You may have heard about a worrying condition termed zombie deer disease that is reported across America and Canada at very high and alarming rates.
So, what is this fatal ailment, what causes it, and what can be done to prevent it from spreading further?
Read on in this article to find out more information on the key facts surrounding what it is, and what you need to know about it.
Zombie Deer Disease
Also commonly known as chronic wasting disease (CWD), this is a prion disease. Prions are types of proteins which causes natural proteins in an animal’s brain and spinal cord to fold abnormally and ultimately causes the brain function to degenerate. As one of the most concerning afflictions for the mammal, in the end, it is an incurable and fatal condition for the animals it infects.
CWD was first reported in a captive research facility in Colorado in the 1960s. So what causes it to spread if it first occurred in captivity? Well, it is passed through direct contact as well as through the bodily fluids of animals. This includes through their saliva and their blood. This makes it difficult to curb the spread of the ailment, especially in the wild.
Twenty years after its emergence in Colorado, it was reported to be found in the wild. It then spread to surrounding areas north of Colorado by 1990. As of March 2019, there are reported incidences of CWD in twenty-four states of North America.
These states include Arkansas, Colorado, Illinois, Iowa, Kansas, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Mexico, New York, North Dakota, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, Wisconsin, and Wyoming.
Canada, Norway, Finland, and South Korea have also reported counts of infections in their populations too.
Symptoms
To spot zombie deer disease is not as simple as it may seem. This is because the symptoms can take a long time, sometimes up to a year to show. What this means is that a herd that looks healthy may in fact, carry the prion disease.
As you may expect from the informal and fearful name, the observable symptoms experienced when the animal becomes infected are similar to that of what we have seen from horror movies. When infected, the animals are reported to look vacant, be aggressive, confused, and scared.
This is mainly due to the fact that it is the brain and nervous system that is affected and attacked first. Therefore, most of the symptoms are neurological, initially.
A reduced fear of people is an easy way to tell if a herd is infected. You will spot the animals out in open land, away from the cover that they would usually favor.
Animals infected typically display some or all of the following symptoms. These worsen over time and ultimately result in the death of the animal.
What To Look Out For
- Vacant staring
- Listless
- Poor coordination and disorientation which results in stumbling
- Drooling with a thick saliva most often
- Extreme and insatiable thirst
- Excessive urination
- Aggressive behavior
- Drooping of their heads
- Dementia symptoms and confusion
- Hallucinations and sight difficulties
- Difficulty when walking and standing
- Difficulty eating which will result in the wasting of muscle mass
The symptoms listed above are often slow to appear in the animals. This means that usually these symptoms won’t show or make the infected animals obviously distinguishable from a healthy one. Only in the final few months of the animal’s life will the condition become apparent. At this point, the most obvious signs are dramatic weight loss with exposed ribs.
Which Type of Deer Does It Affect?
Only four species are currently known to be affected. These are elk, mule, white-tailed, and moose. However, Korea has reported that some sika and red species have also contracted it from elk that were infected.
Whitetail species are the worst affected. However, the signs in whitetail deer are difficult to spot as the symptoms are similar to other ailments that they get.
The signs of zombie deer disease in whitetail deer are the same for other members of the Cervidae family. There also aren’t any limitations on the ages of the animal that it can infect. In fact, some young yearlings and fawns are known to have contracted the condition when in the womb of their infected mother.
Treatment Options
Unfortunately, currently, there are no available vaccines or treatments for the condition.
Prevention
An animal that has become infected is at risk of spreading it through direct or indirect contact with bodily fluids. This includes saliva, urine, and blood.
What this means is that it can contaminate food, vegetation, water, or soil that has been in contact with an infected animal. It can then be passed onto a healthy animal very easily.
The prion protein is a trigger for the symptoms in the animals. This is able to bind to the soil and water molecules and unfortunately, has a long residence time.
What this means is that it can survive for a substantial period through binding to water and soil. Some reports suggest this could be for over ten years in certain cases. So when plants begin to grow from contaminated soil or water bodies, prions can become integrated into their structures. This includes leaves which the animals eat.
With this in mind, the best way to prevent it from spreading further is to limit the transmission to the surrounding environment and to otherwise healthy animals. Without a cure, prevention is simply the only available option.
Tick Awareness
As we are aware, this ailment can easily spread through bodily fluids.
Ticks are instrumental in spreading this, as they are found in the same environments as the animals themselves. They attach to animals, as they in their bodily fluids. When the tick moves on to find a new deer to attach to, these fluids then come into contact with another animal. They then pass it on.
They thrive on whitetail, elk, and fallow species so can often be found on them. Eastern USA is a particularly common place to find them.
A little like Lyme disease, CWD can be spread faster via the ticks that bite Cervidae species.
There is no conclusive evidence that it could reach and impact humans. However, we urge caution as not all the facts are known. Diligently check for ticks, both on yourself and any deer that you come across. In addition, handle meat from hunting safely so as not to take unnecessary risks.
Handling and Eating Meat
If you are hunting, preparing and eating meat from areas known to have reported incidences, there are considerations that the public are urged to think about. You can find out more from the the American Center for Disease Control and Prevention.
It is important not to shoot, handle or eat meat from animals that are showing the symptoms mentioned above. You especially want to avoid any roadkill.
Remember that symptoms may not always be showing. Therefore, it is important to test for zombie deer disease in most cases.
Precautionary Measures
Even if you do not suspect that the animal is infected, you should take the following precautions as the symptoms take a long time to show.
- If you are field-dressing, be sure to wear protective clothing like latex or rubber gloves.
- While prions are present in most parts of the tissue and muscle of infected animals, they are most prevalent in the brain, eyes, spinal cord, lymph nodes, tonsils, and spleen. Therefore, you should minimize how much you handle the animal and organs, especially the brain and spine which are the most likely to be infected.
- Make sure you do not use your normal household utensils and knives that plan to continue using on the animal. Set aside and use designated tools for this purpose only.
- Some states will vary in their advice but you should consider a test of the animal for CWD before you eat the meat. If the test is positive, do not eat meat from that animal. Unfortunately, a test can only pick up CWD at a certain stage so it may be unreliable. Your local State Wildlife Agencies will be able to advise best practice in your area.
- Process animal meat individually, especially when you are commercially processing it. This will minimize cross-contamination with other meat types.
The Chronic Wasting Disease Alliance has shared several practical videos for hunters to learn more about what they can do here.
It is always advisable to keep track of Zombie Deer Disease using a map and be aware of any reports where you hunt. The American Centers for Disease Control and Prevention website also publishes up to date information.
Another disease that whitetails are susceptible to is EHD.
Related: Can deer get the Rabies infection?
