Possible Origins of Chronic Wasting Disease

Evidence related to the origination of chronic wasting at a Fort Collins, Colorado, research facility where deer were apparently penned near sheep which may have had with scrapie, a related disease

... A state Division of Wildlife biologist believes a nutritional study he conducted with deer, sheep and goats in the late 1960s might have been the genesis of chronic wasting disease. Gene Schoonveld suspects some of the sheep in his study had scrapie, a relative of chronic wasting disease. Some of the deer might have become infected with scrapie, which then mutated into CWD and spread to other deer... he said if the sheep had scrapie, it might have “jumped” from the sheep and mutated in deer as CWD. The deer and sheep were penned together from 1968 to 1971 ...
    [in the article Schoonveld notes that the sheep came from a scrapie project but didn't show signs of the disease at the time ... some does in the project were captured from the wild and released when the research project was over] ...

Transmission of scrapie and sheep-passaged bovine spongiform encephalopathy prions to transgenic mice expressing elk prion protein.  The Journal of General Virology, 04 Mar 2009, 90(Pt 4):1035-1047  DOI: 10.1099/vir.0.007500-0 
...  scrapie occurs relatively frequently: at least 1117 cases were diagnosed between 1947 and 1992 and, since the start of the regulatory scrapie slaughter surveillance programme in the USA in 2003, 359 scrapie cases from among 168 593 screened animals have been reported (USDA, 2008; Wineland et al., 1998)... Considering that some sheep or sheep-passaged prion strains can be transmitted to Tg(ElkPrP) mice, it is surprising that CWD cases have not been reported elsewhere in the world where cervids and scrapie-infected sheep coexist...
 
... The first cases of classic "chronic wasting" appeared in the late 1960's in captive wild deer held in interchangeable deer research facilities operated by Colorado State University (CSU) and the Colorado Division of Wildlife (CDOW) at Ft Collins, Larimer County, Colorado. Wild deer cases were not observed until the late 1970's and then only with in a 50-kilometers (usually within a 5-km radius) of the research facilities even though sampling occurred outside that radius...

Fire May Be the Only Remedy for a Plague Killing Deer and Elk June 26, 2017 Chronic Wasting Disease, New York Times
 ... Scientists long suspected that deer and related species developed chronic wasting disease by picking up scrapie from sheep flocks kept at Colorado State University. The disease then turned up in other states and Canada as animals were shipped to private game farms... [this article also refers to the Norway outbreak, which is also suspected as resulting from transporting deer or parts, the Dr. Zabel works at Colorado State] ...

Chronic wasting disease implications for humans are alarming December 17, 2017 Wisconsin, Madison.com
 ... a captive herd of ungulates with CWD had been killed in Colorado. The land had been burned, tilled, poisoned and left fallow for years. When a new herd was put into the enclosure, they contracted CWD from the land...

... included in the comments for this article:   "Professor Adriano Aguzzi, an expert on Chronic Wasting Recently made this comment in a Facebook discussion about the disease:  ''it pains me to no end to even comtemplate the possibility, but it seems entirely plausible that CWD originated from scientist-made spread of scrapie from sheep to deer in the colorado research facility. If true, a terrible burden for those involved.'' 

Chronic wasting disease linked to Fort Collins for 50 years August 23, 2018 Colorado, The Coloradoan
... he was conducting experiments on mule deer in those pens to help them survive starvation during harsh winters ... about a dozen mule deer were brought in from various areas of Colorado... the deer might have already been infected... the disease might have crossed species. CSU was conducting scrapie research on domestic sheep and the sheep and deer were together in pens at times... [Gene Schoonveld, retired Colorado Division of Wildlife senior wildlife biologist] ...

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

Disease Threatening Deer Population Has Spread to 26 States February 7, 2019 By Cameron McWhirter, WSJ.com
... Early on, every case of CWD could be traced back to ... the Front Range experimental station in Fort Collins... Infected subjects were unwittingly sent to other states and then released into wild populations. Although it was accidental, it is still noteworthy that wildlife agencies tasked to protect deer unleashed the worst deer epidemic in history...

Minnesota needs to fight CWD January 15, 2017 La Crosse Tribune
... CWD most likely originated from sheep scrapies in a Colorado research facility in the late 1960s. Intentional and unintentional movement of CWD-infected animals has distributed the disease and it was found in Wisconsin in 2002...

Chronic wasting disease linked to Fort Collins for 50 years August 30, 2018 The Coloradan
When the disease was discovered, he was conducting experiments on mule deer in those pens to help them survive starvation during harsh winters. He said about a dozen mule deer were brought in from various areas of Colorado. He believes the deer might have already been infected... CSU was conducting scrapie research on domestic sheep and the sheep and deer were together in pens at times...


Transmission of scrapie and sheep-passaged bovine spongiform encephalopathy prions to transgenic mice expressing elk prion protein.  The Journal of General Virology, 04 Mar 2009, 90(Pt 4):1035-1047  DOI: 10.1099/vir.0.007500-0 
...  scrapie occurs relatively frequently: at least 1117 cases were diagnosed between 1947 and 1992 and, since the start of the regulatory scrapie slaughter surveillance programme in the USA in 2003, 359 scrapie cases from among 168 593 screened animals have been reported (USDA, 2008; Wineland et al., 1998)... Considering that some sheep or sheep-passaged prion strains can be transmitted to Tg(ElkPrP) mice, it is surprising that CWD cases have not been reported elsewhere in the world where cervids and scrapie-infected sheep coexist...

The Challenge of CWD: Insidious and Dire  2017 Living Legacy White Paper Series, Alliance for Public Wildlife
... By 2005, based on extensive documentation of presence (or absence), growth, spread, and persistence, it had become clear that CWD could not possibly be
a longstanding disease of North American deer ... Leading experts Beth Williams, Tom Thorne, and Michael
Miller postulated that: “It is possible, though never proven, that deer came into contact with scrapie infected sheep either on shared pastures or in captivity somewhere along the front range of the Rocky Mountains...

CWD Part One  Boone and Crocket Club  
... the widely held belief that all CWD occurrences can be traced back to a single Colorado research facility has precluded wildlife and animal health professionals from considering that some outbreaks may be arising from unrecognized exposure events that occur repeatedly over time...

Montana's game farm industry| An indictment for abolishment  2001 Gary R. Holmquist, The University of Montana
... the Colorado Division of Wildlife set out plans to depopulate the core mule deer herds around the Ft. Collins Research facility by more than 40% during the year 2000 big game hunting season. Despite these occurrences in wild populations, there is ample evidence that CWD is appearing much more frequently in facilities where animals that are confined to small areas, such as game farms and not in the wild... (page 59)

Cousin to mad-cow disease hits deer, elk March 16, 1998 High Country News
... "That's how scrapie got spread around," says Pringle, who operates the Mad Cow Disease home page for the Sperling Foundation. "They brought in (infected) Suffolk sheep from England (in the 1940s). They were buying and selling them all over, then pretty soon you have it in 39 states."...

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