What is the 'zombie deer disease'? 10 things to know about CWD
Brian BroomChronic wasting disease — commonly called CWD and sometimes referred to as the "zombie deer disease" or "zombie deer virus" — has become one of the biggest topics of discussion among deer hunters.
The disease affects deer, elk, moose and other members of the cervidae family. It is spreading across the nation and was discovered in Mississippi in 2018 and more recently in Tennessee.
Here are answers to common questions and things you should know about CWD.
What causes CWD?
Wildlife biologists have generally accepted that mutated prions, or misfolded proteins, were the cause of the disease, which is a type of transmissible spongiform encephalopathy (TSE). The CWD prions are thought to be shared between white-tailed deer and other members of the Cervidae family directly and indirectly through saliva, urine and feces.
Once the prions enter a deer, they cause healthy prions in a deer's brain and central nervous system to become misfolded. These rogue proteins effectively eat holes in the animals' brains over an extended period of time, and the animals die within months of exhibiting clinical signs of the disease.
However, a neuropathologist with the Louisiana State University College of Agriculture, Dr. Frank Bastian, said his research shows a bacteria known as spiroplasma is the root cause of CWD.
Can humans get chronic wasting disease?
There have been no confirmed cases of CWD in humans. However, people are warned against consuming or handling meat from any deer that appears sick. And because deer can be infected with CWD and not exhibit symptoms for months or possibly years, all hunters are encouraged to handle meat with extra care.
The Mississippi Department of Wildlife, Fisheries, and Parks asks hunters to avoid contact with certain parts of a deer, especially the spinal cord and brain. Meat should be deboned with all fatty tissues cut away to ensure removal of lymph nodes, and hunters should wear latex or rubber gloves when cleaning a deer.
Why is it called 'zombie deer disease'?
"Zombie deer virus" has become a popular term recently, presumably due to the listlessness, unsteadiness and emaciation associated with the disease. However, it's not an accurate depiction of the life of CWD.
Deer can be infected for months or possibly years and appear healthy and normal before clinical signs appear, and at no point are they stumbling around in search of brains to eat. In fact, the disease is actually eating the infected animals' brains.
Also, because of the long life of the disease, many CWD-positive deer are killed before exhibiting symptoms.
Can you eat deer with CWD?
According to the Centers for Disease Control and Prevention, eating meat from a CWD-positive animal should be avoided. Normal cooking temperatures will not denature prions or kill spiroplasma bacteria.
Hunters in areas known to be CWD-positive should have their deer tested before consuming the meat. If a hunter has a deer or elk commercially processed, he or she should request it be processed individually and not mixed with meat from other animals.
Where did chronic wasting disease come from?
The origin of CWD is unknown, and we may never know where it came from. According to the CWD Alliance, it was first recognized in the late 1960's in a mule deer. The deer was located in a research facility in Colorado.
It is possible, though never proven, that CWD came from sheep that were infected with scrapie, which is another form of TSE. The CWD Alliance also says the disease could have spontaneously arose in the wild, though that has never been proven either.
Is CWD always fatal for deer?
It is generally accepted that CWD is 100 percent fatal if the deer lives long enough for the disease to run its course. However, many are killed indirectly by the disease. In their weakened and confused state, CWD-positive animals are more susceptible to being hit by vehicles and killed by predators. Their weakened immune system commonly causes infected animals to die from illnesses such as pneumonia.
What are the symptoms of CWD?
Animals with CWD show no visible signs of the disease until the final months. According to the Mississippi Department of Wildlife, Fisheries, and Parks, infected animals lose weight, lose their appetite, and develop an insatiable thirst in the final stages. They tend to stay away from herds, walk in patterns, carry their head low, salivate, and grind their teeth.
Where does chronic wasting disease occur?
According to the CDC, as of January 2019, CWD has been found in free-range animals in 24 states and two Canadian provinces. It has also been found in Norway, Finland and South Korea.
In Mississippi, more than 7,300 deer were tested during the 2018-19 deer season and 15 cases have been detected as of Feb. 21, 2019. The counties where it has been detected include:
- Benton County
- Issaquena County
- Marshall County
- Panola County
- Pontotoc County
- Tallahatchie County
Can livestock get CWD?
According to the CWD Alliance, there are no known cases of CWD being transmitted to cattle or other domestic livestock. Although there are no known cases of natural transmissions, it has been contracted in cattle through experimental cranial injection.
What if I see a deer with CWD?
There is no way to determine if a deer or other cervid has CWD by looking at it. Other common diseases cause similar symptoms. If you see a sick deer, the Quality Deer Management Association recommends it be quickly reported to your state's department of natural resources so it can be tested in a laboratory.
What other questions do you have about chronic wasting disease? Contact Brian Broom at 601-961-7225 or bbroom@gannett.com. Follow Clarion Ledger Outdoors on Facebook and @BrianBroom on Twitter.
