Colorado experiments on humans
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Colorado dementia experiment in humans
Feds need to take control over Colorado CWD
Surveillance for chronic wasting disease in Colorado
CWD by river drainage
Some early history of CWD
Chronic Wasting Disease in Canada
More chronic wasting disease news: 1, 2 on-site, off-page

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Colorado dementia experiment in humans

14 Feb 98 Denver Post Jason Blevins
Excerpts from a 14 Feb 98 story in the Denver Post entitled 'Ill Animals spook hunters.'

"But some hunters in the area are expressing concern over what they feel is a real problem that wildlife officials are not properly addressing. "it's got me worried," said Chris Melani of Longmont. "It's got me down to the point where I won't be meat-hunting in that area any more.

Melani, who has hunted in Larimer County for more that 20 years, shot a deer last season that tested positive for chronic wasting disease.

Melani said he followed all the requirements outlined by the Division of Wildlife but [had to wait] six weeks before the division notified him that his deer was infected. By then he had brought the deer to a meat processing company, where it was mixed with hundreds of other deer and made into sausage, he said.

"You know they said to wait three weeks, so three weeks went by and I went ahead and ate it," he said. "Next time I'll wait longer."

"They say they don't have any evidence that it is transferable to humans, but at the same time, they don't have any evidence that it is not," Melani said, noting that when severing the head from the body for submission to the Division of Wildlife, the hunter must be exposed to the spinal cord.

John Pape, an epidemiologist at the Colorado Departmen of Public Health had said that there is no evidence that suggests that humans can contract scrapie or chronic wasting disease from handling or consuming mead taken from an infected animal."

Federal government needs to take control over CWD

Listserve 24 Feb 98 -- webmaster opinion
Isn't this odd that a hunter would know about MJ Rees "absence of evidence is not evidence of absence" and the precautionary principle but that the state epidemiologist would not?

This is really scary what they are doing, worse than I had ever thought, mixing hundreds of deer brains [those not sent in] and spinal chords and contaminating the rendering equipment, with rogue prion sausage going out to thousands of people. The federal government needs to step in and take control away from these incompetent local authorities.

I want to see Miller, Williams, and especially Pape stand up in front of the TV cameras and eat a big heaping plate of tainted sausage themselves -- it's not right to give out this advice to hunters when you would never follow it yourself in a million years. It is like England, BSE, and nvCJD never happened.

Do we need another large-scale experiment on humans? This one has been running for 30 years and has exposed hundreds of thousands of Americans. All so the Department of Wildlife doesn't lose sales on game tags? This disease shows very strong lateral/horizontal transmission. It crosses species barriers easily, being found in three cervids with different prion sequences -- what is stopping CWD from passing back to cattle and sheep grazed on these shared public and private lands?

Does the purchase of a hunting tag with an accompanying inaccurate brochure about CWD constitute informed medical consent -- agreement by the hunter to participated in a deer-to-human dementia transmission experiment? I don't think so.

Question: Could the disease simply have originated de novo in deer and not be connected to livestock TSE?


De novo is definitely possible. This is the theory of the sailor acquiring VD from a toilet seat -- hard to rule out but seldom taken seriously when other risk factors are present.

TSEs have never been seen in the wild in any species anywhere in the world. Every non-experimental TSE is linked to feeding contaminated stock or confined, concentrated already-infected animals. Winter protein cake favors bovine, shared sheep pasture ovine. Strictly game farm, captive research animals, winter-ranged animal outbreak history -- why didn't CWD occur in Yellowstone or Sheldon, 4 million TSE-free acres with lots of ungulates? Maybe because these animals never came in contact with rendered product or infected livestock.

["Indeed, in California, which has had a scrapie program since 1953, there has never been a case reported in a range sheep. ALL reported cases have been purebred blackface sheep, except for one Dorset and two goats." -- Paul Michelsen,M.S., D.V.M.,Mendocino Equine Clinic]

A good illustration apparent effects of transmission between animals in close quarters is the USDA facility in Mission, Texas. While I haven't seen a description of the physical layout, animal housing/concentration factors may have come into play here. The researchers commented on the extraordinary high rates of transmission, up to 30% in lambs, transmission to freshly imported ANZ sheep, seldom-seen transmission to goats, and transmission to cattle (one hopes from the inocula). These rates are not those free-ranging sheep flocks.

DOW/CSU has never disclosed what happened to the original captive mule deer in 1967 -- were they released into the wild after the experiment, did any escape, did they exchange animals with the Wyoming facility, what were they fed, had there been prior scrapie sheep in the enclosure? It is ludicrous that they have never released the details -- as if the people who worked didn't keep lab notebooks.

My guess is that relevent documents were shredded long ago when they realized that the disease had gotten out of their facility -- with potentially devastating consequences to game tag sales and hence the very revenues that pay their salaries, never mind the legal liability. Now they are in too deep to confess. Just like MAFF.

The only other scenario that makes sense to me is a western Stetsonville: winter-ranged protein-caked deer, some of these got accidentally brought into the captive study.

Chronic wasting disease transmits to humans -- meeting gossip

Sun, 8 Mar 1998 webmaster
"I heard at a meeting over the weekend that CWD rogue prions have supposedly been shown to convert normal human prions with some efficiency by an experienced laboratory in the western US. While not surprising in the least if true, let's wait to see the published version if any before jumping to conclusions.

In vitro tests alone would not determine the risk factor for the estimated 1 million Americans who may have eaten tainted deer and elk sausage over the 30+ year duration of the epidemic. The Ft. Collins area would be a good one for intensive 14-3-3 epidemiology or on a nexus questionaire for sporadic CJD generally. The area has had explosive population growth which has to be separated out from 'old-timer' incidence data."

Here are the highlights from two CWD papers that I recently obtained, the oldest (1980) and the newest (1997). The oldest does not contain any relevent cites to earlier reports on the disease. The map below shows where animals have been found.

CWD was first seen at an unnamed wildlife facility in Ft. Collins in 1967, though "morbidity and mortality from CWD have not been accurately recorded among mule deer in these facilities during the period 1967-74". It may be the Wild Animal Disease Center though that could also be the name of the Wheatland, Wyoming facility as Tom Thorne was evidently a staff member in 1980.

There is no discussion of the Wyoming facility or history of its experimental animals. The operators are not identified for either facility. I don't know if either facility is still operative, whether they are still experiencing CWD 30 years later, or whether they are still releasing animals back out into the wild or shipping them to game farms, zoos or other facilities. Williams and Young wrote in 1992 that CWD "should be viewed with concern in the light of international movements of wild ruminants and the current expansion of the game farming and ranching industry in many parts of the world."

The Colorado facility was evidently totally contaminated over at least a 12 year period, with 54/67 deer affected, at ages 2.5-4, during 1974-79. It is disgusting to see fawn after fawn, year after year, brought in to meet its doom. Ironically, the purpose of the facility is experimental nutritional, metabolic and disease studies of deer and other non-domesticated rumants -- how could meaningful experiments be conducted in such a barbaric setting?

"The majority ( approximately 90%) of mule deer were hand raised from infancy after they received colostrum and were separated from does at 1-5 days of age. Most were born to does trapped in the wild during pregnancy, brought to the facility, and released [back to the wild] after parturition. The remainder were either born to resident does brfed in captivity or orphan fawns captured in the wild....From time to time a few young adult deer trapped in the wild have been added to the permanent captive populations."

"Fawns were bottle fed cow's milk supplemented with vitamins and weaned at 70-80 days. thereafter, groups of 2-10 deer occupied pens aprrocimately 0.1 to 1.0 hectares in size and recived rations of alfalfa hay, commercially mixed grains supplemented with minerals and vitamins, and fresh water. Over the years a variety of grain mixes have been used...."

"Within the facilities, deer have had irregular and discontinuous contact with other wild ruminants [elk, white-tailed deer, proghorns, bighorns, and mouflon, Ovis musimon] and domestic cattle, goats, and sheep. [Mice, rabbit, raccoon, skunk, ground squirrels, dogs and cats also reside within or traverse the facility.] "


1. These data strongly support efficient horizontal transmission within the facility. It is improbable, 10 years prior to the disease being seen in the wild, that 80% of the wild does carried the disease _and_ transmitted it vertically to fawns. Close confinement favors lateral spread. The disease had passed to three species by 1982 within the facility. Have the facilities been shut down and isolated or are they still operating?

The facility made five horrible mistakes:
-- in confining sheep (and their diseases) with wild ungulates,
-- in letting 13 years go by without studying or recording dying animals,
-- in releasing post-partem does back to the wild from a facility contaminated with an infectious disease, and
-- in possibly trans-shipping pre-symptomatic animals to other facilities worldwide, -- in extreme complacency in documenting the disease and alerting hunters and ranchers to risks involved.

2. The origin of CWD is unclear. Feed within the facility, if accurately described, could not account for origin. A sick wild animal might have been brought in and amplified the disease along under conditions of close contact. This animal may have had access to downer cow protein supplement or scrapie sheep pastures or been a sporadic case.

Spraker et al. write, "it is possible that feeding of deer and elk by local residents in Estes Park and other developments may be a contributing factor. If this disease is transmitted horizontally, either by direct contact or environmental contamination, then artificial feeding stations for wild cervids could be exacerbating the problem at a local level." Rations at the feeding stations are not described.

The first wild ungulates with CWD was seen in 1981, a year after the disease was first described as a spongiform encephalopathy and 14 years into the disease in the facility. Their pathology was identical to that of the original confined animals. Numbers detected remained low until quite recently: 49 in Colorado, 11 in Wyoming, to 1995; however monitoring has intensified recently. Symptoms are not particularly striking: depression, weight loss, excessive salivation, dull hair coat, fear of humans, drooping ears, etc.

Alternately, the disease could simply be scrapie passed from sheep [goats and cattle much less likely] The sheep in the captive facility not adequately described in terms of numbers, contact, disposition, and scrapie history. Wild does brought in to fawn could have become infected at the facility prior to release to the wild, introducing it there. The other concern is that sheep and cattle confined in the facility were back-infected from the deer and then released to commercial herds or put into the human food chain.

It is highly likely that the facilities exacerbated the disease in the wild by releasing infected pre-symptomatic does year after year, whatever its ultimate origin.

J Wildl Dis 1997 Jan;33(1):1-6 
Spongiform encephalopathy in free-ranging mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus 
virginianus) and Rocky Mountain elk (Cervus elaphus nelsoni) in northcentral Colorado.
Spraker TR, Miller MW, Williams ES, Getzy DM,  Adrian WJ, Schoonveld GG, Spowart RA, O'Rourke KI, Miller JM, Merz PA

J  Wildl Dis 1980 Jan;16(1):89-98 
Chronic wasting disease of captive mule deer
ES, Young S 

Rev Sci Tech 1992 Jun;11(2):551-567
Spongiform encephalopathies in Cervidae.
Williams ES, Young S 

Chronic wasting disease: from wild animals to beef?

19 Feb 98 Western Producer p. 97
DENVER, Colo. -- When chronic wasting disease, a transmissible spongiform encephalopathy that affects deer and elk was diagnosed in American elk and deer this winter, the spectre of mad cow disease loomed close by. The story says that chronic wasting disease was recognized in Colorado about 30 years ago.

Frank Garry, of Colorado State University was quoted as saying that, "We don't have very good tools to work with these diseases like we do bacterial or viral diseases." The story also notes that recent tests from Glasgow University compared BSE infected brain tissue to scrapie and CWD. Tests showed they are not the same disease.

Garry was cited as saying that in the last year there have been several studies on how these diseases are transmitted. One study in Iowa has injected infected elk tissue into cattle to see if CWD travels across the species barrier. A feeding program that includes feeding infected tissue from elk to cattle started recently at the University of Wyoming.

Michael Blackwell, deputy director of the FDA s veterinary health division was cited as saying there are already diligent steps undertaken in Canada and the United States to prevent the possibility of BSE happening here.

If American cattle producers feed a non-prohibited animal protein they must maintain copies of invoices for feeds containing the protein for at least a year. They must also keep copies of feed labels from feeds containing animal proteins for one year.

Question: Never mind the cattle producers, does this regulation applies to game farm operators? It seems captive animals is where the outbreaks have been observed. I heard from Canadian authorities that game farm feed recipes are a bit of a secret and that may represent quite the loophole. If CWD back-transmits to cattle on open western range-- and there is room for lateral transmission -- then this becomes everybody's problem. Plus this has been going on for 30 years -- why isn't the USDA testing cattle and sheep from Larimer County? Why isn't anyone at FDA Div of Animal doing something?-- webmaster


Dave Harlan 28 Feb 98
"It is illegal to feed prohibited animal proteins to any ruminant animal in the US. Does not matter if the animal is a domestic cow, sheep, goat, or wild/game farm elk, deer or whatever ruminant. "Do not feed to cattle or other ruminants" is the precautionary statement on labeling for prohibited animal proteins. I think one may apply for a research exemption to the prohibition though."

Question: Do the new federal rendering regs and their various revisions still allow ruminant blood products and similar things to be feed back to ruminants? Also, they sort of gerrymandered pigs out of ruminants, plus they allow cow-to-chicken/pig-to-cow feedback loop exemptions. Sheep are not so welcome any more, but aren't there cross-contamination possibilities for rendering streams for road-kill deer, cows, and pigs in the US?


"In a nutshell, the rule bans all mammalian proteins in ruminant feeds, but then it exempts blood, gelatin and milk products and those which are produced at sites that are 100% porcine or equine in origin. "

In addition, "plate waste" is exempt from the prohibition. This may contain material which has been cooked and offered for human consumption, but left on the plate (refused) by the consumer. A small amount of this material, scraped from plates at food establishments, enters a raw material stream which is further cooked, dried and ground to manufacture a feed ingredient. Non-mammalian animal proteins (poultry & fish) are not regulated by the rule. FDA rule addresses applicable cross contamination possibilities in the regulation."

Question: Do you have any figures on how many inspection/enforcement visits have been made to US game farms since the regs went into place? The story from North Dakota indicated the regs weren't ever distributed and are being ignored.


"Contact the FDA-CVM Division of Compliance."

Question: My impression is that game farmers are surprisingly unregulated, either because of the lack of laws or because of their (relatively) small size. What I do know is that the Denver Buffalo company (a restaurant) makes a big deal of its relationship with specific, long-term bison ranchers, leading me to believe that >quality control is up to the consumer and not the government.


webmaster opinion 28 Feb 98
The bison prion sequence will not provide a species barrier. Bison are ruminants that would be covered in theory under the US feed ban, modulo its weaknesses.

I came across some very interesting new factoids at the Canadian Cooperative Wildlife Health Center, namely CWD was first recognized as a disease in 1967 in a herd of captive mule deer and mule deer/white-tailed hybrids and was determined to be a form of TSE only in 1977, first recognized in free-ranging wild deer in 1981. It subsequently was diagnosed in other captive deer and elk in the Colorado facility AND in a research facility in neighbouring Wyoming.

So there were two different research places reporting it in captive animals. If these did not exchange animals, it makes one wonder about the prevailing incidence. Wyoming and Colorado are both seeing it in three free-ranging species: mule deer, elk, and white-tailed deer.

Alberta has a monitoring program going on: target of 200 samples total, hunter and road kill, plus passive submissions [voluntary?] of all adult elk and mule deer from game ranches to the Animal Health Laboratories are presently being routinely examined for spongiform encephalopathies. Also a surveillance system in conjunction with the Alberta Venison Council of samples of farmed elk, mule deer and white-tailed deer 18 months or older with any of the CWD clinical signs.

So far, so good. But this sounds ominous:

"Reports on individual cases shall be forwarded to the owner while overall results and estimates of risk can be shared with the Alberta Venison Council, Fish and Wildlife Division and Agriculture and Agri-Food Canada (AAFC). Because there is no formal eradication program in place, positive case shall be kept confidential and reported only to the owner and AAFC.... Chronic Wasting Disease is not a "reportable disease", and the Office International des Epizooties (OIE) (the organization that establishes international animal health guidelines), does not require notification its presence. "

Miller, Williams, and Thorne wrote on Promed on 20 June 96 that "A few surveys of wild deer and wapiti outside this enzootic area (and in other parts of North America) have failed to detect CWD...The natural host range of CWD appears limited to species in the genera Cervus and Odocoileus: spongiform encephalopathies have not been diagnosed in sympatric herbivorous or carnivorous species... CWD appears to be neither BSE nor scrapie, but rather a unique transmissible spongiform encephalopathy of native North American cervids whose occurrence and distribution are limited when compared to the former diseases of domestic ruminants...."

But I think outside surveys were essentially zero (three hundred) at the time they wrote this and in point of fact no TSE surveys whatsoever have been on conducted on mountain goats, bighorns, or mountain lions etc.

I am fascinated by the elementary mistake made by these advise-giving local authorities. By definition, scrapie can only occur in sheep and BSE can only occur in cows. This is covered in Mad Cows 101. Upon cross-species transmission, a different prion sequence is henceforth responsible, that of the new host animal. I see no published evidence whatsoever mitigating against scrapie-to-deer or bovine TSE-to-deer. I hope they do

Maybe other areas in US with scrapie are not reporting CWD, but there aren't monitoring programs and expertise, plus which states are not ke

en about reporting scrapie or about losing of game tag money. If it is a naturallly occuring disease of deer, why isn't it all over the West?

The Ft. Collins epicenter and timing of onset makes me think something crossed the species barrier at that time, either from feed or co-pasturing captive animals at these two research facilities. Most likely a scrapie or bovine TSE origin in my opinion. As with TME, there is some possibility that strain-typing could resolve the origin question.

Chronic Wasting Disease - Canada & USA (2)

Promed discussion forum 20 June 96
We were concerned with several apparent misrepresentations related in the 13 June 1996 posting from Dr. Michael Woodford, IUCN/VSG, on chronic wasting disease of deer and wapiti; the quotes in this posting were credited to Dr. Francois Moutou and excerpted from an article that appeared in the 19 May 1996 issue of Le Monde, although the latter was not entirely clear from the posting. Unfortunately, we were unable to acquire a copy of Dr. Moutou's original article in La Semaine Veterinaire prior to preparing this response.

Chronic wasting disease (CWD) has occurred in captive deer and wapiti from wildlife research facilities in northcentral Colorado and southeastern Wyoming, USA, since the late 1960's. Since its recognition as a transmissible spongiform encephalopathy in the late 1970's, various aspects of the signs, pathology, and epizootiology of CWD have been described in some 50 reports, presentations, press releases, and peer-reviewed articles beginning in 1979 -- the occurrence of this disease has been anything but a well-kept secret. Subsequent to its recognition in captive deer and wapiti, CWD was also diagnosed in free-ranging conspecifics beginning in 1981.

Although most of the 65 free-ranging cases have been submitted in recent years, this appears largely coincident with the inception of active surveillance programs for suspect deer and wapiti in the enzootic area and increased recognition of suspect cases in the wild. To date all free-ranging cases have arisen within about 100 km of affected research facilities, although it's not clear whether CWD in captive animals truly preceded the disease in free-ranging animals or vice versa.

A few surveys of wild deer and wapiti outside this enzootic area (and in other parts of North America) have failed to detect CWD, although additional surveillance may be warranted. Within the enzootic area, as in captivity, CWD appears to be maintained naturally in affected deer and wapiti populations via lateral (and perhaps vertical) transmission.

The natural host range of CWD appears limited to species in the genera Cervus and Odocoileus: spongiform encephalopathies have not been diagnosed in sympatric herbivorous or carnivorous species in either the enzootic area or in affected research facilities. With the exception of the recent Canadian case (a captive wapiti imported to Saskatchewan from South Dakota, USA, as a calf), all cases of CWD diagnosed since the mid-1970's have come from this localized area; to our knowledge, the origin of infection in the Canadian case remains undetermined.

Based on the information available to date, CWD appears to be neither BSE nor scrapie, but rather a unique transmissible spongiform encephalopathy of native North American cervids whose occurrence and distribution are limited when compared to the former diseases of domestic ruminants. [Confusing terminology: scrapie can only occur in sheep, BSE can only occur in cows. Upon cross-species transmission, a different prion sequence is henceforth responsible, that of the new host animal. Seem to be saying here that areas in US with scrapie are not reporting CWD. -- webmaster]

Dr. Michael W. Miller
Colorado Division of Wildlife
Wildlife Research Center
317 West Prospect Road
Fort Collins, Colorado 80526-2097 USA
Voice: (970)484-2836, ext. 348
FAX: (970)490-6066

Dr. Elizabeth S. Williams
Department of Veterinary Sciences
University of Wyoming
1174 Snowy Range Road
Laramie, Wyoming 82070 USA
Voice: (307)742-6683
FAX: (307)721-2051

Dr. E. Tom Thorne
Wyoming Game and Fish Department
Game and Fish Research Laboratory
Box 3312 University Station
Laramie, Wyoming 82070 USA
Voice: (307)766-5629
FAX: (307)766-5630

Surveillance for chronic wasting disease in Colorado

TSE Conference 2 May 1997
M. W. Miller, Colorado Division of Wildlife, Fort Collins
E. S. Williams, University of Wyoming, Laramie
Chronic wasting disease (CWD) is a spongiform encephalopathy of mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni). To date, the only documented focus of CWD is in northcentral Colorado and southeastern Wyoming.

To understand epizootiology of CWD, to determine its distribution, and to reliably model its dynamics and effects on wild populations, methods for efficiently and effectively surveying free-ranging populations of deer and elk are needed. Active surveillance of free-ranging cervids in the endemic areas began in 1981, but has been more intense since 1992.

Two strategies are currently being employed in the endemic areas of Colorado and Wyoming, as well as many other states and provinces in western North America, to survey for CWD:

1) Recognition, collection, and submission of suspect CWD cases to veterinary diagnostic laboratories by wildlife agencies. The CWD *suspect* profile includes deer or elk; over18 months of age; emaciated and showing abnormal behavior, and/or increased salivation, and/or tremor, stumbling, incoordination, and/or difficulty in swallowing, and/or polydipsia/polyuria.

Diagnostic evaluation of each suspect includes brain histopathology and, in more recent years, sometimes includes ancillary evaluation by immunocytochemistry, SAF, or Western blot. Using this approach, about 80 CWD-positive cervids were identified in the five-county endemic area in Colorado and Wyoming since 1981; at least 168 additional *suspects* submitted from throughout Colorado and Wyoming have been examined and found to be affected by maladies other than CWD.

2) Collections of heads (or brain stem and tonsils) from harvested deer and elk via check stations or specified drop-off points. Brains were examined by histopathology and, beginning in 1995, immunocytochemistry; selected cases were also examined for SAF and by Western blot analysis.

Estimated prevalences from pooled harvest survey data were 0.4% in elk (1992-1996; n=487; range 0-1%/management unit/yr) and about 2.9% (1983-1996; n=687; range 0-7.3%/management unit/yr) in endemic populations; none of over 300 samples from cervids harvested outside endemic areas of Colorado and Wyoming were positive.

Based on results obtained to date, we believe this combination of extensive clinical surveillance and intensive population sampling represents an effective and efficient strategy for detecting, studying, and monitoring CWD in free-ranging cervid populations in Colorado and Wyoming, and also may be useful in studies of CWD occurrence and distribution elsewhere.

Chronic Wasting Disease in Canada

Canadian Cooperative Wildlife Health Center  Newsletter Summer 1997
Chronic Wasting Disease (CWD) is known to affect Mule Deer, Elk (Wapiti) and White-tailed Deer. It was first recognized as a disease in a herd of captive Mule Deer and Mule Deer hybrids at Fort Collins, Colorado in 1967 and was determined to be a form of TSE in 1977.

It subsequently was diagnosed in other captive deer and elk in the Colorado facility and in a research facility in neighbouring Wyoming. CWD has been recognized in free-ranging wild deer since 1981. From that year to June 1995, the disease was diagnosed in 41 Mule Deer, 6 Elk and 2 White-tailed Deer, all from free-ranging populations in north-central Colorado within a 100 km radius of Fort Collins. A total of 11 diseased wild animals of the same three species have been found in an adjacent area of southeastern Wyoming.

In Canada, the disease has never been identified in wild deer, but two cases have occurred in captive deer: in 1978 in a Mule Deer at the Metro Toronto Zoo and in 1996 in an elk imported from the United States and held on farms in Saskatchewan. No further cases have occurred at the zoo and a comprehensive eradication program was undertaken by Agriculture and Agri-Food Canada in cooperation with the game farming industry with respect to the case in Saskatchewan.

CWD gets its name from the progressive emaciation, or wasting away, that occurs in affected animals. Abnormal behaviour is the other central feature of the disease. Affected animals are weak and have an odd gait, reduced fear of humans, drooped heads and ears, and excess salivation. There are no gross abnormalities except emaciation. Diagnosis is based on microscopic changes in the brain. Nerve cells and the brain substance around them develop large, clear vacuoles that give the tissue the appearance of a sponge with its many holes - hence the name "spongiform" encephalopathy - literally a spongy abnormality of the brain. These vacuoles develop in association with accumulations of a special protein found only in TSE-affected brains. This protein can be identified by special techniques, and its presence together with the vacuoles is generally accepted as the ultimate criterion for making a diagnosis.

... Wildlife personnel must respond to the legitimate public concerns about CWD without the benefit of much firm information. No one knows whether or not CWD poses any risk to human health or to domestic animal health, or if it is a significant threat to wild deer populations. Its mode and rate of transmission are unknown, as is its relationship to other TSE's such as Scrapie and CJD (BSE does not occur in North America). In Colorado and Wyoming, major surveillance programs for CWD are underway; the results may help define the geographic extent of the disease and other aspects of its biology. Even in the affected area of north-central Colorado, the prevalence of affected animals appears relatively low, being highest among mature male Mule Deer with about 6% of animals affected.

Both Saskatchewan and Alberta have initiated limited surveys for CWD based on available specimens, but quite large samples will be needed to determine the prevalence of a disease that probably does not occur or at least is very rare. Dr. Beth Williams, University of Wyoming, has established a battery of tests for detection of CWD and the application of these tests to large samples of animals will help determine the best methods for detection and their limitations. We are at a very early stage in our understanding of this disease.

We must communicate this honestly to the public and enlist its support for the research necessary to learn enough about this disease to respond to it wisely. (For more detailed information, readers are directed to the following publication and references cited therein: Spraker, T.R. et al. 1997. Spongiform encephalopathy in mule deer, white-tailed deer and Rocky Mountain elk in north central Colorado. Journal of Wildlife Diseases 33: 1-6.)

Alberta Project to Examine Brains of Deer and Elk for Chronic Wasting Disease Survey

Contact: Dr. Detlef Onderka
AAFRD Fax: 403 422-3438
Alternative Livestock Surveillance Task Force of Animal Industry Division of Alberta Agriculture Food and Rural Development(AAFRD) has developed a surveillance project to examine brain tissue from free ranging hunter killed or road killed elk and deer (mule deer and white-tailed deer) for evidence of spongiform encephalopathy, a syndrome termed "Chronic Wasting Disease" (CWD). After consultation and approval by the Alberta Venison Council an active surveillance system including farmed, elk, mule deer and white -tailed deer was also implemented. This project was proposed because of the risk that CWD might have been introduced into Alberta before the moratorium on elk movement from the United States was in place or it could perhaps be present in wild and be unrecognized.


All submissions are made to the nearest Animal Health Laboratory, identified with location (for wildlife samples: Wildlife Management Unit), owner (if applicable), approximate age (young of year, yearling or adult), species and sex. Clinical signs are noted.

Phase 1A

A surveillance of hunter and road killed mule deer, elk and white tailed deer has been initiated for the 1996 - 1997 season by Alberta Fish and Wildlife Division. Sampling is based on availability of carcasses and hunter compliance and is run in conjunction with other programs. A target of 200 samples total was set and location of animal take is tracked geographically. Wildlife surveillance samples consist of at least intact heads of mule deer, elk, or white tailed deer otherwise entire carcasses are submitted. Most submissions from the field are expected to be frozen.

Phase 1B

Passive submissions of all adult elk and mule deer from game ranches to the Animal Health Laboratories are presently being routinely examined for spongiform encephalopathies.

Phase 2

An active surveillance system in conjunction with the Alberta Venison Council was initiated which includes samples of farmed elk, mule deer and white-tailed deer 18 months or older with any of the following clinical signs as confirmed by the owner or a veterinarian: emaciation, abnormal behaviour or indifference to human activity, increased salivation or tremors, stumbling, in coordination, difficulty or inefficiency in chewing or swallowing, and increased drinking and urination. An incentive to participate in the project includes a free of charge complete necropsy and results sent immediately to the owner.

Necropsies of the brain and histologic preparations of brain sections are in accordance with the ALBERTA BSE surveillance protocol. Frozen samples of suspect or inconclusive cases will be used for Western blot, negative stain electron microscopy or bioassay. This will be done in confidence through the Wyoming State Veterinary Laboratory.

Expected submissions based on previous records are about 25 ranched elk and deer and maximum of 200 wildlife specimens. Recent figure suggest that there are 450 farmed mule deer, 3200 farmed white tail deer and 12,000 farmed elk in the province of Alberta. Numbers collected in the first year are not expected to give us strong evidence of disease free status but will be able to produce maximum prevalence based on sample size.

Results from this project are expected to support the hypothesis that in Alberta's game ranching industry and wildlife, CWD is a very low risk disease. Reports on individual cases shall be forwarded to the owner while overall results and estimates of risk can be shared with the Alberta Venison Council, Fish and Wildlife Division and Agriculture and Agri-Food Canada (AAFC). Because there is no formal eradication program in place, positive case shall be kept confidential and reported only to the owner and AAFC. Industry and Federal officials are in consultation regarding this disease. It is hoped that the outcome of this type of surveillance across Canada will help in these discussions.

The elk in Canada with CWD

 1 May 1996 Listserve
Steve Sullivan
Senior Communications Advisor
(Animal Health/Welfare Issues)
Agriculture and Agri-Food Canada
Ottawa, Canada
K1A 0C7
In early 1996, Agriculture and Agri-Food Canada (AAFC) confirmed a case of Chronic Wasting Disease (CWD) in a single elk located on a small game farm facility in southern Saskatchewan. The affected animal was imported as a yearling, in 1989, as part of a small shipment of elk originating from the U.S.

(You should be aware that, in 1990, Canada imposed a prohibition on the importation of cervids (such as deer and elk) and camelids (notably, llamas and alpacas) from the U.S. The ban was a reaction to the presence of sporadic outbreaks of tuberculosis among some captive ungulate herds in the U.S. The ban has been extended (by regulation) until December 31, 1997.)

The game farm in question is not located near other (alternative or conventional) livestock operations. No animals on this farm have died, nor have any animals moved off the premises, for any reason, since the elk herd was established. Following the confirmation of CWD, the carcass of the affected elk was incinerated and the following actions took place:

1) AAFC carried out an inventory of all elk on the farm; 2) no 'movement permits' for the elk were issued to the owner; (All captive ungulates in Canada require numbered permits to allow their movement anywhere within the country, including farm-to-farm) 3) all animals that were part of the original shipment from the U.S. were traced and located; and 4) the affected herd was put in isolation.

Chronic Wasting Disease is not a "reportable disease", and the Office International des ?pizooties (OIE) (the organization that establishes international animal health guidelines), does not require notification its presence.

Agriculture and Agri-Food Canada has developed a policy for the eradication of CWD in ranched deer and elk, and in the case of a confirmed case of CWD, we will order the destruction of all animals considered to be at risk.

As you may be aware, Tony, CWD, like BSE of cattle and scrapie of sheep, belongs to the transmissible spongiform encephalopathies disease group. According to the available scientific literature, it affects the mule deer family (including mule deer, black-tailed deer, and mule/white-tailed hybrids) and elk. White-tailed deer have not developed the disease, to date.

The cause of CWD is unknown, there is no treatment, and no test for the disease in live animals. CWD was first seen in Colorado (U.S.), in 1967, in deer belonging to research facilities. Since then, the disease has been diagnosed in captive and wild deer and elk in northern Colorado and southern Wyoming.

At the risk of sounding repetitive, I would like to emphasize that no U.S.-origin captive wild cervids or camelids have been imported to Canada since 1990. In fact, relatively few of the animals imported before 1990 are currently alive.

Mad-cow-like disease prompts slaughter of sheep in Quebec

Feb. 21/98 Globe and Mail ANIMALNET Erin Anderssen and Andre Picard
An outbreak of scrapie has, according to this story, forced the federal government to slaughter almost 5,000 sheep in Quebec over the past 14 months.

Only a small number of the animals tested positive for scrapie but entire flocks have been destroyed to prevent it from spreading further. The story says the disease typically shows up nationally in about five flocks a year, but in 1997 and early 1998 infected sheep were discovered in 17 Quebec flocks, as well as two small herds in Ontario. In the Maritimes, more than 65 animals were traced back to Quebec farms and destroyed.

The story adds that while government officials played down the public-health impact, saying scrapie poses no proven risk to humans [misleading: no tests have been done. Scrapie transmits experimentally to a wide range of species, including primates -- webmaster], the outbreak has had a dramatic economic impact on some cash strapped farmers. Georges Parent, a breeder in Saint-Gabriel-des-Hauteurs, Que., has seen his entire flock of 1,200 animals destroyed since the beginning of the year, a loss of more than $500,000.

He was cited as saying yesterday that he was too devastated to discuss the issue, but hoped that compensation will be sufficient to ensure that he can resume his operations. Mr. Parent added the government has offered between $150 and $300 for each animal that was slaughtered, while he estimates that each head was worth between $175 and $600.

The story says the Canadian food inspection agency has adopted the practice of destroying all sheep that may have been exposed to the disease, by tracing farm records and animal registrations. If the records aren't available, the entire flock is depopulated.

Ron Rogers, acting chief of epidemiology for the food inspection agency, was cited as saying the control program we have is really quite drastic. And if you look at other countries, you will see that it is.

But Dr. Rogers added that the measures were precautions only and there was no proof that the disease can be passed to humans. Rogers was quoted as saying, the first thing that we have to remember is that there's never been any link from this disease to human health. But we've been taking the stance in the last few years that it could be a human-health problem. So we are always trying to be proactive.

The incidence of scrapie remains low in Canada, and only a tiny fraction of the countrys 12,000 flocks - 1,100 of which are in Quebec - ever turn up with disease.

The story goes on to describe BSE and infectious proteins, and then says there have not been any recorded cases of Canadians contracting scrapie or the human form of BSE, nv Creutzfeldt-Jakob disease.

New Reports Of Scrapie Put Canadian Disease Sleuths On Alert

Mar. 3 /98 Ontario Farmer RAY FORD p. 10
Another story about how the Canadian Food Inspection Agency is investigating a further five scrapie-infected sheep flocks this year, following an upsurge in diagnoses of the brain disease that has forced the slaughter of more than 4,000 sheep since the beginning of 1997.

Dr. Ron Rogers, CFIAs acting chief of epidemiology was quoted as saying, "We're hoping we won't have any more reports, but that's why we react as quickly as we can. We're trying to prevent this disease from spreading, because nobody wants to bring in this disease when they buy sheep."

Rogers was cited as saying the agency usually handles an average of five infected flocks a year, but an outbreak in Quebec led to 14 infected flocks in Quebec last year; and another two infected flocks in Ontario. In the first two months of this year CFIA staff have probed similar outbreaks in two more Ontario flocks and another three Quebec flocks.

Rogers was further quoted as saying, "The consensus is it's transmitted through the placenta and placental fluid of infected ewes. The fluid gets on the lambs, bedding or feed, the ewes lick the lambs or each other, and they contract the disease. There may also be a direct spread through the birth canal, so we try to trace back animals within the same bloodline."

OMAFRA epidemiologist David Alves was quoted as saying, "Once it's diagnosed it's something the federal government comes down quite hard on, because we don't want it being transmitted. They have quite a quick eradication process. ... It's a brain disease, and with the occurrence of mad cow disease people are quite sensitive to that issue."

The story adds that scrapie is a reportable disease, so when a shepherd or veterinarian suspects its presence the CFIA must be notified.

Alves was cited as saying the disease has existed at a low level in the Ontario sheep population for years, and is among the livestock conditions monitored through the Ontario Animal Health Surveillance Network, a group linking veterinarians and animal health specialists, including the University of Guelph's Animal Health Laboratory.

Scrapie eradication possible for US?

Sat, 16 Jan 1988  Susan Noh D.V.M.
University of Idaho Caine Veterinary Teaching Center
It was recently suggested that scrapie can be eradicated through breeding genetically "resistant" animals. The jury is still out on this issue however.

Since genotyping has been available, all known clinical cases of scrapie in the United States have been in genetically susceptible animals (denoted QQ). However, it is unknown whether animals with a resistant genotype (QR or RR) may be infected and is so contagious. It is possible that the incubation period in theses animals is slow, such that they die of a another disease before clinical signs of scrapie develop.

There was a survey done in New Hampshire by USDA for scrapie in cull ewes. This is in the process of being written up and may contain more conclusive information about scrapie and genetics.

Two good sources are:

1.  L.A. Detwiler.  Rev. Sci. Tech. OIE. 11(2): 491-537, 1992.

2.  K.I O'Rourke. Allelic Frequencies of an Ovine Scrapie Susceptibility
Gene. Animal Biotechnology, 7(2): 155-162, 1996
. Comment: These codons are insufficient and do not represent the known spectrum of alleles in sheep. -- webmaster

Welcome to Stetsonville

Stetsonville and Taylor County, Wisc.

The Scrapie and BSE situation in Sweden

2 May 1997 TSE Conference
Marianne Elvander
National Veterinary Institute
Uppsala, Sweden 
One outbreak of Scrapie was diagnosed in Sweden in 1986 in tvo ewes of the Swedish Landrace in a flock with 30 ewes. The diagnosis was confirmed by experimental inoculation of goats and mice, which both proved positive. All animals in the flock were killed and destructed after removal of the brains. No further histo-pathological cases of Scapie were found in the flock. Unfortunately it was impossible to trace the origin of the infected sheep. No new cases of Scrapie has been diagnosed in Sweden since, even though sheep owners and veterinarians have been notified of the clinical signs to look for.

Scrapie is included under the list of diseases within the Swedish Act of Epizootices.

No case of BSE has been diagnosed in Sweden. Meat and bone meal from fallen stock has not been used as ruminant feedstuff in Sweden since 1986, a decision based on ethical grounds. In 1987, there was a voluntary agreement among producers not to feed ruminant protein to ruminants. No animals were imported from UK after 1988. Of 100 animals imported prior to 1988, 21 were still alive in 1991, and were from 1991 to 1997 closley monitored. In January 1997, all 21 animals were killed and destroyed and the brains examined for BSE lesions with negative results.

BSE is a notifiable disease in Sweden, even on clinical grounds, and has to be reported to the Swedish Board of Agriculture and to the County Veterinary Officer. A Swedish surveillance program for BSE is under development.

Denmark also has described its monitoring practises without however disclosing case numbers.

Surveillance system of ruminant neuropathies in Mexico

Dr Elisa Rubi
Mexico-US Exotic Animal Diseases Commission
Neuropathies are reportable diseases (BSE and included in the exotic animal diseases list). Since 1991, there is a prohibition of importation of bovines and most ruminant products and by-products from affected countries.

The use of meat and bone meal to cattle is very limited and of local origin. This product is mostly diverted to nourish poultry and swine.

The Mexico-USA Commission to Prevent Foot and Mouth Disease and Other Exotic Animal Diseases is responsible of the surveillance of the exotic animal diseases. For practical purposes, Mexico has been divided into eight regions, for which a coordinator is appointed. Their tasks involve the attention of every suspicion of an exotic disease outbreak and to promote the awareness of private and official vets, as well of producers on the importance of these diseases. This is done through regular visits and meetings.

Since late 1996, a nationwide specific active surveillance system was officially established for ruminant neuropathies. This ongoing surveillance consists in the search on-farm of ruminants considered at risk: neurological cases, aged animals, animals known to have been fed with meat and bone meal originated in affected countries, imported animals or descendants of imported animals from affected countries.

Follow up from farms to slaughterhouse, collection of samples and submission to the official laboratory (CENASA). Tested for rabies, if negative, examined by the official test, histopathology. This is done by specially trained technicians.

The later is complemented with the passive surveillance, in which the reports of neuropathies are received through various means and are rapidly attended. Samples are collected and submitted to rabies approved laboratories or CENASA. If negative to IF test (in the first case), samples are sent to CENASA in order to be tested by histopathology.

Regarding sheep and goats, due to the Mexican tradition of eating their meat and offals, they are slaughtered at a very young age (ovines: 6m to 1 year, and kids: 15 days old) and consumed almost totally. The live animals importations, mainly from the USA are exclusively for slaugther. The shipments are bound for officially supervised abattoirs. Considering the latter, in Mexico, mature or parent stock population is low.

Qualitative risk analysis had been performed for BSE and with minimal risk.Up to date, CENASA has examined 55 brain samples from 13 states. No BSE/ evidence has been found up to now.

Presently, arrangements are being made with USA colleagues in Ames Iowa, in order to send official laboratory technicians to be trained inimmunohistochemistry. We feel this could be of support in the diagnosis, especially in cases where histopathology is not clear enough.

We are trying to keep updated on new releases in the subject, so we can make modifications wherever needed in our surveillance system.

BSE -- will it become endemic?

 1 Mar 1998  Listserve commentaries
"I was just last Monday told by Dr.Zeidler from the WHO (while talking with him at the Blood safety and screening conference in McLean VA.) that the number of cats in the UK with FSE [feline spongiform encephalopathy] has stayed at a constant level yearly and that this is a bit of a puzzle as to why that is. My suggestion was that even though the cat food has been "cleaned up" and no longer contains ruminant meat in the UK they probably are still being given "table scraps." This in turn could be an ominous sign of what is still on people's dinner plates in the UK."

Response: UK-