Cause of spread of "mad elk", "mad deer" disease found

It’s in their droppings, and the infectious prions never go away!

Really, really bad news about chronic wasting disease.  Study Spells Out Spread of Brain Illness in Animals. By Sandra Blakeslee. New York Times.

“Dr. Aiken said prions tended to bind to clay in soil and to persist indefinitely. When deer graze on infected dirt, prions that are tightly bound to clay will persist for long periods in their intestinal regions. So there is no chance chronic wasting disease will be eradicated, he said. Outside the laboratory, nothing can inactivate prions bound to soil. They are also impervious to radiation.” [emphasis mine]

Update. Here is the link to the abstract in Nature

New Update: Wyoming boosts CWD survey. This season, more state and federal agents will take samples from hunters’ deer and elk. By Cory Hatch. Jackson Hole News and Guide.



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  1. jdubya Avatar

    From the article in Nature:

    “Based on our titration results, an infected deer may shed nearly as many prions in faeces over the disease course as accumulate in its brain in terminal disease.”

    “Although prion titres in faeces were relatively low,
    exposing deer to multiple oral doses in faeces-contaminated environments could increase their overall probability of infection. Moreover, both the persistence and infectivity of prions shed in faeces may be enhanced by interaction with clay soil microparticles, and mule deer may consume 8–30 g of soil daily depending on season, thereby facilitating infection by faecal prions. The foregoing mechanism is consistent with observed conditions under which captive mule deer have shown remarkably high rates of prion infection, and explains how CWD could effectively transmit among mule deer in the wild.”

  2. TC Avatar

    It would help not to call chronic wasting disease “mad elk” or “mad deer” disease, implying significant similarities to bovine spongiform encephalopathy (“mad cow” disease), when critical factors about the epidemiology (and known risk to human health) are very very different.

  3. Ralph Maughan Avatar


    I think the opposite is true. When faced with the potential loss of most of our cervids, the use of terms like a “transmissible spongiform encephalopathy” or “chronic wasting disease” doesn’t quite do the trick in getting the public’s attention.

    What is the big threat to elk in Wyoming, Colorado, and a growing list of other states and provinces? It is wolves, or is it “mad elk disease?”

    In Wisconsin and Minnesota is it wolves, or is it mad deer disease?

  4. ProWolf in WY Avatar
    ProWolf in WY

    Ralph, it seems that if this disease reached epidemic proportions then it would do a lot more damage than wolves could do. Especially if it hits the Yellowstone herds.

  5. Ralph Maughan Avatar

    If it hits Yellowstone Park, the Park will become a place to watch geysers and bison. That’s about it.

    Every other aspect of the Park seems to be under siege from diseases such as whirling disease or whitebark pine blister rust, or from introduced species such as New Zealand mud snails and lake trout.

  6. Ralph Maughan Avatar

    One reason I posted this is because there is a class of hunter that can’t seem to distinguish real threats like this disease from minor inconveniences like wolves.

  7. ProWolf in WY Avatar
    ProWolf in WY

    Wolves are too easy of a scapegoat. Diseases are not something that hunters can see and demonize so easily.

  8. Pronghorn Avatar

    “If it hits Yellowstone Park, the Park will become a place to watch geysers and bison. That’s about it. Every other aspect of the Park seems to be under siege from diseases such as…”

    Don’t forget–bison are under siege from the disease of greed permeating the livestock industry and the disease of spinelessness infecting bureaucrats and politicians. Also that class of hunter that can’t seem to distinguish fair chase from gunning down an animal not even considered wildlife and with no designated habitat. Just an observation…and not to minimize the seriousness of the CWD revelation.

    When I think of “the end of nature,” I increasingly fear it will come about just like this. Drug-resistant staph on beaches, mutant strains of flu, brain-wasting diseases–could THIS be the face of the Apocalypse?

  9. Save bears Avatar
    Save bears

    There are two things that are the major threat to wildlife in this country, especially the western populations, that is Chronic Wasting and Habitat encroachment, even if we can turn somethings around in Yellowstone, the habitat encroachment is going to be one of the biggest problem we face. There are political boundaries for Yellowstone and unfortunately wildlife can’t, don’t and have no concept of a political boundary..Bark beetle will play a big part in things over the next 20 or so years, but it will eventually die off and be back under control beings fires are managed for resource betterment, instead of stop all fires…bark beetle is a direct result of so many years of suppressing fires…we are now reaping the rewards of our so called management…

    Pronghorn, there will be no “end to nature” only the end of “Humans” Nature will continue on, long after humans do…those that think we can destroy the earth, are being quite arrogant…we can only destroy ourselves…

  10. jdubya Avatar

    R, I don’t know if CWD hitting Yellowstone will be quite so devastating now. Pre-wolf, it would be worse since the elk just stood in one spot and ate the park apart. But now the wolves keep the elk on the run, in the trees, and away from a lot of aggregation. So the transfer and disease should be tolerable. Besides, if it is in the Tetons, it is already in Yellowstone.

    I frankly would worry more about the bison. Wait for Mad Bison to hit the park. That could be a lot more devastating for the the few wild bison left.

  11. ProWolf in WY Avatar
    ProWolf in WY

    Jdubya, I didn’t know that CWD had made it to Yellowstone. I agree, if buffalo got that it would be bad. Considering that there are cattle near Grand Teton, it is entirely possible.

  12. Ralph Maughan Avatar

    I do not believe that bison get CWD.

  13. Tom Page Avatar
    Tom Page

    From the studies I’ve seen, infection among elk is much lower than deer, even in high-density wild herds such as CO. This article doesn’t mention elk or any other species, so I’m curious to know if there were any elk (or bison) in this study and what the results were there.

    My sense is that the disease has actually been around a lot longer than 40 years, it’s only with the growth of game farms and higher herd densities on poorer habitat that it’s effect has been noticeable.

  14. Save bears Avatar
    Save bears

    There is no evidence as of yet, that Bison or Cattle contract CWD, it has not been proven that it can’t happen, but there is no recorded instance of it happening that I know of.

  15. ProWolf in WY Avatar
    ProWolf in WY

    I guess I was thinking about mad cow disease.

  16. Ralph Maughan Avatar

    Tom Page

    Raises a good question. It might affect species that can be infected differently. For example, it can also infect moose. The only confirmed case in Wyoming west of Continental Divide was a moose, but I have heard of no other moose infected anywhere, although that might reflect my lack of knowledge.

  17. jdubya Avatar

    I was implying that if Bison get any form of CWD whether its origin if from cows, sheep, elk, moose, etc. it would be more devastating than for the elk to get CWD just cause of their lifestyles.

  18. Save bears Avatar
    Save bears

    I have read studies that indicate that although CWD is in the elk population that the major portion of the disease pool is deer, in Canada, studies have shown that in areas with the disease that up to 1% of elk have it, while about 10% deer have it, this would be indicative that even though elk can contract, that deer are the major player in the spread of the disease.

    I have never read of an instance of Bison contracting the Bovine version anywhere in the world, but it could happen if the correct set of circumstances present themselves, which would be a remote situation as the bovine version is highly monitored… hopefully we never have an outbreak in the GYE in cattle, that would dramatically change the management of bison for the worse(if possible), given this new research showing these types of diseases don’t go away.

    I would like to see a study done to see if the bovine version exhibits the same tenacity in clays and soils as CWD.

  19. jdubya Avatar

    Save Bears, Any misfolded prion protein shows great tenacity. These were first found in human samples and were shown to be very resistant to degradation via heat, protease digestion, etc. , One classic study showed the transfer from one human patient to another was due to contaimination of a brain probe that was autoclaved prior to surgery: autoclaving had no effect.

    What defines transmission is the structure of the protein itself. Thus the human and cow proteins are similar enough that the cow mis-folded prion protein can convert the human and cause disease. The way we use mice these days is to replace the mouse prion protein with a deer, human, cow, etc. prion gene so now the mouse actually only makes the human protein. That mouse is resistant to mouse prion disease but can transmit and die from infected human tissues. Such mice have now been made with many different species prion genes.

    I do not know the sequence of the bison prion protein, but I am sure someone knows. So the big question is what is it similar to? Cow, elk, sheep, mouse, or is it unique enough that none of these other species diseases could convert the bison protein to the infectious form? If I had the money, I would clone the bison prion gene, make a mouse to express, and then infect that mouse with human, cow, elk, deer, etc. CWD and find out if the mouse came down with disease. That would be the real test and could predict when and if bison come down with the infection.

  20. jdubya Avatar

    Oh, you also said: I would like to see a study done to see if the bovine version exhibits the same tenacity in clays and soils as CWD.

    All prion proteins regardless of species would show the same tenacity.

  21. Ralph Maughan Avatar

    Perhaps we can save our cervids by genetically engineering them to resist the prions that can now infect them, breed the modifed deer, etc., and turn them loose into the wild herds. Natural selection would probably cause the percentage of resistant deer to increase.

  22. jdubya Avatar

    Ralph, that IS working for whirling disease rainbow trout. They shipped ‘bows to Germany a century or more ago. Those fish developed a natural resistance to WD that was endemic in German waters (the German browns were already resistant). So now those German ‘bows have come back to the states and in Colorado are interbreeding with wild fish in the rivers and streams to create a wild, WD resistant strain. I also heard that Madison river ‘bows have developed resistance all by themselves.

    But, to my knowledge, the only animal that is resistant to prion disease is an animal that is already dead. And they don’t breed too well.


Dr. Ralph Maughan is professor emeritus of political science at Idaho State University. He was a Western Watersheds Project Board Member off and on for many years, and was also its President for several years. For a long time he produced Ralph Maughan’s Wolf Report. He was a founder of the Greater Yellowstone Coalition. He and Jackie Johnson Maughan wrote three editions of “Hiking Idaho.” He also wrote “Beyond the Tetons” and “Backpacking Wyoming’s Teton and Washakie Wilderness.” He created and is the administrator of The Wildlife News.

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