Hazard identification for the risks to terrestrial animal health from the import of hay and straw, BSE, CWD, Scrapie, TSE, Prion
Independent report
Hazard identification for the risks to terrestrial animal health from the import of hay and straw
Published 8 June 2026
Contents 1. Executive summary 2. Background 3. Methodology 4. Results 5. Discussion 6. Appendices 7. Bibliography Print this page 1. Executive summary
Defra’s UK Office for Sanitary and Phytosanitary Trade Assurance (UK SPS Office) is responsible for dealing with reactive risk assessments among other requests. One recent request has been commissioned to the Animal and Plant Health Agency (APHA), asking to undertake a hazard identification (ID) for terrestrial animal health hazards in hay and straw imports from trading partners. No specific countries are listed for this request.
The aim of this project was to conduct a hazard ID to identify hazards relevant to the general risk question:
“What are the terrestrial animal health risks to Great Britain from the import of hay and straw?”
An animal health hazard was defined as a potential causative agent of disease found in hay and straw, that is, bacteria, viruses, parasites (both ectoparasites and endoparasites), fungi and prions. Vectors such as mosquitos and flies were not considered. Antimicrobial resistance, veterinary drug residues and pathogens of plants or seeds were out of scope, as were specific food safety risks and any impact to public health.
We considered the following as definitions for hay and straw:
straw is cereal straw and husks, unprepared, whether or not chopped, ground, pressed or in the form of pellets hay is swedes, mangolds, fodder roots, hay, lucerne (alfalfa), clover, sainfoin, forage kale, lupines, vetches, and similar forage products whether or not in form of pallets: other than lucerne (alfalfa) meal and pellets The hazard identification involved carrying out a short review of available information for each hazard to assess whether there was sufficient evidence to conclude that there was a negligible risk to terrestrial animal health in Great Britain from the import of hay and straw. If insufficient information was available, or there was evidence that a risk was present, then the conclusion was that the risk was non-negligible. Note that the conclusion of non-negligible risk is an indication that further investigation should be carried out, such as a full risk assessment, it is not a conclusion that there is a serious concern of entry of this pathogen to Great Britain via import of hay and straw. This hazard ID included an assessment of the data availability for contamination, survivability and transmission capabilities of each of the hazards deemed as non-negligible. A summary of the outcomes is available in Table E1. Further information for those hazards that have a low data availability level would go towards reducing uncertainty should a full risk assessment for these hazards be commissioned.
A total of 67 animal health hazards were initially identified from a number of sources including the UK notifiable disease list (APHA, 2019) and diseases (other than Notifiable Diseases) specified on Model Health Certificates for (Great Britain Imports) (APHA, 2023).
Pathogens listed in the World Organisation for Animal Health (WOAH) aquatic animal health code were removed (such as infectious haematopoietic necrosis virus). Chronic wasting disease (CWD) and classical scrapie were grouped together, as were Brucella abortus, B. melitensis and B. suis. Bovine spongiform encephalitis (BSE) was kept on its own, due to differences in transmission to CWD and classical scrapie. A total of 64 hazards were then fed through preliminary screening criteria, which included considering whether the hazards were vector-borne or incapable of indirect transmission. The UK Office was consulted to define and refine the hazards. This resulted in 32 hazards being removed at this stage, with the remaining 32 hazards taken through to a full hazard ID stage.
The full hazard ID screening criteria were as follows:
-C1 can the pathogen contaminate hay and straw?
-C2 can the pathogen survive in hay and straw?
-C3 can the pathogen directly infect animals from contaminated hay and straw?
Three hazards were classified as negligible. Peste des petites ruminant (PPR) virus (small ruminant morbillivirus) was considered negligible due to the strong evidence of inability to survive for a long time in the environment, unless in shaded conditions where it can survive for up to 72 hours (Health and Welfare, 2015) he BSE agent and Rabies virus were classed as negligible risk as the chance of contraction through hay and straw is unlikely. This is because the occurrence of contamination, survival, and transmission conditions required to cause disease are improbable as stated in literature and confirmed by expert opinion (Health and Welfare, 2015, WHO, 2010, Matouch et al., 1987, McElhinney et al., 2014).
Of the initial 32 hazards, 29 were considered to be of non-negligible risk to the UK after the hazard ID (Table E1). All of these were considered to be non-negligible due to insufficient information to rule them out as a risk. A data availability assessment was completed alongside to provide a category for each hazard. Only Anthrax, African Swine Fever and Foot and Mouth qualified for the highest category. Further consideration of these hazards is required, through commissioning a full risk assessment or consideration whether sufficient mitigation measures are already in place. Taking these hazards forward to a full risk assessment may not necessarily clarify the risk further, especially for hazards that were assessed as having a low level of data available (Table E1), however it may provide sufficient context to inform decision making based on the risk appetite at the time.
1.1 Table E1. Summary of hazards considered non-negligible after the hazard identification process.
Hazard Type Data Availability Risk
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Chronic wasting disease and classical scrapie (Chronic wasting disease prion and Classical scrapie prion) Prion Medium Non-negligible
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3. Methodology
The aim of this project was to conduct a hazard ID to identify hazards relevant to the risk question:
“What are the terrestrial animal health risks to Great Britain from imports of hay and straw?”
For this particular hazard ID, an animal health hazard was defined as a causative agent of disease, such as bacteria, viruses, parasites (both ectoparasites and endoparasites), fungi and prions. Antimicrobial resistance, veterinary drug residues and pathogens of plants or seeds were out of scope, as were specific food safety risks and any risks to public health. This is because the UK SPS Office has other sources of specific expertise in these areas. It was also determined that specific animal health concerns (those health concerns not as a direct result of a disease or pathogen) (MSDVetManual, 2022) would not be considered at this stage, unless they were directly related to the risk of import of the hazard, but would be a factor in the final decision of whether to allow the import.
The following sources were used to create a preliminary list of terrestrial animal health hazards:
UK notifiable disease list (APHA, 2019) diseases (other than notifiable diseases) specified on Model Health Certificates (Great Britain Imports) (APHA, 2023) From this preliminary list of pathogens, those listed in the WOAH Aquatic Animal Health Code (WOAH, 2023a) were removed (such as infectious haematopoietic necrosis virus, due to being out of the scope. Chronic wasting disease (CWD) and classical scrapie were grouped together due to their noted similarities in survival in the environment but kept separate from bovine spongiform encephalopathy (BSE), due to their differences in transmission. Brucella abortus, B. melitensis, and B. suis were also grouped together. This provided a total of 64 hazards.
The list was then put through a pre-screening stage to identify if the hazards have any potential to be transmitted indirectly. This was intended to capture all methods of indirect transmission, prior to assessing the likelihood of whether the hazard may, or may not, be present in hay and straw. For the purposes of this hazard ID, vector transmission was considered out of scope. While not specifically considered here, we note that for any final decisions it will be important to consider whether the vectors have a specific association with hay and straw. In the event of full risk assessment, the effect of dust and humidity levels on survivability of hazards should also be taken into consideration.
The remaining 32 hazards were then put through the full screening hazard ID decision tree using the following criteria:
C1 can the pathogen contaminate hay and straw?
Whilst completing the hazard ID process, we assess the potential a hazard may have to contaminate hay and straw either via faeces, respiratory droplets, nasal secretions or via systemic infection in wild birds and or mammals C2 can the pathogen survive in hay and straw?
The survivability of biological organisms varies outside the host organism. Where specific information in scientific publications was available it was used to decide if survival was possible. Where such information was not found, decisions were based on extrapolation of general knowledge of the hazards ability to survive in environmental conditions. In literature, such classifications were often related to similar and or related pathogens C3 can the pathogen infect animals from contaminated hay and straw?
Hazards may be transmitted between susceptible hosts in different ways. We have excluded hazards associated with direct and vector-borne transmission in the preliminary criteria, retaining only the mode of indirect transmission for consideration. This includes spread via airborne droplets, contaminated fomites, food and drinking water, and environmental factors (for example: soil, water, and plants) Hazards can be considered of negligible risk to Great Britain at this stage, such that no further consideration is necessary, if it can be concluded that the act of importing hay and straw will not lead to a change in the Great Britain animal (meaning vertebrate animals) health status with respect to that hazard, in accordance with the criteria listed in the relevant disease-specific chapter or Chapter 1.4. of the WOAH Terrestrial Code (WOAH, 2023b). This will be the case if, after an exhaustive search, they do not meet the predefined criteria for classification as being of concern. Hazards of particular interest are those which can be transmitted indirectly through environmental contamination and are associated with livestock and or other terrestrial animals.
The data availability was assessed after completing a literature review for contamination, survivability, and transmission. The criteria for the assessment were based on the definitions laid out in Table 1. Using this table, the sum of the data for each hazard was awarded a rating which directly translated to a score between 1 and 3. These were then added together, producing a final score which equates to a low, medium or high level of confidence in the data availability based on the data found and origin for each hazard. Final scores of 3 or 4 translated to a low level of data availability, scores of 5,6 or 7 were medium and 8 or 9 were considered to be the highest level of data availability.
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4.3 Table 2. Negligible and non-negligible pathogens by species category.
| Hazard | Negligible risk | Non-negligible risk | Total |
|---|---|---|---|
| Bacteria | 0 | 11 | 11 |
| Fungi | 0 | 1 | 1 |
| Prions | 1 | 1 | 2 |
| Parasites | 0 | 2 | 2 |
| Viruses | 2 | 14 | 16 |
| Total | 3 | 29 | |
| Grand Total | 32 |
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4.6 Prions
Classical BSE, CWD, and classical scrapie were all considered in the full screening criteria. BSE was concluded to be negligible and Cwd and classical scrapie were considered non-negligible. All 3 prion hazards had a medium data availability level.
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4.9 Table 3. Summary of the decision-making process for the full hazard screening ID and data availability assessment. For * and ** see footnote.
Chronic Wasting Disease or Classical scrapie (Chronic wasting disease prion or Classical scrapie prion) | prion | Yes (Pritzkow, 2015, Pritzkow et al., 2021) | Yes (Miller et al., 2004) | Yes (Spickler, 2019a) (Ricci, 2017) | Non-negligible | 2+2+2=6 | Medium |
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5. Discussion
This hazard ID analysed 64 potential hazards with respect to whether they presented a non-negligible risk to terrestrial animal health in Great Britain from the imports of hay and straw. Preliminary screening removed those hazards that were vector borne or were not capable of indirect transmission. The remaining hazards were then assessed with regards to whether they were able to contaminate and survive in hay and straw and go on to infect a susceptible animal exposed to contaminated hay and straw. In total, 29 hazards were considered to be non-negligible after assessing peer reviewed literature for relevant data and after disease expert consultation, and 3 hazards were considered of negligible risk after expert review. PPR virus was considered negligible due to the evidence available on its lack of ability to survive outside of the host organism. Rabies virus and classical BSE prions were considered negligible as the concurrence of contamination, survival, and transmission conditions required to cause disease is improbable.
Finding specific data for hay and straw was difficult for a number of pathogens and so proxy data had to be used, such as survival on other media or the survivability of other pathogens considered biologically similar. As such, the data availability for each criterion and hazard was assessed and given a score of low, medium or high indicating whether the data were directly relevant to hay and straw or whether proxy data had been used. Overall, 3 hazards (Anthrax, ASF and FMD) had a high level of data availability reflecting either experimental or real-life data demonstrating that they could contaminate and survive in hay and straw and go on to transmit to other animals via contaminated hay and straw. A total of 22 hazards had a medium level of data availability, however, only 6 of these hazards had a high score for one of the criteria indicating that there was no direct evidence for hay and straw for the remaining 2 criteria. Further information for those hazards that have a low data availability level would go towards reducing uncertainty should a full risk assessment for these hazards be commissioned.
snip…6. Appendices
6.1 Appendix 1
Full list of hazards excluded from the full hazard identification, after the pre-screening phase (Total = 32).
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Classical bovine spongiform encephalitis (BSE (BSE prion):Contamination of feed, spread via consumption of meat contaminated with prion.
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Chronic wasting disease (CWD) or classical scrapie (CWD or scrapie prion): Prions contaminating environment – high capabilities of pathogen to contaminate and possibly survive in environment.
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6.5 Prions
Classical BSE, CWD, and classical scrapie were considered. BSEwas classed as negligible (see page 36) and CWD and classical scrapie was considered non-negligible.
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Chronic wasting disease and classical scrapie = Non-negligible and medium data availability
Contamination = 2
CWD prions were observed to contaminate soil; clay content affected this as well as pH, with bioavailability decreasing when under a pH of 6.6 and decreasing when clay content in soil was above 18% (Dorak et al., 2017). However, an opposite trend has also been found with clay particle size in soil increasing infectivity (David Walter et al., 2011). However, it has been observed that CWD prions have been able to remain persistent in soil for up to 3 years (Pritzkow et al., 2021).
CWD prions have also been observed to contaminate inorganic surfaces like glass, wood and metal and thuis is very likely to be able to contaminate farming equipment that could be used in the harvesting and transportation of hay and straw (Yuan et al., 2022).
While there aren’t any specific studies on hay and straw contamination, classical scrapie prions and CWD prions have been demonstrated to be absorbed by plants (wheat grass roots and leaves), via infected urine or faeces as well as other means, and have has the potential to subsequently infect animals that consume contaminated plant matter (Pritzkow, 2015).
Survival = 2
There is currently no literature accessible that describes persistence of scrapie or CWD prions on hay or straw in the environment, and limited literature on the ability of CWD prions to persist in the presence of multiple environmental factors.
In a study reviewing multiple strains of mouse and hamster-passaged scrapie strains, ionization, ultraviolet and microwave irradiation had little effect on the prions, and had practically no effect on inactivation. Heat resistance was also high, a strain of 263k hamster passaged scrapie managed to survive an hour of dry heat at 360°c (Taylor, 2000). While this study was not conducted on CWD or sheep scrapie prions directly, this level of temperature resistance is likely indicative of the ability of CWD and classical scrapie prions to persist in the environment at both temperature extremes.
Boiling a medium containing classical scrapie prion isolates for 30 minutes and inoculating mice with these also demonstrated an onset of clinical signs (Zlotnik and Rennie, 1967).
Sheep paddocks remained infectious for between 1-3 years post exposure of sheep with classical scrapie (Miller et al., 2004).
Transmission = 2
CWD prions are shed in saliva, blood, semen, urine, blood, most bodily fluids in general, nasal secretions and faeces. Oral transmission has been observed. Decomposing carcasses are also a reservoir for infection (Ricci, 2017, Nicholas J. Haley, 2015).
Potential transmission via hay mites has also been observed for scrapie, so CWD could also be a potential risk (Carp et al., 2000).
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The following hazards were identified as negligible:
Classical bovine spongiform encephalopathy = Negligible and medium data availability
Contamination = 3
No evidence of horizontal transmission. However, feed contaminated with BSE prions could in theory contaminate hay and straw, but uncertain of the pathway by which this would happen, especially given the tissues confirmed to contain BSE prions. (WHO, 2010).
Soil contamination of haylage is mentioned as a possible transmission risk in one APHA Epi Report. (APHA, 2018).
Survival = 1
No information specific to survival on hay or straw.
BSE prions remained infective in buried skulls for up to 5 years (Somerville et al., 2019).
Not enough evidence to draw accurate conclusions on survival time but estimated to be decades (Swire and Colchester, 2023).
BSE prions were detectable in urban sewage, seawater and a buffer solution for up to 265 days (C et al., 2008).
Transmission = 1
Spread via consumption of meat contaminated with prions, therefore consumption of hay containing prion contaminated feed could transmit. (Spickler, 2016).
List of materials and intermediaries capable of transmitting prion infection: Wood, Rocks, Plastic, Glass, Cement, Stainless Steel, Aluminium, Aerosols, Soil and sludge, Salt licks, Dust, Wild mammals, Birds, Invertebrates and Insects (Swire and Colchester, 2023).
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“CWD and classical scrapie were considered non-negligible.”
AI Overview
Something that is non-negligible is significant enough to matter, requiring attention or consideration rather than being dismissed as too small or unimportant.
4.3 Table 2. Negligible and non-negligible pathogens by species category.
| Hazard | Negligible risk | Non-negligible risk | Total |
|---|---|---|---|
| Bacteria | 0 | 11 | 11 |
| Fungi | 0 | 1 | 1 |
| Prions | 1 | 1 | 2 |
| Parasites | 0 | 2 | 2 |
| Viruses | 2 | 14 | 16 |
| Total | 3 | 29 | |
| Grand Total | 32 |
4.6 Prions
Classical BSE, CWD, and classical scrapie were all considered in the full screening criteria. BSE was concluded to be negligible and CWD and classical scrapie were considered non-negligible. All 3 prion hazards had a medium data availability level.
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Carrot plants as potential vectors for CWD transmission
Paulina Sotoa,b, Francisca Bravo-Risia,b, Claudio Sotoa, and Rodrigo Moralesa,b
aDepartment of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Texas, USA; bUniversidad Bernardo O’Higgins, Santiago, Chile
Prion diseases are infectious neurodegenerative disorders afflicting humans and other mammals. These diseases are generated by the misfolding of the cellular prion protein into a disease-causing isoform. Chronic wasting disease (CWD) is a prevalent prion disease affecting cervids (captive and free-range). CWD is thought to be transmitted through direct animal contact or by indirect exposure to contaminated environments. Many studies have shown that infectious prions can enter the environment through saliva, feces, or urine from infected animals and decaying carcasses. However, we do not fully understand the specific contribution of each component to disease transmission events. Plants are logical environmental components to be evaluated since they grow in environments contaminated with CWD prions and are relevant for animal and human nutrition.
Aims: The main objective of this study is to study whether prions are transported to the roots and leaves of carrots, an edible plant commonly used in the human diet and as deer bait.
Methods: We have grown carrot plants in CWD-infected soils. After 90 days, we harvested the carrots and separated them from the leaves. The experiment was controlled by growing plants in soil samples treated with brain extracts from healthy animals. These materials were interrogated for their prion seeding activity using the Protein Misfolding Cyclic Amplification (PMCA) technique. Infectivity was evaluated in mouse bioassays (intracerebral injections in Tg1536 mice). The animals were sacrificed when they showed established signs of prion disease. Animals not displaying clinical signs were sacrificed at 600 days post-inoculation.
Results: The PMCA analysis demonstrated CWD seeding activity in soils contaminated with CWD prions, as well as in carrot plants (leaves and roots) grown on them. Bioassays demonstrated that both leaves and roots contained CWD prions in sufficient quantities to induce disease (92% attack rate). As expected, animals treated with prion-infected soils developed prion disease at shorter incubation periods (and complete attack rates) compared to plant components. Animals treated with soil and plant components exposed with CWD-free brain extracts did not display prion-associated clinical signs or evidence of sub-clinical prion infection.
Conclusions: We show that edible plant components can absorb prions from CWD contaminated soils and transport them to their aerial parts. Our results indicate that plants could participate as vectors of CWD transmission. Importantly, plants designated for human consumption represent a risk of introducing CWD prions into the human food chain.
Funded by: NIH
Grant number: R01AI132695
P.157: Uptake of prions into plants
Christopher Johnson1, Christina Carlson1, Matthew Keating1,2, Nicole Gibbs1, Haeyoon Chang1, Jamie Wiepz1, and Joel Pedersen1 1USGS National Wildlife Health Center; Madison, WI USA; 2University of Wisconsin - Madison; Madison, WI USA
Soil may preserve chronic wasting disease (CWD) and scrapie infectivity in the environment, making consumption or inhalation of soil particles a plausible mechanism whereby na€ıve animals can be exposed to prions. Plants are known to absorb a variety of substances from soil, including whole proteins, yet the potential for plants to take up abnormal prion protein (PrPTSE) and preserve prion infectivity is not known. In this study, we assessed PrPTSE uptake into roots using laser scanning confocal microscopy with fluorescently tagged PrPTSE and we used serial protein misfolding cyclic amplification (sPMCA) and detect and quantify PrPTSE levels in plant aerial tissues. Fluorescence was identified in the root hairs of the model plant Arabidopsis thaliana, as well as the crop plants alfalfa (Medicago sativa), barley (Hordeum vulgare) and tomato (Solanum lycopersicum) upon exposure to tagged PrPTSE but not a tagged control preparation. Using sPMCA, we found evidence of PrPTSE in aerial tissues of A. thaliana, alfalfa and maize (Zea mays) grown in hydroponic cultures in which only roots were exposed to PrPTSE. Levels of PrPTSE in plant aerial tissues ranged from approximately 4 £ 10 ¡10 to 1 £ 10 ¡9 g PrPTSE g ¡1 plant dry weight or 2 £ 105 to 7 £ 106 intracerebral ID50 units g ¡1 plant dry weight. Both stems and leaves of A. thaliana grown in culture media containing prions are infectious when intracerebrally-injected into mice.
***Our results suggest that prions can be taken up by plants and that contaminated plants may represent a previously unrecognized risk of human, domestic species and wildlife exposure to prions.
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***Our results suggest that prions can be taken up by plants and that contaminated plants may represent a previously unrecognized risk of human, domestic species and wildlife exposure to prions.
*** SEE ; Friday, May 15, 2015 Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions Report
DISCUSSION
This study shows that plants can efficiently bind prions contained in brain extracts from diverse prion infected animals, including CWD-affected cervids. PrPSc attached to leaves and roots from wheat grass plants remains capable of seeding prion replication in vitro. Surprisingly, the small quantity of PrPSc naturally excreted in urine and feces from sick hamster or cervids was enough to efficiently contaminate plant tissue. Indeed, our results suggest that the majority of excreted PrPSc is efficiently captured by plants’ leaves and roots. Moreover, leaves can be contaminated by spraying them with a prion-containing extract, and PrPSc remains detectable in living plants for as long as the study wasperformed (several weeks). Remarkably, prion contaminated plants transmit prion disease to animals upon ingestion, producing a 100% attack rate and incubation periods not substantially longer than direct oral administration of sick brain homogenates. Finally, an unexpected but exciting result was that plants were able to uptake prions from contaminated soil and transport them to aerial parts of the plant tissue. Although it may seem farfetched that plants can uptake proteins from the soil and transport it to the parts above the ground, there are already published reports of this phenomenon (McLaren et al., 1960; Jensen and McLaren, 1960; Paungfoo-Lonhienne et al., 2008). The high resistance of prions to degradation and their ability to efficiently cross biological barriers may play a role in this process. The mechanism by which plants bind, retain, uptake, and transport prions is unknown. Weare currently studying the way in which prions interact with plants using purified, radioactively labeled PrPSc to determine specificity of the interaction, association constant, reversibility, saturation, movement, etc.
Epidemiological studies have shown numerous instances of scrapie or CWD recurrence upon reintroduction of animals on pastures previously exposed to prion-infected animals. Indeed, reappearance of scrapie has been documented following fallow periods of up to 16 years (Georgsson et al., 2006), and pastures were shown to retain infectious CWD prions for at least 2 years after exposure (Miller et al., 2004). It is likely that the environmentally mediated transmission of prion diseases depends upon the interaction of prions with diverse elements, including soil, water, environmental surfaces, various invertebrate animals, and plants. However, since plants are such an important component of the environment and also a major source of food for many animal species, including humans, our results may have far-reaching implications for animal and human health. Currently, the perception of the risk for animal-to-humanprion transmissionhas beenmostly limited to consumption or exposure to contaminated meat; our results indicate that plants might also be an important vector of transmission that needs to be considered in risk assessment.
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Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions
PRION UPDATE VIA VEGETABLE PLANTS FROM THE SOIL
56. Members considered that there is no evidence that crops grown on the land which received composted excreta from BSE-challenged animals pose a TSE risk to humans or animals. One member suggested that, as some of these animals are orally challenged with high doses of BSE-infected materials, and the distribution of infectivity in the digestive system is not completely understood, it might be premature to conclude that there is no infective agent in the manure.
Furthermore, an unpublished study had indicated low level absorption of PrP from soil by tomato plants although it should be noted that this study had not been repeated. Details of this work would be sent to the SEAC Secretary. Dr Matthews explained that most of the manure from animals challenged with high doses of BSE had already been composted and used for coppicing. Members agreed that the risks from disposal of residual manure from experimental animals would be much less than historic risks of on farm contamination from naturally infected animals at the height of the BSE epidemic. ...SNIP...END
http://www.seac.gov.uk/minutes/final91.pdf
***> GRAINS, WHEAT, HAY, STRAW, FROM COUNTRIES WITH CWD TSE ENDEMIC AREAS PRICE OF PRION POKER GOES UP$
FRIDAY, OCTOBER 18, 2019
TAHC Exotic CWD Susceptible Species Rules, Regulations, TSE PRION, WHEAT, GRAINS, HAY, STRAY, GLOBAL CONCERNS GROW, UPDATE, October 17, 2019
WEDNESDAY, OCTOBER 16, 2019
Australia Assessment of bulk wheat from Canada Part B: Animal biosecurity risk advice, CWD TSE Prion concerns are mounting
THURSDAY, OCTOBER 25, 2018
***> Norway New additional requirements for imports of hay and straw for animal feed from countries outside the EEA due to CWD TSE Prion
MONDAY, JUNE 12, 2017
Rethinking Major grain organizations opposition to CFIA's control zone approach to Chronic Wasting CWD TSE Prion Mad Deer Type Disease 2017?
FRIDAY, MAY 15, 2015
Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions Report
FRIDAY, SEPTEMBER 05, 2014
CFIA CWD and Grain Screenings due to potential risk factor of spreading via contamination of grain, oil seeds, etc.
FRIDAY, SEPTEMBER 27, 2013
Uptake of Prions into Plants
Detection of chronic wasting disease prions in soil at an illegal white-tailed deer carcass disposal site
Published online: 06 Jun 2025
Abstract
Chronic wasting disease (CWD) is a contagious prion disorder affecting cervids such as deer, elk, caribou, and moose, causing progressive and severe neurological degeneration followed by eventual death. As CWD prions (PrPSc) accumulate in the body, they are shed through excreta and secreta, as well as through decomposing carcasses. Prions can persist in the environment for years, posing significant concerns for ongoing transmission to susceptible cervids and pose an unknown risk to sympatric species. We used a validated protocol for real-time quaking-induced conversion (RT-QuIC) in vitro prion amplification assay to detect prions in soil collected within and around an illegal white-tailed deer (Odocoileus virginianus, WTD) carcass disposal site and associated captive WTD farm in Beltrami County, Minnesota. We detected PrPSc in 26 of 201 soil samples across 15 locations within the illegal disposal site and one on the farm that housed the cervids. Importantly, a subset of RT-QuIC positive soil samples was collected from soils where carcasses were recovered, providing direct evidence that environmental contamination resulted from this illegal activity. These findings reveal that improper cervid carcass disposal practices may have important implications for ongoing CWD transmission through the environment.
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Conclusions
Using RT-QuIC, we detected PrPSc in 26 of 201 soil samples collected across 16 locations on public land where WTD carcasses had been disposed and the captive facility from where they originated. Within the disposal site, 25 out of 124 soil samples (20%) tested positive for PrPSc. Among those positive detections, 17, or 68%, were collected from locations where CWD-positive WTD remains had been previously recovered. This environmental investigation demonstrates how improper cervid carcass disposal practices can result in persistent environmental contamination, posing a potential risk to wildlife health. Given that disposal of livestock on the landscape is a common practice among producers [Citation54–56], these findings underscore the need for improved disposal practices and further investigation of environmental impacts. Expanding on this area of environmental research is crucial as the geographic range of CWD continues to expand [Citation57]. The use of RT-QuIC for prion detection in environmental samples offers an exciting advancement to environmental surveillance for prions, though as we demonstrate here and in Grunklee et al. [Citation41], assay optimization and validation for use with different environmental samples, including new soil types, is still necessary. Further enhancements to RT-QuIC and other methodologies for prion detection will facilitate more opportunities to explore the persistence, degradation, transport, and remediation of environmental prions.
While the disease control measures effectively eliminated prion seeding activity in CWD-affected farms, CWD recurred at two of the 18 remediated farms 4 to 5 years after restocking animals. It remains unclear whether the recurrence of CWD at the two farms was due to residual prions in the environment after the control measures, or the introduction of the infected animals from other farms. This uncertainty is heightened by the annual occurrence of CWD at multiple farms and the absence of a traceability system for farmed cervids.
Keywords: Chronic wasting disease (CWD); NaOH; Protein-misfolding cyclic amplification (PMCA); Republic of Korea; farm; prions; remediation; topsoil.
Rapid recontamination of a farm building occurs after attempted prion removal
First published: 19 January 2019 https://doi.org/10.1136/vr.105054
The data illustrates the difficulty in decontaminating farm buildings from scrapie, and demonstrates the likely contribution of farm dust to the recontamination of these environments to levels that are capable of causing disease.
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This study clearly demonstrates the difficulty in removing scrapie infectivity from the farm environment. Practical and effective prion decontamination methods are still urgently required for decontamination of scrapie infectivity from farms that have had cases of scrapie and this is particularly relevant for scrapie positive goatherds, which currently have limited genetic resistance to scrapie within commercial breeds.24 This is very likely to have parallels with control efforts for CWD in cervids.
***>This is very likely to have parallels with control efforts for CWD in cervids.
Front. Vet. Sci., 14 September 2015 | https://doi.org/10.3389/fvets.2015.00032
Objects in contact with classical scrapie sheep act as a reservoir for scrapie transmission
In conclusion, the results in the current study indicate that removal of furniture that had been in contact with scrapie-infected animals should be recommended, particularly since cleaning and decontamination may not effectively remove scrapie infectivity (31), even though infectivity declines considerably if the pasture and the field furniture have not been in contact with scrapie-infected sheep for several months. As sPMCA failed to detect PrPSc in furniture that was subjected to weathering, even though exposure led to infection in sheep, this method may not always be reliable in predicting the risk of scrapie infection through environmental contamination.
SUNDAY, APRIL 06, 2025
Failure to prevent classical scrapie after repeated decontamination of a barn
Chronic wasting disease (CWD) prion detection in environmental and biological samples from a taxidermy site and nursing facility, and instruments used in surveillance activities
Available online 9 April 2025
Highlights
• CWD prions were identified in a taxidermy and deer nursing facility.
• Contaminated samples included waters, soils, dermestid beetles, domestic flies and a dumpster.
• Surgical instruments used to collect deer samples can get contaminated with CWD prions.
• Some of the infectious particles are readily released from surgical instruments when washed.
• Our results suggest that taxidermy practices actively contribute in the spreading of CWD.
Snip…
In summary, the information provided in this report demonstrate how anthropogenic activities, specifically taxidermy practices, animal processing, and rehabilitation of CWD susceptible species, may facilitate CWD transmission through the environmental dissemination of CWD prions. This study, along with future research efforts characterizing the overall level of infectivity, provides relevant information on managing CWD and to control its rapid geographic expansion. …
Chronic wasting disease detection in environmental and biological samples from a taxidermy site
Results: The PMCA analysis demonstrated CWD seeding activity in some of the components of this facility, including insects involved in head processing, soils, and a trash dumpster.
Conclusions: Different areas of this property were used for various taxidermy procedures. We were able to detect the presence of prions in
i) soils that were in contact with the heads of dead animals, ii) insects involved in the cleaning of skulls, and iii) an empty dumpster where animal carcasses were previously placed.
This is the first report demonstrating that swabbing is a helpful method to screen for prion infectivity on surfaces potentially contaminated with CWD. These findings are relevant as this swabbing and amplification strategy may be used to evaluate the disease status of other free-ranging and captive settings where there is a concern for CWD transmissions, such as at feeders and water troughs with CWD-exposed properties. This approach could have substantial implications for free-ranging cervid surveillance as well as in epidemiological investigations of CWD.
Prion 2022 Conference abstracts: pushing the boundaries
Artificial mineral sites that pre-date endemic chronic wasting disease become prion hotspots
The Ames Research and Educational Center property, centrally located within the CWD zone of southwest Tennessee, contains 49 historical mineral supplementation sites that were decommissioned in 2012. Here, we demonstrate that 32 of the 49 (65%) mineral sites within Ames established prior to the regional CWD outbreak, serve as foci of environmental PrPCWD contamination. Detection of PrPCWD in soils from these artificial mineral sites was dependent on site-specific management efforts. Soil physical properties were very similar across sites and no correlation between PrPCWD detection and soil physical properties was found. The detection of PrPCWD in soils at attractant sites within an endemic CWD zone significantly advances our understanding of environmental PrPCWD accumulation dynamics, providing valuable information for advancing adaptive CWD management approaches.
Shedding of Chronic Wasting Disease Prions in Multiple Excreta Throughout Disease Course in White-tailed Deer
Conclusions: These studies demonstrate: (a) CWD prion excretion occurs throughout infection; (2) PRNP genotype (GG≫GS/NT) influences the excreta shedding; and (3) detection sensitivity in excreta can vary with different RT-QuIC protocols. These results provide a more complete perspective of prion shedding in deer during the course of CWD infection.
Prion 2022 Conference abstracts: pushing the boundaries
"Additionally, we have determined that prion seeding activity is retained for at least fifteen years at a contaminated site following attempted remediation."
***> 15 YEARS!!!
Detection of prions in soils contaminated by multiple routes
Results: We are able to detect prion seeding activity at multiple types of environmental hotspots, including carcass sites, contaminated captive facilities, and scrapes (i.e. urine and saliva). Differences in relative prion concentration vary depending on the nature and source of the contamination. Additionally, we have determined that prion seeding activity is retained for at least fifteen years at a contaminated site following attempted remediation.
Conclusions: Detection of prions in the environment is of the utmost importance for controlling chronic wasting disease spread. Here, we have demonstrated a viable method for detection of prions in complex environmental matrices. However, it is quite likely that this method underestimates the total infectious prion load in a contaminated sample, due to incomplete recovery of infectious prions. Further refinements are necessary for accurate quantification of prions in such samples, and to account for the intrinsic heterogeneities found in the broader environment.
Funded by: Wisconsin Department of Natural Resources
Meeting-book-final-version prion 2023 Prion 2023 Congress Organizing Committee and the NeuroPrion Association, we invite you to join us for the International Conference Prion2023 from 16-20 October 2023 in Faro, Portugal.
https://prion2023.org/wp-content/uploads/2023/10/Meeting-book-final-version2.pdf
***> Infectious agent of sheep scrapie may persist in the environment for at least 16 years
***> Nine of these recurrences occurred 14–21 years after culling, apparently as the result of environmental contamination, but outside entry could not always be absolutely excluded.
JOURNAL OF GENERAL VIROLOGY Volume 87, Issue 12
Infectious agent of sheep scrapie may persist in the environment for at least 16 years Free
“While the disease control measures effectively eliminated prion seeding activity in CWD-affected farms, CWD recurred at two of the 18 remediated farms 4 to 5 years after restocking animals.”
“Additionally, we have determined that prion seeding activity is retained for at least fifteen years at a contaminated site following attempted remediation.”
***> Infectious agent of sheep scrapie may persist in the environment for at least 16 years
***> Nine of these recurrences occurred 14–21 years after culling, apparently as the result of environmental contamination, but outside entry could not always be absolutely excluded.
I remember what “deep throat” told me about Scrapie back around 2001, during early days of my BSE investigation, after my Mom died from hvCJD, I never forgot, and it seems it’s come to pass;
***> Confidential!!!!
***> As early as 1992-3 there had been long studies conducted on small pastures containing scrapie infected sheep at the sheep research station associated with the Neuropathogenesis Unit in Edinburgh, Scotland. Whether these are documented...I don't know. But personal recounts both heard and recorded in a daily journal indicate that leaving the pastures free and replacing the topsoil completely at least 2 feet of thickness each year for SEVEN years....and then when very clean (proven scrapie free) sheep were placed on these small pastures.... the new sheep also broke out with scrapie and passed it to offspring. I am not sure that TSE contaminated ground could ever be free of the agent!! A very frightening revelation!!!
---end personal email---end...tss
and so it seems…
so, this is what we leave our children and grandchildren?
Chronic wasting disease prions in cervids and wild pigs in North America Preliminary Outbreak Assessment DEFRA 26 January 2026 Department for Environment, Food and Rural Affairs
Preliminary Outbreak Assessment
Chronic wasting disease prions in cervids and wild pigs in North America
26 January 2026
Disease report
Chronic wasting disease (CWD) is a fatal neurodegenerative disease of cervids, such as deer, elk, moose and reindeer. It is caused by prions – infectious proteins that cause normal cellular prion proteins to misfold (CIDRAP, 2025). The disease is widespread in captive and free-ranging cervids in North America (Figure 1). For the first time, CWD prions have also been detected in the tissues of wild pigs (Sus scrofa) caught in CWD-affected areas of the USA (Soto et al. 2025). This discovery emerged from a study designed to investigate potential interactions between wild pigs and CWD prions, as wild pigs often coexist with cervids, which can shed prions into the environment. The following assessment discusses the epidemiology of CWD in North America and the detection of CWD prions in wild pigs. It also considers the potential implications for Great Britain.
Conclusion
CWD has continued to spread among captive and free-ranging cervids in North America since it was first detected in the 1960s. The finding of CWD prions in wild pigs in the USA suggests they could contribute towards transmission of the disease, influencing its epidemiology, geographic distribution and interspecies spread. However, further research is needed to confirm this. CWD has never been reported in Great Britain and the current risk of CWD prions being introduced into Great Britain’s wild pig or cervid population ranges from very low to negligible.
Readers are reminded to be vigilant for signs of CWD. Information on how to spot the disease can be found here. Suspected cases must be reported immediately to the Defra Rural Services Helpline on 03000 200 301. In Wales, call 0300 303 8268. In Scotland, contact your local Field Services Office. Failure to do so is an offence. We will continue to monitor the situation.
Authors • Lawrence Finn • Dr. Lauren Perrin • John Spiropoulos • Dr. Helen RobertsDepartment for Environment, Food and Rural Affairs
References
snip…see;
Detection of Prions in Wild Pigs (Sus scrofa) from Areas with Reported Chronic Wasting Disease Cases, United State Volume 31, Number 1—January 2025
WEDNESDAY, JANUARY 28, 2026
Chronic wasting disease prions in cervids and wild pigs in North America Preliminary Outbreak
Confucius Ponders, what about Wild Pigs (Sus scrofa), they can cover some distance rather quickly, what about Wild Pigs (Sus scrofa) digging up the terrain, and as they do it, what if these Wild Pigs (Sus scrofa) were exposed to CWD TSE Prion, and then they go on exposing and saturating the land with CWD TSE Prion, then the soil becomes contaminated with CWD TSE Prion, then what about the plants that grow from that soil for the decades to come, what if???
Research Project: Elucidating the Pathobiology and Transmission of Transmissible Spongiform Encephalopathies
“ARS researchers in Ames, Iowa, showed that white-tailed deer sick with scrapie from sheep can infect other deer under conditions mimicking natural exposure. Furthermore, this work shows that CWD is difficult to differentiate from WTD infected with scrapie. WTD scrapie prions accumulate in the lymphoreticular system in a manner similar to CWD, meaning that environmental contamination may occur through feces, saliva, and other body fluids of scrapie affected WTD as has been shown for CWD. The presence of WTD infected with scrapie could confound mitigation efforts for chronic wasting disease. This information informs regulatory officials, the farmed cervid industry, and officials tasked with protecting animal health such as state Departments of Agriculture, Natural Resources, or Parks and Wildlife with regard to a disease similar to CWD but arising from sheep scrapie that could be present in WTD that have contact with scrapie affected sheep and/or goats.”
Research Project: Elucidating the Pathobiology and Transmission of Transmissible Spongiform Encephalopathies
Location: Virus and Prion Research
2025 Annual Report
Objectives
Objective 1: Develop highly sensitive detection tools to determine the distribution of CWD and scrapie prions in natural hosts (sheep, goats, cervids) and their environment.
Objective 2: Investigate the pathobiology of CWD, scrapie prion strains, and atypical TSEs in natural hosts including potential cross species transmission events.
Objective 3: Investigate the genetics of CWD susceptibility and resistance in white-tailed deer.
Objective 4: Evaluate the presence of and determine the appropriate methodology for CWD strain determination.
Approach
Eradication or control of a family of diseases is unlikely or impossible when an understanding of the basic mechanisms and influences on transmission are unknown and for which methods to evaluate disease status are lacking. Scrapie and BSE represent the most thoroughly studied TSEs; however, significant knowledge gaps persist with regard to the atypical variants of these diseases. Further, much of the research emphasis to date on genetics of prion disease has focused on the recipient genotype rather than the source. Since both atypical BSE and atypical scrapie have been suggested to occur spontaneously, eradication of these diseases may not be possible unless we expand our understanding of the disease at both the source and recipient level. A better understanding of the tissue distribution and potential transmission of these atypical isolates is critical to understanding what risk these disease variants may pose to ongoing control and eradication efforts. The European epizootic of BSE is waning and efforts to eradicate scrapie in the U.S. and abroad have progressed but are not complete. In the U.S., chronic wasting disease (CWD) presents the most serious challenge to regulatory efforts. CWD appears to be spreading unchecked in both free-ranging and farmed cervids. Methods for antemortem detection of TSEs in general and CWD in particular are needed to fulfill the goal of eradicating scrapie and controlling CWD. Performing these studies will allow us to address critical knowledge gaps that are relevant to developing measures to restrict further disease expansion beyond current, affected populations. Understanding prion disease persistence in animal populations is challenging due to lack of tools for study and a less than complete understanding of transmission among animals within a flock or herd or in naturally occurring reservoirs. In addition to transmission between hosts of like species, free-ranging cervids may come in contact with numerous other species including cattle, sheep, and other susceptible hosts. Transmission of CWD to other species has been studied but limited with regard to the source genotype used. The four primary objectives are inherently linked. Our focus is on developing tools needed for control and research, and using those tools to advance our understanding the complex disease process with the overall goal of eradication and control of disease in livestock, wildlife of economic importance, and potential wildlife reservoirs.
Progress Report
The goals of the project plan for fiscal year (FY) 2025 consisted of 12 milestones, 11 of which were either fully or substantially met. The only milestone in this plan that was not met was due to insufficient animal availability and space constraints. Previous studies utilizing this space are not complete due to longer than anticipated incubation periods and cannot be initiated until those studies are complete. In work toward addressing
Objective 1, “Develop highly sensitive detection tools to determine the distribution of chronic wasting disease (CWD) and scrapie prions in natural hosts (sheep, goats, cervids) and their environment”, we have worked closely with ARS researchers in Pullman, Washington, Animal and Plant Health Inspection Service (APHIS), and university partners. The tools under development are directly utilized by state diagnostic labs and have been shared with the appropriate end users for evaluation. We have also assessed alternative dyes that have do not induce amyloid formation in the amplification based diagnostic assay known as RT-QuIC. While no increase in sensitivity was observed, differences between strains were found offering an additional means to differentiate strains for some TSEs.
Objective 2, “Investigate the pathobiology of CWD, scrapie prion strains, and atypical TSEs in natural hosts including potential cross species transmission events”, the studies in question have been initiated with the goal of furthering the understanding of these TSEs in agriculturally relevant species including the natural host species and other that may be exposed to these TSEs in an agricultural environment. The studies are ongoing and anticipated to last upwards of 5 year and observation of the animals is ongoing. No anticipated signs of disease or relevant reportable information have been seen nor are they expected until near the onset of clinical signs, but if they are observed they will be reported.
Objective 3, “Investigate the genetics of CWD susceptibility and resistance in white-tailed deer”, consists of two subobjectives:
A) Investigate the susceptibility of white-tailed deer to CWD modeling direct contact exposure with infected deer, and
B) Investigate the susceptibility of white-tailed deer to CWD after direct inoculation.
The first of these has been initiated on schedule while the second has been delayed considerably (greater than 3 years at this point) due to insufficient animal space.Upon completion these two studies will aid in understanding the disease and disease progression.
Objective 4, “Evaluate the presence of and determine the appropriate methodology for CWD strain determination”, is dependent upon obtaining a diverse set of CWD isolates. We are continuing the acquisition of these samples. . Strains are one of the least understood aspects of TSEs as a whole and of importance in understanding the risks of CWD. We have initiated studies that will address the biochemical nature of prion strains and how these strains are maintained in a host which will aid in addressing features and differentiation of strains as additional samples become available.
Accomplishments
1. 01 Determined that white-tailed deer (WTD) infected with scrapie from sheep can transmit the disease to other deer under conditions mimicking natural exposure. It has long been suggested that prion disease in deer (chronic wasting disease (CWD)) was caused by the prion agent from sheep. The prion disease that affects sheep, scrapie, has been recognized for hundreds of years. However, chronic wasting disease, a similar disease found in WTD, has only been recognized since the 1960s. ARS researchers in Ames, Iowa, showed that white-tailed deer sick with scrapie from sheep can infect other deer under conditions mimicking natural exposure. Furthermore, this work shows that CWD is difficult to differentiate from WTD infected with scrapie. WTD scrapie prions accumulate in the lymphoreticular system in a manner similar to CWD, meaning that environmental contamination may occur through feces, saliva, and other body fluids of scrapie affected WTD as has been shown for CWD. The presence of WTD infected with scrapie could confound mitigation efforts for chronic wasting disease. This information informs regulatory officials, the farmed cervid industry, and officials tasked with protecting animal health such as state Departments of Agriculture, Natural Resources, or Parks and Wildlife with regard to a disease similar to CWD but arising from sheep scrapie that could be present in WTD that have contact with scrapie affected sheep and/or goats.
2. 02 Showed that gene-targeted mice are capable of reproducing strain specific effects typically limited to natural host species of chronic wasting disease (CWD). CWD is a highly contagious disease of deer, elk, moose, and reindeer found in North America, South Korea, and Scandinavian countries that is caused by misfolded proteins called prions. CWD prions transmit through direct contact between infected animals, or through contaminated soil, grass, or water. All prion diseases exhibit progressive neurodegeneration and ultimately death. Scientists typically study CWD by injecting prions into susceptible animals' brains in lab experiments. Intracranial prion injections are favored because they typically produce shorter incubation periods and higher disease attack rates compared to natural infection. ARS researchers in Ames, Iowa, along with university collaborators showed that this inoculation method can cause the prion strains to change in a way that does not accurately reflect how the disease spreads naturally. They found that using a combination of peripheral inoculation (injection outside the brain) in natural hosts and using novel gene-targeted mice generated in a manner that provides a more natural expression of the inserted prion gene that gives a more accurate picture of how CWD behaves in the real world. The novel mouse model provides an important strategy to precisely assess the zoonotic potential (likelihood of transmission from animals to humans) of CWD and other animal prion diseases using natural routes of transmission. This will impact the tools used and direction of future studies of CWD and other prion diseases allowing more rapid and comprehensive responses to emerging questions aiding both the researchers at the producers they support…end
ARS Research Elucidating the Pathobiology and Transmission of Transmissible Spongiform Encephalopathies 2025 Annual Report
CWD, transmission to, Cattle, Sheep, Pigs, Cervid, oh my!
Price of TSE Prion Poker Goes Up Again…terry
Chronic Wasting Disease CWD vs Scrapie TSE Prion
Volume 30, Number 8—August 2024
Research
Scrapie Versus Chronic Wasting Disease in White-Tailed Deer
Zoe J. Lambert1, Jifeng Bian, Eric D. Cassmann, M. Heather West Greenlee, and Justin J. Greenlee
Author affiliations: Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee, USA (Z.J. Lambert); US Department of Agriculture, Ames, Iowa, USA (Z.J. Lambert, J. Bian, E.D. Cassmann, J.J. Greenlee); Iowa State University, Ames (Z.J. Lambert, M.H. West Greenlee) Suggested citation for this article
Abstract
White-tailed deer are susceptible to scrapie (WTD scrapie) after oronasal inoculation with the classical scrapie agent from sheep. Deer affected by WTD scrapie are difficult to differentiate from deer infected with chronic wasting disease (CWD). To assess the transmissibility of the WTD scrapie agent and tissue phenotypes when further passaged in white-tailed deer, we oronasally inoculated wild-type white-tailed deer with WTD scrapie agent. We found that WTD scrapie and CWD agents were generally similar, although some differences were noted. The greatest differences were seen in bioassays of cervidized mice that exhibited significantly longer survival periods when inoculated with WTD scrapie agent than those inoculated with CWD agent. Our findings establish that white-tailed deer are susceptible to WTD scrapie and that the presence of WTD scrapie agent in the lymphoreticular system suggests the handling of suspected cases should be consistent with current CWD guidelines because environmental shedding may occur.
snip…
The potential for zoonoses of cervid-derived PrPSc is still not well understood (6,18,45–47); however, interspecies transmission can increase host range and zoonotic potential (48–50). Therefore, to protect herds and the food supply, suspected cases of WTD scrapie should be handled the same as cases of CWD.
Research Project: Elucidating the Pathobiology and Transmission of Transmissible Spongiform Encephalopathies
Location: Virus and Prion Research
Title: Differentiation of scrapie from chronic wasting disease in white-tailed deer
Author item LAMBERT, ZOE - Oak Ridge Institute For Science And Education (ORISE) item Bian, Jifeng item Cassmann, Eric item WEST GREENLEE, HEATHER - Iowa State University item Greenlee, Justin
Submitted to: Emerging Infectious Diseases Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/13/2024 Publication Date: N/A Citation: N/A
Interpretive Summary: Prion diseases are a neurodegenerative disease that can spread between animals. They are caused when the normal cellular prion protein misfolds and accumulates in the host’s central nervous system. This change is irreversible and invariably causes neurological disease and death of the host. The prion disease that affects sheep, scrapie, has been recognized for hundreds of years. However, chronic wasting disease, a similar disease found in white-tailed deer (WTD), has only been recognized since the 1960s. It has long been suggested that prion disease in deer (chronic wasting disease) was caused by the prion agent from sheep (scrapie). Recently, our lab confirmed that WTD will become infected by scrapie from sheep under conditions that mimic natural exposure. The disease produced in these animals was termed WTD scrapie. This manuscript addresses the next step in disease spread: whether sick WTD can pass WTD scrapie on to other deer. We found that white-tailed deer sick with scrapie can infect other deer under conditions mimicking natural exposure. The work reported in this manuscript demonstrates that CWD is difficult to differentiate from WTD scrapie. Regardless, WTD scrapie prions accumulate in the lymphoreticular system, meaning that environmental contamination is likely through feces, saliva, and other body fluids. Controlling WTD scrapie would require precautions similar to those taken with chronic wasting disease. The presence of WTD scrapie could confound mitigation efforts for chronic wasting disease. This information will be of interest to regulatory officials, the farmed cervid industry, and officials tasked with protecting animal health such as state Departments of Agriculture, Natural Resources, or Parks and Wildlife.
Technical Abstract: White-tailed deer (WTD) are susceptible to the scrapie agent from sheep after oronasal inoculation, termed WTD scrapie. However, results from western blotting these brainstems and lymph nodes are difficult to differentiate from WTD infected with chronic wasting disease (CWD). In order to assess the transmissibility of WTD scrapie and tissue phenotypes upon its further passage in WTD, three wildtype WTD (QQ95/GG96) were oronasally inoculated with WTD scrapie. These WTD presented with clinical signs and were euthanized between 21 and 26 months post-inoculation. Enzyme immunoassay (IDEXX) confirmed the presence of misfolded prion protein in the central nervous and lymphoreticular systems of all WTD in the study. Immunohistochemical staining, western blotting, and conformational stabilities were generally similar between the misfolded prion protein of WTD scrapie and CWD, though some differences were noted. Specifically, intraneuronal accumulation of misfolded prion protein was present in retinal ganglion cells of a WTD with WTD scrapie, not CWD. Additionally, epitope mapping revealed that the misfolded prion protein of CWD is slightly longer than that of WTD scrapie. Strong differences were seen in bioassays of cervidized mice, which exhibit significantly longer survival periods when inoculated with WTD scrapie as compared to those inoculated with CWD. Overall, this article establishes that WTD are highly susceptible to the WTD scrapie agent. Though subtle molecular differences exist between the misfolded prion protein of WTD scrapie and CWD, the presence of WTD scrapie in the lymphoreticular system determines that suspected cases be handled consistent with current guidelines for CWD.
Title: Characterization of classical sheep scrapie in white-tailed deer after experimental oronasal exposure
Author item Greenlee, Justin item MOORE, SARAH - Orise Fellow item Cassmann, Eric item LAMBERT, ZOE - Orise Fellow item Kokemuller, Robyn item Smith, Jodi item Kunkle, Robert item KONG, QINGZHONG - Case Western Reserve University (CWRU) item WEST GREENLEE, HEATHER - Iowa State University
Submitted to: Journal of Infectious Diseases Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/4/2022 Publication Date: 11/8/2022
Citation: Greenlee, J.J., Moore, S.J., Cassmann, E.D., Lambert, Z.J., Kokemuller, R., Smith, J.D., Kunkle, R.A., Kong, Q., West Greenlee, H.M. 2022. Characterization of classical sheep scrapie in white-tailed deer after experimental oronasal exposure. Journal of Infectious Diseases. 227(12):1386-1395. Article jiac443. https://doi.org/10.1093/infdis/jiac443.
DOI: https://doi.org/10.1093/infdis/jiac443
Interpretive Summary: Chronic Wasting Disease (CWD), a fatal neurodegenerative disease that occurs in farmed and wild cervids (deer and elk) of North America, is a transmissible spongiform encephalopathy (TSE). TSEs are caused by infectious proteins called prions that are resistant to decontamination and environmental degradation. The origin of chronic wasting disease is not known, but it has many similarities to the TSE of sheep called scrapie. It has long been hypothesized that CWD could have arisen through transmission of sheep scrapie to deer. The purpose of this study was to determine if scrapie derived from sheep could be transmitted to white-tailed deer. This study reports that the deer inoculated with sheep scrapie developed clinical signs of TSE and that the abnormal prion protein could be detected in a wide range of neural and lymphoid tissues. These results indicate that deer may be susceptible to sheep scrapie if exposed to the disease in natural or agricultural settings . In addition, several strong similarities between CWD in white-tailed deer and the experimental cases of scrapie in white-tailed deer in this report suggest that it would be difficult to identify scrapie in deer were a case to occur. This information should be considered when developing plans to reduce or eliminate TSEs or advising farmers that wish to keep their deer herds free from prion diseases.
Technical Abstract: Scrapie is a prion disease of sheep and goats that is associated with widespread accumulation of abnormal prion protein (PrPSc) in the central nervous and lymphoid tissues. Chronic wasting disease (CWD) is the natural prion disease of cervid species and is similar to scrapie in sheep. The purpose of this study was to determine susceptibility of white-tailed deer (WTD) to the scrapie agent. We inoculated WTD (n=5) by a concurrent oral and intranasal exposure with the scrapie agent from sheep and (n=6) with the scrapie agent from goats. All deer exposed to the agent of scrapie from sheep had evidence of PrPSc accumulation. PrPSc was detected in lymphoid tissues at preclinical time points, and deer necropsied after 28 months post-inoculation had clinical signs, spongiform lesions, and widespread distribution of PrPSc in neural and lymphoid tissues. Western blots done on samples from the brainstem, cerebellum, and lymph nodes of scrapie-infected WTD have a molecular profile similar to CWD and distinct from western blots of samples from the cerebral cortex, retina, or the original sheep scrapie inoculum. WTD are susceptible to the agent of scrapie from sheep and differentiation from CWD may be difficult.
*** Grant Agreement number: 222887 ***
*** Project acronym: PRIORITY ***
*** Project title: Protecting the food chain from prions: shaping European priorities through basic and applied research Funding ***
Scheme: Large-scale integrating project Period covered: from Oct. 1, 2009 to Sept. 30, 2014
Name of the scientific representative of the project's co-ordinator1, Title and Organisation: Jesús R. Requena, Ph.D., Associate Professor, Department of medicine, University of Santiago de Compostela, Spàin. Tel: 34-881815464 Fax: 34-881815403 E-mail: jesus.requena@usc.es
Project website¡ Error! Marcador no definido. address: www.prionpriority.eu
PRIORITY, PROJECT FINAL REPORT
*** 14) Concluding that atypical scrapie can transmit to Humans and that its strain properties change as it transmits between species ***
snip...
http://cordis.europa.eu/docs/results/222/222887/final1-priority-final-report.pdf
see full text;
Block D: Prion epidemiology
Studies on atypical scrapie were identified as a key element of this block, given the potential risk associated to this agent. We studied the permeability of Human, bovine and porcine species barriers to atypical scrapie agent transmission. Experiments in transgenic mice expressing bovine, porcine or human PrPC suggest that this TSE agent has the intrinsic ability to propagate across these species barriers including the Human one. Upon species barrier passage the biological properties and phenotype of atypical scrapie seem to be altered. Further experiments are currently ongoing (in the framework of this project but also in other projects) in order to: (i) characterize the properties of the prion that emerged from the propagation of atypical scrapie in tg Hu; (ii) to confirm that the phenomena we observed are also true for atypical scrapie isolates other than the ones we have studied.
In parallel, studies in sheep have concluded that:
*** Atypical scrapie can be transmitted by both oral and intracerebral route in sheep with various PRP genotypes
*** Low but consistent amount of infectivity accumulates in peripheral tissue (mammary gland, lymph nodes, placenta, skeletal muscles, nerves) of sheep incubating atypical scrapie.
*** The combination of data from all our studies leads us to conclude that:
*** Atypical scrapie passage through species barriers can lead to the emergence of various prions including classical BSE (following propagation in porcine PRP transgenic mice).
*** Atypical scrapie can propagate, with a low efficacy, in human PrP expressing mice. This suggests the existence of a zoonotic potential for this TSE agent.
snip...
We advance our main conclusions and recommendations, in particular as they might affect public policy, including a detailed elaboration of the evidence that led to them. Our main recommendations are:
a. The issue of re-introducing ruminant protein into the food-chain The opinion of the members of Priority is that sustaining an absolute feed ban for ruminant protein to ruminants is the essential requirement, especially since the impact of non-classical forms of scrapie in sheep and goats is not fully understood and cannot be fully estimated. Therefore, the consortium strongly recommends prohibiting re-introduction of processed ruminant protein into the food-chain. Arguments in support of this opinion are:
• the large (and still uncharacterized) diversity of prion agents that circulate in animal populations;
• the uncertainties related to prion epidemiology in animal populations;
• the unknown efficacy of industrial processes applied to reduce microbiological risk during processed animal protein (PAP) production on most prion agents; • the intrinsic capacity of prions to cross interspecies transmission barriers; • the lack of sensitive methodology for identifying cross contamination in food.
• the evolution of natural food chains in nature (i.e. who eats whom or what) has generated an efficient barrier preventing, to some extent, novel prion epidemies and that this naturally evolved ecology should be respected.
The consortium is also hesitant to introduce processed ruminant proteins into fish food considering the paucity of data on prion infections in fishes and sea animals including those of mammalian origin, and the risk of establishing an environmental contamination of the oceans that cannot be controlled.
b. Atypical prion agents and surveillance
Atypical prion agents (see below) will probably continue to represent the dominant form of prion diseases in the near future, particularly in Europe.
*** Atypical L-type BSE has clear zoonotic potential, as demonstrated in experimental models.
*** Similarly, there are now some data that seem to indicate that the atypical scrapie agent can cross various species barriers.
*** Moreover, the current EU policy for eradicating scrapie (genetic selection in affected flocks) is ineffective for preventing atypical scrapie.
*** The recent identification of cell-to-cell propagation and the protein-encoded strain properties of human neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease, suggest that they bear the potential to be transmissible even if not with the same efficiency as CJD. More epidemiological data from large cohorts are necessary to reach any conclusion on the impact of their transmissibility on public health. Re-evaluations of safety precautions may become necessary depending on the outcome of these studies. In that context it would appear valuable
• to develop knowledge related to the pathogenesis and inter-individual transmission of atypical prion agents in ruminants (both intra- and inter-species)
• to improve the sensitivity of detection assays that are applied in the field towards this type of agent
• to maintain a robust surveillance of both animal and human populations
c. The need for extended research on prions
Intensified searching for a molecular determinants of the species barrier is recommended, since this barrier is a key for many important policy areas - risk assessment, proportional policies, the need for screening of human products and food. In this respect, prion strain structural language also remains an important issue for public health for the foreseeable future. Understanding the structural basis for strains and the basis for adaptation of a strain to a new host will require continued fundamental research. Prions maintain a complex two-way relationship with the host cell and fundamental research is needed on mechanisms for their transmission, replication and cause of nervous system dysfunction and death.
Early detection of prion infection, ideally at preclinical stage, also remains crucial for development of effective treatment strategies in humans affected by the disease.
Position of the Priority consortium
Nearly 30 years ago, the appearance in the UK of Bovine Spongiform Encephalopathy (BSE) quickly brought the previously obscure “prion diseases” to the spotlight. The ensuing health and food crises that spread throughout Europe had devastating consequences. In the UK alone, there were more than 36,000 farms directly affected by BSE and the transmission of BSE prions to humans via the food chain has caused over 200 people in Europe to die from variant Creutzfeldt-Jakob disease (vCJD) http://www.cjd.ed.ac.uk
Origins of prion epidemies
Classical BSE now appears to be under control, with 18 EU Member States having achieved the World Organisation for Animal Health (Office International Epizooties) „negligible risk‟ status (May 2014; http://www.oie.int/en/animal-health-in-the-world/official-disease-status/bse/list-of-bse-risk-status/), and the remaining MS assessed as „controlled‟ risk. Of note, research, including EU-funded research, has played a key role in this success: while the origin of the infection was never defined, the principle driver of the epidemic was identified as prions in Meat and Bone Meal (MBM). Tests based on prion protein-specific antibodies were developed, allowing detection of infected animals, and a better understanding of disease pathogenesis and the distribution of infectivity in edible tissues; experimental investigation of transmission barriers between different species allowed a rational estimation of risks, etc. All of this led to the implementation of rational and effective policies, such as the MBM ban to protect the animal feed chain, and the Specified Risk Material (SRM) regulations to protect the human food chain.
In spite of this progress, prions are still a threat. Epidemiological re-assessment indicates that the ∼10 year incubation period separating the peaks of the BSE and the vCJD epidemics is probably too short. In addition, results from a large number of human tonsil and appendix analyses in the UK suggest that there may be a high number of asymptomatic individuals who are positive for the disease-associated conformer prion protein PrPSc. While vCJD is the only form of human prion disease that has been consistently demonstrated to have lymphoreticular involvement, there has been no systematic investigation of lymphoid tissue in cases with other prion diseases.
The human prion problem
The clinical cases of vCJD identified to date have all shared a common PrP genotype (M129M), although one pre-clinical case was confirmed as an M129V heterozygote, and it has been mooted that perhaps only the M129M proportion of the population is susceptible. However, in the UK appendix study, PrP accumulation was described in samples representing every codon 129 genotype, raising the possibility that genotype does not confer resistance but instead modulates incubation period. Apart from the two UK studies, the lymphoid tissues of non-CJD patients have not been examined for the presence of PrPSc, so, these cases may not solely represent pre-clinical vCJD, but also other forms of prion disease.
Recent experiments in highly susceptible mouse models indicate the presence of infectivity in blood or blood components at late disease stages in sporadic CJD. The significance of this experimental finding for humans has to be explored in more detail and, at the present time, there is no evidence for the transmission of prions via blood in sporadic CJD. However a likely scenario is that all those with signs of infection or abnormal PrP accumulation in peripheral tissue could have infective blood, posing the risk for transmission via blood products, which has been clearly demonstrated in experimental models, and confirmed in several cases of vCJD in man. Altogether, these data clearly demonstrate the potential risk of a second wave of vCJD, particularly when the number people identified with lymphoid accumulation of PrPSc (16/32,411) gives a prevalence estimate in the UK of 493 per million, much higher than the number of clinical cases seen to date.
The animal prion problem
An increasing number of reports on cases of “atypical” BSE in cattle throughout the EU and beyond may lead to a new epidemic, particularly since we still do not understand all factors determining the species barrier. Ovine scrapie is another concern, because it could mask ovine BSE, presumably transmissible to humans. Scrapie is endemic and not likely to be eradicated soon, although current control measures are effective at greatly reducing disease incidence. Atypical forms, which may be spontaneous, are not affected by these control measures and these forms of disease will persist in the global animal population. The low prevalence of these disease forms makes effective surveillance very challenging. However, there is a clear risk attendant on ignoring these cases without an understanding of their possible zoonotic potential, particularly when most forms of human disease have no established aetiology. In summary, atypical cases of BSE and scrapie presently clearly outnumber classical cases in cattle and sheep in all member states.
We will highlight the state-of-the-art knowledge and point out scientific challenges and the major questions for research. Strategic objectives and priorities in Europe in the future for research that aims to control, eliminate or eradicate the threat posed by prions to our food and health are also indicated.
The Priority project has focused on 4 themes, namely the structure, function, conversion and toxicity of prions; detection of prions; mechanisms of prion transmission and spreading and epidemiology of prion diseases. This paper summarizes the opinions/positions reached within these themes at the end of the project.
http://cordis.europa.eu/docs/results/222/222887/final1-priority-final-report.pdf
see;
https://nor-98.blogspot.com/2016/09/goat-k222-prpc-polymorphic-variant-does.html
https://transmissiblespongiformencephalopathy.blogspot.com/2026/04/us-report-scrapie-cwd-cattle-sheep-pigs.html
*** Project acronym: PRIORITY ***
*** Project title: Protecting the food chain from prions: shaping European priorities through basic and applied research Funding ***
Scheme: Large-scale integrating project Period covered: from Oct. 1, 2009 to Sept. 30, 2014
Name of the scientific representative of the project's co-ordinator1, Title and Organisation: Jesús R. Requena, Ph.D., Associate Professor, Department of medicine, University of Santiago de Compostela, Spàin. Tel: 34-881815464 Fax: 34-881815403 E-mail: jesus.requena@usc.es
Project website¡ Error! Marcador no definido. address: www.prionpriority.eu
PRIORITY, PROJECT FINAL REPORT
*** 14) Concluding that atypical scrapie can transmit to Humans and that its strain properties change as it transmits between species ***
snip...
http://cordis.europa.eu/docs/results/222/222887/final1-priority-final-report.pdf
see full text;
Block D: Prion epidemiology
Studies on atypical scrapie were identified as a key element of this block, given the potential risk associated to this agent. We studied the permeability of Human, bovine and porcine species barriers to atypical scrapie agent transmission. Experiments in transgenic mice expressing bovine, porcine or human PrPC suggest that this TSE agent has the intrinsic ability to propagate across these species barriers including the Human one. Upon species barrier passage the biological properties and phenotype of atypical scrapie seem to be altered. Further experiments are currently ongoing (in the framework of this project but also in other projects) in order to: (i) characterize the properties of the prion that emerged from the propagation of atypical scrapie in tg Hu; (ii) to confirm that the phenomena we observed are also true for atypical scrapie isolates other than the ones we have studied.
In parallel, studies in sheep have concluded that:
*** Atypical scrapie can be transmitted by both oral and intracerebral route in sheep with various PRP genotypes
*** Low but consistent amount of infectivity accumulates in peripheral tissue (mammary gland, lymph nodes, placenta, skeletal muscles, nerves) of sheep incubating atypical scrapie.
*** The combination of data from all our studies leads us to conclude that:
*** Atypical scrapie passage through species barriers can lead to the emergence of various prions including classical BSE (following propagation in porcine PRP transgenic mice).
*** Atypical scrapie can propagate, with a low efficacy, in human PrP expressing mice. This suggests the existence of a zoonotic potential for this TSE agent.
snip...
We advance our main conclusions and recommendations, in particular as they might affect public policy, including a detailed elaboration of the evidence that led to them. Our main recommendations are:
a. The issue of re-introducing ruminant protein into the food-chain The opinion of the members of Priority is that sustaining an absolute feed ban for ruminant protein to ruminants is the essential requirement, especially since the impact of non-classical forms of scrapie in sheep and goats is not fully understood and cannot be fully estimated. Therefore, the consortium strongly recommends prohibiting re-introduction of processed ruminant protein into the food-chain. Arguments in support of this opinion are:
• the large (and still uncharacterized) diversity of prion agents that circulate in animal populations;
• the uncertainties related to prion epidemiology in animal populations;
• the unknown efficacy of industrial processes applied to reduce microbiological risk during processed animal protein (PAP) production on most prion agents; • the intrinsic capacity of prions to cross interspecies transmission barriers; • the lack of sensitive methodology for identifying cross contamination in food.
• the evolution of natural food chains in nature (i.e. who eats whom or what) has generated an efficient barrier preventing, to some extent, novel prion epidemies and that this naturally evolved ecology should be respected.
The consortium is also hesitant to introduce processed ruminant proteins into fish food considering the paucity of data on prion infections in fishes and sea animals including those of mammalian origin, and the risk of establishing an environmental contamination of the oceans that cannot be controlled.
b. Atypical prion agents and surveillance
Atypical prion agents (see below) will probably continue to represent the dominant form of prion diseases in the near future, particularly in Europe.
*** Atypical L-type BSE has clear zoonotic potential, as demonstrated in experimental models.
*** Similarly, there are now some data that seem to indicate that the atypical scrapie agent can cross various species barriers.
*** Moreover, the current EU policy for eradicating scrapie (genetic selection in affected flocks) is ineffective for preventing atypical scrapie.
*** The recent identification of cell-to-cell propagation and the protein-encoded strain properties of human neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease, suggest that they bear the potential to be transmissible even if not with the same efficiency as CJD. More epidemiological data from large cohorts are necessary to reach any conclusion on the impact of their transmissibility on public health. Re-evaluations of safety precautions may become necessary depending on the outcome of these studies. In that context it would appear valuable
• to develop knowledge related to the pathogenesis and inter-individual transmission of atypical prion agents in ruminants (both intra- and inter-species)
• to improve the sensitivity of detection assays that are applied in the field towards this type of agent
• to maintain a robust surveillance of both animal and human populations
c. The need for extended research on prions
Intensified searching for a molecular determinants of the species barrier is recommended, since this barrier is a key for many important policy areas - risk assessment, proportional policies, the need for screening of human products and food. In this respect, prion strain structural language also remains an important issue for public health for the foreseeable future. Understanding the structural basis for strains and the basis for adaptation of a strain to a new host will require continued fundamental research. Prions maintain a complex two-way relationship with the host cell and fundamental research is needed on mechanisms for their transmission, replication and cause of nervous system dysfunction and death.
Early detection of prion infection, ideally at preclinical stage, also remains crucial for development of effective treatment strategies in humans affected by the disease.
Position of the Priority consortium
Nearly 30 years ago, the appearance in the UK of Bovine Spongiform Encephalopathy (BSE) quickly brought the previously obscure “prion diseases” to the spotlight. The ensuing health and food crises that spread throughout Europe had devastating consequences. In the UK alone, there were more than 36,000 farms directly affected by BSE and the transmission of BSE prions to humans via the food chain has caused over 200 people in Europe to die from variant Creutzfeldt-Jakob disease (vCJD) http://www.cjd.ed.ac.uk
Origins of prion epidemies
Classical BSE now appears to be under control, with 18 EU Member States having achieved the World Organisation for Animal Health (Office International Epizooties) „negligible risk‟ status (May 2014; http://www.oie.int/en/animal-health-in-the-world/official-disease-status/bse/list-of-bse-risk-status/), and the remaining MS assessed as „controlled‟ risk. Of note, research, including EU-funded research, has played a key role in this success: while the origin of the infection was never defined, the principle driver of the epidemic was identified as prions in Meat and Bone Meal (MBM). Tests based on prion protein-specific antibodies were developed, allowing detection of infected animals, and a better understanding of disease pathogenesis and the distribution of infectivity in edible tissues; experimental investigation of transmission barriers between different species allowed a rational estimation of risks, etc. All of this led to the implementation of rational and effective policies, such as the MBM ban to protect the animal feed chain, and the Specified Risk Material (SRM) regulations to protect the human food chain.
In spite of this progress, prions are still a threat. Epidemiological re-assessment indicates that the ∼10 year incubation period separating the peaks of the BSE and the vCJD epidemics is probably too short. In addition, results from a large number of human tonsil and appendix analyses in the UK suggest that there may be a high number of asymptomatic individuals who are positive for the disease-associated conformer prion protein PrPSc. While vCJD is the only form of human prion disease that has been consistently demonstrated to have lymphoreticular involvement, there has been no systematic investigation of lymphoid tissue in cases with other prion diseases.
The human prion problem
The clinical cases of vCJD identified to date have all shared a common PrP genotype (M129M), although one pre-clinical case was confirmed as an M129V heterozygote, and it has been mooted that perhaps only the M129M proportion of the population is susceptible. However, in the UK appendix study, PrP accumulation was described in samples representing every codon 129 genotype, raising the possibility that genotype does not confer resistance but instead modulates incubation period. Apart from the two UK studies, the lymphoid tissues of non-CJD patients have not been examined for the presence of PrPSc, so, these cases may not solely represent pre-clinical vCJD, but also other forms of prion disease.
Recent experiments in highly susceptible mouse models indicate the presence of infectivity in blood or blood components at late disease stages in sporadic CJD. The significance of this experimental finding for humans has to be explored in more detail and, at the present time, there is no evidence for the transmission of prions via blood in sporadic CJD. However a likely scenario is that all those with signs of infection or abnormal PrP accumulation in peripheral tissue could have infective blood, posing the risk for transmission via blood products, which has been clearly demonstrated in experimental models, and confirmed in several cases of vCJD in man. Altogether, these data clearly demonstrate the potential risk of a second wave of vCJD, particularly when the number people identified with lymphoid accumulation of PrPSc (16/32,411) gives a prevalence estimate in the UK of 493 per million, much higher than the number of clinical cases seen to date.
The animal prion problem
An increasing number of reports on cases of “atypical” BSE in cattle throughout the EU and beyond may lead to a new epidemic, particularly since we still do not understand all factors determining the species barrier. Ovine scrapie is another concern, because it could mask ovine BSE, presumably transmissible to humans. Scrapie is endemic and not likely to be eradicated soon, although current control measures are effective at greatly reducing disease incidence. Atypical forms, which may be spontaneous, are not affected by these control measures and these forms of disease will persist in the global animal population. The low prevalence of these disease forms makes effective surveillance very challenging. However, there is a clear risk attendant on ignoring these cases without an understanding of their possible zoonotic potential, particularly when most forms of human disease have no established aetiology. In summary, atypical cases of BSE and scrapie presently clearly outnumber classical cases in cattle and sheep in all member states.
We will highlight the state-of-the-art knowledge and point out scientific challenges and the major questions for research. Strategic objectives and priorities in Europe in the future for research that aims to control, eliminate or eradicate the threat posed by prions to our food and health are also indicated.
The Priority project has focused on 4 themes, namely the structure, function, conversion and toxicity of prions; detection of prions; mechanisms of prion transmission and spreading and epidemiology of prion diseases. This paper summarizes the opinions/positions reached within these themes at the end of the project.
http://cordis.europa.eu/docs/results/222/222887/final1-priority-final-report.pdf
see;
https://nor-98.blogspot.com/2016/09/goat-k222-prpc-polymorphic-variant-does.html
https://transmissiblespongiformencephalopathy.blogspot.com/2026/04/us-report-scrapie-cwd-cattle-sheep-pigs.html
ORIGIN OF CHRONIC WASTING DISEASE TSE PRION?
COLORADO THE ORIGIN OF CHRONIC WASTING DISEASE CWD TSE PRION?
*** 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.
IN CONFIDENCE, REPORT OF AN UNCONVENTIONAL SLOW VIRUS DISEASE IN ANIMALS IN THE USA 1989
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 its subsequent recognition as a new disease of cervids, therefore justifying direct investigation, no specific research funding was forthcoming. The USDA viewed it as a wildlife problem and consequently not their province!” page 26.
***Moreover, sporadic disease has never been observed in breeding colonies or primate research laboratories, most notably among hundreds of animals over several decades of study at the National Institutes of Health25, and in nearly twenty older animals continuously housed in our own facility.
***> Even if the prevailing view is that sporadic CJD is due to the spontaneous formation of CJD prions, it remains possible that its apparent sporadic nature may, at least in part, result from our limited capacity to identify an environmental origin.
***> ”Our data suggest that the phenotype of CWD in sheep is indistinguishable from some strains of scrapie in sheep. Given our results, current detection techniques would be unlikely to distinguish CWD in sheep from scrapie in sheep if cross-species transmission occurred naturally.”
APHIS USDA Captive CWD Herds Update by State December 2025 Update
CHRONIC WASTING DISEASE CASES
APHIS USDA Captive CWD Herds Update by State December 2025 Update
***> CWD Action Plan National Program 103 Animal Health 2022-2027 UPDATE JANUARY 2026
***> SCRAPIE TSE Prion USA RAPID RESPONSE URGENT UPDATES DECEMBER 25, 2025
***> CWD vs Scrapie Urgent Update
SATURDAY, FEBRUARY 28, 2026
atypical Nor-98, CH1641, Scrapie, TSE Prion, USA Update 2026
Terry S. Singeltary Sr.
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