Chronic Wasting Disease In Deer

Nov 23, 2020

With the deer hunting season going on, there are undoubtedly some people wondering just how concerned they need to be about Chronic Wasting Disease. The Masked Biologist shares some thoughts in this week’s Wildlife Matters.


Wisconsin is nearing a grim milestone, the twentieth anniversary of the detection of Chronic Wasting Disease in wild deer. Since that time, hunters down south seem to have resigned themselves to the disease’s increasing presence in the deer herd. Up here in Northern Wisconsin, it was detected five years ago inside a game farm and shortly thereafter in the wild south of Rhinelander. Ongoing CWD sampling efforts have yielded additional positive deer in both locations.


Chronic Wasting Disease is bad. It eats holes into the brains of deer, elk, moose, and reindeer, causing them to starve themselves, drool excessively, feel unquenchable thirst, and die a slow agonizing death. This disease is 100% fatal. Once the clinical signs are outwardly visible, the animal will typically die in 6 months to two years. The only reliable test we have for CWD right now requires the deer to be dead, although there is a study using a small piece of rectal tissue from live deer that is showing promise. While there have been some indications that there are some deer that have a genetic resistance to contracting CWD, once they contract it, they die just like any other deer. The mutated cell protein, or prion, is transmissible through contact with body fluids. In the years it may take to die, an animal can shed a lot of prions across the landscape in saliva, feces, urine and blood. You are most likely to find it in the central nervous system, like the brain and spinal column. When an animal dies, as it decomposes, the prion is left behind and can persist for up to ten years in the soil, and studies have shown that it can be taken up by growing vegetation. This is why it is so great that now the DNR has dumpsters available to dispose of the deer carcass. It is free, and the deer parts are disposed of safely to minimize the amount of potential disease transmission on the landscape from discarded deer parts.


What about human health? There has never been a documented case of a human developing the human variant, Creutzfeld-Jacobs Disease, from eating meat from an infected animal. However, there have been indications from studies that it is possible for the prion to infect other mammals, including primates and mice. There is a study underway that is trying to use gene splicing to determine just how difficult it would be for CWD to jump species from bovids or cerivids to humans. There is no treatment for CJD; it is a fatal neurological disease like CWD.


I can tell you that regardless of what diseases or health concerns you may or may not have, you should take every precaution when harvesting and processing your deer. Wear gloves, avoid severing the spine or brain case, and take good care of the meat. Peel the hide and cool the meat at your first opportunity, especially if the temperatures are warm. Watch for anything unusual, especially nodules on the vital organs or inside the rib cage, discolored or unhealthy-looking organs. Chronic Wasting Disease may not show any external symptoms, so the only way you could detect it would be to submit the lymph nodes for testing. If you have your deer tested, you will be notified if the test comes back positive, although this year with Covid as a complicating factor, officials say it could take two to three weeks to get your test results back. Submitting a sample is easy and free; you just have to locate a sample kiosk location, saw off the antlers, drop the head in a bag with the requested information provided. All this information is available on the DNR webpage or hunting app.


If your deer comes back positive, you have to decide whether to eat it or discard it. The CDC recommends not eating the meat from an animal that has Chronic Wasting Disease. I am certain that there are hunters down south that are eating the meat from CWD positive deer. Personally, I debone my deer and put the meat in the deep freeze until I hear that the test is negative. Then we thaw the meat and cut and wrap it to enjoy in the following months.