MissouriWhitetails.com

Chronic Wasting Disease

Due to the vast number of inquiries we have had for information about Chronic Waste Disease (CWD) we have expanded our coverage on this subject. We wish to thank the following institutions, organizations and web-sites for their cooperation and contributions to this article.

This fact sheet about Chronic Wasting Disease (CWD) is being
shared by the Texas Parks and Wildlife Department (TPWD)
to help answer questions about this wasting disease
of deer and elk.

Carla Everett, Information Officer, Texas Animal Health
Commission (TAHC), 1-800-550-8242


FREQUENTLY ASKED QUESTIONS ON CHRONIC WASTING DISEASE    (posted 7-5-02)

What is Chronic Wasting Disease (CWD)?
CWD is an untreatable, fatal neurological (brain and nervous system)
disease found in deer and elk in certain geographical locations in North
America.  The disease belongs to a family of diseases known as
transmissible spongiform encephalopathies (TSE) or prion diseases.  The
disease attacks the brain and neural tissue of infected deer and elk. 
While CWD is similar to mad-cow disease in cattle and scrapie in sheep,
there is no known relationship between CWD and any other TSE of animals or
people.

How is it spread?
It is not known exactly how CWD is spread.  It is believed that the agent
responsible for the disease may be spread both directly (animal to animal
contact) and indirectly (soil or other surface to animal).   It is thought
that the most common mode of transmission from an infected animal is via
saliva, feces, and urine.

Where has it been found?
CWD is known to infect free-ranging deer and elk in northeastern Colorado
and free-ranging deer in western Colorado, southern Wyoming, western
Nebraska, South Dakota, Wisconsin, New Mexico and Saskatchewan.  It has
been diagnosed in elk in game ranches in Colorado, Nebraska, South Dakota,
Montana, Oklahoma, Kansas, Alberta and Saskatchewan.

Is it dangerous to humans?
Epidemiologists with the federal Centers for Disease Control and Prevention
in Atlanta and epidemiologists at the Colorado Department of Public Health
and Environment have studied chronic wasting disease and found no evidence
that CWD poses a risk to humans or domestic animals. (Over 16 years of
monitoring in the infected area in Colorado has found no disease in people
or cattle living there.)  The World Health Organization has likewise said
there is no scientific evidence CWD can infect humans. However, as a
precaution the WHO also says no part of a deer or elk with evidence of CWD
should be consumed by people or other animals.

What Precautions should hunters take?
Health officials advise hunters not to consume meat from animals known to
be infected with the disease.  Boning out meat is recommended.  In
addition, they suggest hunters take simple precautions such as wearing
latex gloves when field dressing carcasses, minimize handling of brain and
spinal tissues, wash hands and instruments thoroughly after field dressing
is completed, avoid consuming brain, spinal cord, eyes, spleen, tonsils,
and lymph nodes of harvested animals, and finally request that your animal
is processed individually, without meat from other animals being added to
meat from your animal.

How can you tell if a deer has CWD?
Because the brain is the organ affected by the disease, infected animals
begin to lose bodily functions and display abnormal behavior such as
staggering or standing with very poor posture.  Animals may have an
exaggerated wide posture, or may carry the head and ears lowered.  Infected
animals become very emaciated (thus "wasting" disease) and will appear in
very poor body condition.  Infected animals will also often stand near
water and will consume large amounts of water.  Drooling or excessive
salivation may be apparent.

What should I do if I see a deer that shows CWD symptoms?
Accurately document the location of the animal and immediately contact the
nearest Wildlife Division or Law Enforcement Division office of the Texas
Parks and Wildlife Department or call TPWD headquarters in Austin toll-free
at (800) 892-1112 and enter 5 for wildlife and 1 for general wildlife
information.   Or contact, the Texas Animal Health Commission toll-free at
(800) 550-8242.  Do not attempt to touch, disturb, kill, or remove the
animal.

Can I have deer venison tested?
Deer "venison" cannot be tested-only brain and neural and lymph node tissue
can be tested to detect the presence of CWD.  There is no means of testing
deer tissue samples for CWD in Texas at present.  However, the Texas
Veterinary Medical Diagnostic Lab in College Station is in the process of
being certified by the U.S. Department of Agriculture to be able to test
CWD samples.  Eventually, the public may be instructed to contact the Texas
Animal Health Commission for information on testing. 

Is the meat safe to eat?
While the agent that produces chronic wasting disease in deer and elk has
not been positively identified, there is strong evidence to suggest that
abnormally shaped proteins called prions are involved.  Research completed
to date indicates that the prions accumulate only in certain parts of
infected animals-the brain, eyes, spinal cord, lymph nodes, tonsils, and
spleen.  Based on these findings, hunters are recommended to bone out their
meat and consume only muscle tissue from harvested animals.

What is being done to combat CWD?
Texas officials have restricted importation of live deer and elk into the
state.  The Texas Parks and Wildlife Department and the Texas Animal Health
Commission are also working with deer and elk breeders to set up a
voluntary CWD monitoring program.  This fall, TPWD will begin testing
hunter-killed deer and other suspect animals from the state's various
ecological regions. 

Nationwide efforts to address CWD are accelerating rapidly.   In other
states with captive animals known to have or have been exposed to CWD,
management is concentrating on quarantining or depopulating captive or
free-ranging animals in the affected area.  In some cases around captive
populations, double fencing is recommended to prevent direct contact
between captive and wild animals

In wild populations, the management option recommended is to reduce the
density of animals in the infected area to slow the transmission of the
disease.   This is being done by selective culling of animals suspected to
have been directly exposed to the disease.  In Colorado and Wisconsin,
large numbers of animals are being killed to reduce density of animals and
thus slow the transmission of the disease.  There is still a large need for
research on the disease as many questions go unanswered.  There is also a
need for increased funding to support additional laboratories for testing
animals for the disease.

Almost every state wildlife agency is now planning an increased effort at
surveillance to detect if CWD is present.  Many state agencies have banned
the importation of cervids into the state.  Some states have also halted
intra-state movement of deer and elk and banned supplemental feeding
programs. 

What can hunters do?
Hunters should be vigilant when afield for deer or elk that display
abnormal behavior such as staggering or standing with very poor posture. 
Animals may have an exaggerated wide posture, or may carry the head and
ears lowered.  Infected animals become very emaciated (thus wasting
disease) and will appear in very poor body condition.  Infected animals
will also often stand near water and will consume large amounts of water. 
Drooling or excessive salivation may be apparent.  Report any suspected
cases of CWD to the proper authorities immediately.

Hunters should also support Texas efforts to restrict deer or elk
importation and report any suspected violations.

Finally, hunters should arm themselves with information, especially practical
tips for hunting and field dressing game.

Where can I learn more?
For Texas information, check the Web sites of the Texas Parks and Wildlife
Department (www.tpwd.state.tx.us) and the Texas Animal Health Commission
(www.tahc.state.tx.us) for periodic updates.  Various others sites offer
information about CWD, including the U.S.D.A. site
(http://www.aphis.usda.gov/vs/nahps/cwd/index.html).  Human health
information for transmissible spongiform encephalopathy diseases is on the
federal Center for Disease Control and Prevention site
(http://www.cdc.gov/nip/vacsafe/concerns/bse/bseparentqa.htm).  Some
excellent information is available on Web sites of states where CWD has
been detected in free-ranging deer
(http://www.dnr.state.wi.us/org/land/wildlife/whealth/issues/CWD/index.htm
and http://wildlife.state.co.us/cwd/ and
http://www.ngpc.state.ne.us/wildlife/cwd/cwdinfo.html).  In early July, the
Chronic Wasting Disease Alliance web site will be up and running
(www.cwd-info.org).

JEFFERSON CITY, Mo. (AP) - Ten elk that came to Missouri from Colorado have tested negative for chronic wasting disease, state animal health officials said Tuesday.

The animals were the only elk remaining here that had come from Colorado, where an outbreak of the disease had occurred last year.

Chronic wasting disease is a progressive degenerative disease of the central nervous system. The most common sign of the disease is chronic weight loss leading to death.

It is unknown how the disease occurs or spreads, but at this time there is no evidence that chronic wasting disease can spread to cattle or people.

To test for the disease, the state first had to kill the elk and then examine their brains.

Some had raised concerns that if Missouri elk were infected with the deadly disease, it could spread through the state's deer population.

"Although further tests are pending, the Department of Conservation reports there is currently no evidence of the disease in our deer population, so these latest (elk) test findings are really the icing on the cake," said state veterinarian Taylor Woods.

After the Missouri Department of Agriculture was notified in October of the Colorado cases, the agency filed emergency rules prohibiting the entry of elk or deer from areas known to have animals with chronic wasting disease.

The rules also require livestock owners to have a permit to bring elk or deer into Missouri.

Agriculture officials estimate there are 2,000 elk on about 80 farms in Missouri.

North American Elk Breeders Association

Reprinted with permission from NAEBA

LAKEWOOD, Colo. - The final results are completed on domestic elk in Northeastern Colorado that were tested for chronic wasting disease (CWD). Of the 1,019 elk that were quarantined, 30 animals tested positive: 29 from a herd in Stoneham, Colo., and one in Ault, Colo.

"We're relieved that this task was achieved so quickly and efficiently," said Wayne Cunningham, state veterinarian at the Colorado Department of Agriculture. "Since we're in the business of saving animals' lives, it was an extremely difficult task of depopulating these herds, knowing that only a few of the elk had the disease."

Earlier this year, state and federal officials euthanized elk at nine facilities in the state. Test results on the first 542 animals found two animals that were positive for CWD. Both were among the 337 elk in Del Norte, Colo., and none of the 205 animals at the Cowdery, Colo., facility tested positive. Of the total 1,561 elk that were killed at all nine facilities, about 2 percent of animals tested positive for CWD.

Testing for CWD is required of all domestic elk mortalities in Colorado. Since there is no reliable live test for CWD on elk, the animals are killed, so samples of their brains can be tested.

During the depopulation, an air curtain incinerator was used to burn the carcasses and inactive the CWD prion, which classifies the disease in the family of transmissible spongiform encephalopathies. The incinerator helped process the remains, leaving about a 2 percent residue.

In Colorado, CWD testing has been required of all domestic elk deaths since 1998. The Colorado Department of Agriculture was the first state to require mandatory surveillance of domestic elk herds for CWD. In addition, Colorado elk ranchers have been required to identify and inventory all domestic elk since July of 1994.

Chronic wasting disease is a neurological disease that attacks the brains of infected animals, causing them to become emaciated, display abnormal behavior, lose bodily functions and die. At this time, there is no evidence that CWD is a risk to human health.

CWD on Nebraska Game Farm Came From Wild Animals
by Henry Kriegel (406) 585-8085
Reprinted with permission from NAEBA

Harrison, Neb. - The recent appearance of chronic wasting disease (CWD) in domestic elk and deer on a game farm in Nebraska can be attributed to the presence of the disease in wild game populations, according to Eric Mohlman, president of the Nebraska Elk Breeders Association.

The disease, which mysteriously appeared on a game ranch in Nebraska's northwest panhandle, has prompted wildlife officials to take drastic measures to halt its spread, including killing at least one hundred deer around the ranch and testing them for signs of CWD.

In addition, all of the domestic animals on the ranch must be depopulated in accordance with the US Department of Agriculture's (USDA) national CWD Eradication and Control Program. The program will provide indemnity payments of up to $3,000 per animal for the elk that must be destroyed. The program will not pay indemnity for the whitetail deer on the ranch that must be destroyed as well.

The adoption of the USDA CWD Eradication and Control Program was due in large part to the efforts of the North American Elk Breeders Association, which drafted the initial outline of the program.

Recently, testing done by the Nebraska Game and Parks Department uncovered nine positive cases of CWD from the wild deer population in the area, leading many people to believe that the disease originated in the wild and spread into the ranched animals.

"The ranch is only a few miles from the endemic area in Wyoming, so it's only logical that some infected deer came across the border and brought CWD into Nebraska and onto this ranch," Mohlman said.

Furthermore, CWD was recently confirmed in a single wild deer in southwestern South Dakota, just across the border from the infected wild deer in Nebraska.

"Because of the contagious nature of the disease, we felt there was a very real possibility that it might show up in our state," said Dr. Sam Holland, state veterinarian for the South Dakota Animal Industry Board in Pierre.

Colorado wildlife officials say the finding is no surprise, as the infected Nebraska deer were near the historic epicenter of the disease-far northeastern Colorado and southeastern Wyoming.

"Given that animals do move along the South Platte River, it's not surprising the disease would extend to the panhandle of Nebraska," said Todd Malmsbury, a spokesman for the Colorado Division of Wildlife.

In a study published in the Journal of Animal Diseases (Vol. 36, No. 4, Oct. 2000), scientists determined wild whitetail and mule deer in Wyoming management unit 16 are infected with CWD. Wyoming management unit 16 is less than 30 miles from the affected ranch in Nebraska, and results from the study show the unit has a disease prevalence of 4.1% in free-ranging mule deer and 15.4% in free-ranging whitetail deer.

"The study didn't even look at the wild deer populations in Nebraska and South Dakota," said Mohlman. "More than likely, CWD has been here in the wild for years, undetected until we started looking for it," Mohlman added.

Seven of the elk on the ranch tested positive for CWD; however, according to a detailed analysis of herd inventory records, none of the animals could be traced to another herd that had been exposed to a confirmed case of CWD.

Lynn Creekmore of the USDA, in a presentation at the recent World Deer Congress in Texas, noted that since the Nebraska ranch has no epidemiological link to a CWD source herd, it is possible that the disease had spread from the endemic area in Wyoming. An epidemiological study has been proposed to examine this question.

The affected rancher has been cooperating with Nebraska Game and Parks officials and the Nebraska Bureau of Animal Industry, as well as the USDA and Animal and Plant Health Inspection Services (APHIS), to quickly depopulate any animals that were potentially exposed to the fatal brain-wasting malady.

According to state officials working closely with the issue, depopulation could occur within the next month. The animals in Nebraska will be destroyed as soon as Colorado officials are finished with the daunting task of killing and incinerating some 1,600 domestic elk in Colorado.

Wildlife officials, veterinarians, and ranchers have been at odds over the source of the disease. However, all parties agree that the most important issues are eliminating the disease from both domestic and wild populations and continuing research into CWD.

"Right now, we are focused on eradicating CWD from domestic herds," said Mohlman. "And we really want to work with state agencies to develop a plan for eliminating CWD in the wild, so that scenarios like this don't happen again" Mohlman added.

"We also want to do more research on CWD so that we know how to contain and eliminate it," continued Mohlman. "We need a clear understanding of what causes the disease and how it's spread so that we can fight it," said Mohlman.

United States Department of Agriculture
Animal and Plant Health Inspection Services
Veterinary Services

Chronic Wasting Disease
Reprinted with Permission APHIS

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of North American deer and elk. First recognized as a clinical "wasting" syndrome in 1967 in mule deer in a wildlife research facility in northern Colorado, it was identified as a TSE in 1978. CWD is typified by chronic weight loss leading to death. There is no known relationship between CWD and any other spongiform encephalopathy of animals or people.

In the mid - 1980's, CWD was first detected in free ranging deer and elk in contiguous portions of northeastern Colorado and southeastern Wyoming. In May 2001 CWD also was found in free-ranging deer in the southwestern corner of Nebraska (adjacent to CO and WY). The limited area of northern CO, southern WY, and southwestern NE in which free-ranging deer and/or elk positive for CWD have been found is referred to as the endemic area. Soon after diagnosis of the disease as a TSE, Colorado and Wyoming wildlife management agencies stopped the movement of deer and elk from their research facilities; wild cervids have not been translocated from the endemic area. CWD has also been diagnosed in farmed elk herds in a number of states. The first positive farmed herd in the U.S. was detected in 1997 in South Dakota. Since then, 13 additional positive herds have been found; South Dakota (6), Nebraska (3), Oklahoma (1), Montana (1), and Colorado (2). As of May 2001, three of these fourteen positive herds remain under quarantine. Ten of the herds have been removed and the quarantine has been lifted from one herd that underwent rigorous surveillance with no further evidence of disease. CWD also has been found in farmed elk and free-ranging mule deer in the Canadian province of Saskatchewan. For more information on CWD in Canada visit the Canadian Food Inspection Agency website at:

http://www.inspection.gc.ca/english/anima/heasan/disemala/cwdmdce.shtml

Species that have been affected with CWD include Rocky Mountain elk, mule deer, white-tailed deer, and black-tailed deer. Other ruminant species, including wild ruminants and domestic cattle, sheep, and goats, have been housed in wildlife facilities in direct or indirect contact with CWD-affected deer and elk. No cases of CWD or other TSE's have been detected in these other ruminant species. There is ongoing research to further explore this possibility.


Causative Agent
The agent responsible for CWD (and other TSEs, such as scrapie and bovine spongiform encephalopathy) has not been completely characterized.  There are three main theories on the nature of the agent that causes CWD:  (1) the agent is a prion, an abnormal form of a normal protein (known as cellular prion protein) most commonly found in the central nervous system.  The abnormal prion protein "infects" the host by promoting the conversion of normal cellular protein to the abnormal form; (2) the agent is an unconventional virus; (3) the agent is a virino, or "incomplete" virus composed of nucleic acid protected by host proteins.  The CWD agent is smaller than most viral particles and does not evoke any detectable immune response or inflammatory reaction in the host animal.  Based on experience with other TSE agents, the CWD agent is assumed to be resistant to enzymes and chemicals that normally break down proteins, as well as resistant to heat and normal disinfection procedures.

Clinical Signs
Most cases of CWD occur in adult animals. The disease is progressive and always fatal. The most obvious and consistent clinical sign of CWD is weight loss over time. Behavioral changes also occur in the majority of cases, including decreased interactions with other animals in the pen, listlessness, lowering of the head, blank facial expression, and repetitive walking in set patterns within the pen. In elk, behavioral changes may also include hyperexcitability and nervousness. Affected animals continue to eat grain but may show decreased interest in hay. Excessive salivation and grinding of the teeth are seen. Most deer show increased drinking and urination.


Diagnosis
Research is being conducted to develop live-animal diagnostic tests for CWD. Currently, definitive diagnosis is based on necropsy examination and testing. Gross lesions seen at necropsy reflect the clinical signs of CWD, primarily emaciation and aspiration pneumonia, which may be the cause of death. On microscopic examination, lesions of CWD in the central nervous system resemble those of other spongiform encephalopathies. In addition, using a technique called immunohistochemistry, scientists test brain tissues for the presence of the abnormal prion protein.


Epidemiology
The origin and mode of transmission of CWD is unknown. Animals born in captivity and those born in the wild have been affected with the disease. Based on epidemiology of the disease, transmission is thought to be lateral or from animal to animal; although maternal transmission may occur, it appears to be relatively unimportant in maintaining epidemics. Transmission by contaminated feed is not believed to occur.

Management
Colorado and Wyoming wildlife management agencies and USDA are continuing to invest resources in CWD research efforts. In addition, the Colorado Division of Wildlife is currently developing and implementing a management plan for CWD in free-ranging cervids. The U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) has provided assistance to State officials in diagnosing CWD and in monitoring international and interstate movements of animals to help prevent further spread of CWD. In addition APHIS is developing a program to eliminate CWD from farmed elk. These agencies are committed to limiting the distribution of the disease in free-ranging deer and elk to the current localized area and decreasing its occurrence in both the free-ranging and farmed deer and elk populations.


Surveillance
Surveillance for CWD in free-ranging deer and elk in Colorado and Wyoming has been ongoing since 1983, and to date, has confirmed the limits of the endemic areas in those States. An extensive nationwide surveillance effort was started in 1997-98 to better define the geographic distribution of CWD. This surveillance effort is a two-pronged approach consisting of hunter-harvest cervid surveys conducted in many states, as well as surveillance throughout the entire country targeting deer and elk exhibiting clinical signs suggestive of CWD. Over 15,000 harvested free-ranging deer and elk have been tested to date, including over 8,000 animals harvested from outside of the endemic area. There have been no free-ranging animals found to be positive that did not originate from the endemic area. 

Surveillance for CWD in farmed elk began in 1997 and has been a cooperative effort involving State Agriculture and Wildlife Agencies and APHIS. Farmed cervid surveillance has been increasing each year since 1997, and will be an integral part of the USDA program to eliminate CWD from farmed elk. 

For more information from APHIS about CWD in farmed cervids, contact:
Dr. Lynn Creekmore
Staff Veterinarian, Wildlife Disease Liaison
USDA, APHIS, VS
National Animal Health Programs
4101 Laporte Avenue
Fort Collins, CO 80521
lynn.h.creekmore@aphis.usda.gov

For more information about CWD in free-ranging cervids, contact:
Dr. Michael Miller
Colorado Division of Wildlife
317 West Prospect Road
Fort Collins, CO 80526
mike.miller@state.co.us
or
http://wildlife.state.co.us/hunt/HunterEducation/chronic.asp

Dr. Tom Thorne
Wyoming Game and Fish Department
5400 Bishop Boulevard
Cheyenne, WY 82006
tthornl@missc.state.wy.us

Dr. Elizabeth Williams
Department of Veterinary Science
University of Wyoming
Laramie, WY 83070
storm@uwyo.edu

Current information on animal diseases and suspected outbreaks is also available on the Internet. Point your Web browser to http://www.aphis.usda.gov to reach the APHIS home page. 

Other Links on CWD

Wisconsin DNR
Rocky Mountain Elk Foundation
Canadian Food Inspection Agency   
Texas Bans Whitetail Imports

This link should be active sometime in June 2002
CWD-Info.org