Chronic Wasting Disease

An infected deer Source: texas.gov

By Daniel Allred

The industry cannot afford to turn a blind eye to chronic wasting disease. But what do we really know about it? Where do the facts end and speculations begin?

In terms of how it operates as a disease, here are the basics:

CWD is a disease of the mind. Medically speaking, it is designated an ‘encephalopathy’, which means it’s a disorder or disease that causes overall brain and nervous system dysfunction. Specifically, it is a ‘transmissible spongiform encephalopathy’. Let’s break down those two additional bits of jargon.

Transmissible: something capable of being spread or transmitted between people and/or animals.

Spongiform: the visual aftermath of the disease. Brain tissue deteriorates and dies as small holes form, causing the brain tissue to look like a kitchen sponge when samples are gathered from the deceased and observed with a microscope.

Chronic Wasting Disease

The sponge-like brain tissue of a dead specimen Source: Wikipedia

Transmissible spongiform encephalopathies are also sometimes called ‘prion diseases,’ because their infectious agents are malformed proteins called prions. This term, short for proteinaceous infectious particle, was coined by the American neurologist and biochemist Stanley Prusiner as a combination of the words protein and infection. Prions are rather unique in the way they form, spread and cause damage.

Unlike viruses, bacteria, fungi and parasites, which are foreign to the body, prions are native to the brain and nervous system of the afflicted organism. Similar to cancer, these are integral cells to the body that have ‘gone rouge’ and turned against the body in which they reside. Prions are proteins that have folded themselves in ways that cause damage to the brain or nervous system. These malformed proteins then cause other local proteins to follow suit and take the same debilitating shape.  Unlike cancer, these mutated proteins seem to have the ability to jump ship and affect new hosts. Prion diseases are also unique in the way they can show up in a body. Unlike other infectious microbes, prion diseases can be caused by genetics, infected food, tainted blood transfusions, or even through a seemingly random, unfortunate mutation.

This transmissible aspect in combination with the damage it causes to the brain is what makes CWD the potentially serious threat it is. Furthermore, CWD is a death sentence. Even the equivalent human version, Creutzfeldt–Jakob disease, cannot be cured or effectively treated with modern medicine. Once prions have taken root, the brain slowly and surely deteriorates, causing severe impairments in physical and mental functions.

This is what led to the understandable yet possibly overblown reaction to ‘mad cow disease,’ aka bovine spongiform encephalopathy. The thought that a hamburger could lead to inevitable death, and a painful, slow and maddening one at that, is pretty troubling.

Chronic Wasting Disease

As you can see from this chart, CWD is spreading at an alarming rate across the nation. Source: cdc.gov

Chronic Wasting Disease

Recent map of infected areas in North America Source: nwhc.usgs.gov

But mad cow disease spread like wildfire because of an odd (and pretty messed up when you think about it) practice: Cows were being fed the remains of other cows. The incubation period for mad cow disease is about 2.5 to 8 years, meaning that infected cows were slaughtered and fed back into the food chain a dozen times over before the signs and extent of the disease was understood. By the time we caught wind of it, over 180,000 cows were infected. Ultimately 4.4 million cattle were slaughtered to eradicate the disease, and an estimated 229 people died as a result of the infected meat. Feeding cows the remains of other cows is now illegal in most countries.

Although CWD is a serious issue, luckily it doesn’t have the same potential to spread as mad cow disease did. But that doesn’t mean it’s not on the rise, and the cause of this is still somewhat of a mystery.

CWD was first recognized in mule deer at a research facility in Colorado in 1967. The name ‘chronic wasting disease’ comes from the observation that the infected deer were wasting away, losing weight steadily until their death.

Currently, CWD has been found in mule deer, whitetail deer, elk, moose and now European reindeer. It’s been observed in 21 US states, two Canadian provinces, South Korea, and Norway. The recent case in Norway has sparked a lot of speculation. Did it somehow spread from another continent? Did it randomly occur like we know prion diseases can? Had it been there all along and just gone unobserved? These questions remain to be answered.

Chronic Wasting Disease

A lab testing tissue samples from local animals Source: flickr

Back on the home front, CWD continues to spread among wild and free-ranging members of the deer family.

In 2016 alone, Arkansas has seen a rather alarming rate of infection. An elk was shot in early October 2015 and samples were sent for testing. The tissue tested positive on February 23, 2016, making this the first confirmed case in the entire state. This prompted a statewide effort to determine the severity of the disease. Out of 266 randomly collected deer, 62 tested positive. That’s a 23 percent infection rate. Wisconsin, one of the most common states for CWD, has an estimated 9.4 percent infection rate. That comparison is indeed startling. If a state with an assumed clean population can actually be harboring a sizable infection rate, then hunters need to be extra vigilant across the nation.

Signs to look for are: difficulties in movement, lack of body weight, listlessness, lowering of the head, tremors, repetitive walking in set patterns, and nervousness. Excessive salivation and grinding of the teeth have also been observed. Odd behavior in general should be cause for alarm, considering the effect CWD has on the mind.

The Center for Disease Control and Prevention is still not fully aware of the effect this disease may have on humans and so they urge hunters not to eat any tissue that can harbor this pathogen, namely: brain, spinal cord, eyes, spleen, tonsils and lymph nodes.

Ultimately this is something that everyone who hunts or even enjoys the outdoors needs to be aware of. There’s a lot of work to be done before we fully understand chronic wasting disease.  The only way we can stem the tide is to keep an eye out for the signs and symptoms and report them to state wildlife departments. Stay vigilant, and spread the word before this gets even more out of hand.

For more resources on CWD go here: http://cwd-info.org/

List of states and counties with reported CWD:

Arkansas

1. Newton
2. Boone
3. Carroll
4. Madison
5. Pope

Colorado

1. Boulder
2. Douglas
3. Eagle
4. El Paso
5. Grand
6. Jackson
7. Jefferson
8. Larimer
9. Logan
10. Mesa
11. Moffatt
12. Morgan
13. Phillips
14. Pueblo
15. Rio Blanco
16. Routt
17. Sedgwick
18. Summit
19. Weld
20. Yuma

Illinois

1. Boone
2. Dekalb
3. DuPage
4. Grundy
5. Jo Daviess
6. Kane
7. Kankakee
8. Kendall
9. Lake
10. LaSalle
11. Livingston
12. McHenry
13. Ogle
14. Stephenson
15. Will
16. Winnebago

Iowa

1. Allamakee

Kansas

1. Cheyenne
2. Decatur
3. Ellis
4. Ford
5. Graham
6. Gray
7. Grove
8. Hodgeman
9. Kearny
10. Logan
11. Meade
12. Norton
13. Pawnee
14. Rawlins
15. Scott
16. Sheridan
17. Sherman
18. Smith
19. Stafford
20. Thomas
21. Trego
22. Wallace

Maryland

1. Allegany

Michigan

1. Clinton
2. Ingham

Minnesota

1. Olmsted

Missouri

1. Adair
2. Cole
3. Macon

Nebraska

1. Arthur
2. Banner
3. Box Butte
4. Buffalo
5. Cherry
6. Cheyenne
7. Custer
8. Dawes
9. Deuel
10. Furnas
11. Garden
12. Grant
13. Hall
14. Hitchcock
15. Holt
16. Hooker
17. Keith
18. Kimball
19. Lincoln
20. Loup
21. Morrill
22. Red Willow
23. Scotts Bluff
24. Sheridan
25. Sioux
26. Webster

New Mexico

1. Dona Ana
2. Otero
3. Socorro

New York

1. Oneida

North Dakota

1. Grant
2. Sioux

Pennsylvania

1. Blair
2. Bedford

South Dakota

1. Custer
2. Fall River
3. Lawrence
4. Pennington

Texas

1. El Paso
2. Hudspeth

Utah

1. Daggett
2. Grand
3. San Juan
4. Sanpete
5. Uintah
6. Utah

Virginia

1. Frederick
2. Shenandoah

West Virginia

1. Hampshire
2. Hardy

Wisconsin

1. Adams
2. Columbia
3. Dane
4. Grant
5. Green
6. Iowa
7. Jefferson
8. Juneau
9. Kenosha
10. Lafayette
11. Portage
12. Racine
13. Richland
14. Rock
15. Sauk
16. Walworth
17. Washburn
18. Waukesha

Wyoming

1. Albany
2. Big Horn
3. Carbon
4. Converse
5. Crook
6. Goshen
7. Hot Springs
8. Johnson
9. Laramie
10. Lincoln
11. Natrona
12. Niobrara
13. Platte
14. Sheridan
15. Washakie
16. Weston