Mad deer, mad elk: sources, definitions, and diagnosis
Successful transmission of CWD to primate and goat
State-by-state update on CWD: 27 Jan 99
States sorry they ever allowed game farms
US Animal Health Association (USAHA) meeting of 8 Oct 98
CWD in captive elk: Guidelines for monitoring, control, and eradication
CWD policies in Colorado, Nebraska, South Dakota, Montana, and Canada
Links to CWD stories archived elsewhere on this site
Contact information: CWD officials and scientists
Abstracts on Medline concerning CWD
Reindeer/scrapie policy based on CWD research
Last update: 25 Apr 99. Contact webmaster by email or fax (541-484-0669) to provide additional information or corrections Sources: 1: Wildlife Disease Committee Report 8 Oct 98 VF Nettles 706-542-1741 Minneapolis meeting 2: Montana Fish Wildlife and Parks memo of 29 Sept 98. Pat Graham to Gov Racicot 3: Montana Briefing paper 9 Sept 98 attached to memo 4: Montana Department of Livestock summary of CWD 9 Sep 98 5: Colorado Big Game Regulations 1998 pg 11 6: Madison Wisconsin Wildlife Disease Conference 1998 7: Wisconsin Outdoor News 11 Sept 98 Dean Bortz 8: SCWDS Briefs 1997-1999 newsletters 9: Medline scientific literature 10:Earlier full-text reports on this site 11.North American Elk Breeders Association (NAEBA)
Chronic Wasting Disease (CWD): a spongiform encephalopathy (prion disease) in deer or elk that is closely related to mad cow disease, scrapie in sheep, and Creutzfeldt-Jakob disease in humans. CWD has been reported in mule deer, black-tailed deer, white-tailed deer, Rocky Mountain elk, and possibly one pronghorn antelope [9, 4]. CWD transmits efficiently to mink and then to hamster experimentally [6, 9]. Tens of thousands of hunters in the Ft. Collins area have eaten tainted game from game procesing facility pools ; efficiency of transmission to humans is unknown. The incubation period for kuru is 40 years (dated from cessation of exposure) and counting .
Origins of CWD: The first case of CWD was seen in 1967 in a captive mule deer at the Foothills Wildlife Research Station (operated by the Colorado Dept. of Wildlife) in Ft. Collins and was attributed then by station employees  to close confinement of deer to former (scrapie) sheep pasture or to horizontal transmission from sheep allowed  into the pens. The shortest known incubation time in deer is 17 months, dating the exposure back to 1965-66 or earlier. Surplus does were released back into the wild after fawning in the facility; the first case in free-ranging wild deer was seen in 1981. Other infected animals were shipped to zoos (Denver, Toronto, Laramie), game farms (see below), and similar research facilities in Colorado and Wyoming.
Alternate theories of CWD origin: These posit a naturally occurring prion genetic disease; possible but not supported by recent genotyping studies by O'Rourke ) or transmission at winter feeding stations via rendered downer cow protein (ie, a non-UK strain of bovine spongiform encephalopathy) or CWD deer or elk recycled as rendered road kill. CWD deer are commonly observed at a feeding station on Lexington Lane in Estes Park, Colorado .
Trace-back: A game farm, zoo, or research facility that sold an elk or deer to a second facility where CWD was later positively diagnosed for the first time. The trace-back farm is presumed to be contaminated even if it has never reported CWD. Examples: Colorado has numerous trace-back game farms among the 11 in the Ft. Collins disease epicenter; improbably, none of these have ever reported CWD. Ear tags had been discarded in the Oklahoma CWD elk case, causing uncertainty in trace-back (limited to Montana, Idaho, or Utah).
Trace-forward: A game farm, zoo, or research facility that bought an elk or deer from a contaminated facility (possibly in another state) where CWD was later positively diagnosed. Sometimes broadened to include animals imported from a state or region known to have CWD because under-reporting is rampant [the economic impacts are devastating]. Animals at the trace-forward facility must be closely monitored and not be allowed to furnish animals to still other game farms. Examples: Vermont has trace-forward elk from Colorado but does not require autopsy of adult elk deaths as recommended . Trace-forward could not be conducted  on Nebraska elk sold at auction in Missouri and Colorado because records are not kept.
Exposed herdsconsist of trace-back plus trace-forward herds.
Ingress or egress: Deer and elk can escape or be released from game farm facilities and introduce the disease into wild cervids of that state. Alternately, deer or elk attracted to plentiful feed or captive members of their own species and enter the large fenced pastures, sometimes fawning there and contracting disease. [1,4, 9] Typical initiating events are a tree falling on a fenceline during a storm or erosion at a stream or gully crossing. Fenceline contact of wild animals with captive animals (possibly nose rubbing, urine, faeces,or hay mites) in facilities that are not double-fenced may also suffice to transmit CWD [1,9]. Example: wild deer on the same premises as a captive elk herd acquired CWD in South Dakota (see A, B).
Conflict of interest: A state fish and game department that derives most or all of its salary and program revenue from the sale of game tags jeopardizes this revenue by disclosure of CWD or by safety warnings to hunters. This revenue model is applicable to all 11 western states. Also includes departments of agriculture for different reasons. Conflicts of interest can affect the design of monitoring programs, choice of sampling techniques and pathology method, disclosure of results, and non-adherence to the precautionary principle. Diagnosis: public relation releases from the agency equate absence of evidence to evidence of absence. Example: Colorado fish and game officials held a news conference in 1998 stating they would continue to enjoy eating venison from untested deer and elk from epidemic strongholds because it had not been proven to transmit to human , a vacuous reassurance as no study has ever been conducted.
Nebraska Fish & Game Recommendations
If the animal is still struggling, kill it with a shot in the neck just under the ear.. .enough blood vessels will often be severed to bleed the deer or bleed kill by sticking... Admittedly, the field dressing chore is not the most enjoyable part of the hunt.... your heavy hunting coat should be removed and your sleeves rolled up so they won't be soiled. Blood and digestive juices must be removed from the body cavity quickly... Disposable vinyl or latex gloves lessen the chances of passing infectious diseases and make hand cleaning easier
Make a cut along the centerline of belly from breastbone to base of tail...Unless the head will be mounted, the cut should pass through the sternum and extend up the neck to the chin to allow removal of as much of the windpipe as possible. The windpipe sours rapidly and is a leading cause of tainted meat.
With a small sharp knife, cut around the anus and draw it into the body cavity... Loosen and roll out the stomach and intestines. Save liver. Split the pelvic bone to hasten cooling....
Diagnosis of CWD: The most desirable area of brain to collect is medulla. Colorado requires  hunters to turn in the head within 5 days, warm storage allowed; this would cause under-reporting of CWD using all methods. Many states only began sample collecting in 1998.
-- Histopathology: method requires brain fixed in formalin soon after death. Material from an animal dead more than 48 hours or frozen material is of little value. Slides are stained with dyes and examined under a light microscope. This method by itself misses many cases; it allows a state to announce a survey but have low or zero levels of CWD to report.
-- Immunohistochemistry (IHC): formalin-fixed material preferred, works on animals dead for longer time and frozen brain. Prion antibody stains cells around vacuoles seen with hematolyins and eosin staining. Amyloid plaque is most obvious in white-tailed deer, present but less conspicuous in mule deer, not usable diagnositically in elk. Parasympathetic vagal nucleus is first site of prion deposition in sub-clinical animals..
-- Western blot: can only be done on brain not fixed in formalin but is still applicable to brains that have undergone substantial decomposition or freezing. Prion protein resistant to protease K is stained on a molecular weight gel with prion antibody. The bes
-- Capillary gel electrophoresis: a very sensitive new method for detecting tiny amounts of rogue prion protein, tests on elk and deer now underway at ARS, Ames, Iowa to measure degree of contamination of blood.
-- In vitro conversion: the efficiency of CWD prion at converting normal prion of other species to rogue prion of that species. This test showed BSE and scrapie equally capable of converting normal human prion to the form associated with disease . Results with CWD and human prion are expected to be published shortly.
-- Strain-typing: Different strains of CWD may exist. These involve different degrees of glycosylation, different fragments of the full prion protein, and varying 3-dimensional conformations. Strain properties are generally maintained fairly well during passage to a new species, possibly allowing a dietary source of human infection to be identified. CWD strains expected to pass easily to sheep and cattle because the prion gene sequences are very similar; deer and elk commonly share pastures with cow and sheep. Strain-typing results with CWD in experimental animals are expected shortly.
-- Diagnostic video available: The Wyoming Game and Fish Department, in cooperation with the University of Wyoming, the Colorado Division of Wildlife, and the Colorado Department of Public Health and Environment, through the Western Wildlife Health Cooperative of the Western Association of Fish and Wildlife Agencies, has produced a video on chronic wasting disease.›
"This video informs viewers about CWD, describes and demonstrates the appearance of animals with this disease, and explains how to collect appropriate samples for diagnosis.› The intended audience is wildlife biologists and veterinarians; video footage includes images (brains and blood) that may be too graphic for some public audiences.› The program is 13 minutes long.› The cost is $10 a copy, plus $4 shipping and handling charge (the $4 charge does not increase when multiple copies are ordered).› The video may be ordered from:› Wyoming Game and Fish Department, Attention:› AE, 5400 Bishop Boulevard, Cheyenne, Wyoming 82006 (telephone 307-777-4570)"
[The video is excellent. Pape and Miller focus as usual on game tag sales: business as usual until people start dying. The most questionable sequence has Dr. Williams minimizing problems with transmission to livestock. In fact, she published a report in 1992 stating CWD has been transmitted to goats (very similar to sheep) by intra-cerebral injection with an incubation time of 6 years. 13 years have gone by without the experiment ever being written up. Williams has not responded to queries for clarification.
Williams ES, et al. ››››››› Spongiform encephalopathies in Cervidae. Rev Sci Tech. 1992 Jun;11(2):551-67. Review.Successful transmission to squirrel monkey [new world monkey, RF Marsh, U Wisc. pers. comm to Beth Williams] is in the published record too -- this is worrisome because people are primates too. The key point is that Wyoming published this in 1992 paper, yet:
-- "Wyoming has yet to issue health recommendations for deer and elk hunters, but 'the risk is so small, I wouldn't worry about it all,' says Tom Thorne of Wyoming Game and Fish, who adds that he regularly hunts and eats deer from southeastern Wyoming." [High Country News article by Chris Carrel 16 March 1998]
-- "The meat itself does not appear to be infectious in any situations," said John Pape, Coloado Dept. of hHealth epidemiologist..... "Since there are unknowns in our research, we will err on the side of caution and recommend that [simple common sense] measures be taken." [Denver Post 14 Feb 98]
-- Both Wyoming and Colorado have historically reported scrapie in sheep. Colorado reported scrapie in 1966 and Wyoming twice (1959 and earlier) [Hourrigan, J et al 1979 Epidemiology of scrapie the the US. Vol 1 of Slow transmissible diseases of the nervous systerm. Academic Press NY pg331-356.-- webmaster]
25 Jan 99 webmaster: based on published sources listed aboveColorado:
Wyoming: [based in part on mid 1998 brochure by Chris Madson sent 1 Feb 99,
-- infected Fish and Game research facility in Laramie; 3 failed decontamination efforts
-- CWD found in wild elk and deer
-- Swapped animals with Ft. Collins facility for many years.
-- "between 1974 and 1979, 66 mule deer and 1 black-tail were held in captive in Colorado and Wyoming research corrals, mainly as subjects in long-term studies of deer food habits and nutrition. Of these 67 long-term residents, 57 contracted the strange disease. None survived."
-- between 1981 and 1985, 60 cases in the wild were found: 44 in mule deer, 6 in white-tailed, and 10 in elk. The first affected wild Wyoming elk was found in 1986. First clinically affected captive animal found in 1978.
-- the 1997 Wyoming survey obtained usable samples from137 deer in hunting units 16, 59, 60, 62,63, and 64. 8 positives were found, of which 7 were from unit 64.
-- 93 samples in 1997 from units 15, 55,57, and 73 tested negative. 15 elk samples from areas 5, 7, 12, 13, 21, 82, and 110 were also negative.
-- of the 100 cases reported in the wild, 11 have been found in Wyoming.
-- Feb 1998 CWD confirmed by NVSL in 4.5 year old male elk in north central Nebraska game farm, affected herd quarantined
-- CWD elk trace-backs to endemic region of Colorado, purchased as 2 year old, symptoms 26 months later.
-- The affected elk had been on 2 farms in western Colorado before arriving.
-- Sick elk pastured with 12 other velvet bulls 3-5 years of age in 80 acre pasture.
-- 6 high risk bulls: blood samples sent for capillary electrophoresis.
-- 2 high risk bulls tested negative by IHC; 6 bulls with fenceline contact also negative.
-- frequent fenceline contact observed with white-tailed and mule deer.
-- trace-forward to buyers in 2 Nebraska herds and 4 other states (IA, IL, TX, WI) which were notified.
-- elk from the affected herd were sold through two auctions in Colorado and Missouri.
-- Any farmed elk or deer over 16 months dying from any cause must have brain stem tested (30 negatives so far)
-- free ranging deer (no elk) surveyed in 1997 on borders, 350 negatives.
South Dakota: 
-- First CWD diagnosis in game farm elk on 8 Dec 97; now 5 infected herds,11 exposed herds
-- all 5 infected herds placed on 5 year quarantine; animals in 1 herd given to research project.
-- 38/86 animals from infected herds tested positive for CWD.
-- 2 wild white-tailed deer or ingress offspring within premises of an infected facility tested posivitve.
--30 deer on elk farm premises killed, 1 tested positive for CWD.
-- one suspected case reported in antelope on infected premises 
-- index herd tested at USDA: 10 of 17 positive by IHC, only 3 by histopathology, only 2 animals clinical
-- In June,1998 CW) was diagnosed in a captive elk in Oklahoma.
-- The Oklahoma herd received more than 80 elk from commercial sources in Montana and Idaho.
-- Animals from the same origins as the Oklahoma herd went to 13 other ranches in Colorado, Idaho, Iowa, Montana, Nebraska, Alberta, and Saskatchewan in the past 11 years, plus many secondary movements. 
-- no control or surveillance program.
-- one trace-back zoo in Salt Lake City from elk possibly associated to Oklahoma game farm.
-- One 30 year old hunter dying of CJD of unknown origin (not familial or iatrogenic).
-- 135 deer sampled in 1998, 90 tested, all negative so far, pathology done in-state. Unpublished UF&G.
-- Single trace-back elk game farm under quarantine from Oklahoma case, though importer destroyed ear tag.
-- Single trace-forward elk game farm that had bought elk from trace-back game farm connected to Oklahoma
Iowa, Illinois, Texas, and Wisconsin:
-- These states have trace-forward herds from an infected herd in Nebraska.
-- Missouri also sold elk from this herd at auction to buyers in unknown states.
-- Wisconsin has additional trace-forward game farms from affected South Dakota game farms 
-- Michigan allows deer to concentrate at bait stations, spread of tuberculosis attributed to this in NE Lower Peninsula .
-- ancedotal trace-forward herds from Colorado and Wyoming
-- no reported CWD, possible trace-back herd based on Oklahoma case, hold order on elk farm.
-- elk ranchers forced regulatory change to ag department to avoid regs.
-- Diagnosed first elk with CWD in 1996. 23 elk herd destroyed, other animals tested negative.
-- Second affected animal seen in April 98, siblings negative 68 elk in herd.
-- imported as a yearling, in 1989, as part of a small shipment of elk from S. Dakota,mother still healthy.
-- No trace-forward herds from this elk farm.
-- quarantine lifted on 4 herds, no more testing except voluntary.
-- index herd and 3 traceback herds will be inspected every 6 months.
-- farm surveys conducted in 7 mule deer, 13 white-tails, 15 elk, no CWD found.
-- 81 wild animals also free of disease ( 4 elk, 45 mule deer, 32 white-tails) as of May 98.
-- In the 1970's, CWD occurred at the Metro Toronto Zoo, in a mule deer imported from a zoo in Colorado.
-- CWD has not been reported in wild deer or elk in Canada.
USAHS 8 Oct 98 Next USAHA meeting is in San Diego in October 8-15, 1999 Non Member Fee $190.00 WESTERN REGION March 3-4, 1999 Nugget Hotel Reno, NV Dr. Jerry Bohlender, CO [no email] 303/239-4161 NORTH CENTRAL REGION March 29, 1999 - 8-12 noon Nashville, TN (in conjunction with LCI meeting) Doubletree Hotel Dr. Sam Holland, SD 605/773-3321 Poster sessions: Summary of Current Bovine Spongiform Encephalopathy Surveillance Data in the United States: Bovine Brain Examinations - A.J. Davis, A.L. Jenny, W.D. Taylor, A.J. Wilson, T. Gidlewski Improvements in a competition assay to detect scrapie prion protein by capillary electrophoresis.--Schmerr MJ, Goodwin, Kathryn R, Cutlip RC, Jenny AL"Dr. Michael Miller of the Colorado Division of Wildlife provided an update of chronic wasting disease (CWD) surveillance in Colorado; Drs. Terry Spraker, Beth Williams, and Katherine O'Rourke are collaborators on this work. Chronic wasting disease is a spongiform encephalopathy of mule deer, white-tailed deer, and Rocky Mountain elk. To date, the only documented focus of CWD in free-ranging cervids is in northeastern Colorado and southeastern Wyoming. Methods for surveying free-ranging populations of deer and elk have been described by these collaborators previously. Dr. Miller briefly reported on results of ongoing harvest surveys in the endemic areas of Colorado. Brain tissues from over 2,500 deer and elk from northeastern Colorado and over 350 deer and elk from elsewhere in Colorado harvested during 1995-1997 were examined microscopically after staining with anti-prion protein immunostains (USDA-ARS F89/160.1.5), as well as hematoxylin and eosin; deer and elk showing positive immunostaining, with or without typical light microscopic lesions, were regarded as CWD-affected. All deer and elk harvested outside northeastern Colorado tested negative."
"In northeastern Colorado, prevalence estimates within species have not differed over the last three years. Survey data show that CWD is at least five times more prevalent in deer than in elk in northeastern Colorado. Similarly, geographic distribution of CWD is wider among deer than among elk; the primary focus of CWD in free-ranging deer appears to be the eastern half of Larimer County, although a few positive deer have been detected along the South Platte River corridor; elk cases have been confined to Larimer County."
"Contrary to previous reports based on data from clinical cases, CWD is as prevalent among female deer as among male deer. Age distributions of positive cases among male and female deer were skewed toward older age classes as compared to age distributions of unaffected deer harvested, suggesting transmission among adult deer was not uncommon. Field data support the hypothesized importance of lateral transmission in CWD epidemiology. Harvest survey techniques developed in Colorado and Wyoming offer an effective and efficient approach for detecting, studying, and monitoring CWD in free-ranging cervid populations, and are now being used to survey for CWD elsewhere in North America."
"Dr. Sam Holland, State Veterinarian for South Dakota, gave a brief summary of his state's experience with CWD in captive elk. After an initial diagnosis of CWD on December 8, 1997, his investigation revealed three infected and five exposed captive elk farms. All infected herds have been placed on quarantine for 5 years, and animals in one herd have become part of a research project. Eighty-six animals have been tested from positive herds, and 38 have been infected with CWD. Of the exposed herds, 2 of 35 animals tested were infected. The Department of Agriculture has developed a memorandum of understanding with the state wildlife agency to evaluate the wild cervids in the state. To date, two white-tailed deer within the enclosures of an infected premise were positive. One deer was a wild animal and the other was privately owned."
"Dr. Butch Sahara of Nebraska provided an overview of the Nebraska Department of Agriculture's experience with CWD. His agency received word from NVSL in April 1998 that a 4-year-old male elk had tested positive for CWD. The domesticated cervid ranch that submitted the animal was located in north- central Nebraska and contained 150 head of elk housed at three facilities. The home ranch was completed first and received all of the purchased elk. A second breeding unit was completed in the summer of 1997. A third hunt pasture was completed in the spring of 1998. All elk were purchased from TB-accredited herds in Colorado, with the first elk coming to this facility in December 1995."
"The positive bull had clinical signs in February 1998, and traceback records indicated he had originated in the Colorado CWD endemic area. He was purchased as a 2-year-old and began to show clinical signs about 26 months after arriving in Nebraska. Free ranging white-tailed and mule deer are observed frequently outside the elk facility and could have fence-line contact with the elk."
"Only three other elk had died on this facility previous to the positive bull; lightning, a broken neck from hitting a fence, and sudden death of a spiker were the causes of acute death. The positive bull was pastured with 12 other velvet bulls 3-5 years of age in an 80-acre pasture."
"An epidemiological investigation was completed, the affected herd was quarantined, and 17 animals that had been sold were traced to buyers in Nebraska and five other states. None of the animals that had been sold had been in the same pasture with the positive bull, and they did not have fence-line contact during the time that clinical signs were observed. All states were notified, and Nebraska placed a hold order on the two Nebraska herds that had received animals."
"As of this date, Dr. Sahara has examined the complete herd every 30-45 days with no symptoms of CWD observed. Of the 12 high risk bulls, 3 are dead (2 negative and 1 pending), 3 will be harvested in the hunt pasture this fall, and 6 have had blood submitted for the new Capillary Electrophoresis PrP test. Six other mature elk that have had fence-line contact with the bull pasture have been sent to slaughter and were negative on the brain tissue immunohistochemistry test at NVSL."
"The Nebraska Department of Agriculture, with support from its Cervid Advisory Board, began a policy that any domesticated elk, white-tailed, or mule deer over 16 months of age that dies from any cause must have the brain stem submitted for PrP testing. Approximately 30 brain stems have been submitted with no positive animals identified. Dr. Sahara stated that early detection and removal are the key to control of CWD. He also recognized the need for a program that does not destroy the producer who is unfortunate enough to detect the disease. His agency is working with the cervid industry to develop a CWD monitoring program that could provide buyers with verified inventory tracing and documentation of CWD testing from targeted animals. Free ranging deer and elk will also be included in surveillance programs in 1998."
USAHA 1998 Committee Reports"Beth Williams, DVM, presented an overview of Chronic Wasting Disease (CWD) which is a prion disease of wild and captive mule deer, white-tailed deer, and Rocky Mountain elk. It has been recognized as a syndrome in deer for approximately 30 years. CWD occurs in free-ranging deer and elk in limited portions of southeastern Wyoming and north-central Colorado. In captive animals, it occurs in deer and elk held in wildlife research facilities in Wyoming and Colorado and, more recently, has been diagnosed in privately owned elk on game farms in South Dakota, Nebraska, Oklahoma, and Saskatchewan, Canada."
"Clinical signs include loss of body condition, behavioral changes, excessive drinking and urinating, excessive salivation, and occasionally, incoordination and tremors. Affected animals have varied in age from 17 months to greater than 15 years of age. Animals may be recognized as being sick for a few days or for as long as a year; most animals succumb to CWD within 3 to 4 months. Minimum incubation periods appear to be approximately 17 months, but maximum incubation periods are not known."
"Based on epidemiologic observations, CWD appears to be laterally transmitted, but the importance of maternal transmission is not known. The mode of transmission has not be determined. The origin of CWD is not known but its relationship to other transmissible spongiform encephalopathies indicates it is not bovine spongiform encephalopathy or a previously characterized strain of scrapie. Considerable research is ongoing to determine the host range of CWD and the pathogenesis of CWD in deer and elk."
"Katherine O'Rourke, DVM, presented prion genotype studies of elk with CWD. Prion proteins are a marker of transmissible spongiform encephalopathies (TSE) of which CWD is a subset family of diseases. All TSE's have deposition of prion proteins folded in an abnormal manner. The prion gene is polymorphic (varies among individuals). A study of the prion genotypes of captive and free-ranging elk in Colorado, Wyoming and South Dakota were found to be similar. Very preliminary work lent some hope that allele differences may change the susceptibility of the animals to disease. However, further examination of the data is less convincing. Much more work needs to be done with larger numbers of affected elk as well as experimentally inoculated animals."
"Dr. O'Rourke has developed a live-animal test for scrapie in sheep. This is performed on the lymphoid tissue from the third eyelid. Early indications suggest that elk do not respond on the third eyelid test the same way as sheep. However, there is hope that further adaptation of this test in elk will prove effective."
"Michael Miller, DVM, briefly reviewed key epidemiological features of chronic wasting disease (CWD) with an emphasis on implications for managing this disease in captive and free-ranging cervids. Chronic wasting disease is a spongiform encephalopathy believed to be caused by one or more cervid- specific prion strains (PrPCWD) that differ from all other animal and human prion strains studied to date. The origin of PrPCWD remains unknown. As with other prion diseases, this agent shows extraordinary resistance to environmental degradation. Mule deer, white-tailed deer, and Rocky Mountain elk appear to be the only species naturally susceptible to CWD; other closely related cervid species might be expected to be more susceptible than bovids or other mammals, but this remains to be studied. "
"Experiences with captive and free-ranging cervids in Colorado and Wyoming suggest deer (Odocoileus spp.) may be more susceptible then elk; however, recent epidemics in farmed South Dakota elk show a different pattern that could be explained by herd management and/or PrPCWD strain differences. Both sexes and all age classes of animals can be affected, underscoring the likely importance of animal-to-animal (lateral) transmission in sustaining epidemics. Both intra- and inter-specific transmission (e.g., mule deerwhite-tailed deer, elkwhite-tailed deer) can occur. Precise transmission mechanisms are unknown, but shedding in saliva, feces, urine, and/or other excretions have been hypothesized; although transmission via tissue-contaminated feed could occur, this route appears unimportant in sustaining epidemics. "
"Persistence of the agent in the environment may exacerbate epidemics and present an obstacle to eradicating CWD from infected premises. The potential role of invertebrate and/or vertebrate reservoirs in CWD epidemiology warrants further study, as does the influence of climate on disease persistence, especially in free-ranging populations. Epidemiological uncertainties, combined with lack of reliable live-animal tests, present significant obstacles to the prospects for effectively controlling or eradicating CWD. "
"Sam Holland, DVM, State Veterinarian from South Dakota, presented "CWD, the State Regulatory Experience." In December 1997, South Dakota confirmed the diagnosis of CWD in a captive elk herd. This occurrence was treated as an animal health emergency. Dr. Holland reviewed a program to prevent, prepare, respond and recover. Great pains were taken to include all stakeholders in the process. The response included quarantine, immediate epidemiologic traceback, and the notification of all stakeholders, which included fact sheets and letter writing. A meeting of all stakeholders was organized to glean support from the industry, support from regulators, to determine a scientific based process, to devise a risk based program, and attempt an indemnity program (the latter being unsuccessful.)"
"The group consensus was that a mandatory control program needed to be enacted. Legislation was passed to enforce the control program. The control program includes detailed definitions, outlines official tests, and delineates movement criteria. "
"Dr. Holland reviewed the present status of CWD in South Dakota. There have been a total of three affected herds, those with confirmed CWD. A total of five herds were exposed to the affected herds and have been quarantined from one to five years. The source elk herd had 30 free-ranging white-tailed deer that were on the property but did not share a pasture. It was uncertain whether there had been contact. These 30 white-tailed deer were harvested, and one was found positive for CWD. A surveillance program of free-ranging wildlife was developed via cooperation between the various state agencies involved. About 0.5 percent of annual hunter harvest in designated areas are being examined for CWD. "
"Glen Zebarth, DVM, gave the North American Elk Breeders Association (NAEBA) perspective on CWD. He updated the committee on the activities of the Elk Research Council and presented a study plan for the ante-mortem diagnosis, pathogenesis and epidemiology of CWD in elk. The objectives of the study plan are to evaluate the potential utility of early diagnosis using third eyelid and tonsilar lymphoid tissue; characterize the biochemical properties of CWD using capillary electrophoresis; and determine the pathogenesis as well as the epidemiology of CWD. The elk breeders have identified two sets of study animals. The first is the index herd from the South Dakota outbreak. The second herd has a negative history for the disease. They plan to utilize these animals in extensive and comprehensive ante-mortem and post-mortem testing. The NAEBA put forth two resolutions and one recommendation for this Committee's consideration. "
[Reportedly 52 animalswill be tested over a four-year period. Four different tests will be conducted: third eyelid, tonsil, placenta screening , and blood. The cost of the study is $250,000, not including personnel costs. The Elk Research Council's portion is $140,000 over the four-year study period.]
"Ms. Barbara Fox, Executive Director of the North American Deer Farmers Association, presented the Deer Farmers Perspective on CWD. She apprized the committee that a majority of the deer farmers are in the eastern states and do not have personal, first-hand knowledge of CWD, except possibly from some written publications. Currently, typical deer farmers do not recognize CWD as a problem for their animals. The association is embarking on a intensive education program of its members to inform them of the serious nature of this disease. While Ms. Fox expressed a willingness to support the call by various stakeholders for further research, control and eradication, she indicated that the cost of testing deer would create an undue burden on the deer farmers at this time. The American Deer Farmers Association supports the concept of minimum guidelines as proposed by NAEBA to control CWD in elk. They believe it is important to note that at this time, CWD is a wildlife and farmed-elk problem and not a problem currently recognized in the deer-production industry. However, the deer industry would cooperate with regulatory efforts to understand the disease better. "
USAHA 1998 ReportDr. Robert Temple, Chairman of the Committee on Captive Wildlife and Alternative Livestock, and Mr. Steve Wolcott of the North American Elk Breeders Association (NAEBA) presented two draft resolutions and a Model Program for Surveillance, Control, and Eradication of CWD in Domestic Elk. One resolution encouraged wildlife agencies to continue or start surveillance for CWD. The other resolution requested that the USDA provide several types of support for control and eradication of CWD. Both resolutions were approved unanimously by the Committee and will be jointly sponsored with the Committee on Captive Wildlife and Alternative Livestock.
The Model Program for Surveillance, Control, and Eradication of CWD in Domestic Elk was discussed by the Committee. The Committee voted to approve the Model and to co- publish it as a Recommendation in conjunction with the Committee on Captive Wildlife and Alternative Livestock. The Committee commended NAEBA and its representatives for this highly appropriate response to an important disease problem.
The Committee reviewed the criteria for histologic diagnosis of CWD provided by Dr. Beth Williams of the University of Wyoming and expressed agreement with the guidelines as presented below:
The histopathologic features of deer (Odocoileus spp.) and elk (Cervus elaphus) with clinical chronic wasting disease (CWD) are qualitatively typical of the spongiform encephalopathies and include the usually recognized histopathologic features in the brain: spongiform change (status spongiosis) of the gray matter; intracytoplasmic vacuoles within neurons; astrocytosis; neuronal degeneration and loss; and in deer, amyloid plaque formation. The distribution of lesions is very consistent among affected deer and elk with the degree of severity being somewhat greater in deer than elk. The most consistent, readily discerned, and objectively evaluated lesions are spongiform change and intracytoplasmic vacuoles in neurons. Immunohistochemistry (IHC) consistently demonstrates enzyme resistant prions (PrPres) in brain of clinically affected deer and elk with distribution similar to lesions observed by routine H&E histopathology.
Spongiform change: associated with focally dilated dendrites and varies from scattered patches of small holes to diffuse porosity of gray matter. This lesion must be differentiated from autolytic change, fixation artifacts, and edema. The distribution of spongiform change is relatively stereotyped (see below).
Intracytoplasmic vacuolation: large single or multiple intracytoplasmic vacuoles usually without obvious content. Astrocytosis is often subtle and best appreciated with special stains (GFAP immunohistochemistry or Cajal's gold sublimate).
Neuronal loss: dark, shrunken, angular neuronal cell bodies are uncommon and must be differentiated from artifact.
Amyloid plaques: these are most obvious in white-tailed deer, present but often less obvious in mule deer, and are not a diagnostic feature in elk. They vary in size and number. Plaques may be difficult to appreciate on H&E stained sections but are easily identified by IHC.
Lesion distribution: consistent spongiform change in clinically affected deer and elk is present in the parasympathetic vagal nucleus (dorsal motor nucleus of the vagus), thalamus and hypothalamus, and olfactory tubercle and gyri. Spongiform lesions are always found in the parasympathetic vagal nucleus, and this can be used for diagnostic purposes. Amyloid plaques are most obvious in the diencephalon in deer but are occasionally found in other parts of the brain.
Immunohistochemistry: PrPres is consistently demonstrated in the parasympathetic vagal nucleus in clinically affected deer and elk, and is usually abundant throughout the brain stem. The parasympathetic vagal nucleus is the first site of PrPres deposition in the brain of subclinically affected animals. PrPres deposition may be found as granular or amorphous aggregates on the neuronal membranes or as extracellular accumulations; often these are in the form of plaques sometimes surrounded by spongiform change.
Minimum requirements for histopathologic diagnosis (additional changes as described above may be present to support the diagnosis):
1.Spongiform change in gray matter of the brain with appropriate distribution (particularly parasympathetic vagal nucleus, thalamus, hypothalamus, olfactory cortex); and/or
2. Demonstration of PrPres in gray matter of the brain (particularly parasympathetic nucleus of the vagus).
For more information, readers are referred to (1) Hadlow, W. J. 1996. Differing neurohistologic images of scrapie, transmissible mink encephalopathy, and chronic wasting disease of mule deer and elk. In Bovine spongiform encephalopathy: The BSE dilemma, C. J. Gibbs, Jr. (ed.). Springer-Verlag, New York, New York, pp. 122-137, and (2) Williams, E. S., and S. Young. 1993. Neuropathology of chronic wasting disease of mule deer (Odocoileus hemionus) and elk (Cervus elaphus nelsoni). Veterinary Pathology 30: 36-45.
Dr. Victor Nettles presented a Protocol for Diagnostic Criteria for Chronic Wasting Disease (CWD) in Captive Cervids. This protocol was done with the consultation of Drs. Linda Detwiler, Al Jenny, Janis Miller, Mike Miller, Terry Spraker, and Beth Williams. It was stressed that this protocol was for brain tissue only and was intended for captive cervids only. During the investigation of suspected CWD cases, there are multiple test result combinations that may develop that depend upon the type of samples that are submitted. Diagnosis of an index case should be made through use of both histopathology and IHC as a minimum effort.
Histopathology: This test requires good quality brain tissue that is preserved in formalin soon after death. Brain tissue from animals that have been dead more that 48 hours and/or frozen is of doubtful use for histopathology. Candidates for histopathology include animals that are sampled at slaughter, euthanized, or necropsied soon after death.
Immunohistochemistry: The brain from any animal that is suitable for histopathology is suitable for immuno- histochemistry. In addition, animals that have been dead for longer periods or when there is only frozen brain available are candidates as well. Samples for immuno-histochemistry can be derived from brain tissue that is still structurally intact but may be unsuitable for histopathology due to postmortem degeneration. A laboratory could conduct this test on either fixed or unfixed brain tissue submitted from the field; however, fixed is preferred.
Western blot: This test can be conducted only on unfixed brain tissue, but it has the advantage of being applicable even if the brain that has substantial autolysis (decomposition). However, this test cannot be conducted on formalin-fixed tissue.
All of the above!: The accuracy of all of the above tests is dependent upon examination of the proper area of the brain. Guidelines for specimen collection have been developed by the National Veterinary Services Laboratories, APHIS, USDA, Ames, Iowa, in conjunction with Colorado State University and the University of Wyoming. The most desirable area of the brain to collect is the medulla, and it is important that full cross-sections are available. Tests on inappropriate areas of the brain that do not have lesions or the prion protein in the early stages of the disease process could result in false negative results in pre-clinical animals.
The test interpretations in the following tables are made on the assumption that appropriate areas of the brain are examined. [Emphasis in original text -- some states evidently have been tempted to examine inappropriate areas of the brain. -- webmaster] The following guidelines are for diagnosis of an index case. More aggressive interpretation may be indicated in known infected herds.
SCWDS BRIEFS April 1998 Issue State Fish & Game Departments: all 50 states
Dept of Agriculture and Game and ParksOn April 9, 1998, chronic wasting disease (CWD) was diagnosed in a captive elk in Nebraska.› This discovery follows the confirmation of CWD in two captive elk herds in South Dakota earlier this year.› The Nebraska elk was a 4 1/2-year old male that was among a privately owned herd of approximately 150 elk.› The health of the animal had deteriorated for about 2 months before it died.› Confirmation of CWD was made by the USDA's National Veterinary Services Laboratories in Ames, Iowa.
The case history revealed that the affected elk was born on a farm on the Western Slope of the Rocky Mountains in Colorado, but it was on two additional Colorado farms before it arrived in Nebraska at 2 to 2 1/2 years of age.› One of the Colorado premises was in the known CWD-endemic region along the Eastern Slope of the Rocky Mountains in northcentral Colorado.
The Nebraska State Veterinarian's Office has quarantined the affected herd, and a hold order was placed on two additional herds in Nebraska that received animals from the affected herd.› It also has been determined that elk farmers in four states (IA, IL, TX, WI) have received elk from the infected herd, and these states were notified by the Nebraska Bureau of Animal Industry.› Additional tracing may be forthcoming because elk from the affected herd were sold through two auctions in Colorado and Missouri.› A CWD Working Group is being formed to develop Voluntary CWD Management Guidelines.› The first goals of the Nebraska Bureau of Animal Industry are:› (1) to implement a policy requiring disease reporting of animals over 16 months of age; (2) to require identification of individual animals and reporting change of ownership; and (3) to establish a data base to monitor change of ownership.
South Dakota has taken legislative action to create a CWD control program for captive cervids.› Their program calls for a 5-year quarantine with monitoring of all affected, adjacent, or exposed captive cervid herds.› Monitored herds that maintain clean status are given certificates at annual milestones for years 1 through 4 and are designated "Certified CWD Cervid Herd" after 5 years of negative surveillance.› The Cervid CWD Surveillance Identification Program includes required examination of brain tissue from all dead cervids 18 months or older, including deaths by slaughter, hunting, illness, and injury.› The South Dakota State Veterinarian has forwarded the description of his State's program to the United States Animal Health Association along with the suggestion that it should be considered as a "starting place" for developing a Model CWD Control Program.› Persons interested in this document can obtain a copy from Dr. Sam Holland, South Dakota State Veterinarian, SD Animal Industry Board, 411 South Fort Street, Pierre, South Dakota 57501-4503.›
United States Animal Health Association (703) 451-3954 For immediate release:Contact - Larry MarkMINNEAPOLIS, Minn., Oct. 7, 1998 -- A model program for the containment and eradication of chronic wasting disease (CWD) in captive elk herds was developed and carried out in South Dakota last year in response to the diagnosis of this disease in December 1997 in a captive elk herd in South Dakota.
Dr. Sam Holland, South Dakota State Veterinarian, reviewed for the USAHA committee on captive wildlife and alternative livestock a program that was put together in a short period of time and was highly successful. Dr. Holland noted that the occurrence of CWD was treated as an animal health emergency and that great pains were taken to involve all people with a stake in the issue in developing a way to deal with the disease. The group consensus was that a mandatory control program needed to be enacted with official tests and movement criteria.
To date in South Dakota, there have been three elk herds with confirmed CWD and five others that were exposed to the affected herds. The latter have been quarantined for from one to five years. The source elk herd had 30 free-ranging white-tailed deer on the property but not in the same pasture. These 30 deer were harvested and one was found positive for CWD. A surveillance program of free-ranging wildlife has been developed that includes examination of deer and elk killed by hunters....
6. CHRONIC WASTING DISEASE: IMPORTS:
a. All cervidae entering South Dakota MUST have one of the following statements on the signed official original certificate of veterinary inspection (HC):
1. "all Cervidae Identified On This Certificate Originate From A Herd In Which All Cervidae Have Been Kept For At Least One Year Or Into Which They Were Born. There Has Been No Exposure To Or Additions From Any Other Source In The Past Year. There Have Been No Diagnosis, Signs Or Epidemiological Evidence Of Cwd In This Herd For The Past Year. Records And Causes Of Death For The Past Year In This Herd Of Origin Are Available To The Animal Health Official Of The State Of Origin."
2. "all Cervidae Identified On This Certificate Originate From A Herd Which Has Been Determined To Have The Stated Monitored Status By The Animal Health Official Of The State Of South Dakota."
3. "all Cervidae Identified On This Certificate Originate From A Herd Which Has Been Determined To Have Certified Cwd Cervid Herd Status By The Animal Health Official Of The State Of South Dakota."
CERVIDAE FROM MONTANA: Other than any Elk originating from any herds susceptible to post-quarantine assurance testing-will be eligible for importation into South Dakota after meeting current import testing requirements.
27 Jan 99 Dept. of Agriculture Animal Industry Division Colorado Division of Wildlife: -- Ranching for Wildlife See also proposed amended rules Search hunting regs using 'chronic'"The Colorado Department of Agriculture has taken strong preventative measures to protect Colorado's domesticated deer and elk populations from chronic wasting disease, a nervous system disease causing holes in the brain. The Colorado Department of Agriculture passed rules in April 1998 requiring all domesticated deer and elk producers to submit samples from any sick or dying deer or elk to Colorado State University for lab analysis to determine if that animal tests positive for chronic wasting disease (CWD). To date, there have been no positive cases.
Chronic wasting disease has been found in approximately five percent of free-roaming deer and less than one percent in free-roaming elk in two small geographic areas in Northcentral Colorado. The agriculture department examines all resident domesticated herd inventories, making sure that free-roaming deer or elk are not incorporated. All deer and elk with CWD in other states have been quarantined and cannot be transported into Colorado. [Does this mean all trace-back and trace-forward herds or only clinically ill animals? -- webmaster] All resident and imported domesticated deer and elk are tattooed; tested for other diseases, then tagged with an official USDA tag. Again, any animal testing positive is not allowed in the state. [There is no test on live animals -- webmaster]The department also requires all domesticated deer and elk to have health certificates, and entry permits to track their movement....
Colorado has a scrapie eradication plan as well adopting a directive at the 71st Annual Convention on June 21, 1998. Recall the first case of scrapie was diagnosed in the United States in sheep originating from Britain via Canada in 1947,. From this initial case until September 30, 1996, scrapie has been diagnosed in 1281 sheep in 850 flocks throughout the U.S.
The Rocky Mountain Regional Animal Health Laboratory offers a free CWD test kit.
Dept of Wildlife Funding: " Unlike most other agencies, the Division receives no tax monies appropriated from the General Tax Fund. Since being directed to do so by the state Legislature in 1921, the Division relies primarily on fees paid for hunting and fishing licenses to pay for its operations.... But the economic benefits to the state are far greater than the income generated by license sales. Hunters and anglers annually inject $1.7 billion into the economy when they purchase the equipment, gas, lodging and other materials in pursuit of their sport....
The Colorado Division of Wildlife receives no state tax money. Instead, the agency is funded by the purchase of fishing and hunting licenses; by federal funds generated by an excise tax on the manufacture of arms, ammunition and other sporting equipment; by donations to the nongame fund and by federal endangered species funds." ›
Elk tags were the single largest source of money, providing $27.1 million in 1996-97; deer tags provided a further $11.8 million. These figures represent 49.7% and 21.&% of the entire agency budget. Fishing licenses provided most of the remainder of the total budget of $76.7 million. Non-residents contributed $37.8 million to the total; an elk tag costs $250.
Using game tag receipts and cost of tags, it can be calculated that non-residents purchased 92,000 elk tags while residents purchased 125,000. With deer, non-residents pruchased 65,890 tags; residents purchased 93,827. While not all hunts are successful, not all hunts are in an endemic area, and not all animals harbor CWD, still 376,000 total tags were sold in the 1996-97 season. Pooling of carcasses at game processing facilities both dilutes CWD infectious titre while ensuring that many more hunters get some. The elk population is estimated at 216,000 and deer at 547,000. Hunters were not required to submit heads of elk in 1998.
Chronic Wasting Disease Information and Regulations
Middle park free of chronic wasting disease DoW press release date: 01/19/1999 "...Sportsmen who hunted in 18 units were required to submit the heads of their harvested deer to the Division during the 1998 big game hunting seasons. Colorado State University pathologists examined the brains of the animals for evidence of infection. More than 350 heads from deer killed in management units 18, 28, 37 and 371 (in the Middle Park area) were submitted and all tested negative for chronic wasting disease. Miller said he is satisfied with the test results of Middle Park, and added that hunters in the Middle Park area will not be required to submit deer heads in 1999.
In addition to the Larimer County units where chronic wasting disease is known to be endemic, sampling was also conducted in the San Luis Valley, Gunnison and an area immediately northeast of Denver to make sure the disease had not spread to those areas. "We didn't expect to find chronic wasting disease in these areas, but we were sampling just to make sure," Miller said. "The results were as expected, with no evidence of the disease."
The incidence of chronic wasting disease in Larimer County remains at about 5 percent on average. In the units east of Larimer County, about 1 to 3 percent of deer on the Platte River drainage tested positive for the disease.
"Base on results over the last several years the incidence of chronic wasting disease in northeastern Colorado is not increasing," Miller said. The Division will continue to monitor chronic wasting disease. For the 1999 hunting seasons, sportsmen in 14 game management units will be required to submit deer heads to the Division for testing. Some units in northeastern Colorado will continue to be sampled. In addition, the Division will test in North Park and may conduct voluntary sampling other West Slope areas.
Units where deer head submission will be required are: 6, 7, 8, 9, 16, 17, 19, 20, 29, 87, 94, 161, 171 and 191. Heads of elk will not be required for submission because less than one percent of 1,000 animals [so about 10 elk -- these may be pooled at game processing facilities affecting everyone's meat -- webmaster] tested in Larimer County during 1996-98 showed any evidence of the disease. Researchers will test elk again in a few years to monitor any changes or possible spread of the disease.
There is no evidence to show that cattle or other domestic livestock can contract the disease, Miller said. [CWD has been passed experimentally to goat -- webmaster] Health department officials added that there is also not evidence that shows humans can contract it.
"There is no indication that chronic wasting disease is a threat to human health," said John Pape, an epidemiologist with the Colorado Department of Public Health and Environment. "But we do recommend that sportsmen who hunt in the area take some common-sense precautions."
Hunters should not take or consume any animal that appears sick, regardless of the cause. Other simple precautions when field dressing game include wearing rubber gloves, minimizing handling of brain and spinal tissues, and washing hands afterwards. Hunters should also avoid consuming brain, spinal cord, eyes, spleen and lymph nodes of animals.
The Division has sought the recommendations from public health officials because chronic wasting disease is one of several diseases collectively called transmissible spongiform encephalopathies. This group of maladies also includes scrapie, a disease of domestic sheep and goats, and bovine spongiform encephalopathy (BSE) that affects some European cattle. British researchers have linked BSE with a new variant of Creutzfeldt-Jakob disease, an extremely rare, but fatal, disease in humans...."
dated 17 Nov 97 [received in response to 1 Feb 99 request]:-- "The pathogen that causes this disease has not been identified... Neither the agent causing chronic wasting disease nor its mode of transmission have been identified." The words prion and CJD are nowhere mentioned.
-- Scrapie and BSE are discussed as "similar in some respects"; successful experimental transmission to goat is not mentioned though "according to experts, there's no evidence that chronic wasting disease can be transferred naturally to domestic livestock."
-- Range: northern Front Range from Wyoming border south to Lyons and east to Ft. Morgan. Most cases from Estes Park or foothills between Ft. Collins and Loveland.
-- Two cases documented along South Platte River just SE of Larimer County. [Jan 1999 press release gives this as 1-3% of deer in this drainage]
--CWD has been documented in 11 game management units [GMU]; 85% of documented cases are from units 19 and 20.
-- A map showing affected hunting units as of November 1997 is provided. Units 7, 8, 9, 19, 20, 29, 93, 94, 95, 96, and 191 are documented as affected. Units 87, 91, 92, and 954 have mandatory carcass head checks.
-- Lack of enforcement by DoW of feeding stations regs: "Artificial feeding of deer and elk may comound the problem -- in recent years the disease has been most prevalent in areas in the Estes Valley where residents put out feeders to attract deer and elk. Although that practice has been specifically prohibited by regulations approved by the Colorado Wildlife Commission in 1992, many well-meaning individuals coninue to ignore the law and may be exacerbating this problem."
-- Hunter safety: " There is no evidence that chronic wasting disease affects humans, but the Divison of Wildlife advises hunters to take simple precautions when handling the carcass of any deer or elk harvested in the units where CWD occurs Wear rubber gloves when filed dressing carcasses, minimize handling of brain and spinal column and wash hands afterwards. Hunters shoud bone out carcasses or at least avoid consuming brain, spinal cord, eyes, spleen and lymph nodes of harvested animals."
Times Argus Rutland Herald Sunday Magazine (cover story) Feb. 7. 1999 Terry J. Allen 10 Feb 99"...Chronic wasting disease -- the TSE that affects deer and elk-- is worrying Vermont officials. CWD is endemic in some states in the western US, regions from which Vermont elk farmers have imported stock. There are currently four farms in Vermont raising elk--in Isle La Mott, Tunbridge, Hinesberg, and Derby. ....
Concern about CWD has prompted Vermont state officials to tighten controls on the importation of elk into the state and to mandate better fencing for those already here. According to State Veterinarian Dr. Samuel Hutchins, as far as can be determined , none of Vermont's imported elk came from herds of farm-raised elk found to contain animals with CWD.
But there is really no way to know. The state, according to Hutchins, "relies totally on the federal or state government" to notify it which elk farms were contaminated and whether they shipped animals to Vermont. The problem is that there is no national tracking or notification program.
According to Lisa Ferguson , senior staff veterinarian at the National Center for Import Export and part of the government's TSE Working Group, "Farms [breeding and selling elk] would be under the authority of individual states. Vermont would have to call each state and ask for more information. That is up to the state if they want to do that."
John Buck, wildlife biologist with the Vermont Department of Fish and Wildlife, also believes that there have been no known cases of chronic wasting disease in Vermont in either deer or elk. But since there is no formal testing program, "there is no way to know for sure," he said. Indeed, there is no way to test live animals and no animals in Vermont have been autopsied looking for TSEs.
That uncertainty had led some officials to recommend a quarantine period for imported animals. But for how long? "Admittedly," said Buck, "the incubation period is unknown and the symptoms can be vague. Unfortunately, we don't know how effective a quarantine is that is shorter than the incubation period." Furthermore, it appears that apparently healthy animals can be carriers.....
Last year, Vermont instituted a ban on importation from farms with CWD-infected deer and elk. It still accepts animals from high-risk regions so long as the animal does not present obvious symptoms....
"We are concerned," said Buck, "about all kinds of exotic diseases that could enter the population and and could do irreparable harm to our wild life." One TSE, scrapie, is already found in most states. While no cases have been reported recently in Vermont sheep, according to Ferguson "there is no state where we can guarantee that there is no scrapie. The reporting program is voluntary, but there is no eradication program. To make a statement that the state is free of disease implies that there is a level of surveillance in place." The same might be said for chronic wasting disease in deer and elk.
Derby Elk farmer Doug Nelson is concerned, but believes his herd is healthy. He has 130 head, and had bought 25 animals from Idaho, Saskatchewan (both regions that have reported isolated cases) and possibly other western areas. He has begun reading up on CWD, "I know what disease can do to a herd. I lost 1,000 head of cows to brucellosis in 1978," he said.
Paul Casey of Hinesberg, who recently bought 25 elk from Nelson doesn't know where the animals originated but doesn't see any need for Vermont to investigate further or impose more regulations. "I think its being worked on by a lot of different people from a lot of different angles and I think it would be very premature for Vermont to get involved at this stage."
Despite their reassurances that everything in Vermont is under control, state officials have no idea where the animals imported into the state really originated. One expert said, "no elk farm can be certified CWD-free. Elk are traded around like baseball cards. Everyone assumes they have the best quality elk from best herd, but quite a few farms have been seriously contaminated."
The paperwork that accompanies each shipment of elk to Vermont certifies only that each animal tested negative for tuberculosis and brucellosis. It states the place where the animals were bought, not where they were a year or even a month before that."You can't say the farm or herd of origin," says Hutchins. "Doug [Nelson]'s herd was an `assembled herd.' He bought animals from one individual who assembled them from various herds."
Asked for an example, Hutchins explained, "Somebody buys five animals from one person, five from another, and five from another." When the animals are sold, the place where they were "assembled" is listed on the health chart as the place of origin. Because of the requirements for testing, "they've probably been there for at least two weeks. The ear tag would give us a clue [further back] if we wanted to pursue it."
Apparently, though they have not wanted to. Nonetheless, Hutchins says he is confident that CWD has not entered the state. He did, however, note that the rules have been tightened and because of new regulations, any animals now coming into Vermont would be covered by a stricter regulatory process. "People would have to address the issue of whether the animals were exposed." If they knew.
In a further measure, on January 1, the state sent notices to vets about CWD and reminded them to report any suspicious symptoms or deaths. "There is also in draft form a requirement to test any animal over 16 months of age for TSE that is killed, died or has clinical symptoms," said Hutchins. That will cost owner $100 per animal...."
While an outbreak of TSE in the Vermont elk population may be unlikely, if it did occur, and if it spread to the native deer population, the consequences could be serious. The Vermont Department of Agriculture is in a difficult position. It combines two functions: promoting agriculture and protecting the public interest. Although these functions are performed by separate subdivisions, a fundamental conflict of interest exists in those roles. "You are asking an agency to do impossible if it is supposed to be promoting agriculture at same time as being asked to blow it out of water," said one observer.
Hutchins had no doubt that the public good would come before the profits of agribusiness. "As a vet, I have an ethical standard to meet," he said. Another potential problem for Vermont is that it is generally up to farmers and herders to report sick livestock, whether, elk and deer, or cows. And when destruction of the whole herd is possible, no compensation is guaranteed, and the facilities cannot be used again for livestock of any kind, farmers can be sorely tempted to keep quiet about potentially infections diseases. "We would hope someone would say something about it," said Hutchins, "With past outbreaks of TB and brucellosis, there was no automatic compensation, but the legislature did approve some. But with those diseases there were tests." Until test are cheap and available, the danger remains. And until a treatment is found, the prognosis for those infected is grim.
| Chronic wasting disease (CWD) is relatively rare in wild deer and elk. Ongoing surveys show that on average CWD affects 3 percent of deer and far
less than 1 percent of elk in 13 units in northeast Colorado. It appears most prevalent in northeastern Larimer County. The disease causes brain
damage in deer and elk. Affected animals are emaciated, behave abnormally, salivate excessively and eventually die. There is no evidence CWD
affects domestic livestock.
There also is no evidence CWD affects humans, but the DOW and state public health officials advise hunters to take simple precautions when handling the carcass of a deer or elk harvested in units where it occurs. Wear rubber gloves when field dressing carcasses and minimize handling of brain and spinal tissues and wash hands afterward. Hunters should bone out carcasses or at least avoid consuming brain, spinal cord, eyes, spleen and lymph nodes of harvested animals. Hunters should not handle or consume wild animals that appear sick, regardless of the cause.
If you see or kill a deer or elk that may have CWD, contact the DOW in Fort Collins, (970) 484-2836. You can also request a brochure from us on CWD.
MANDATORY HEAD SUBMISSIONS
1. To support ongoing CWD surveys, hunters who harvest deer during regular or late rifle seasons in units 7, 8, 9, 18, 19, 20, 28, 29, 37, 87, 90, 91, 92, 93, 94, 95, 96, 191, 371 and 951 must submit the heads to the DOW for sampling within 5 days after harvesting their animal. Take the head to any DOW officer in those units or drop it at one of these locations:
2. Hunters who harvest deer in the above units must complete a special survey tag that will be mailed to them or is available at the locations listed above. The tag must be securely attached to the animalľs head before the head is presented to a DOW officer or is taken to a drop-off site.
3. Hunters can remove antlers and capes from harvested deer before submitting heads for sampling. Trophy heads can be sampled by appointment by calling (970) 484-4371. Mounts othr than European should be caped before sampling.
4. These surveys provide information on CWD occurrence in northeast Colorado deer populations. Sampling and testing procedures are neither designed nor intended to provide quality assurance for individual carcasses. When adequate information is provided, hunters will be notified by mail of indivdual testing results and will be asked for more information on harvest location. However, four to six weeks may be required to complete sampling and testing.
5. Hunters harvesting deer that test positive for CWD will be offered a refund of their license fees. Refunds are limited to the license cost. Game processing fees and other incidental expenses are not eligible for refunds.
Montana FWP web siteDuring the upcoming fall big game hunting season, Fish, Wildlife & Parks' Wildlife Laboratory will be conducting surveys for Chronic Wasting Disease (CWD) in FWP administrative regions 2, 3, 4, 5 and 7. The surveys will include collection of heads from mule deer, white-tailed deer and elk. Sampled animals will be tagged at check stations to indicate that the head was removed for the CWD survey to prevent enforcement problems with evidence of sex. Specific brain tissues and tonsils will be extracted from the heads. Laboratory technicians will be assisting at several check stations to collect the tissues and these will be forwarded to a laboratory where histologic sections will be examined by a pathologist to look for lesions typical of CWD.
CWD has been identified in wild deer and elk in Colorado and Wyoming and in seven game farms in South Dakota, Nebraska, Oklahoma and Saskatchewan. For the past several years, Montana FWP monitored a limited number of big game animals for CWD and has found no evidence of the disease in free ranging wildlife. CWD was not believed to be present in Montana game farms until late June of this year, when the Department of Livestock notified FWP that a game farm elk reportedly shipped from Montana to Oklahoma was confirmed with CWD.
FWP has proposed increasing the surveillance for this disease in wild elk and deer. The surveillance will provide monitoring the southern perimeters of the state where the disease is most likely to naturally spread from Wyoming and Colorado. Emphasis will be placed on animals that are 1.5 years old and older of both sexes.
Tom Palmer of Montana FWP writes us about concerning a leaked "secret memo" circulating on the Internet:
"We don't have "internal" memos and this notion of something being "leaked" is odd. All of FWP's communications are open, public, and straight forward. The .memo released to the press by FWP and Gov. Marc Racicot. FWP is taking the CWD threat to wildlife very seriously.
Karen Zachheim, our Game Farm Coordinator, will send you any material requested .Should you want to talk to Karen about the CWD issue, call 406-444-4039, or Paul Sihler in the Director's office at 406-444-5620. If the material doesn't arrive early next week, please call me (406-444-3051)."
Montana has 93 game farms with 4,000 animals; 12 further facilities approved. Elk hunters pend an estimate $75 million per year for 22,000 elk, deer hunters $68 million to kill 75,000 mule deer and 60,000 white-tailed deer.
AP 11 Oct 98No indication of disease, goal of 500 deer and elk brains in 1998
State biologists are launching a study to determine whether deer or elk in Nevada have been infected with a malady -- similar to 'mad cow disease' -- that has turnedup in other Western states.
"We want to stress that there is nothing to indicate that the disease is in Nevada," said Gregg Tanner game bureau chief for the Nevada Division of Wildlife. "This is simple a concerted effort to confirm that we do not have it because of its potential ramifications."
... Deer infected with it show changes in behavior, including a lack of fear of humans. In later stages, the animals may wander aimlessly or spend unusual amounts of time with their ears and head drooping.
"It is the wildlife version of mad cow disease," said Chris Healy, wildlife division spokesman. ...Nevada biologists plan to analyze brain tissue samples for at least 500 deer and elk killed by hunters in the coming season.
Wildlife officials said there is some concern that elk and deer might be able to transmit the disease to cattle but there is no evidence of that so far. Brain tissue samples will be collected at game meat processing plats, field contacts with hnters and hunter check stations. They must come from deer at least 18 months old which have been dead for 24 hours or less...
Tanner suggested hunters not shoot an animal that is acting abnormal or looks sick. He said it is always a good idea to wear rubber gloves when field dressing any big game and recommends minimizing contact with the brains and spinal column of deer and elk. David Rice, the diveision's chief conservation educator, said those recomendations are intended as extra safety precautions.
ND Department of Agriculture Press Release January 23, 1998State Veterinarian Dr. Larry Schuler said the surveillance program will apply to all domestic elk and deer owners, and will go into effect in February. It has never been detected in either wild or domestic animals in North Dakota. Schuler said the surveillance program will require that any death among domestic elk or deer must be reported immediately to the owner's veterinarian. The veterinarian will arrange for removal of the animal's brain which will be sent first to North Dakota State University and then to an approved lab for diagnostic analysis. If the laboratory confirms a positive diagnosis for CWD, further action, including possible quarantines, will be determined by the North Dakota Board of Animal Health.
June 19, 1998What does the Canadian Food Inspection Agency (CFIA) do to prevent CWD from entering or becoming established in Canada?
Under the Health of Animals Act, the CFIA has the power to act when a suspect case of CWD is found. This may include quarantine and destruction of all exposed animals.
The CFIA routinely monitors for CWD. Each herd is tested every three years for tuberculosis, and at that time agency inspectors examine each animal for signs of neurological disease. In addition, all deer and elk sent to provincial laboratories for post mortem are screened for CWD as part of an ongoing surveillance program.
In 1988 a Captive Ungulate Program was created because the health status of game farmed deer, elk and bison was not well known, and they posed a potential health risk for the spread of tuberculosis and brucellosis to Canadian cattle. In 1990 it became mandatory for a permit to be issued in order to move an animal, thus allowing for the monitoring of all movement of these species.
Since 1990 there has been a ban on the importation of deer and elk from the United States.
Are products like venison or powdered antler velvet from animals that have been exposed to CWD safe?
According to Health Canada there are no studies available on the safety of tissues from elk with CWD. In studies using mice experimentally infected with scrapie, another TSE, muscle and skin tissues were not found to be infectious, at any detectable level.
However, we have to be very cautious in using these results to predict the safety of products from infected or exposed elk, since test results from one species do not necessarily apply to another.
1 May 1996 Steve Sullivan, Agriculture and Agri-Food Canada, writes:"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.
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."
27 Apr 99 Site search results [See also link collection to TSE in other wild animals.]CWD News:
Under-diagnosis in elk: 10/17 prove positive with better method
21 Jan 99 -- Utah hunter: CWD blood recall?
20 Dec 98 -- Bad news on game farm elk CWD
12 Nov 98 --Colorado CJD tragedy and CWD concerns
11 Oct 98 -- Nevada testing deer and elk for CWD
23 Jun 98 -- Elk CWD spreading on game farms
19 Mar 98 -- BSE Inquiry: Day 6 -- Mink and CWD misinformation
19 Mar 98 -- CWD: spreading it around
19 Mar 98 -- CWD: failed eradication attempts
19 Mar 98 -- CWD in Estes Park: what goes on at Lexington Lane?
19 Mar 98 -- 14 facilities where CWD has been found
19 Mar 98 -- How did CWD get started and spread?
19 Mar 98 -- Elk growers ask for surveillance in N. Dakota
19 Mar 98 -- Ban on elk antlers in human food rejected
19 Mar 98 -- CWD in High Country News
19 Mar 98 -- CWD Web Resources
14 Feb 98 -- Colorado's dementia experiment in humans
24 Feb 98 -- Feds need to take control over Colorado CWD
14 Feb 98 -- Surveillance for chronic wasting disease in Colorado
14 Feb 98 -- CWD by river drainage
14 Feb 98 -- Some early history of CWD
10 Jul 97 -- Chronic Wasting Disease in Canada23 Jul 98 -- Saskatchewan elk disease waning?
14 Feb 98 -- More chronic wasting disease news: 1, 2
14 Feb 98 -- Welcome to Stetsonville
07 Feb 98 -- Deer in three Wyoming counties infected with chronic wasting disease
07 Feb 98 -- Chronic wasting disease: deer-to-cattle shown
07 Feb 98 -- Worry over CWD hazards
05 Feb 98 -- Canada reports CWD in mule deer on game farms
07 Feb 98 -- Dr. Steven Dealler on CWD risks
27 Jan 98 -- Concerned rancher writes in about deer feeding habits
03 Feb 98 -- To eat or not to eat is the hunter's question
01 Mar 97 -- CWD and hunters square off in Colorado
01 Apr 97 -- CWD: lab progress is slow
01 Mar 97 -- Mystery of CWD in US deer, elk explained?
Chronic wasting disease update
Host range of CWD is altered on passage in ferrets (Virology 1998 Nov 25;251(2):297-301)
Mule Deer with CWD: 3 new prion alleles reported
Pronghorn and fallow deer prion sequences released
Is scrapie genetic?
Cervid prion genes in context
Capillary isoelectric focusing of the scrapie prion protein
Dermal prions: enough to make your skin crawl
Chronic wasting disease shows TSEs loose in US
Chronic Wasting Disease: Research Directions
(Contact information for other USAHA emembers and TSE researchers are proveded separately) State Fish & Game Departments: all 50 states
Colorado Department of Agriculture State Veterinarian Dr. Jerry Bohlender Assistant State Veterarian Dr. Wayne Cunningham 700 Kipling St., #1100 Lakewood, CO 80215-5894 Tel: 303/239-4161 Fax 303/239-4164 Colorado Division of Wildlife:
-- Ranching for Wildlife -- Financing of Division of Wildlife Colorado Elk and Game Breeders Association Veterinarian Dr. Liz Chandler (970) 984-3269 Colorado Division of Wildlife Veterinarian Dr. Mike Miller (970) 472-4348 Colorado State University Diagnostic Lab Veterinarian Dr. Barb Powers Veterinarian Dr. Terry Spraker Veterinarian Dr. Dan Gould (970) 491-1281 Colorado Department of Public Health and Environment Epidemiologist John Pape (303) 692-2628 Idaho Dr. Bob R. Hillman, State Veterinarian Idaho Dept. of Agriculture P.O.Box 7249, Boise, ID 83707 Tel: 208/332-8540 Fax: 208/334-4062 Iowa Dr. Walter D. Felker, State Veterinarian Iowa Dept. of Agriculture Wallace Bldg., 2nd Fl. East 9th & Grand Ave. Des Moines, IA 50319 Tel: 515/281-5305 Fax: 515/281-4282 Nontana Fish, Wildlife, and Parks Tom Palmer 406-444-3051 Paul Sihler, Director's office 406-444-5620 Karen Zachheim, Game Farm Coordinator and Regs 406-444-4039 Montana Dept. of Agriculture Dr. Arnold A. Gertonson, State Veterinarian Dr. Linfield P O.Box 202001 Helena, MT 59620-2001 Tel: 406/444-2043 Fax 406/444-1929 Nebraska Dr. Butch [Roger John] Sahara Nebraska Dept of Agriculture tel: (402)471-2351 Nebraska Dept. of Agriculture phone book Dr. Larry L. Williams, State Veterinarian P.O.Box 94787 Lincoln, NE 68509-4787 Tel: 402/471-2351 Fax: 402/471-3252 North Dakota Dr. Larry Schuler state Veterinarian (701) 328-2654 Dr. Susan Keller (701) 328-2654 deputy state veterinarian Nevada Chris Healy, wildlife division spokesman Oklahoma Dr. Burke L. Healey, State Veterinarian Oklahoma Dept. of Agriculture Animal Industry Services 2800 North Lincoln Blvd. Oklahoma City, OK 73105 Tel: 405/521-3891 Fax: 405/522-0756 Rocky Mountain Lab in Hamilton, Montana Byron Caughey tel:406-363-9264/9291 Bruce Chesebro tel 406-363-9354 South Dakota Dr. Sam D. Holland, State Veterinarian South Dakota Animal Industry Board 411 S. Fort St. Pierre, SD 57501 Tel: 605/773-3321 Fax 605/773-5459 Utah Dr. Michael R. Marshall, State Veterinarian Utah Dept. of Agriculture 350 N Redwood Rd., Box 146500 Salt Lake City, UT 84114-6500 Tel: 801/538-7160 Fax 801/538-7169 Wisconsin Steven W.Miller [concerned about wild deer and captive deer George E Meyer Dr. Sarah Hurley AD/5 Dr. Clarence Siroky DATCP Tom Hauge WM/4 RF Marsh's colleagues, co-author of CWD-to-monkey transmission paper University of Wisconsin, Madison, Dept of Animal Health and Biomedical Sciences Aiken Judd M 608-262-7362, 608-262-0427 McKenzie Debbie I, 608-262-0427 Bartz Jason C 608-262-0427 , 53706, USA. Wyoming Pathologist Dr. Beth Williams Department of Veterinary Science University of Wyoming Laramie, WY 83070 Telephone (307) 742-6638 Wyoming Fish & Game Dr. Tom Thorne 5400 Bishop Blvd. Cheyenne, WY 82006 Telephone (307) 777-4586 Wyoming Livestock Board Dr. Jim Logan, Interim State Veterinarian 862 Paradise Valley Road Riverton, WY 82501 Tel: 307/777-6443 or (307) 777-7515 Fax 307/777-6561 CANADA Steve Sullivan Senior Communications Advisor (Animal Health/Welfare Issues) Agriculture and Agri-Food Canada Ottawa, Canada Dr. N. G. Willis, Director Animal Health Div. 930 Carling Ave. Ottawa, Ont. Canada K1A 0C5 Tel: 613/993-6671 Alberta (Edmonton) MJ Pybus Alberta Fish and Wildlife DK ONderka Animal Health S. Honour Norway Tom Warren [reindeer + scrapie] Biol. Inst., Blindern Univ. of Oslo Norway Tel. 472 285 4794 Telefax 472 285 4605 Dr. Victor F. Nettles, Chairman USAHA Wildlife Diseases Committee SCWDS/College of Veterinaty Medicine The University of Georgia Athens, GA 30602 Phone: 706/542-1741 Fax: 706/542-5865 North American Elk Breeders Association Mr. Dave Whittlesey P.O.Box 1640 Platte City, MO 64079 Phone: 816/431-3605 Fax: 816/431-2705 North American Deer Farmers Assn NADeFA Rocky Mt Elk Foundation USDA ARS Ames, Iowa Randall Cutlip, Supvy Vetnry Medcl Offcr 2300 Dayton Road, P.O. Box 70 , Ames, IA 50010 Phone: 515-239-8316 FAX: 515-239-8458 Allen L. Jenny 515-239-8521 Kathryn R. Goodwin 515 239-8287 X287 William D.Taylor 515-239-8521 Schmerr, Mary Jo Research Chemist Ames, Iowa National Animal Disease Center Respiratory & Neurologic Disease Research tel (515) 239-8287 X287 fax (515) 239-8458 Miller, Janice M Veterinary Medical Officer Ames, Iowa National Animal Disease Center tel (515) 239-8349 X349 fax (515) 239-8458 Katherine O'Rourke Pullman Washington expert on early diagnostic techniques, cervid prion genetics. USDA, ARS, ADRU WSU 337 Bustad Pullman, WA tel 509-335-6020 fax 509-335-8328 Joel Stone, D.V.M., Ph.D [scrapie and cwd origins] Merck Research Laboratories Rahway, N.J. Mon, 6 May 1996 ProMed message from Dr. Stone: "I'm not sure about this specific case, but before going to vet school, I worked for the Colorado Division of Wildlife in Fort Collins, CO. We had captive bred mule and elk that acquired a Chronic wasting syndrome similar to what you describe. Though the animals were fed alfalfa hay, native grass in their pens were also available. This particular tract of land had once been domestic sheep range and at the time it was speculated that scrapie or something similar to scrapie was responsible for the disease."
Medline search by webmaster for scientific articles on CWD 17 Jan 99
Virology 1998 Nov 25;251(2):297-301 Bartz JC, Marsh RF, McKenzie DI, Aiken JM[This paper also cites transmission to goat and transmission to squirrel monkey] Chronic wasting disease (CWD), a member of the transmissible spongiform encephalopathies (TSEs), was first identified in captive mule and black-tail deer in 1967. Due to the failure to transmit CWD to rodents, we investigated the use of ferrets (Mustela putorius furo) as a small animal model of CWD. The inoculation of CWD into ferrets resulted in an incubation period of 17-21 months on primary passage that shortened to 5 months by the third ferret passage. The brain tissue of animals inoculated with ferret-passaged CWD exhibited spongiform degeneration and reactive astrocytosis. Western blot analysis of ferret-passaged CWD demonstrated the presence of PrP-res. Unlike mule deer CWD, ferret-passaged CWD was transmissible to Syrian golden hamsters (Mesocricetus auratus). Increasing the passage number of CWD in ferrets increased the pathogenicity of the agent for hamsters. This increase in host range of a field isolate on interspecies transmission emphasizes the need for caution when assessing the potential risk of transmission of TSEs, such as bovine spongiform encephalopathy, to new host species. Copyright 1998 Academic Press.
J Wildl Dis 1998 Jul;34(3):532-8 Miller MW, Wild MA, Williams ESBetween June 1986 and May 1997, chronic wasting disease (CWD) was the only natural cause of adult mortality among captive Rocky Mountain elk (Cervus elaphus nelsoni) held at a wildlife research facility near Fort Collins, Colorado (USA). Of 23 elk that remained in this herd > 15 mo, four (17%) developed CWD. All affected elk were unrelated females from the founding cohort, captured as neonates and raised in 1986. The index case was diagnosed in 1989; time intervals between subsequent cases ranged from 13 to 32 mo. Initial age at onset of clinical signs ranged from about 2.9 to 8.1 yr; duration of clinical disease ranged from 5 to 12 mo (mean = 7.5 mo) prior to death. Intraspecific lateral transmission of CWD seemed the most plausible explanation for the epidemic pattern observed; neither periparturient nor maternal transmission appeared necessary to sustain this outbreak. Early detection and elimination of incubating or clinical individuals may have aided in reducing exposure or infection rates as compared to a previous outbreak in the same facility. Transmission routes and rates, pathogenesis, antemortem diagnostic tools, and the potential role of reservoirs or environmental contamination in perpetuating CWD epidemics warrant further investigation.
J Clin Microbiol 1998 Jun;36(6):1750-5 O'Rourke KI, Baszler TV, Miller JM, Spraker TR, Sadler-Riggleman I, Knowles DPThe transmissible spongiform encephalopathies are a heterogeneous group of fatal neurodegenerative disorders occurring in humans, mink, cats, and ruminant herbivores. The occurrence of novel transmissible spongiform encephalopathies in cattle in the United Kingdom and Europe and in mule deer and elk in parts of the United States has emphasized the need for reliable diagnostic tests with standardized reagents. Postmortem diagnosis is performed by histologic examination of brain sections from affected animals. The histopathological criteria for transmissible spongiform encephalopathies include gliosis, astrocytosis, neuronal degeneration, and spongiform change. These lesions vary in intensity and anatomic location depending on the host species and genetics, stage of disease, and infectious agent source. Diagnosis by histopathology alone may be ambiguous in hosts with early cases of disease and impossible if the tissue is autolyzed. Deposition of the prion protein (an abnormal isoform of a native cellular sialoglycoprotein) in the central nervous system is a reliable marker for infection, and immunohistochemical detection of this marker is a useful adjunct to histopathology. In the present paper we describe monoclonal antibody (MAb) F89/160.1.5, which reacts with prion protein in tissues from sheep, cattle, mule deer, and elk with naturally occurring transmissible spongiform encephalopathies. This MAb recognizes a conserved epitope on the prion protein in formalin-fixed, paraffin-embedded sections after hydrated autoclaving. MAb F89/160.1.5 will be useful in diagnostic and pathogenesis studies of the transmissible spongiform encephalopathies in these ruminant species.
Lancet. 1997 Jul 19;350(9072):219-20. No abstract available. Cervenakova L, Rohwer R, Williams S, Brown P, Gajdusek DC
Schatzl HM, Wopfner F, Gilch S, von Brunn A, Jager G Lancet. 1997 May 31;349(9065):1603-4. No abstract available.
Acta Vet Hung 1998;46(3):381-94 Mackintosh CGThis paper describes the most significant diseases of farmed deer which have emerged over the last 30 or so years. It describes their characteristic signs, how control measures have evolved, their current status and gives an indication of future diagnostic and control measures. Overall, it shows that wild deer brought into a farming environment have developed some of the production limiting diseases which affect sheep and cattle, such as parasitism and trace element deficiencies. In addition, farmed deer are susceptible to potentially fatal diseases such as tuberculosis, malignant catarrhal fever and yersiniosis. A disease which has recently emerged and has the potential to be more serious than any of the above is Johne's disease. In North America, Chronic Wasting Disease occurs in captive and wild deer in only two states but has the potential to be a serious threat to wild and farmed deer elsewhere if it spreads. The zoonotic risks of diseases affecting deer are discussed, as well as stress, welfare and deer restraint. The productivity of farmed deer can be maximised by using a well-designed deer health programme integrated with good management and feeding.
J Wildl Dis 1997 Jan;33(1):1-6 Spraker TR, Miller MW, Williams ES, Getzy DM, Adrian WJ, Schoonveld GG, Spowart RA, O'Rourke KI, Miller JM, Merz PABetween March 1981 and June 1995, a neurological disease characterized histologically by spongiform encephalopathy was diagnosed in 49 free-ranging cervids from northcentral Colorado (USA). Mule deer (Odocoileus hemionus) were the primary species affected and accounted for 41 (84%) of the 49 cases, but six Rocky Mountain elk (Cervus elaphus nelsoni) and two white-tailed deer (Odocoileus virginianus) were also affected. Clinical signs included emaciation, excessive salivation, behavioral changes, ataxia, and weakness. Emaciation with total loss of subcutaneous and abdominal adipose tissue and serous atrophy of remaining fat depots were the only consistent gross findings. Spongiform encephalopathy characterized by microcavitation of gray matter, intraneuronal vacuolation and neuronal degeneration was observed microscopically in all cases. Scrapie-associated prion protein or an antigenically indistinguishable protein was demonstrated in brains from 26 affected animals, 10 using an immunohistochemical staining procedure, nine using electron microscopy, and seven using Western blot. Clinical signs, gross and microscopic lesions and ancillary test findings in affected deer and elk were indistinguishable from those reported in chronic wasting disease of captive cervids. Prevalence estimates, transmissibility, host range, distribution, origins, and management implications of spongiform encephalopathy in free-ranging deer and elk remain undetermined.
Folia Neuropathol 1994;32(3):171-3 Guiroy DC, Liberski PP, Williams ES, Gajdusek DCWe report here the electron microscopic findings in brain of Rocky Mountain elk with chronic wasting disease (CDW), a progressive and fatal neurological disorder of wild ruminants characterized neuropathologically by intraneuronal vacuolation, spongiform change of the neuropil and astrocytic hypertrophy and hyperplasia. Ultrastructural findings included membrane-bound vacuoles in neuronal elements, increased number of glial filaments, dystrophic neurites, numerous neuritic plaques, Hirano bodies and perikaryal inclusion bodies. Similar findings have been observed in CWD-affected mule deer, as well as in bovine spongiform encephalopathy, and in natural and experimental scrapie and Creutzfeldt-Jakob disease indicating a common etiopathogenesis.
Acta Neuropathol (Berl) 1993;85(4):437-44 Guiroy DC, Williams ES, Liberski PP, Wakayama I, Gajdusek DCChronic wasting disease (CWD), a progressive and uniformly fatal neurological disorder, is characterized neuropathologically by intraneuronal vacuolation, spongiform change of the neuropil and astrocytic hyperplasia and hypertrophy. Ultrastructural neuropathological findings consist of (1) extensive vacuolation in neuronal processes, within myelin sheaths, formed by splitting at the major dense lines or within axons; (2) dystrophic neurites (dendrites, axonal preterminals and myelinated axons containing degenerating mitochondria and pleomorphic, electron-dense inclusion bodies); (3) prominent astrocytic gliosis; (4) amyloid plaques; and (5) giant neuronal autophagic vacuoles. Other findings include activated macrophages and occasional spheroidal structures containing densely packed fibrillar material of unknown origin, abundant structures suggestive of degenerating microtubules entrapped in filamentous masses, vacuoles and myelin figures. Similar findings have been previously observed in scrapie-infected hamsters and Creutzfeldt-Jakob disease (CJD)-infected mice, bovine spongiform encephalopathy, and CJD indicating that CWD in captive mule deer belongs to the subacute spongiform encephalopathies (transmissible brain amyloidoses).
Vet Pathol 1993 Jan;30(1):36-45 Williams ES, Young SThe pathology of the central nervous system of nine mule deer (Odocoileus hemionus) and six elk (Cervus elaphus nelsoni) with chronic wasting disease, a spongiform encephalopathy of mule deer and elk, was studied by light microscopy. Lesions were similar in both species and were characterized by spongiform transformation of gray matter, intracytoplasmic vacuolation of neurons, neuronal degeneration and loss, astrocytic hypertrophy and hyperplasia, occurrence of amyloid plaques, and absence of significant inflammatory response. Distribution and severity of lesions were evaluated at 57 locations; there were only minor differences between deer and elk. Consistent, severe lesions occurred in olfactory tubercle and cortex, hypothalamus, and the parasympathetic vagal nucleus of deer, and sections examined from these regions would be sufficient to establish a diagnosis of chronic wasting disease. Lesions were milder in these locations in elk but were sufficiently apparent to be of diagnostic value. Other differences included increased severity of lesions in some thalamic nuclei in elk in contrast to deer, the occurrence of amyloid plaques demonstrable by hematoxylin and eosin and histochemical stains in deer in contrast to elk, and the presence of mild white matter lesions in elk but not in deer. Lesions of chronic wasting disease were qualitatively comparable to those of scrapie, bovine spongiform encephalopathy, transmissible mink encephalopathy, and the human spongiform encephalopathies. Topographic distribution and lesion severity of chronic wasting disease were most similar to those of scrapie and bovine spongiform encephalopathy. Duration of clinical disease did not significantly influence lesion distribution or severity in either species.
Acta Neuropathol (Berl) 1993;86(1):77-80 Guiroy DC, Williams ES, Song KJ, Yanagihara R, Gajdusek DCChronic wasting disease (CWD), a progressive, fatal neurological disorder of captive mule deer and Rocky Mountain elk, is characterized neuropathologically by spongiform change in the neuropil, intraneuronal vacuolation and astrocytic hypertrophy and hyperplasia. Recently, scrapie amyloid-immunoreactive plaques have been demonstrated in brain tissues of CWD-affected captive mule deer, Rocky Mountain elk and hybrids of captive mule deer and white-tailed deer. We now report on the presence of abnormal fibrils isolated from brain tissues of Rocky Mountain elk using negative-stain electron microscopy. These fibrils resemble those found in scrapie-infected hamster brain. Furthermore, protein bands with relative molecular masses of 26 to 30 kilodaltons were shown to be immunoreactive to antibodies raised against scrapie amyloid by Western immunoblotting. Immuno-dot blot showed similar reactivity. Our data support the clinical and pathological diagnosis of the disease and provide further evidence that CWD belongs to the subacute spongiform encephalopathies.
Rev Sci Tech 1992 Jun;11(2):551-67 Williams ES, Young SThe known host range of naturally-occurring transmissible spongiform encephalopathies has expanded in recent years to include wild ruminants. Chronic wasting disease (CWD) occurs in mule deer (Odocoileus hemionus hemionus) and Rocky Mountain elk (Cervus elaphus nelsoni) in Colorado and Wyoming, United States of America. These species belong to the family Cervidae. Cases have occurred primarily in captive animals but a few affected free-ranging animals have been identified. Clinical disease in both species is characterised by progressive weight loss, behavioural alterations and excessive salivation. In deer polydipsia and polyuria also commonly occur. Significant lesions are confined to the central nervous system and consist of spongiform change in grey matter, intraneuronal vacuolation, astrocytosis and amyloid plaques. Inflammatory reaction is absent. The origin of this disease is not known. In contrast to the cases of spongiform encephalopathy recognised in five species of antelope (family Bovidae) in British zoological parks, which are an extension of the current bovine spongiform encephalopathy epizootic, CWD is not the result of food-borne exposure to the infectious agent. CWD appears to be maintained within captive populations by lateral and, possibly, maternal transmission. Spongiform encephalopathies in wild ruminants are currently geographically isolated and involve relatively small numbers of animals. However, these potentially transmissible diseases could be of greater importance in the future and 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.
Neurosci Lett 1991 May 27;126(2):195-8 Guiroy DC, Williams ES, Yanagihara R, Gajdusek DCScrapie amyloid-immunoreactive plaques are present in brain tissues of captive mule deer with chronic wasting disease (CWD), a progressive neurological disorder characterized neuropathologically by widespread spongiform change of the neuropil, intracytoplasmic vacuolation in neuronal perikarya and astrocytic hypertrophy and hyperplasia. We report here the immunolocalization of scrapie amyloid (PrP27-30) in plaques observed in brain tissues of Rocky Mountain elk (Cervus elaphus nelsoni) and hybrids of mule deer and white-tailed deer (Odocoileus virginianus) naturally affected with CWD. Similar findings have been shown in kuru, Creutzfeldt-Jakob disease, and Gerstmann-Straussler syndrome in humans. Our data corroborate that CWD in Rocky Mountain elk and hybrids of mule deer and white-tailed deer belongs to the subacute spongiform virus encephalopathies (transmissible cerebral amyloidoses).
Acta Neuropathol (Berl) 1991;81(5):475-8 Guiroy DC, Williams ES, Yanagihara R, Gajdusek DCChronic wasting disease (CWD), a progressive neurological disorder of captive mule deer, black-tailed deer, hybrids of mule deer and white-tailed deer and Rocky Mountain elk, is characterized neuropathologically by widespread spongiform change of the neuropil, intracytoplasmic vacuolation in neuronal perikarya and astrocytic hypertrophy and hyperplasia. We report the topographic distribution of amyloid plaques reactive to antibodies prepared against scrapie amyloid in CWD-affected captive mule deer (Odocoileus hemionus hemionus). Scrapie amyloid-immunoreactive plaques were found in the cerebral gray and white matter, in deep subcortical nuclei, in isolation or in clusters in areas of vacuolation, and perivascularly, in subpial and subependymal regions. In the cerebellum, immunoreactive amyloid plaques were observed in the molecular, pyramidal and granular layers. Scrapie amyloid-immunoreactive deposits were also seen in neuronal perikarya. Furthermore, amyloid plaques in CWD-affected captive mule deer were alcianophilic at 0.3 M magnesium chloride indicating the presence of weakly to moderately sulfated glycosaminoglycans. Our data corroborate that CWD in captive mule deer belongs to the subacute virus spongiform encephalopathies.
J Comp Pathol 1985 Jan;95(1):1-5 Bahmanyar S, Williams ES, Johnson FB, Young S, Gajdusek DCAmyloid plaques were demonstrable in central nervous system tissues of adult captive mule deer affected with chronic wasting disease, a transmissible primary spongiform encephalopathy. Plaques were detected in tissues of 13 of 21 (62 per cent) spontaneously affected animals from 2 to 4 years of age or older, but were not found in 16 unaffected deer of from a few months to 12 years of age.
J Wildl Dis 1980 Jan;16(1):89-98 Williams ES, Young SIn the past 12 years (1967-79) a syndrome we identify as chronic wasting disease has been observed in 53 mule deer (Odocoileus hemionus hemionus) and one black-tailed deer (Odocoileus hemionus columbianus) held in captivity in several wildlife facilities in Colorado and more recently in Wyoming. Clinical signs were seen in adult deer and included behavioral alterations, progressive weight loss and death in 2 weeks to 8 months. Gross necropsy findings included emaciation and excess rumen fluid admixed with sand and gravel. Consistent histopathologic change was limited to the central nervous system and characterized by widespread spongiform transformation of the neuropil, single of multiple intracytoplasmic vacuoles in neuronal perikaryons and intense astrocytic hypertrophy and hyperplasia. Presented is a clinical characterization of chronic wasting disease and pathologic evidence supporting the conclusion that the disease is a specific spontaneously occurring form of spongiform encephalopathy.
Utah Fish and Game DeptThe state of Utah has little experience with big game farming. In an effort to understand elk and game farming, the Division has contacted other states that allow elk farming. The following are some of the problems other states associate with elk farming reported to the Division:
In a public hearing, the public voted against game farms in the state of Wyoming. Wyoming's Cattlemen's Association and Department of Agriculture opposed elk and big game farms, as well, particularly due to disease risks. Brucellosis is a major problem for wildlife and livestock in the Yellowstone Basin.
The Colorado Elk Breeders Association (CEBA) told the Division that CEBA did not approve of elk poaching and has turned in fellow elk farmers for poaching live elk calves from the wild.
CEBA told Utah legislators that the Colorado Division of Wildlife did not like elk ranching at first, but has come to see that elk farming is not as bad as they originally thought it would be. The Colorado Division of Wildlife disagreed with CEBA's perception of their relationship.
By STEVE THOMPSON Missoula Independent, also the Whitefish Pilot 13 Sep 1998 Ph: 406/862-3795 Fax: 406/862-5344"Although not everyone sees it the same way, Kalispell legislator Bob Spoklie says his controversial plan to develop an elk shooting gallery on 160 acres near Whitefish is rooted in the richest of Montana traditions-private property, pleasure and profit. Flaring like a bull elk in rut, Spoklie rages against those who disagree with his intentions. "These are not public wildlife," Spoklie told me angrily. "These are our animals and not anyone else's. We'll do as we please."
If his political opponents succeed in banning canned elk hunts, Spoklie warns, the next step will be to eliminate all public hunting. "That's the real agenda here," he said.
By contrast, next door in Wyoming, the suggestion that Rocky Mountain elk can be penned, hand-fed and then shot is more than a disgusting notion. It's illegal. In fact, the Cowboy State has gone so far as to prohibit all private game farms. Utah also prohibits canned elk hunts. Listening to Spoklie, one might be convinced that Utah and Wyoming are governed by a bunch of socialist, animal-rights activists. But the truth is those states are hardly run by left-wing zealots. Rather, lawmakers there have chosen to honor a Western tradition as deeply rooted as Spoklie's rather crass libertarianism.
This conservation heritage was pioneered by Theodore Roosevelt and others who established wildlife as a public commons. Wildlife laws in those states seek to protect hunters' fair-chase pursuit of healthy, free-ranging game. According to Dick Sadler, a long-time Democratic legislator in Wyoming now retired, elk hunting farms violate the very spirit of the West. In the 1970s, he joined forces with Republican John Turner to pass landmark legislation which banned game farms. Sadler and Turner had researched game farms in other states, and they came away with a bitter taste.
Spoklie, however, says elk and other big game have been converted to private livestock around the world. "Montana is so far behind that we think we're leading," he says. As the founder of the Montana Alternative Livestock Association, Spoklie is clearly frustrated about the clamor surrounding his attempts to domesticate elk in Whitefish. But then he has been one of the chief lobbyists for the game farm industry. Due in large part to his influence, Montana legislators have resisted attempts to copy Wyoming's game farm ban, including former Florence Senator Terry Klampe's proposed moratorium in 1995.
But Sadler, a lifelong hunter, offers the following evidence for what's wrong with canned hunting: "I saw a film of one of those canned hunts in Michigan, where the guys get up and have a big breakfast, put on their hunting clothes, walk outside, shoot the animals in an enclosure and then congratulate themselves. "That was one of the most disgusting things I've ever seen."
As the proposal to ban game farms wound through the Wyoming legislature, though, Sadler focused on more pragmatic arguments. Today, he still complains about the threat of disease transmission to wild animals, genetic pollution and loss of habitat to enclosures.
It was the Republican Turner, who later became George Bush's Fish and Wildlife Service director, who invoked the West's sporting heritage. "Turner's argument to the legislature was that you can't take a magnificent animal like an elk and allow some slob to shoot it inside a fence," Sadler says. Ultimately, most Wyoming legislators agreed that it just wasn't proper to domesticate and commercialize a wild animal like elk.
To Spoklie's dismay, the debate locally is getting louder, and his loudest opponents are sportsmen. Making the biggest waves are the Montana Wildlife Federation, the Rocky Mountain Elk Foundation, Orion: The Hunter's Institute, and a coalition of neighbors and hunters in the Whitefish area.
Orion's founder Jim Posewitz, a retired wildlife biologist, says canned hunts jeopardize public acceptance of the real thing. A leading advocate of "fair chase" hunting, which emphasizes the almost sacred relationship between hunter and prey, Posewitz argues that the majority of non-hunting Americans will tolerate hunting only if it is conducted with the highest ethics. "Game farms are an abomination," he says.
Spoklie, an appointed lawmaker who recently lost the Republican primary election, dismisses such statements as "differences of philosophy" that don't stack up against private property rights. If someone's willing to pay thousands of dollars to shoot a penned elk, then that's good both for him and Montana's economy, he says.
Karen Zackheim, game farm coordinator for the state Department of Fish, Wildlife and Parks, says the issue goes beyond philosophy. The most pressing statewide concern, she says, is chronic wasting, an elk version of mad cow disease. The little known disease, for which there is neither a test nor a cure, recently killed captive elk in several Western states and has spread to wild game in some places. Zackheim also has identified other potential problems with the Spoklie elk farm.
Spoklie makes it clear that Zackheim and others should butt out. And some Montana lawmakers seem willing to listen to him, having recently stripped state wildlife officials of some oversight responsibilities. Now, Spoklie would prefer even less state oversight, including his permit application currently under review.
For Montanans, ultimately, the choice looms between the competing visions offered by Bob Spoklie and our Western neighbors. Montana lawmakers should follow Wyoming's lead and remove our wildlife heritage from the private marketplace. For the sake of both the hunter and the hunted, private elk farms should be banned."
Private and public concern over the possible negative effects of sheep and sheep grazing on wild reindeer is not new; there has been competition for access to grazing resources/hunting for years. Since it is difficult on this particular range to argue that sheep "out-graze" reindeer, other possibilities such as disease/parasite transmission (from sheep to reindeer) have been advanced. When reports of scrapie among flocks of sheep which graze sympatrically with reindeer surfaced in 1994, concern for the reindeer was again voiced.
Last year, after a short review of existing literature, we concluded that there "seemed to be" a sufficient species barrier between sheep and reindeer, such that contraction of chronic wasting disease by the latter was unlikely. Inter-species transmission of prion diseases is apparently possible only through ingestion of infected tissue, especially brain/nerve tissue, which would not (likely) occur on the open range. This seems to be the concenses among reseachers working on CWD in the US. There is apparently no corelation between the occurence of CWD and sheep grazing. (Based on work in Colorado and Wyoming)
We found scrapie and the other prion disease so interesting that we wrote a popular account/description of scrapie and prions for the Norwegian Sheep and Goat Association's magazine. This article, written in Norwegian, appeared in February before the latest events in England. Since then, we have been inundated, locally, by requests for more information.
We still maintain that in an open range situation the chances of reindeer contracting CWD due to scrapie-infected sheep are, at best, remote. (Once scrapie is diagnosed, the flock is destroyed and no longer grazes on the open range. Uncertainty arises due to the long incubation times associated with prion diseases.) Our interest was, and remains, in the range management/ecolgy aspects of livestock/reindeer interactions; we are neither pathologists or veterinarians. We are currently following the debate here in Europe on BSE/CJD with great interest, however. Various theories circulate from week to week. Of greatest interest to us (and many others) is the question of the species barrier, and its role/function in extensive grazing situations.'