Sunday, March 30, 2014

Chronic Wasting Disease Agents in Nonhuman Primates

Volume 20, Number 5—May 2014
Chronic Wasting Disease Agents in Nonhuman Primates
Brent RaceComments to Author , Kimberly D. Meade-White, Katie Phillips, James Striebel, Richard Race, and Bruce Chesebro
Author affiliations: National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
Chronic wasting disease is a prion disease of cervids. Assessment of its zoonotic potential is critical. To evaluate primate susceptibility, we tested monkeys from 2 genera. We found that 100% of intracerebrally inoculated and 92% of orally inoculated squirrel monkeys were susceptible, but cynomolgus macaques were not, suggesting possible low risk for humans.
The Study
Squirrel monkeys were inoculated intracerebrally or orally with CWD inocula (7). We initially reported that 11/13 intracerebrally infected monkeys died of CWD at 41 months postinoculation (mpi) on average, and disease developed in 2/12 orally infected squirrel monkeys on average of 69 mpi (7). Disease developed in the 2 remaining intracerebrally infected squirrel monkeys at 61 and 75 mpi, respectively, changing the intracerebral attack rate to 100% (Figure 1, Table 1). Of the 10 remaining orally inoculated squirrel monkeys, disease developed in 9, bringing the overall oral attack rate to 92% and the average incubation period to 68 mpi (Figure 1, Table 1). Clinical signs were subtle; the most prominent finding was gradual weight loss (Table 1). A final diagnosis of CWD agent infection was made by using immunoblotting and immunohistochemical testing to determine accumulation of abnormal, disease-associated prion protein (PrPres) in brain tissue ( Adobe PDF file [PDF - 52 KB - 4 pages]).
To compare the neuropathologic changes in intracerebrally and orally infected squirrel monkeys, we analyzed 10 brain regions for spongiform lesion severity and PrPres deposition (Figure 1, panels B, C). No statistically significant differences were noted between the 2 routes of infection (p<0 .05="" 1="" 2="" 30="" 40="" 46="" 60="" adjacent="" affected="" agent="" aggregates.="" all="" and="" appeared="" appendix="" areas="" at="" brain.="" cerebellum="" commonly="" consistent="" cortical="" cwd="" d="" degeneration="" dense="" deposition="" deposits="" div="" e="" except="" extracellular="" f="" for="" forms:="" frequently="" frontal="" g="" generally="" gray="" h="" had="" igure="" in="" infected="" intracerebrally="" involvement="" j="" least="" lesions="" less="" little="" lobes="" lymph="" matter="" monkeys="" most="" node="" normal="" not="" observed="" occipital="" of="" orally="" panel="" parietal="" pericellular="" plaques="" positive="" prominent="" prpres="" punctate="" regions="" severe="" showed="" spleens="" spongiform="" squirrel="" striatum="" studied="" technical="" temporal="" that="" the="" throughout="" to="" vacuolation.="" was="" were="">
Of the squirrel monkeys under study, 3 PRNP genotypes were represented (7). In the group of orally infected squirrel monkeys, 3 had a unique heterozygous genotype that encoded either 4 or 5 octapeptide repeats. Two of these monkeys were the last orally infected monkeys to be euthanized because of clinical disease (80 and 107 mpi), and the third heterozygote was clinically normal at 108 mpi. Heterozygosity within the PRNP gene has been shown to delay or prevent prion disease (8) and may play a role in this study.
We inoculated cynomolgus macaques as another nonhuman primate model for cross-species transmission of CWD. Compared with squirrel monkeys, cynomolgus macaques are biologically closer to humans, and cynomolgus macaque PrP is more homologous to human PrP (7). Nine cynomolgus macaques were inoculated orally and 6 were inoculated intracerebrally with 1 of 3 CWD pools as described (7). Our first report included negative data from 1 cynomolgus macaque euthanized at 49 mpi (7). Since then, we have euthanized and screened 6 cynomolgus macaques for TSE (Table 2). No evidence of prion infection was detected by immunoblot and immunohistochemical methods (data not shown).
The lack of CWD transmission during >10 years suggests that a substantial species barrier exists between cervids and cynomolgus macaques. In most TSE animal models, PrPres can be detected by 1/3–1/2 of the known incubation periods. If we extrapolate this to the cynomolgus macaques in this study, negative test results at 9 years would suggest that the incubation period would be >18 years. Other prion studies of cynomolgus macaques reported clinical disease within 2–3 years after inoculation with variant Creutzfeldt-Jakob disease agents (9), 3 years after inoculation with bovine spongiform encephalopathy agents (10,11), and 5 years after inoculation with sporadic Creutzfeldt-Jakob disease agents (9,12). In contrast, our findings indicate that CWD is unlikely to develop in cynomolgus macaques.
The cause of susceptibility to CWD agents in squirrel monkeys and resistance to them in cynomolgus macaques is uncertain. Prnp/PRNP gene sequence variation has been linked to disease susceptibility (8), and differences in the PRNP genes of cynomolgus macaques and the genes of squirrel monkeys could play a major role. Comparison of PRNP sequences among cynomolgus macaques and squirrel monkeys showed differences exist at 5 codons (56, 100, 108, 159, and 182) (7). It is not clear which difference or combination of changes might confer protection to cynomolgus macaques, or if resistance is caused by other factors. Of the 5 codon differences described above, those of cynomolgus macaques and humans are identical at positions 56, 159, and 182.
Two SM-CWD brain samples were inoculated into squirrel monkeys and cynomolgus macaques to verify that SM-CWD was infectious, test for further adaptation, and to see if SM-CWD was infectious to a broader range of nonhuman primates. Two squirrel monkeys inoculated intracerebrally with SM-CWD brain homogenates (SMP2-CWD) died as a result of infection at 23–24 mpi (Table 1). These incubation periods decreased by >11 months compared with that of the donor squirrel monkey. Neurologic signs in the 2 SMP2-CWD were more pronounced than observed during the first passage; however, weight loss was reduced. Neuropathologic examination and Western blot for PrPres confirmed TSE in both squirrel monkeys. In contrast to SM-CWD infections, the SMP2-CWD-infected brains had spongiform lesions and PrPres deposition in the occipital lobe (Figure 2, panels A, B). Biochemical comparison of glycoform patterns among CWD, SM-CWD, and SMP2-CWD were made by using 3 different anti-PrP antibodies (L42, 6H4, and 3F4) (Technical Appendix Adobe PDF file [PDF - 52 KB - 4 pages]). In all cases, SM2-CWD had a greater proportion of unglycosylated PrPres and a lower proportion of double glycosylated PrPres than did SM-CWD (Figure 2, panel C). The decreased time of manifestation of disease, differences in glycoform patterns, and distribution of PrPres in brain tissue suggested that the CWD agent was still adapting within the squirrel monkey. However, similar to CWD, SM-CWD had not caused prion disease in cynomolgus macaques by 72 mpi (Table 2).
Our studies have shown that squirrel monkeys, but not cynomolgus macaques, were susceptible to CWD. Although these nonhuman primates are not exact models of human susceptibility, they support the data from transgenic mouse studies (3–6), in vitro experiments (13), and epidemiologic evidence (14,15) that suggest humans are at a low risk of contracting CWD. Nevertheless, it remains sensible to minimize exposure to tissues potentially contaminated with the CWD agent.
Dr Race is a staff scientist in the Laboratory of Persistent Viral Diseases, National Institute of Allergy and Infectious Diseases. His research interests are infectious diseases of humans and animals.
We thank Byron Caughey, Kim Hasenkrug, and James Carroll for critical review of the manuscript; Nancy Kurtz, Lori Lubke, and Dan Long for assistance with histology preparation; Don Gardner and Dana Scott for necropsy assistance and lesion interpretation; Ed Schreckendgust, Rocky Rivera, Michael Wagner, Leslie Trail, and Richard Cole for animal husbandry; Michael Parnell, Douglas Brining, and RMVB staff for assistance with nonhuman primate inoculations and health care; and Mike Miller, Terry Kreeger, Jean Jewell, and Lynn Creekmore for CWD-agent positive and negative cervid tissues. This research was supported by the Intramural Research Program of the NIH, NIAID.
snip... see full text ;

why do we not want to do TSE transmission studies on chimpanzees $

5. A positive result from a chimpanzee challenged severly would likely create alarm in some circles even if the result could not be interpreted for man. I have a view that all these agents could be transmitted provided a large enough dose by appropriate routes was given and the animals kept long enough. Until the mechanisms of the species barrier are more clearly understood it might be best to retain that hypothesis.



1: J Infect Dis 1980 Aug;142(2):205-8

Oral transmission of kuru, Creutzfeldt-Jakob disease, and scrapie to nonhuman primates.

Gibbs CJ Jr, Amyx HL, Bacote A, Masters CL, Gajdusek DC.

Kuru and Creutzfeldt-Jakob disease of humans and scrapie disease of sheep and goats were transmitted to squirrel monkeys (Saimiri sciureus) that were exposed to the infectious agents only by their nonforced consumption of known infectious tissues. The asymptomatic incubation period in the one monkey exposed to the virus of kuru was 36 months; that in the two monkeys exposed to the virus of Creutzfeldt-Jakob disease was 23 and 27 months, respectively; and that in the two monkeys exposed to the virus of scrapie was 25 and 32 months, respectively. Careful physical examination of the buccal cavities of all of the monkeys failed to reveal signs or oral lesions. One additional monkey similarly exposed to kuru has remained asymptomatic during the 39 months that it has been under observation.


The successful transmission of kuru, Creutzfeldt-Jakob disease, and scrapie by natural feeding to squirrel monkeys that we have reported provides further grounds for concern that scrapie-infected meat may occasionally give rise in humans to Creutzfeldt-Jakob disease. PMID: 6997404
*** The potential impact of prion diseases on human health was greatly magnified by the recognition that interspecies transfer of BSE to humans by beef ingestion resulted in vCJD. While changes in animal feed constituents and slaughter practices appear to have curtailed vCJD, there is concern that CWD of free-ranging deer and elk in the U.S. might also cross the species barrier. Thus, consuming venison could be a source of human prion disease. Whether BSE and CWD represent interspecies scrapie transfer or are newly arisen prion diseases is unknown. Therefore, the possibility of transmission of prion disease through other food animals cannot be ruled out. There is evidence that vCJD can be transmitted through blood transfusion. There is likely a pool of unknown size of asymptomatic individuals infected with vCJD, and there may be asymptomatic individuals infected with the CWD equivalent. These circumstances represent a potential threat to blood, blood products, and plasma supplies.
The chances of a person or domestic animal contracting CWD are “extremely remote,” Richards said. The possibility can’t be ruled out, however. “One could look at it like a game of chance,” he explained. “The odds (of infection) increase over time because of repeated exposure. That’s one of the downsides of having CWD in free-ranging herds: We’ve got this infectious agent out there that we can never say never to in terms of (infecting) people and domestic livestock.”
Chad Johnson1, Judd Aiken2,3,4 and Debbie McKenzie4,5 1 Department of Comparative Biosciences, University of Wisconsin, Madison WI, USA 53706 2 Department of Agriculture, Food and Nutritional Sciences, 3 Alberta Veterinary Research Institute, 4.Center for Prions and Protein Folding Diseases, 5 Department of Biological Sciences, University of Alberta, Edmonton AB, Canada T6G 2P5
The identification and characterization of prion strains is increasingly important for the diagnosis and biological definition of these infectious pathogens. Although well-established in scrapie and, more recently, in BSE, comparatively little is known about the possibility of prion strains in chronic wasting disease (CWD), a disease affecting free ranging and captive cervids, primarily in North America. We have identified prion protein variants in the white-tailed deer population and demonstrated that Prnp genotype affects the susceptibility/disease progression of white-tailed deer to CWD agent. The existence of cervid prion protein variants raises the likelihood of distinct CWD strains. Small rodent models are a useful means of identifying prion strains. We intracerebrally inoculated hamsters with brain homogenates and phosphotungstate concentrated preparations from CWD positive hunter-harvested (Wisconsin CWD endemic area) and experimentally infected deer of known Prnp genotypes. These transmission studies resulted in clinical presentation in primary passage of concentrated CWD prions. Subclinical infection was established with the other primary passages based on the detection of PrPCWD in the brains of hamsters and the successful disease transmission upon second passage. Second and third passage data, when compared to transmission studies using different CWD inocula (Raymond et al., 2007) indicate that the CWD agent present in the Wisconsin white-tailed deer population is different than the strain(s) present in elk, mule-deer and white-tailed deer from the western United States endemic region.
Prion Transmission from Cervids to Humans is Strain-dependent
Qingzhong Kong, Shenghai Huang,*Fusong Chen, Michael Payne, Pierluigi Gambetti and Liuting Qing Department of Pathology; Case western Reserve University; Cleveland, OH USA *Current address: Nursing Informatics; Memorial Sloan-Kettering Cancer Center; New York, NY USA
Key words: CWD, strain, human transmission
Chronic wasting disease (CWD) is a widespread prion disease in cervids (deer and elk) in North America where significant human exposure to CWD is likely and zoonotic transmission of CWD is a concern. Current evidence indicates a strong barrier for transmission of the classical CWD strain to humans with the PrP-129MM genotype. A few recent reports suggest the presence of two or more CWD strains. What remain unknown is whether individuals with the PrP-129VV/MV genotypes are also resistant to the classical CWD strain and whether humans are resistant to all natural or adapted cervid prion strains.
*** Here we report that a human prion strain that had adopted the cervid prion protein (PrP) sequence through passage in cervidized transgenic mice efficiently infected transgenic mice expressing human PrP,
*** indicating that the species barrier from cervid to humans is prion strain-dependent and humans can be vulnerable to novel cervid prion strains.
Preliminary results on CWD transmission in transgenic mice expressing human PrP-129V will also be discussed.
Acknowledgement Supported by NINDS NS052319 and NIA AG14359.
Generation of a Novel form of Human PrPSc by Inter-species Transmission of Cervid Prions
Marcelo A. Barria,1 Glenn C. Telling,2 Pierluigi Gambetti,3 James A. Mastrianni4 and Claudio Soto1 1Mitchell Center for Alzheimer's disease and related Brain disorders; Dept of Neurology; University of Texas Houston Medical School; Houston, TX USA; 2Dept of Microbiology, Immunology & Molecular Genetics and Neurology; Sanders Brown Center on Aging; University of Kentucky Medical Center; Lexington, KY USA; 3Institute of Pathology; Case western Reserve University; Cleveland, OH USA; 4Dept of Neurology; University of Chicago; Chicago, IL USA
Prion diseases are infectious neurodegenerative disorders affecting humans and animals that result from the conversion of normal prion protein (PrPC) into the misfolded and infectious prion (PrPSc). Chronic wasting disease (CWD) of cervids is a prion disorder of increasing prevalence within the United States that affects a large population of wild and captive deer and elk. CWD is highly contagious and its origin, mechanism of transmission and exact prevalence are currently unclear. The risk of transmission of CWD to humans is unknown. Defining that risk is of utmost importance, considering that people have been infected by animal prions, resulting in new fatal diseases. To study the possibility that human PrPC can be converted into the infectious form by CWD PrPSc we performed experiments using the Protein Misfolding Cyclic Amplification (PMCA) technique, which mimic in vitro the process of prion replication. Our results show that cervid PrPSc can induce the pathological conversion of human PrPC, but only after the CWD prion strain has been stabilized by successive passages in vitro or in vivo. Interestingly, this newly generated human PrPSc exhibits a distinct biochemical pattern that differs from any of the currently known forms of human PrPSc, indicating that it corresponds to a novel human prion strain.
*** Our findings suggest that CWD prions have the capability to infect humans, and that this ability depends on CWD strain adaptation, implying that the risk for human health progressively increases with the spread of CWD among cervids.
Biochemical and Biophysical Characterization of Different CWD Isolates
Martin L. Daus and Michael Beekes Robert Koch Institute; Berlin, Germany
Key words: CWD, strains, FT-IR, AFM
Chronic wasting disease (CWD) is one of three naturally occurring forms of prion disease. The other two are Creutzfeldt-Jakob disease in humans and scrapie in sheep. CWD is contagious and affects captive as well as free ranging cervids. As long as there is no definite answer of whether CWD can breach the species barrier to humans precautionary measures especially for the protection of consumers need to be considered. In principle, different strains of CWD may be associated with different risks of transmission to humans. Sophisticated strain differentiation as accomplished for other prion diseases has not yet been established for CWD. However, several different findings indicate that there exists more than one strain of CWD agent in cervids. We have analysed a set of CWD isolates from white-tailed deer and could detect at least two biochemically different forms of disease-associated prion protein PrPTSE. Limited proteolysis with different concentrations of proteinase K and/or after exposure of PrPTSE to different pH-values or concentrations of Guanidinium hydrochloride resulted in distinct isolate-specific digestion patterns. Our CWD isolates were also examined in protein misfolding cyclic amplification studies. This showed different conversion activities for those isolates that had displayed significantly different sensitivities to limited proteolysis by PK in the biochemical experiments described above. We further applied Fourier transform infrared spectroscopy in combination with atomic force microscopy. This confirmed structural differences in the PrPTSE of at least two disinct CWD isolates.
*** The data presented here substantiate and expand previous reports on the existence of different CWD strains.
Wednesday, September 08, 2010
Pathological Prion Protein (PrPTSE) in Skeletal Muscles of Farmed and Free Ranging White-Tailed Deer Infected with Chronic Wasting Disease
Martin L. Daus,1,† Johanna Breyer,2 Katjs Wagenfuehr,1 Wiebke Wemheuer,2 Achim Thomzig,1 Walter Schulz-Schaeffer2 and Michael Beekes1 1Robert Koch Institut; P24 TSE; Berlin, Germany; 2Department of Neuropathology, Prion and Dementia Research Unit, University Medical Center Göttingen; Göttingen, Germany †Presenting author; Email:
Chronic wasting disease (CWD) is a contagious, rapidly spreading transmissible spongiform encephalopathy (TSE) occurring in cervids in North America. Despite efficient horizontal transmission of CWD among cervids natural transmission of the disease to other species has not yet been observed. Here, we report a direct biochemical demonstration of pathological prion protein PrPTSE and of PrPTSE-associated seeding activity in skeletal muscles of CWD-infected cervids. The presence of PrPTSE was detected by Western- and postfixed frozen tissue blotting, while the seeding activity of PrPTSE was revealed by protein misfolding cyclic amplification (PMCA). The concentration of PrPTSE in skeletal muscles of CWD-infected WTD was estimated to be approximately 2000- to 10000-fold lower than in brain tissue. Tissue-blot-analyses revealed that PrPTSE was located in muscle- associated nerve fascicles but not, in detectable amounts, in myocytes.
***The presence and seeding activity of PrPTSE in skeletal muscle from CWD-infected cervids suggests prevention of such tissue in the human diet as a precautionary measure for food safety, pending on further clarification of whether CWD may be transmissible to humans.
Transmissible Spongiform Encephalopathy TSE PRION update January 2, 2014
*** chronic wasting disease, there was no absolute barrier to conversion of the human prion protein.
*** Furthermore, the form of human PrPres produced in this in vitro assay when seeded with CWD, resembles that found in the most common human prion disease, namely sCJD of the MM1 subtype.
Wednesday, January 01, 2014
Molecular Barriers to Zoonotic Transmission of Prions
*** chronic wasting disease, there was no absolute barrier to conversion of the human prion protein.
*** Furthermore, the form of human PrPres produced in this in vitro assay when seeded with CWD, resembles that found in the most common human prion disease, namely sCJD of the MM1 subtype.
Sunday, August 25, 2013
HD.13: CWD infection in the spleen of humanized transgenic mice
Liuting Qing and Qingzhong Kong
Case Western Reserve University; Cleveland, OH USA
Chronic wasting disease (CWD) is a widespread prion disease in free-ranging and captive cervid species in North America, and there is evidence suggesting the existence of multiple CWD strains. The susceptibility of human CNS and peripheral organs to the various CWD prion strains remains largely unclear. Current literature suggests that the classical CWD strain is unlikely to infect human brain, but the potential for peripheral infection by CWD in humans is unknown. We detected protease-resistant PrpSc in the spleens of a few humanized transgenic mice that were intracerebrally inoculated with natural CWD isolates, but PrpSc was not detected in the brains of any of the CWD-inoculated mice. Our ongoing bioassays in humanized Tg mice indicate that intracerebral challenge with such PrpSc-positive humanized mouse spleen already led to prion disease in most animals.
***These results indicate that the CWD prion may have the potential to infect human peripheral lymphoid tissues.
Oral.15: Molecular barriers to zoonotic prion transmission: Comparison of the ability of sheep, cattle and deer prion disease isolates to convert normal human prion protein to its pathological isoform in a cell-free system
Marcelo A.Barria,1 Aru Balachandran,2 Masanori Morita,3 Tetsuyuki Kitamoto,4 Rona Barron,5 Jean Manson,5 Richard Kniqht,1 James W. lronside1 and Mark W. Head1
1National CJD Research and Surveillance Unit; Centre for Clinical Brain Sciences; School of Clinical Sciences; The University of Edinburgh; Edinburgh, UK; 2National and OIE Reference Laboratory for Scrapie and CWD; Canadian Food Inspection Agency; Ottawa Laboratory; Fallowfield. ON Canada; 3Infectious Pathogen Research Section; Central Research Laboratory; Japan Blood Products Organization; Kobe, Japan; 4Department of Neurological Science; Tohoku University Graduate School of Medicine; Sendai. Japan; 5Neurobiology Division; The Roslin Institute and R(D)SVS; University of Edinburgh; Easter Bush; Midlothian; Edinburgh, UK
Background. Bovine spongiform encephalopathy (BSE) is a known zoonotic prion disease, resulting in variant Creurzfeldt- Jakob disease (vCJD) in humans. In contrast, classical scrapie in sheep is thought to offer little or no danger to human health. However, a widening range of prion diseases have been recognized in cattle, sheep and deer. The risks posed by individual animal prion diseases to human health cannot be determined a priori and are difficult to assess empirically. The fundamemal event in prion disease pathogenesis is thought to be the seeded conversion of normal prion protein (PrPC) to its pathological isoform (PrPSc). Here we report the use of a rapid molecular conversion assay to test whether brain specimens from different animal prion diseases are capable of seeding the conversion of human PrPC ro PrPSc.
Material and Methods. Classical BSE (C-type BSE), H-type BSE, L-type BSE, classical scrapie, atypical scrapie, chronic wasting disease and vCJD brain homogenates were tested for their ability to seed conversion of human PrPC to PrPSc in protein misfolding cyclic amplification (PMCA) reactions. Newly formed human PrPSc was detected by protease digestion and western blotting using the antibody 3F4.
Results. C-type BSE and vCJD were found to efficiently convert PrPC to PrPSc. Scrapie failed to convert human PrPC to PrPSc. Of the other animal prion diseases tested only chronic wasting disease appeared to have the capability ro convert human PrPC to PrPSc. The results were consistent whether the human PrPC came from human brain, humanised transgenic mouse brain or from cultured human cells and the effect was more pronounced for PrPC with methionine at codon 129 compared with that with valine.
Conclusion. Our results show that none of the tested animal prion disease isolates are as efficient as C-type BSE and vCJD in converting human prion protein in this in vitro assay.
***However, they also show that there is no absolute barrier ro conversion of human prion protein in the case of chronic wasting disease.
Sunday, August 25, 2013
***Chronic Wasting Disease CWD risk factors, humans, domestic cats, blood, and mother to offspring transmission
Friday, November 09, 2012
*** Chronic Wasting Disease CWD in cervidae and transmission to other species
Sunday, November 11, 2012
*** Susceptibilities of Nonhuman Primates to Chronic Wasting Disease November 2012
Friday, December 14, 2012
Susceptibility Chronic Wasting Disease (CWD) in wild cervids to Humans 2005 - December 14, 2012
Saturday, March 09, 2013
Chronic Wasting Disease in Bank Voles: Characterisation of the Shortest Incubation Time Model for Prion Diseases
*** our results raise the possibility that CJD cases classified as VV1 may include cases caused by iatrogenic transmission of sCJD-MM1 prions or food-borne infection by type 1 prions from animals, e.g., chronic wasting disease prions in cervid. In fact, two CJD-VV1 patients who hunted deer or consumed venison have been reported (40, 41). The results of the present study emphasize the need for traceback studies and careful re-examination of the biochemical properties of sCJD-VV1 prions. ***
Thursday, January 2, 2014
*** CWD TSE Prion in cervids to hTGmice, Heidenhain Variant Creutzfeldt-Jacob Disease MM1 genotype, and iatrogenic CJD ??? ***
Thursday, March 20, 2014
Saturday, March 15, 2014
Potential role of soil properties in the spread of CWD in western Canada
Friday, February 08, 2013
*** Behavior of Prions in the Environment: Implications for Prion Biology
Friday, December 14, 2012
DEFRA U.K. What is the risk of Chronic Wasting Disease CWD being introduced into Great Britain? A Qualitative Risk Assessment October 2012
In the USA, under the Food and Drug Administration’s BSE Feed Regulation (21 CFR 589.2000) most material (exceptions include milk, tallow, and gelatin) from deer and elk is prohibited for use in feed for ruminant animals. With regards to feed for non-ruminant animals, under FDA law, CWD positive deer may not be used for any animal feed or feed ingredients. For elk and deer considered at high risk for CWD, the FDA recommends that these animals do not enter the animal feed system. However, this recommendation is guidance and not a requirement by law.
Animals considered at high risk for CWD include:
1) animals from areas declared to be endemic for CWD and/or to be CWD eradication zones and
2) deer and elk that at some time during the 60-month period prior to slaughter were in a captive herd that contained a CWD-positive animal.
Therefore, in the USA, materials from cervids other than CWD positive animals may be used in animal feed and feed ingredients for non-ruminants.
The amount of animal PAP that is of deer and/or elk origin imported from the USA to GB can not be determined, however, as it is not specified in TRACES. It may constitute a small percentage of the 8412 kilos of non-fish origin processed animal proteins that were imported from US into GB in 2011.
Overall, therefore, it is considered there is a __greater than negligible risk___ that (nonruminant) animal feed and pet food containing deer and/or elk protein is imported into GB.
There is uncertainty associated with this estimate given the lack of data on the amount of deer and/or elk protein possibly being imported in these products.
36% in 2007 (Almberg et al., 2011). In such areas, population declines of deer of up to 30 to 50% have been observed (Almberg et al., 2011). In areas of Colorado, the prevalence can be as high as 30% (EFSA, 2011).
The clinical signs of CWD in affected adults are weight loss and behavioural changes that can span weeks or months (Williams, 2005). In addition, signs might include excessive salivation, behavioural alterations including a fixed stare and changes in interaction with other animals in the herd, and an altered stance (Williams, 2005). These signs are indistinguishable from cervids experimentally infected with bovine spongiform encephalopathy (BSE).
Given this, if CWD was to be introduced into countries with BSE such as GB, for example, infected deer populations would need to be tested to differentiate if they were infected with CWD or BSE to minimise the risk of BSE entering the human food-chain via affected venison.
The rate of transmission of CWD has been reported to be as high as 30% and can approach 100% among captive animals in endemic areas (Safar et al., 2008).
In summary, in endemic areas, there is a medium probability that the soil and surrounding environment is contaminated with CWD prions and in a bioavailable form. In rural areas where CWD has not been reported and deer are present, there is a greater than negligible risk the soil is contaminated with CWD prion.
In summary, given the volume of tourists, hunters and servicemen moving between GB and North America, the probability of at least one person travelling to/from a CWD affected area and, in doing so, contaminating their clothing, footwear and/or equipment prior to arriving in GB is greater than negligible. For deer hunters, specifically, the risk is likely to be greater given the increased contact with deer and their environment. However, there is significant uncertainty associated with these estimates.
Therefore, it is considered that farmed and park deer may have a higher probability of exposure to CWD transferred to the environment than wild deer given the restricted habitat range and higher frequency of contact with tourists and returning GB residents.
*** Spraker suggested an interesting explanation for the occurrence of CWD. The deer pens at the Foot Hills Campus were built some 30-40 years ago by a Dr. Bob Davis. At or abut that time, allegedly, some scrapie work was conducted at this site. When deer were introduced to the pens they occupied ground that had previously been occupied by sheep. ...
also, see where even decades back, the USDA had the same thought as they do today with CWD, not their problem...see page 27 below as well, where USDA stated back then, the same thing they stated in the state of Pennsylvania, not their damn business, once they escape, and they said the same thing about CWD in general back then ;
”The occurrence of CWD must be viewed against the contest of the locations in which it occurred. It was an incidental and unwelcome complication of the respective wildlife research programmes. Despite it’s subsequent recognition as a new disease of cervids, therefore justifying direct investigation, no specific research funding was forthcoming. The USDA veiwed it as a wildlife problem and consequently not their province!” 26.
”The occurrence of CWD must be viewed against the contest of the locations in which it occurred. It was an incidental and unwelcome complication of the respective wildlife research programmes. Despite it’s subsequent recognition as a new disease of cervids, therefore justifying direct investigation, no specific research funding was forthcoming. The USDA veiwed it as a wildlife problem and consequently not their province!” 26.
sound familiar $$$
Sunday, January 06, 2013
*** "it‘s no longer its business.”
Wednesday, September 04, 2013
*** cwd - cervid captive livestock escapes, loose and on the run in the wild
Singeltary submission ;
Program Standards: Chronic Wasting Disease Herd Certification Program and Interstate Movement of Farmed or Captive Deer, Elk, and Moose
*** DOCUMENT ID: APHIS-2006-0118-0411
Friday, March 28, 2014
BUCK FEVER What can happen if preserve owners make the rules
Saturday, March 29, 2014
Game Farm, CWD Concerns Rise at Boone and Crockett Club


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