
JUDD AIKEN: Not easy. No.
IRA FLATOW: No. And it just– and a future of soil research perhaps hopeful?
JUDD AIKEN: I’m hoping. Clearly we’re looking at what is in this organic component that’s degrading prions. And I’m quite optimistic about it. I think it’s a bit speculative at this point but certainly something we are actively looking into.
IRA FLATOW: Well, we’ll be following it with you. This is the right time of the year to talk about it since you say reindeer are also affected by it. Anything that gets the public attention right? You don’t hear people talking about prions very much. So thank you very much and have a happy holiday to you, and thank you for taking time to be with us today.
JUDD AIKEN: You’re very, very welcome. Take care. You, too, sir.
IRA FLATOW: Judd Aiken is professor at the Center for Prions and Protein Folding Disease at the University of Alberta in Edmonton.
One last thing, robots, they need nimble fingers and hands if they’re going to be more like us. And researchers at the University of Cambridge unveiled a prototype hand this week that plays the piano with literally just the flick of a wrist. There are no actuators in the fingers, according to lead author Josie Hughes, just the natural mechanics of human bones and tendons. Think of Thing, that unattached hand in The Addams Family, and you get the picture as unveiled in the journal Science. Here’s a little holiday sample.
Yes, on that note.