Deer prions could jump to humans, study says

Currently Chronic Wasting Disease does not infect humans, but . . .

Chronic wasting disease is spreading more and more widely.  Our anti-conservation friends in the Department of Livestock and the various anti-wolf groups worry about brucellosis and dog tapeworms, but here is something that would be truly terrifying. Prions jumped from sheep probably to cows to cause “mad cow disease.”  Then it jumped to humans.  Scientists worry the same could happen to the prions that destroy the brains of deer, elk, and moose and remain in the soil, infectious, for so long it might as well be forever.

Deer prions could jump, study says. Scientists fear chronic wasting disease protein could spawn new human illness. By John Fauber of the Journal Sentinel (Milwaukee, WI)



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  1. Kayla Avatar

    Ralph, Thanks for Posting! I have been aware of this issue
    for awhile. If this indeed happens then things will really
    start getting interesting.

  2. Ken Cole Avatar

    This is what I have suspected ever since I heard about CWD. The proteins that are affected are highly conserved genetically so there is not much difference between species.

  3. JimT Avatar

    What would be the medium of contamination? Eating certain parts of the animal, or are they fearful that it would a soil exposure thing directly?

  4. Immer Treue Avatar
    Immer Treue

    This has been fairly big in the midwest for quite some time. One of many articles.

    Probably the comments are just as interesting as the article. All sorts of stuff; antihunters, wolves, reduce deer auto collisions, Lymes disease….

    1. Ralph Maughan Avatar

      Immer Treue,

      It has been in the midwest for a long time, but it seems to have originated near Boulder, CO. The infection is widespread in Colorado and Eastern Wyoming.

      In the past we discussed CWD a lot on the blog, and the danger it would descend into the crowded elk winter feedlots of Western Wyoming.

      1. jon Avatar

        Ralph, not to change the subject, but have you heard anything new in regards to the wolves that SUPPOSEDLY killed the 1400 pound cow? Has ws found and killed the wolves they think killed the cow? Just curious.

  5. Jeff Avatar

    The concern is primarily with eating any part of the CNS (brain, spinal cord). Most people don’t eat the brains, but in processing plants they usually cut carcasses right down the spinal cord afteh they are skinned. That same saw is used on dozens or even hundreds of animals—cross species. I’ll quit eating elk if CWD shows up in my hunt areas. Elk rates are much lower than mulies, but if the local processor cuts one infected animal their is potential for cross contaminating other carcasses at a game processor. I started cutting my own meat.

    1. JimT Avatar

      Thanks, Jeff. That comports with what I have read in the past. Part of my concern is as a dog owner, and the increasing use of venison as a protein source. Dog food is a LOT less regulated than our food chain..that in itself is cause for concern…

      1. JimT Avatar

        I forgot to add, however, that there is enough in the article to cause watchfulness about the persistence in soil and ensuing issues. Look at what has gone on for decades with the persistence of mange with wolves despite them not being in that environment for a LONG time…

  6. Ralph Maughan Avatar


    Prion, though merely deformed proteins, remind me of radioactive particles. It is like permanent contamination.

    In the case of Creutzfeldt-Jakob Disease disease, the only form that originates among humans, after an autopsy, they sterilize the instruments by boiling them in acid. The autopsy is done in a special room. It is hard to recruit doctors to perform it — dangerous!

  7. JimT Avatar

    So…ramifications for wild game hunting..eating? Watch and see? Eat and ignore? What does this mean for the current localvore movement which has great potential for getting folks to eat more locally, know where their food comes from instead of relying on meat covered by plastic?

    1. SEAK Mossback Avatar
      SEAK Mossback

      This locolvore is going to keep hunting deer on an island in the ocean. Right now I am more worried about being close to the front lines for the Asian bird flu, carried by waterfowl, a few of which transit between Asia and Alaska.

  8. Jeff Avatar

    There are a lot of animals hunted and harvested in the known infected areas. The origianal hot spot was around Ft. Collins, in the past few decades is has spread predictably from Northern Colorado to Southern Wyoming and into Eastern Nebraska. More disturbing is the random detections in Wisconsin, the La Salles of Utah, Kansas and closer every year to Jackson Hole and Yellowstone. Animals are routinely tested in known areas what I am unclear of is how often healthy appearing animals are infected. I wouldn’t shoot or eat an obviously sick animal, but what about the one who just caught the disease?

    1. JimT Avatar

      Good question, Jeff. It isn’t like it is a disease that is easily treated with antibiotics if you are unlucky. Does the risk outweigh the benefits will be a discussion to keep an eye on…I would hate to think that if you wanted traditional game animals to feed your family, you had to go to a canned hunt situation to make sure you were safe…..

      1. Tom Page Avatar
        Tom Page

        Canned hunts would be worse…outbreaks of CWD have been linked to game farms.

        I’ve never gotten a good answer on when CWD came into being. We know when it was detected, but do we have evidence that it didn’t exist before then? My personal theory (totally unproven of course) is that it’s existed for a long time in the wild, but it took concentrations of animals (due to habitat loss and the simultaneous rise of large game herds after the low numbers at the turn of the 19th century) in greater amounts than had been seen in 150 years, to make it apparent. There also had to be someone willing to look for it and test for it, and there weren’t many of those people around until the late 1950’s.

        CWD is a potential problem, but I’ve got a much greater chance of getting killed driving to the trailhead to go hunting. I lived and hunted in CWD units in Colorado for years, and I don’t know one person that stopped eating their own kill because of it. That said, I don’t use a bone saw anymore, and I know that many people went back to butchering their own meat.

        As for the deer and elk, they’re much more likely to die of lead poisoning, predation or roadkill than CWD, I’d bet.

      2. Ralph Maughan Avatar

        Tom Page,

        It appears to me too that CWD is not a current threat to any person who eats venison.

        It’s important that you mentioned game farms are hardly protection from it. In fact, they have been responsible for its spread in part because infected elk have been shipped across many state lines.

        The danger (probability? I wish we knew) it that the prions will jump (evolve?) to infect other species. To livestock and/or humans would be a disaster.

        I think that CDW infected animals are more likely to die of lead poisoning (killed in a hunt) or become prey than healthy animals. They seem to lose their caution and they are not fleet.

  9. Jeff Avatar

    I too think CWD has always been present, but better monitoring and testing have made us aware of its range. The prions in the soil forever make me nervous when one considers the density of elk on feedgrounds here in NW Wyoming, a practice that is no different than game farms or feedlots.

    1. David J Avatar
      David J

      There is evidence that CJD and Kuru studies done at Patuxent Wildlife Research Station in MD may be the source of CWD….the first cases of CWD were discovered at the Wildlife Research Station in Colorado and later at a Wildlife Research Center in Wyoming.
      Mad Cow jumped the species barrier to cattle because of man feeding dead sheep to cows (as protein feed). Scrapie, the sheep disease does not affect humans but once it entered cows it changed it’s form as do so many other disease to become lethal to humans (bird flu/swine flu etc). Cows would never eat sheep naturally.
      It is also theorized that scrapie could have crossed into deer etc because deer and elk do gnaw bone for minerals and may have had access to contaminated animal carcasses.
      The studies done at Patuxant involved innoculating everything from mice to primates with both kuru (human form) and CJD ….in other words we may have caused or helped the disease cross the species barrier. It is also known that Patuxant and the other Wildlife research Stations share various facilities. The time line also fits with the discovery of CWD.

  10. Immer Treue Avatar
    Immer Treue

    Believe me when I say that hunters are aware of CWD. I was not present at the time, but a deer was killed (put out of its misery) on my place in MN by a group who had permission to hunt. The doe was just lying there and would not get up. So they did the right thing. My neighbor got involved, more or less to see what was going on, and the group said they had no intentions to eat a sick deer, and left. My neighbor, being inquisitive, skinned the deer and saw the massive bruising indicative of a car strike, informed the authorities, and was allowed to keep the doe, and continue hunting to fill his quota.

    So, just to say,hunters out there are aware.

  11. Cody Coyote Avatar
    Cody Coyote

    I’ve always been of the opinion that larger predators—especially cougars and wolves—would be the most efficient means of controlling the spread of any CWD outbreak in deer, elk, and moose.

    There is already some anecdotal evidence that a CWD outbreak was ramping up in mule deer herds in northwest Wyoming, the Owl Creek Mountains, in the late 1990’s. A couple of cases were found, and the alarms started turning from yellow to red , when the first roaming wolfpack arrived, the Washakie pack (?) that roamed from Meeteetse all the way around to Dubois WY. No more cases of CWD were reported , to this day . However, a couple of deer were diagnosed over on the other side of the Big Born Basin where there are no permanent wolf packs and cougars are heavily managed. It seems logical that large predators would isolate weaker slower prey animals .

    Just anecdotal, you understand. IMHO, the Wyoming Game & Fish will not broach the topic of predators as CWD control, because they would have to admit the wolf is a good management tool. I’ve asked them just that question at public meetings and gotten nowhere.

    Can the prion be transmitted from ungulates to canivores resulting in cross-species CWD ? That would be worth some research. The result has bearings on all sides of the debate about large predators and hunting, or the ungulate—>—carnivore—>cattle vector , etc.

    1. mikepost Avatar

      Cody, your comment raises another question: predators and scavengers do eat the brain and spinal cord, centers for CWD prion infestation, and yet we do not see any CWD presence in those populations. I agree that CWD suffering animals are probably more likely to be predated and so that makes the lack of predator CWD even more interesting.

      1. Immer Treue Avatar
        Immer Treue

        What comes next, wolves are spreading the prion causing CWD in their scat hysteria?

  12. jdubya Avatar

    This is very contrived study. What they have done is try try to force the issue out of any real real biological scenario. It IS a great test of their test tube model system but it does not describe what would be found in a native ecosystem. Indeed, as they describe in their introduction:

    “”Fortunately, no clinical evidence linking CWD exposed humans and CJD patients has yet been found (5;6). Experimental inoculation of CWD prions into squirrel
    monkeys has produced the disease (7;8), however transgenic mice expressing human PrP did not (9-11), suggesting that the
    species barrier between humans and cervids is greater than between cattle and humans.””

    While the prion proteins between man, mouse elk and cow are highly related, they are not uniformly capable of transmitting disease between each other. For example, to transmit human disease to a mouse, you first have to make a mouse that is expressing the human prion protein: the mouse protein alone will not allow for the disease to promulgate.

    The idea of how these proteins actually transmit disease is still quite controversial, but think of it like putting your hand in a glove. Your hand fits that glove very well and the glove is, in essence, a copy of your hand. A human prion protein, when converted from its normal shape into the disease shape (think the fresh grape versus a dried raisin) is capable of binding to other normal human prion proteins (grapes) and converting them into the disease state (raisin). The cow disease protein can also convert the human protein from grape to raisin, but the elk/deer protein cannot. So the cow hands, as an example, do fit your glove while the elk and deer hand do not. This was shown in the experiments where they innoculated the mice expressing the human normal prion protein with the elk/deer CWD proteins and could not demonstrate disease transmission.

    What would be very interesting to know (but what we will never find out) is how many people have actually already eaten CWD infected deer and elk. I suspect the many, many people have, and yet we have no transmission data to date to suggest the disease can transfer from cervid to human.

    I personally would not eat CWD infected meat and think it makes the most sense to disperse elk/deer/moose such that disease transmission is inhibited (as these pages have promoted by doing away with the feed stations in Wyoming, for example). But for those of you that like to hunt and eat your meat, you have a much higher chance of dying from a bee sting or getting hit by lightning while hiking the ridge line than you doing of getting CWD from your game.

  13. Ann Sydow Avatar

    I read about a study once that showed that mountain lions targeted deer with Chronic Wasting Disease. Naure knows what its doing.

  14. Simon Kenton Avatar
    Simon Kenton

    I kill deer in Boulder County, and always have them tested. Although the incidence is as high here as anywhere (that is, WAY higher than in nearly all other places) none of my deer has come back as infected. I have seen a few deer with a kind of emaciated grogginess that I suspect is emblematic; of course they walked.


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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