TPWD CHAPTER 65 WILDLIFE CWD Texas Register April 11, 2025 Volume 50 Number
Texas Register April 11, 2025 Volume 50 NumberTITLE 31. NATURAL RESOURCES AND CONSERVATION
PART 2. TEXAS PARKS AND WILDLIFE DEPARTMENT
CHAPTER 65. WILDLIFE
Department records indicate that within the last five years (since January 1, 2020), 30 deer breeding facilities where CWD has been confirmed transferred a total of 8,799 deer to 249 additional deer breeding facilities and 487 release sites located in a total of 144 counties in Texas.
https://www.sos.state.tx.us/texreg/archive/April112025/Adopted%20Rules/31.NATURAL%20RESOURCES%20AND%20CONSERVATION.html#56
Chronic Wasting Disease CWD TSE Prion of Cervid
“CWD spreads among wild populations at a relatively slow rate, limited by the natural home range and dispersed nature of wild animals.”
NOW HOLD YOUR HORSES, Chronic Wasting Disease CWD of Cervid can spread rather swiftly, traveling around 50 MPH, from the back of truck and trailer, and Here in Texas, we call it ‘Trucking CWD’…
Preventive Veterinary Medicine Volume 234, January 2025, 106385
Use of biosecurity practices to prevent chronic wasting disease in Minnesota cervid herds
Vehicles or trailers that entered the farm were used to transport other live cervids, cervid carcasses, or cervid body parts in past 3 years in 64.3 % (95 % CI 46.3–82.3) of larger elk/reindeer herds compared to 13.6 % (95 % CI 4.7–22.4) of smaller deer herds.
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Identifying the exact pathway of initial CWD transmission to cervid herds is often not possible, in part due to many potential pathways of transmission for the infection, including both direct and indirect contact with infected farmed or wild cervids (Kincheloe et al., 2021). That study identified that transmissions from infected farmed cervids may occur from direct contact with the movement of cervids from one herd to another and from indirect contact with the sharing of equipment, vehicles, clothing, reproductive equipment, and potentially through semen or embryos.
https://www.sciencedirect.com/science/article/abs/pii/S016758772400271X
“Chronic Wasting Disease (CWD) is a fatal neurological disease and can devastate deer populations by silently spreading through direct animal contact and contaminated environments. Without close monitoring, illegal movement of captive deer increases the risk of introducing CWD to areas it is not known to exist, potentially leading to widespread outbreaks which will impact more than just the health of Texas deer.”
https://tpwd.texas.gov/newsmedia/releases/?req=20250227b
Chronic wasting disease (CWD) prion detection in environmental and biological samples from a taxidermy site and nursing facility, and instruments used in surveillance activities
Paulina Soto a b , Nancy Ho a , Mitch Lockwood c , Austin Stolte c , J. Hunter Reed c , Rodrigo Morales a b
a Department of Neurology, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
b Centro Integrativo de Biologia y Quimica Aplicada (CIBQA), Universidad Bernardo O'Higgins, Santiago, Chile
c Texas Parks and Wildlife Department (TPWD), Kerrville, TX, United States of America
Received 20 September 2024, Revised 27 February 2025, Accepted 31 March 2025, Available online 9 April 2025, Version of Record 9 April 2025.
Cite https://doi.org/10.1016/j.scitotenv.2025.179318
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. Abstract
Chronic wasting disease (CWD) is a transmissible prionopathy affecting free-ranging and captive cervids. CWD is thought to spread through both direct and indirect transmission mechanisms. Along this line, human activities have not been thoroughly explored for their potential to spread this disease. One area of concern involves taxidermy procedures and surveillance activities as handled animals or carcasses are of unknown CWD statuses. Worrisomely, taxidermy facilities can act as foci of prion infectivity if appropriate biosecurity practices are not implemented. In this study, we evaluated the presence of infectious prions in a taxidermy facility that was possibly exposed to CWD prions. To determine this, we collected biological and environmental specimens from this site and screened them using the protein misfolding cyclic amplification (PMCA) technique. Additionally, we swabbed different surfaces possibly exposed to CWD-infected animals or carcasses. We report the presence of prions in i) waters used to digest tissues from deer carcasses, ii) soils that were in contact with the previously mentioned waters, iii) dermestid beetles used to clean skulls, iv) other insects found in the beetle shed, and iv) dumpsters where animal carcasses were disposed. Additionally, we report that surgical materials used in surveillance practices may also hold CWD prions, even after being washed with aqueous solutions. All these results suggest that CWD prions may be disseminated due to human practices and that protocols should be established to decontaminate potentially contaminated materials.
Introduction
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy that affects multiple cervid species, including mule deer, white-tailed deer, elk, reindeer, and moose, among others (Escobar et al., 2020). CWD is widely distributed in the United States and Canada in captive and free-ranging cervids. CWD is characterized by long incubation periods, followed by a relatively short clinical phase (Rivera et al., 2019; Williams, 2005). CWD is fatal in all cases when animals are clinical, and to date, there is no feasible treatment for curing either CWD or any other prion disease (Haley and Hoover, 2015). Unfortunately, CWD is rapidly expanding in both number of animals affected and geographical areas (Bartz et al., 2024; National Wildlife Health Center, 2025). Considering this, efficient containment and diagnostic testing strategies are urgently needed.
CWD can spread within animal populations with relative ease (Otero et al., 2021). The propagation of this disease is thought to be more efficient in captive animals considering the higher animal densities found in these environments (Mathiason et al., 2009; Rivera et al., 2019; Bartelt-Hunt and Bartz, 2017; Zabel and Ortega, 2017). Nevertheless, CWD transmission is still highly efficient in free-ranging cervid populations. CWD transmission is thought to occur mostly through direct animal contacts, or indirectly through the exposure of naïve animals to contaminated environments (Denkers et al., 2013; Escobar et al., 2020; Haley et al., 2011; Mathiason et al., 2009; Miller Michael et al., 2004; Soto et al., 2024). Environmental components, including inert materials and living organisms, are thought to play relevant roles in the spread of CWD (Escobar et al., 2020; Jacobson et al., 2010a; Pritzkow et al., 2018). Different studies have shown that infectious prions can enter the environment through decaying carcasses from diseased animals (Soto et al., 2023), gestational tissues released during parturition (Bravo-Risi et al., 2021), saliva (Haley et al., 2011), and excreta (Bravo-Risi et al., 2023). Once released, prions can bind to soil and other natural and manmade components (Johnson et al., 2006; Smith et al., 2011) and become available to susceptible animals. Other organisms, including plants, predators, scavengers, parasites, insects, and annelids may also participate in these processes by interacting with contaminated environmental components or animal tissues (Carlson et al., 2023; Fischer et al., 2013; Inzalaco et al., 2023; Pritzkow et al., 2015; Soto et al., 2024). Overall, multiple components and processes are involved in CWD prion transmission and dissemination. However, most of them are understudied and/or assayed in laboratory-controlled conditions. As consequence, the specific contribution of each process/element in CWD environmental contamination is contentious.
An essential factor to consider in the spreading of CWD prions includes human activities (Mori et al., 2024). Along this line, regulatory agencies already implemented or are currently considering regulations in several of these activities including containment, animal processing, movement of animals, disposal of carcasses, and breeding practices, among others (Mateus-Pinilla et al., 2013; Mysterud and Edmunds, 2019). Although most of these practices have a potential for CWD transmission, their overall importance in CWD epidemiology is understudied. One example of this involves taxidermy procedures. Deer are regarded as one of the most popular game animals, generating a high economic output and involving various activities including deer breeding, taxidermy, meat processing, and others (Arnot et al., 2009; Bishop, 2004) (https://nri.tamu.edu/media/3968/economic-values-of-white-tailed-deer-in-texas-2022-survey-part-i.pdf). Hunters active in areas with reported CWD cases are requested to follow state, wildlife and public health recommendations (Carlson et al., 2018). In general, all agencies strongly suggest CWD animal testing before processing. Many hunters process game at private facilities and, because of no statutory authority or lack of awareness, CWD-relevant guidelines or rules may not exist for meat processing and taxidermy facilities despite their capacity to transmit CWD. Specifically, the movement of carcasses or carcasses parts from areas with a high CWD incidence to areas with little or no incidence may facilitate CWD introduction and spread. In addition, it should be considered that inappropriate disposal of carcasses and animal products may also contribute to the dissemination of this disease (Angers et al., 2009; Benestad et al., 2016). Considering the above-mentioned scenarios, proper surveillance of CWD and management of activities involving potentially infected animals and animal-derived products might help to contain it. If left unchecked, there could be profound negative impacts on human health and wildlife conservation.
In this study, we evaluated the presence of CWD prions in a taxidermy facility where deer heads are processed to prepare skull mounts. Analyses were made using the protein misfolding cyclic amplification (PMCA) technique in various biological and environmental samples. In addition, we also tested the persistence of CWD prions in surgical materials used in surveillance procedures. Our results show, for the first time, CWD-prion detection in a potentially exposed taxidermy facility. In addition, we also tested the persistence of CWD prions in surgical materials used in surveillance procedures. This information has important implications on several fronts of CWD research including environmental spreading, human-related practices, and exposure of humans to infectious animal prions.
Section snippets
Samples
The samples were collected from a taxidermy and free-ranging deer rehabilitation facility located on the same property in Val Verde County, Texas. Texas Parks and Wildlife Department (TPWD) staff were initially notified of a CWD clinical suspect on this property; this animal was ultimately euthanized and confirmed positive for CWD by the National Veterinary Services Laboratory on January 5th, 2020. Samples were collected from different areas on this property where deer heads were processed to Screening of CWD prions in environmental and processing elements from a taxidermy facility
The European mount technique is a widely utilized taxidermy practice aiming to produce a skull of an animal that is free of tissue. The first critical step in making a European mount is removing the flesh from the animal's head. This is achieved by removing the majority of the external flesh, eyeballs, ears, and the brain. Then, the de-meated skull is subjected to a maceration process using bacteria. The purpose of this step is to soften and degrade any remaining tissue on the skull. This Discussion
CWD continues expanding in distribution and prevalence in North America. Hence, an essential factor in limiting the spread of this disease is to monitor and contain infectivity foci. This has proven to be difficult considering the limited diagnostic tools available to effectively identify the CWD infectious agent (prions). Identifying and mitigating the negative role that anthropogenic activities have in promoting CWD transmission is an essential step in developing a prevention strategy. The Conclusion
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. …
https://www.sciencedirect.com/science/article/abs/pii/S0048969725009544
Failure to prevent classical scrapie after repeated decontamination of a barn
Published: 25 March 2025
Timm Konold, John Spiropoulos, Peter Bellerby & Hugh A Simmons BMC Research Notes volume 18, Article number: 126 (2025) Cite this article
Prions, the causative agent of scrapie in sheep, are extremely resistant to disinfection and can remain biologically active for years, which makes it challenging to prevent re-infection of susceptible animals on farms after a scrapie outbreak. The present study investigated the effectiveness of disinfection of a barn that previously housed scrapie-affected sheep as part of the husbandry of scrapie infected sheep on the farm. The barn was decontaminated with sodium hypochlorite for four times the recommended exposure time. Two cohorts, consisting of 25 and 21 sheep, with susceptible prion protein genotypes (VRQ/VRQ), born 2 years apart, were housed in the barn and infection monitored by examination of rectal biopsies.
Results
One sheep from the first cohort and four from the second were found to be infected from 775 (first cohort) and 550 days (second cohort) post exposure. It is concluded that decontamination with sodium hypochlorite at the recommended concentration and longer exposure time did not prevent re-infection of susceptible sheep. Disinfection of contaminated premises to eradicate scrapie continues to be a challenge.
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Discussion
Cleaning and disinfection (C&D) are imperative in any animal disease outbreak to reduce contamination and prevent re-infection of animals newly introduced animals. Unfortunately, the infectious agent responsible for TSEs, including scrapie, is extremely resistant to disinfection and other inactivation protocols and can persist in the environment for many years, which makes this very challenging [1]. Validated disinfection protocols based on experimental settings commonly applied use either sodium hydroxide or sodium hypochlorite, which are extremely corrosive, hazardous to humans and animals, and its use in a farm setting is questionable. Indeed, previous studies utilising the same farm as the one used in the current study have shown that effective decontamination of an animal barn that housed scrapie-affected sheep is virtually impossible because infection still re-occurs [2, 4]. It was hypothesized that the most likely cause of re-infection was dust from contaminated surroundings because of the detection of prions in dust samples collected in the barn [4]. However, a study assessing infectivity of field furniture suggested that there may be gradual reduction of prion activity through the weathering process (repeated cycle of environmental heat and cold) [9]. If this was the case, it should be possible to achieve sufficient decontamination over time if the disinfection protocol in the barn was continued. The current study aimed to assess whether inactivation may be possible over time by repeated decontamination using longer exposure times than recommended (4 × 1 h rather than a single hour [1]).
It was acknowledged that it may be difficult to assess contamination at very low levels by bioassay because sample size needs to increase. Twenty-five sheep used in the 2016-born cohort would have been sufficient to detect an infection rate of about 11% with 95% confidence. It was unfortunate that infection of a single sheep was only detected at 775 dpe, by which time we had already moved a second group into the barn. Retrospectively, it might have been better to wait until all sheep in the 2016-born had been culled and examined to determine scrapie status and then decide on the future, e.g. another cycle of C&D with introduction of sheep or discontinue, but it would not have taken into account that results may differ between groups at different time points when contamination may increase (due to more dust) or decrease (due to more inactivation of prions from the outside because of the weathering process). There appeared to be an increase in infection rate although the difference between the 2016- and 2018-born cohort was not significant. It is possible that this was a result of gradual increase in contamination, caused by the single scrapie-positive sheep at 775 dpe in the 2016-born cohort, by the scrapie-positive sheep in the 2018-cohort and resulting contamination of the whole barn, by dust from the outside, by dust from the ceiling that was not disinfected or by a combination of these. The first positive animal in the 2018-born cohort was detected by rectal biopsy examination at 550 dpe, which was 358 days after the previous, negative biopsy and considerably earlier than in the 2016-born cohort (775 dpe), which may imply a higher level of prion contamination of the barn. It has been shown that in natural infection prions can be detected by immunohistochemistry in lymphoid tissue in VRQ/VRQ lambs from 2 months of age [10, 11] and may be detected in the enteric nervous system of the small intestine up to 9 months before being detected in rectal tissue [12]. As shedding of the infectious agent from infected sheep may occur very early after infection, particularly in VRQ/VRQ sheep with an extensive lymphoid prion spread, it is likely that infected animals contributed to the subsequent infection of other sheep in the pen or spread of prions in dust prior to their removal from the barn. However, it would not explain the infection of the single sheep in the 2016-born cohort, which was by prions from the outside or by prions within the barn that were not inactivated during the disinfection process. Nevertheless, there was a significant reduction in infection incidence compared to the previous study with the same decontamination regime, which caused infection of 24 or 25 sheep [4], even though complete inactivation of prions was not achieved.
The comparatively long period between exposure and first detection of PrPSc in RAMALT (775 days) and low infection rate (1 of 25) in the 2016-born cohort is suggestive of low infectious titre contamination with the scrapie agent. In 2002, six of eight lambs exposed to pasture on this farm from 2 days of age for 12 months without contact to scrapie-affected sheep had a median survival time of 794 days [13], i.e. they were at or close to clinical end-stage by the time the sheep in the 2016 cohort was just confirmed to be infected. The data from the 2018-born cohort suggest that it may take a minimum of 358 days from the day of first detection of PrPSc in RAMALT to clinical end-stage. Exposure of VRQ heterozygous sheep or sheep without a VRQ allele may result in an even longer incubation period, and infection may go unnoticed for some time leading to the erroneous assumption that sheep are free from the disease. As scrapie surveillance is generally restricted to examination of brain only, sheep at an earlier stage of infection when PrPSc spread to the central nervous system has not yet occurred may be missed.
In conclusion, this study has shown that repeated disinfection with sodium hypochlorite, even using extended decontamination times, did not prevent re-infection so that there is a risk of re-infection if sheep with susceptible genotypes are re-introduced. It is not known whether decontamination was ineffective or recontamination occurred from various sources.
Limitations
Source of contamination could not be established, which would potentially help to suggest prevention strategies.
Study design was not ideal due to the unpredictable nature of prion diseases (long incubation period until detection of infection in the first cohort but unexpectedly shorter in the second cohort).
https://bmcresnotes.biomedcentral.com/articles/10.1186/s13104-025-07188-1
I remember what someone told me, in confidence, about Scrapie back around 2001, 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?
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.
https://bvajournals.onlinelibrary.wiley.com/doi/abs/10.1136/vr.105054
***>This is very likely to have parallels with control efforts for CWD in cervids.
https://pubmed.ncbi.nlm.nih.gov/30602491/
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.
http://journal.frontiersin.org/article/10.3389/fvets.2015.00032/full
"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
Prion 2023 Abstracts
https://prion2023.org/wp-content/uploads/2023/10/Meeting-book-final-version2.pdf
Artificial mineral sites that pre-date endemic chronic wasting disease become prion hotspots
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.
https://int-cwd-sympo.org/wp-content/uploads/2023/06/final-agenda-with-abstracts.pdf
Detection of chronic wasting disease prions in the farm soil of the Republic of Korea
Here, we show that prion seeding activity was detected in extracts from farm soil following 4 years of incubation with CWD-infected brain homogenate.
https://journals.asm.org/doi/10.1128/msphere.00866-24
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
https://www.tandfonline.com/doi/full/10.1080/19336896.2022.2091286
https://intcwdsympo.files.wordpress.com/2023/06/final-agenda-with-abstracts.pdf?force_download=true
***> 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
https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.82011-0
In summary, CWD prions are efficiently transmitted to WTD via aerosolization using a delivered dose substantially lower than previously reported by the oral route. Our results provide further evidence that prions delivered to the nasal passages are sufficient to transmit CWD and allow the inference that aerosolization may facilitate the transmission of prions in general.
https://journals.asm.org/doi/10.1128/jvi.02852-12
In summary, our results establish aerosols as a surprisingly efficient modality of prion transmission. This novel pathway of prion transmission is not only conceptually relevant for the field of prion research, but also highlights a hitherto unappreciated risk factor for laboratory personnel and personnel of the meat processing industry. In the light of these findings, it may be appropriate to revise current prion-related biosafety guidelines and health standards in diagnostic and scientific laboratories being potentially confronted with prion infected materials. While we did not investigate whether production of prion aerosols in nature suffices to cause horizontal prion transmission, the finding of prions in biological fluids such as saliva, urine and blood suggests that it may be worth testing this possibility in future studies.
https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1001257
DEFRA
In summary, in endemic areas, there is a medium probability that the soil and surrounding environment is contaminated with CWD prions and in a bioavailable form. In rural areas where CWD has not been reported and deer are present, there is a greater than negligible risk the soil is contaminated with CWD prion.
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In summary, given the volume of tourists, hunters and servicemen moving between GB and North America, the probability of at least one person travelling to/from a CWD affected area and, in doing so, contaminating their clothing, footwear and/or equipment prior to arriving in GB is greater than negligible... For deer hunters, specifically, the risk is likely to be greater given the increased contact with deer and their environment. However, there is significant uncertainty associated with these estimates.
Friday, December 14, 2012
DEFRA U.K. What is the risk of Chronic Wasting Disease CWD being introduced into Great Britain? A Qualitative Risk Assessment October 2012
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36% in 2007 (Almberg et al., 2011). In such areas, population declines of deer of up to 30 to 50% have been observed (Almberg et al., 2011). In areas of Colorado, the prevalence can be as high as 30% (EFSA, 2011). The clinical signs of CWD in affected adults are weight loss and behavioural changes that can span weeks or months (Williams, 2005). In addition, signs might include excessive salivation, behavioural alterations including a fixed stare and changes in interaction with other animals in the herd, and an altered stance (Williams, 2005). These signs are indistinguishable from cervids experimentally infected with bovine spongiform encephalopathy (BSE). Given this, if CWD was to be introduced into countries with BSE such as GB, for example, infected deer populations would need to be tested to differentiate if they were infected with CWD or BSE to minimise the risk of BSE entering the human food-chain via affected venison.
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The rate of transmission of CWD has been reported to be as high as 30% and can approach 100% among captive animals in endemic areas (Safar et al., 2008).
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In summary, in endemic areas, there is a medium probability that the soil and surrounding environment is contaminated with CWD prions and in a bioavailable form. In rural areas where CWD has not been reported and deer are present, there is a greater than negligible risk the soil is contaminated with CWD prion.
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In summary, given the volume of tourists, hunters and servicemen moving between GB and North America, the probability of at least one person travelling to/from a CWD affected area and, in doing so, contaminating their clothing, footwear and/or equipment prior to arriving in GB is greater than negligible...
UFor deer hunters, specifically, the risk is likely to be greater given the increased contact with deer and their environment. However, there is significant uncertainty associated with these estimates.
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Therefore, it is considered that farmed and park deer may have a higher probability of exposure to CWD transferred to the environment than wild deer given the restricted habitat range and higher frequency of contact with tourists and returning GB residents.
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https://web.archive.org/web/20170404125557/http://webarchive.nationalarchives.gov.uk/20130822084033/http://www.defra.gov.uk/animal-diseases/files/qra_chronic-wasting-disease-121029.pdf
Title: Horizontal transmission of chronic wasting disease in reindeer
Submitted to: Emerging Infectious Diseases Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/29/2016 Publication Date: 12/1/2016
Citation: Moore, S., Kunkle, R., Greenlee, M., Nicholson, E., Richt, J., Hamir, A., Waters, W., Greenlee, J. 2016. Horizontal transmission of chronic wasting disease in reindeer.
Emerging Infectious Diseases. 22(12):2142-2145. doi:10.3201/eid2212.160635.
Interpretive Summary: Chronic wasting disease (CWD) is a fatal neurodegenerative disease that occurs in farmed and wild cervids (deer and elk) of North America and was recently diagnosed in a single free-ranging reindeer (Rangifer tarandus tarandus) in Norway. CWD is a transmissible spongiform encephalopathy (TSE) that is caused by infectious proteins called prions that are resistant to various methods of decontamination and environmental degradation. Little is known about the susceptibility of or potential for transmission amongst reindeer. In this experiment, we tested the susceptibility of reindeer to CWD from various sources (elk, mule deer, or white-tailed deer) after intracranial inoculation and tested the potential for infected reindeer to transmit to non-inoculated animals by co-housing or housing in adjacent pens. Reindeer were susceptible to CWD from elk, mule deer, or white-tailed deer sources after experimental inoculation. Most importantly, non-inoculated reindeer that were co-housed with infected reindeer or housed in pens adjacent to infected reindeer but without the potential for nose-to-nose contact also developed evidence of CWD infection. This is a major new finding that may have a great impact on the recently diagnosed case of CWD in the only remaining free-ranging reindeer population in Europe as our findings imply that horizontal transmission to other reindeer within that herd has already occurred. Further, this information will help regulatory and wildlife officials developing plans to reduce or eliminate CWD and cervid farmers that want to ensure that their herd remains CWD-free, but were previously unsure of the potential for reindeer to transmit CWD.
Technical Abstract: Chronic wasting disease (CWD) is a naturally-occurring, fatal prion disease of cervids. Reindeer (Rangifer tarandus tarandus) are susceptible to CWD following oral challenge, and CWD was recently reported in a free-ranging reindeer of Norway. Potential contact between CWD-affected cervids and Rangifer species that are free-ranging or co-housed on farms presents a potential risk of CWD transmission. The aims of this study were to 1) investigate the transmission of CWD from white-tailed deer (Odocoileus virginianus; CWDwtd), mule deer (Odocoileus hemionus; CWDmd), or elk (Cervus elaphus nelsoni; CWDelk) to reindeer via the intracranial route, and 2) to assess for direct and indirect horizontal transmission to non-inoculated sentinels. Three groups of 5 reindeer fawns were challenged intracranially with CWDwtd, CWDmd, or CWDelk. Two years after challenge of inoculated reindeer, non-inoculated negative control reindeer were introduced into the same pen as the CWDwtd inoculated reindeer (direct contact; n=4) or into a pen adjacent to the CWDmd inoculated reindeer (indirect contact; n=2). Experimentally inoculated reindeer were allowed to develop clinical disease. At death/euthanasia a complete necropsy examination was performed, including immunohistochemical testing of tissues for disease-associated CWD prion protein (PrPcwd). Intracranially challenged reindeer developed clinical disease from 21 months post-inoculation (months PI). PrPcwd was detected in 5 out of 6 sentinel reindeer although only 2 out of 6 developed clinical disease during the study period (< 57 months PI). We have shown that reindeer are susceptible to CWD from various cervid sources and can transmit CWD to naïve reindeer both directly and indirectly.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=328261
Conclusions
Potential sources of infectivity for direct contact animals include urine, feces, and saliva from their CWDwtd-challenged pen-mates, as has been shown for CWD-affected white-tailed deer (6,8,9). Pinpointing the source of infectivity in the indirect contact group is more difficult. Infectious prions can travel at least 30 m in airborne particulate (10), but because the negative control reindeer in the pen adjacent to the indirect contact reindeer did not become positive, a more direct route of transmission is likely in this case. Penning, feeding, and watering protocols were designed to prevent exposure of negative control and indirect contact reindeer to potential infectivity on feed and water buckets, bedding, or fencing (6,11). However, reindeer might have had access to bedding from adjacent pens that had spread into the central alleyway.
During the 5-year course of this study, reindeer were moved between pens several times to maintain an optimal number of animals per pen (Technical Appendix Figure 1). Prolonged persistence of prion infectivity in the natural environment has been documented for both CWD (2 years [5]) and scrapie (up to 16 years [12]). In addition, thorough cleaning and disinfection might not be sufficient to remove all infectivity from the environment, leading to persistence of infectivity under experimental housing conditions (13).
In reindeer challenged orally with the agent of CWD, the SS138 genotype (serine/serine at PRNPcodon 138) has been associated with susceptibility to disease and the NS138 (asparagine/serine) genotype with resistance (1). In the study we report, disease developed in reindeer with the NS138 genotype after intracranial inoculation, although the extent of lymphoreticular system involvement was significantly lower than in NN138 and SS138 reindeer. The potential association of the NN138 polymorphism with shorter survival times is interesting. However, as with all potential genotype versus phenotype interactions, care should be taken not to over-interpret these results given the small group sizes and the large number of PRNPgenotype groups in this study.
Our results demonstrate that reindeer are susceptible to the agent of CWD from white-tailed deer, mule deer, and elk sources after intracranial inoculation. Furthermore, naive reindeer are susceptible to the agent of CWD after direct and indirect exposure to CWD-infected reindeer, suggesting a high potential for horizontal transmission of CWD within and between farmed and free-ranging reindeer (and caribou) populations.
https://wwwnc.cdc.gov/eid/article/22/12/16-0635_article
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5189146/
Artificial mineral sites that pre-date endemic chronic wasting disease become prion hotspots
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.
https://int-cwd-sympo.org/wp-content/uploads/2023/06/final-agenda-with-abstracts.pdf
Detection of chronic wasting disease prions in the farm soil of the Republic of Korea
Here, we show that prion seeding activity was detected in extracts from farm soil following 4 years of incubation with CWD-infected brain homogenate.
https://journals.asm.org/doi/10.1128/msphere.00866-24
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
https://www.tandfonline.com/doi/full/10.1080/19336896.2022.2091286
https://intcwdsympo.files.wordpress.com/2023/06/final-agenda-with-abstracts.pdf?force_download=true
***> 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
https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.82011-0
This old study always brings to light the long term effects of a TSE in the environment…
Transmission of Creutzfeldt-Jakob disease to a chimpanzee by electrodes contaminated during neurosurgery
Gibbs CJ Jr, Asher DM, Kobrine A, Amyx HL, Sulima MP, Gajdusek DC.
Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892. Stereotactic multicontact electrodes used to probe the cerebral cortex of a middle aged woman with progressive dementia were previously implicated in the accidental transmission of Creutzfeldt-Jakob disease (CJD) to two younger patients. The diagnoses of CJD have been confirmed for all three cases. More than two years after their last use in humans, after three cleanings and repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were implanted in the cortex of a chimpanzee. Eighteen months later the animal became ill with CJD. This finding serves to re-emphasise the potential danger posed by reuse of instruments contaminated with the agents of spongiform encephalopathies, even after scrupulous attempts to clean them.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8006664&dopt=Abstract
THE CWD TSE Prion aka mad cow type disease is not your normal pathogen.
The TSE prion disease survives ashing to 600 degrees celsius, that’s around 1112 degrees farenheit.
YOU cannot cook the TSE prion disease out of meat.
YOU can take the ash and mix it with saline and inject that ash into a mouse, and the mouse will go down with TSE.
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production as well.
The TSE prion agent also survives Simulated Wastewater Treatment Processes.
IN fact, you should also know that the TSE Prion agent will survive in the environment for years, if not decades.
YOU can bury it and it will not go away.
The TSE agent is capable of infected your water table i.e. Detection of protease-resistant cervid prion protein in water from a CWD-endemic area.
it’s NOT your ordinary pathogen you can just cook it out and be done
New studies on the heat resistance of hamster-adapted scrapie agent: Threshold survival after ashing at 600°C suggests an inorganic template of replication
http://www.pnas.org/content/97/7/3418.full
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2493038/
March 13, 2025
Prion Partitioning and Persistence in Environmental Waters
https://pubs.acs.org/doi/epdf/10.1021/acs.est.4c11497?ref=article_openPDF
Prions in Waterways
https://vimeo.com/898941380?fbclid=IwAR3Di7tLuU-iagCetdt4-CVPrOPQQrv037QS1Uxz0tX3z7BuvPeYlwIp7IY
Detection of protease-resistant cervid prion protein in water from a CWD-endemic area
https://www.ncbi...nlm.nih.gov/pmc/articles/PMC2802782/pdf/prion0303_0171.pdf
A Quantitative Assessment of the Amount of Prion Diverted to Category 1 Materials and Wastewater During Processing
http://onlinelibrary.wiley.com/doi/10.1111/j.1539-6924.2012.01922.x/abstract
Rapid assessment of bovine spongiform encephalopathy prion inactivation by heat treatment in yellow grease produced in the industrial manufacturing process of meat and bone meals
https://bmcvetres.biomedcentral.com/track/pdf/10.1186/1746-6148-9-134.pdf
THURSDAY, FEBRUARY 28, 2019
BSE infectivity survives burial for five years with only limited spread
https://link.springer.com/content/pdf/10.1007%2Fs00705-019-04154-8.pdf
Texas CWD in the Wild
CWD spreads among wild populations at a relatively slow rate, limited by the natural home range and dispersed nature of wild animals. There is evidence that CWD can also be spread when carcasses, specifically brain and spinal material, are transported from CWD areas to other parts of the state.
Since 2012, CWD has been detected in wild deer in just 9 counties in Texas and is only established in the western panhandle and far west Texas.
Texas CWD in Captive Deer
In that same period of time, captive deer breeders have exposed over half of Texas counties to CWD.
Deer held in captive breeding facilities are confined to much tighter spaces, and have intimate contact with many more animals on a daily basis. By far the greatest factor in amplifying the spread of CWD is the artificial movement of these animals, shipped in livestock trailers hundreds of miles, far outside of their natural home range, and ultimately released to co-mingle with wild deer.
https://www.cwdintexas.com/?fbclid=IwZXh0bgNhZW0CMTEAAR0S-yyIu-Lia3irHlKgo539m0ArjzCe6tLp8Hw45_Lwimg4WYGR9_MDCHM_aem_dg5_E-RqPot9tWyvj38Big
Texas CWD Surveillance Positives Tracking Page is still outdated
https://tpwd.texas.gov/huntwild/wild/diseases/cwd/positive-cases/listing-cwd-cases-texas.phtml#texasCWD
My last figures of Texas CWD Totals To Date were 1061 Confirmed, but that is way outdated.
Texas CWD total by calendar years
https://chronic-wasting-disease.blogspot.com/2024/12/texas-cwd-tse-prion-positive-samples-by.html
Counties where CWD Exposed Deer were Released
https://tpwd.texas.gov/documents/257/CWD-Trace-OutReleaseSites.pdf
Number of CWD Exposed Deer Released by County
https://tpwd.texas.gov/documents/258/CWD-Trace-OutReleaseSites-NbrDeer.pdf
CWD Status Captive Herds
https://www.aphis.usda.gov/sites/default/files/status-of-captive-herds.pdf
Texas Game Wardens Bust Illegal Deer Operations Across the State Feb. 27, 2025
Media Contact: TPWD News, Business Hours, 512-389-8030
AUSTIN – A recent investigation by Texas Game Wardens resulted in approximately 1,200 pending charges and 22 suspects from across the state involved in the deer breeding industry and black-market wildlife trade.
The suspects and charges are associated with three deer breeding facilities, ten release sites, one deer management pen and three illegal facilities not registered in the Texas Wildlife Information Management Services (TWIMS) database, meaning they were operating or receiving deer in violation of registration requirements and disease monitoring protocols.
"The hard work and commitment of our Texas Game Wardens to uncover these violations cannot be overstated," said TPWD Executive Director David Yoskowitz. "Their pivotal role in conservation law enforcement helps ensure the health of all deer populations in the state. These violations don’t just break the law—they undermine the very foundation of responsible wildlife management in Texas."
Texas Parks and Wildlife Department (TPWD) has referred the cases to prosecutors’ offices in 11 Texas counties.
The cases stem from a prior investigation involving the illegal smuggling of captive white-tailed deer, ultimately leading wardens to uncover this much larger network of alleged offenders after the arrest and conviction of two individuals that occurred in Montgomery County.
The investigation uncovered approximately 500 Class C charges, 700 Class B charges, 22 Class A charges and multiple state jail felony charges. Due to the ongoing nature of this case, the final number of charges filed may vary.
"I am incredibly proud of the dedication and diligence Texas Game Wardens devoted to this case," said Col. Ronald VanderRoest, TPWD law enforcement director. "An operation of this size and scope did not develop overnight and the widespread violations may have continued unchecked, posing an even greater threat to Texas’ deer populations and the integrity of the deer breeding industry, if not for their hard work.”
TPWD has established science-based regulations and procedures to both manage deer breeding in Texas and prevent major disease outbreak, all with the goal of ensuring the long-term sustainability of native and captive deer in Texas.
Chronic Wasting Disease (CWD) is a fatal neurological disease and can devastate deer populations by silently spreading through direct animal contact and contaminated environments. Without close monitoring, illegal movement of captive deer increases the risk of introducing CWD to areas it is not known to exist, potentially leading to widespread outbreaks which will impact more than just the health of Texas deer.
Yoskowitz also noted that with many rural Texans depending on hunting as their full or supplemental income, a large-scale outbreak of CWD could pose a significant threat to white-tailed deer hunting, which has a $9.6 billion annual economic contribution and could irreversibly alter Texas’ rich outdoor heritage.
By circumventing requirements, disregarding regulations and falsifying official records, the suspects in this case intentionally placed the state’s entire deer population at risk, explained VanderRoest.
"These individuals and ranches operated with impunity, repeatedly violating established laws designed to protect Texas’ natural resources and safeguard the state’s wildlife against disease transmission," VanderRoest said. "Systematic abuse of the regulatory framework governing the deer breeding industry will not be tolerated as we focus on our mission of conservation law enforcement."
Class C pending charges include transferring deer without valid antemortem CWD tests, lack of identifying tattoos or valid transfer permits, failure to report mortality within the required seven-day period following detection and failure to submit CWD samples within seven days of collection. Additional pending charges include illegally selling and purchasing wild white-tailed deer and hunting deer in a closed season to falsify and circumvent CWD testing requirements by submitting samples from free-ranging wild white-tailed deer in place of breeder deer.
Class B pending charges include possession of wild deer in breeder facilities to replace dead breeder deer, multiple Trap, Transport and Transplant (TTT) permit violations and criminal mischief for the destruction of county and state property.
TTT charges stem from the illegal trapping, transporting and transplanting of free-ranging white-tailed deer for release for hunting, trapping previously released wild deer and reselling them, illegal operation of unregistered facilities participating in the same TTT activities and the undocumented and unauthorized transportation and release of unidentified fawns.
Suspects face Class A charges for taking white-tailed deer without landowner consent and for hunting exotic animals from a public roadway or right of way.
Pending state jail felony charges include tampering with government records falsifying information in TWIMS reports, which were certified as accurate. These incidents include falsifying tests through the submission of tissue samples from poached wild deer for CWD testing in place of the samples of breeder deer, tag swapping between breeder deer, and swapping tags between breeder deer and replacement deer captured in the wild.
TPWD remains committed to enforcing these laws and will hold violators accountable. Texas Game Wardens will continue to pursue those who disregard regulations and illegally exploit Texas’ natural resources, putting both captive and native populations at risk.
About Texas Game Wardens
Texas Game Wardens, within the Law Enforcement Division of TPWD, are responsible for enforcing laws related to the conservation and management of natural resources and public safety through community-based law enforcement. Their mission is to provide hunting, fishing and outdoor recreation opportunities for the use and enjoyment of present and future generations. Additionally, they play a crucial role in search and rescue operations during natural disasters, exemplifying their commitment to protecting both the environment and the people of Texas.
If you witness a wildlife violation in progress, please call 1-800-792-GAME (4263) immediately and report it to Operation Game Thief (OGT), Texas’ Wildlife Crime-Stoppers Program. Dispatchers are available 24/7. Reports can be made anonymously, and tipsters may be eligible for rewards up to $1,000 for information leading to a conviction.
https://tpwd.texas.gov/newsmedia/releases/?req=20250227b
https://chronic-wasting-disease.blogspot.com/2025/02/texas-game-wardens-bust-illegal-deer.html
https://chronic-wasting-disease.blogspot.com/2025/02/texas-animal-health-commission-423rd.html
So, this is what we leave our children and grandchildren?
TEXAS ANIMAL HEALTH COMMISSION AGENCY STRATEGIC PLAN FISCAL YEARS 2025 - 2029 CWD
https://www.tahc.texas.gov/agency/pdf/TAHC_Strategic_Plan_2025_2029.pdf
Texas Kimble County Farm Chronic Wasting Disease CWD TSE Prion Approximate Herd Prevalence 12%
SUMMARY MINUTES OF THE 407th COMMISSION MEETING Texas Animal Health Commission
September 22, 2020
Chronic Wasting Disease (CWD):
A new CWD positive breeding herd was disclosed in February 2020 in Kimble County. This herd depopulation was completed in July 2020. Including the two index positive deer, an additional eight more positive deer were disclosed (approximate herd prevalence 12%). Since July 2015 and prior to this discovery, five positive captive breeder herds have been disclosed and four of those are in Medina County. One herd in Lavaca and three herds in Medina County were depopulated leaving one large herd in Medina County that is managed on a herd plan. A new zone was established in Val Verde County in December 2019 as a result of a positive free-ranging White-tailed Deer (WTD). A second positive WTD was also disclosed in February 2020 in the same area.
SUMMARY MINUTES OF THE 407th COMMISSION MEETING – 9/22/2020
Scrapie: The flock identified in April 2016 remains under quarantine in Hartley County.
https://www.tahc.texas.gov/agency/meetings/minutes/SummaryMinutes_CommMtg_2020-09-22
http://web.archive.org/web/20201017124040/https://www.tahc.texas.gov/agency/meetings/minutes/SummaryMinutes_CommMtg_2020-09-22.pdf
Texas CWD Surveillance Positives Tracking Page is outdated
https://tpwd.texas.gov/huntwild/wild/diseases/cwd/positive-cases/listing-cwd-cases-texas.phtml#texasCWD
My last figures of Texas CWD Totals To Date were 1061 Confirmed, but that is way outdated.
Texas CWD total by calendar years
https://chronic-wasting-disease.blogspot.com/2024/12/texas-cwd-tse-prion-positive-samples-by.html
terry
Chronic wasting disease (CWD) is a transmissible prionopathy affecting free-ranging and captive cervids. CWD is thought to spread through both direct and indirect transmission mechanisms. Along this line, human activities have not been thoroughly explored for their potential to spread this disease. One area of concern involves taxidermy procedures and surveillance activities as handled animals or carcasses are of unknown CWD statuses. Worrisomely, taxidermy facilities can act as foci of prion infectivity if appropriate biosecurity practices are not implemented. In this study, we evaluated the presence of infectious prions in a taxidermy facility that was possibly exposed to CWD prions. To determine this, we collected biological and environmental specimens from this site and screened them using the protein misfolding cyclic amplification (PMCA) technique. Additionally, we swabbed different surfaces possibly exposed to CWD-infected animals or carcasses. We report the presence of prions in i) waters used to digest tissues from deer carcasses, ii) soils that were in contact with the previously mentioned waters, iii) dermestid beetles used to clean skulls, iv) other insects found in the beetle shed, and iv) dumpsters where animal carcasses were disposed. Additionally, we report that surgical materials used in surveillance practices may also hold CWD prions, even after being washed with aqueous solutions. All these results suggest that CWD prions may be disseminated due to human practices and that protocols should be established to decontaminate potentially contaminated materials.
Introduction
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy that affects multiple cervid species, including mule deer, white-tailed deer, elk, reindeer, and moose, among others (Escobar et al., 2020). CWD is widely distributed in the United States and Canada in captive and free-ranging cervids. CWD is characterized by long incubation periods, followed by a relatively short clinical phase (Rivera et al., 2019; Williams, 2005). CWD is fatal in all cases when animals are clinical, and to date, there is no feasible treatment for curing either CWD or any other prion disease (Haley and Hoover, 2015). Unfortunately, CWD is rapidly expanding in both number of animals affected and geographical areas (Bartz et al., 2024; National Wildlife Health Center, 2025). Considering this, efficient containment and diagnostic testing strategies are urgently needed.
CWD can spread within animal populations with relative ease (Otero et al., 2021). The propagation of this disease is thought to be more efficient in captive animals considering the higher animal densities found in these environments (Mathiason et al., 2009; Rivera et al., 2019; Bartelt-Hunt and Bartz, 2017; Zabel and Ortega, 2017). Nevertheless, CWD transmission is still highly efficient in free-ranging cervid populations. CWD transmission is thought to occur mostly through direct animal contacts, or indirectly through the exposure of naïve animals to contaminated environments (Denkers et al., 2013; Escobar et al., 2020; Haley et al., 2011; Mathiason et al., 2009; Miller Michael et al., 2004; Soto et al., 2024). Environmental components, including inert materials and living organisms, are thought to play relevant roles in the spread of CWD (Escobar et al., 2020; Jacobson et al., 2010a; Pritzkow et al., 2018). Different studies have shown that infectious prions can enter the environment through decaying carcasses from diseased animals (Soto et al., 2023), gestational tissues released during parturition (Bravo-Risi et al., 2021), saliva (Haley et al., 2011), and excreta (Bravo-Risi et al., 2023). Once released, prions can bind to soil and other natural and manmade components (Johnson et al., 2006; Smith et al., 2011) and become available to susceptible animals. Other organisms, including plants, predators, scavengers, parasites, insects, and annelids may also participate in these processes by interacting with contaminated environmental components or animal tissues (Carlson et al., 2023; Fischer et al., 2013; Inzalaco et al., 2023; Pritzkow et al., 2015; Soto et al., 2024). Overall, multiple components and processes are involved in CWD prion transmission and dissemination. However, most of them are understudied and/or assayed in laboratory-controlled conditions. As consequence, the specific contribution of each process/element in CWD environmental contamination is contentious.
An essential factor to consider in the spreading of CWD prions includes human activities (Mori et al., 2024). Along this line, regulatory agencies already implemented or are currently considering regulations in several of these activities including containment, animal processing, movement of animals, disposal of carcasses, and breeding practices, among others (Mateus-Pinilla et al., 2013; Mysterud and Edmunds, 2019). Although most of these practices have a potential for CWD transmission, their overall importance in CWD epidemiology is understudied. One example of this involves taxidermy procedures. Deer are regarded as one of the most popular game animals, generating a high economic output and involving various activities including deer breeding, taxidermy, meat processing, and others (Arnot et al., 2009; Bishop, 2004) (https://nri.tamu.edu/media/3968/economic-values-of-white-tailed-deer-in-texas-2022-survey-part-i.pdf). Hunters active in areas with reported CWD cases are requested to follow state, wildlife and public health recommendations (Carlson et al., 2018). In general, all agencies strongly suggest CWD animal testing before processing. Many hunters process game at private facilities and, because of no statutory authority or lack of awareness, CWD-relevant guidelines or rules may not exist for meat processing and taxidermy facilities despite their capacity to transmit CWD. Specifically, the movement of carcasses or carcasses parts from areas with a high CWD incidence to areas with little or no incidence may facilitate CWD introduction and spread. In addition, it should be considered that inappropriate disposal of carcasses and animal products may also contribute to the dissemination of this disease (Angers et al., 2009; Benestad et al., 2016). Considering the above-mentioned scenarios, proper surveillance of CWD and management of activities involving potentially infected animals and animal-derived products might help to contain it. If left unchecked, there could be profound negative impacts on human health and wildlife conservation.
In this study, we evaluated the presence of CWD prions in a taxidermy facility where deer heads are processed to prepare skull mounts. Analyses were made using the protein misfolding cyclic amplification (PMCA) technique in various biological and environmental samples. In addition, we also tested the persistence of CWD prions in surgical materials used in surveillance procedures. Our results show, for the first time, CWD-prion detection in a potentially exposed taxidermy facility. In addition, we also tested the persistence of CWD prions in surgical materials used in surveillance procedures. This information has important implications on several fronts of CWD research including environmental spreading, human-related practices, and exposure of humans to infectious animal prions.
Section snippets
Samples
The samples were collected from a taxidermy and free-ranging deer rehabilitation facility located on the same property in Val Verde County, Texas. Texas Parks and Wildlife Department (TPWD) staff were initially notified of a CWD clinical suspect on this property; this animal was ultimately euthanized and confirmed positive for CWD by the National Veterinary Services Laboratory on January 5th, 2020. Samples were collected from different areas on this property where deer heads were processed to Screening of CWD prions in environmental and processing elements from a taxidermy facility
The European mount technique is a widely utilized taxidermy practice aiming to produce a skull of an animal that is free of tissue. The first critical step in making a European mount is removing the flesh from the animal's head. This is achieved by removing the majority of the external flesh, eyeballs, ears, and the brain. Then, the de-meated skull is subjected to a maceration process using bacteria. The purpose of this step is to soften and degrade any remaining tissue on the skull. This Discussion
CWD continues expanding in distribution and prevalence in North America. Hence, an essential factor in limiting the spread of this disease is to monitor and contain infectivity foci. This has proven to be difficult considering the limited diagnostic tools available to effectively identify the CWD infectious agent (prions). Identifying and mitigating the negative role that anthropogenic activities have in promoting CWD transmission is an essential step in developing a prevention strategy. The Conclusion
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. …
https://www.sciencedirect.com/science/article/abs/pii/S0048969725009544
Failure to prevent classical scrapie after repeated decontamination of a barn
Published: 25 March 2025
Timm Konold, John Spiropoulos, Peter Bellerby & Hugh A Simmons BMC Research Notes volume 18, Article number: 126 (2025) Cite this article
Prions, the causative agent of scrapie in sheep, are extremely resistant to disinfection and can remain biologically active for years, which makes it challenging to prevent re-infection of susceptible animals on farms after a scrapie outbreak. The present study investigated the effectiveness of disinfection of a barn that previously housed scrapie-affected sheep as part of the husbandry of scrapie infected sheep on the farm. The barn was decontaminated with sodium hypochlorite for four times the recommended exposure time. Two cohorts, consisting of 25 and 21 sheep, with susceptible prion protein genotypes (VRQ/VRQ), born 2 years apart, were housed in the barn and infection monitored by examination of rectal biopsies.
Results
One sheep from the first cohort and four from the second were found to be infected from 775 (first cohort) and 550 days (second cohort) post exposure. It is concluded that decontamination with sodium hypochlorite at the recommended concentration and longer exposure time did not prevent re-infection of susceptible sheep. Disinfection of contaminated premises to eradicate scrapie continues to be a challenge.
Snip…
Discussion
Cleaning and disinfection (C&D) are imperative in any animal disease outbreak to reduce contamination and prevent re-infection of animals newly introduced animals. Unfortunately, the infectious agent responsible for TSEs, including scrapie, is extremely resistant to disinfection and other inactivation protocols and can persist in the environment for many years, which makes this very challenging [1]. Validated disinfection protocols based on experimental settings commonly applied use either sodium hydroxide or sodium hypochlorite, which are extremely corrosive, hazardous to humans and animals, and its use in a farm setting is questionable. Indeed, previous studies utilising the same farm as the one used in the current study have shown that effective decontamination of an animal barn that housed scrapie-affected sheep is virtually impossible because infection still re-occurs [2, 4]. It was hypothesized that the most likely cause of re-infection was dust from contaminated surroundings because of the detection of prions in dust samples collected in the barn [4]. However, a study assessing infectivity of field furniture suggested that there may be gradual reduction of prion activity through the weathering process (repeated cycle of environmental heat and cold) [9]. If this was the case, it should be possible to achieve sufficient decontamination over time if the disinfection protocol in the barn was continued. The current study aimed to assess whether inactivation may be possible over time by repeated decontamination using longer exposure times than recommended (4 × 1 h rather than a single hour [1]).
It was acknowledged that it may be difficult to assess contamination at very low levels by bioassay because sample size needs to increase. Twenty-five sheep used in the 2016-born cohort would have been sufficient to detect an infection rate of about 11% with 95% confidence. It was unfortunate that infection of a single sheep was only detected at 775 dpe, by which time we had already moved a second group into the barn. Retrospectively, it might have been better to wait until all sheep in the 2016-born had been culled and examined to determine scrapie status and then decide on the future, e.g. another cycle of C&D with introduction of sheep or discontinue, but it would not have taken into account that results may differ between groups at different time points when contamination may increase (due to more dust) or decrease (due to more inactivation of prions from the outside because of the weathering process). There appeared to be an increase in infection rate although the difference between the 2016- and 2018-born cohort was not significant. It is possible that this was a result of gradual increase in contamination, caused by the single scrapie-positive sheep at 775 dpe in the 2016-born cohort, by the scrapie-positive sheep in the 2018-cohort and resulting contamination of the whole barn, by dust from the outside, by dust from the ceiling that was not disinfected or by a combination of these. The first positive animal in the 2018-born cohort was detected by rectal biopsy examination at 550 dpe, which was 358 days after the previous, negative biopsy and considerably earlier than in the 2016-born cohort (775 dpe), which may imply a higher level of prion contamination of the barn. It has been shown that in natural infection prions can be detected by immunohistochemistry in lymphoid tissue in VRQ/VRQ lambs from 2 months of age [10, 11] and may be detected in the enteric nervous system of the small intestine up to 9 months before being detected in rectal tissue [12]. As shedding of the infectious agent from infected sheep may occur very early after infection, particularly in VRQ/VRQ sheep with an extensive lymphoid prion spread, it is likely that infected animals contributed to the subsequent infection of other sheep in the pen or spread of prions in dust prior to their removal from the barn. However, it would not explain the infection of the single sheep in the 2016-born cohort, which was by prions from the outside or by prions within the barn that were not inactivated during the disinfection process. Nevertheless, there was a significant reduction in infection incidence compared to the previous study with the same decontamination regime, which caused infection of 24 or 25 sheep [4], even though complete inactivation of prions was not achieved.
The comparatively long period between exposure and first detection of PrPSc in RAMALT (775 days) and low infection rate (1 of 25) in the 2016-born cohort is suggestive of low infectious titre contamination with the scrapie agent. In 2002, six of eight lambs exposed to pasture on this farm from 2 days of age for 12 months without contact to scrapie-affected sheep had a median survival time of 794 days [13], i.e. they were at or close to clinical end-stage by the time the sheep in the 2016 cohort was just confirmed to be infected. The data from the 2018-born cohort suggest that it may take a minimum of 358 days from the day of first detection of PrPSc in RAMALT to clinical end-stage. Exposure of VRQ heterozygous sheep or sheep without a VRQ allele may result in an even longer incubation period, and infection may go unnoticed for some time leading to the erroneous assumption that sheep are free from the disease. As scrapie surveillance is generally restricted to examination of brain only, sheep at an earlier stage of infection when PrPSc spread to the central nervous system has not yet occurred may be missed.
In conclusion, this study has shown that repeated disinfection with sodium hypochlorite, even using extended decontamination times, did not prevent re-infection so that there is a risk of re-infection if sheep with susceptible genotypes are re-introduced. It is not known whether decontamination was ineffective or recontamination occurred from various sources.
Limitations
Source of contamination could not be established, which would potentially help to suggest prevention strategies.
Study design was not ideal due to the unpredictable nature of prion diseases (long incubation period until detection of infection in the first cohort but unexpectedly shorter in the second cohort).
https://bmcresnotes.biomedcentral.com/articles/10.1186/s13104-025-07188-1
I remember what someone told me, in confidence, about Scrapie back around 2001, 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?
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.
snip...
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.
https://bvajournals.onlinelibrary.wiley.com/doi/abs/10.1136/vr.105054
***>This is very likely to have parallels with control efforts for CWD in cervids.
https://pubmed.ncbi.nlm.nih.gov/30602491/
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.
http://journal.frontiersin.org/article/10.3389/fvets.2015.00032/full
"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
Prion 2023 Abstracts
https://prion2023.org/wp-content/uploads/2023/10/Meeting-book-final-version2.pdf
Artificial mineral sites that pre-date endemic chronic wasting disease become prion hotspots
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.
https://int-cwd-sympo.org/wp-content/uploads/2023/06/final-agenda-with-abstracts.pdf
Detection of chronic wasting disease prions in the farm soil of the Republic of Korea
Here, we show that prion seeding activity was detected in extracts from farm soil following 4 years of incubation with CWD-infected brain homogenate.
https://journals.asm.org/doi/10.1128/msphere.00866-24
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
https://www.tandfonline.com/doi/full/10.1080/19336896.2022.2091286
https://intcwdsympo.files.wordpress.com/2023/06/final-agenda-with-abstracts.pdf?force_download=true
***> 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
https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.82011-0
In summary, CWD prions are efficiently transmitted to WTD via aerosolization using a delivered dose substantially lower than previously reported by the oral route. Our results provide further evidence that prions delivered to the nasal passages are sufficient to transmit CWD and allow the inference that aerosolization may facilitate the transmission of prions in general.
https://journals.asm.org/doi/10.1128/jvi.02852-12
In summary, our results establish aerosols as a surprisingly efficient modality of prion transmission. This novel pathway of prion transmission is not only conceptually relevant for the field of prion research, but also highlights a hitherto unappreciated risk factor for laboratory personnel and personnel of the meat processing industry. In the light of these findings, it may be appropriate to revise current prion-related biosafety guidelines and health standards in diagnostic and scientific laboratories being potentially confronted with prion infected materials. While we did not investigate whether production of prion aerosols in nature suffices to cause horizontal prion transmission, the finding of prions in biological fluids such as saliva, urine and blood suggests that it may be worth testing this possibility in future studies.
https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1001257
DEFRA
In summary, in endemic areas, there is a medium probability that the soil and surrounding environment is contaminated with CWD prions and in a bioavailable form. In rural areas where CWD has not been reported and deer are present, there is a greater than negligible risk the soil is contaminated with CWD prion.
snip…
In summary, given the volume of tourists, hunters and servicemen moving between GB and North America, the probability of at least one person travelling to/from a CWD affected area and, in doing so, contaminating their clothing, footwear and/or equipment prior to arriving in GB is greater than negligible... For deer hunters, specifically, the risk is likely to be greater given the increased contact with deer and their environment. However, there is significant uncertainty associated with these estimates.
Friday, December 14, 2012
DEFRA U.K. What is the risk of Chronic Wasting Disease CWD being introduced into Great Britain? A Qualitative Risk Assessment October 2012
snip.....
36% in 2007 (Almberg et al., 2011). In such areas, population declines of deer of up to 30 to 50% have been observed (Almberg et al., 2011). In areas of Colorado, the prevalence can be as high as 30% (EFSA, 2011). The clinical signs of CWD in affected adults are weight loss and behavioural changes that can span weeks or months (Williams, 2005). In addition, signs might include excessive salivation, behavioural alterations including a fixed stare and changes in interaction with other animals in the herd, and an altered stance (Williams, 2005). These signs are indistinguishable from cervids experimentally infected with bovine spongiform encephalopathy (BSE). Given this, if CWD was to be introduced into countries with BSE such as GB, for example, infected deer populations would need to be tested to differentiate if they were infected with CWD or BSE to minimise the risk of BSE entering the human food-chain via affected venison.
snip.....
The rate of transmission of CWD has been reported to be as high as 30% and can approach 100% among captive animals in endemic areas (Safar et al., 2008).
snip.....
In summary, in endemic areas, there is a medium probability that the soil and surrounding environment is contaminated with CWD prions and in a bioavailable form. In rural areas where CWD has not been reported and deer are present, there is a greater than negligible risk the soil is contaminated with CWD prion.
snip.....
In summary, given the volume of tourists, hunters and servicemen moving between GB and North America, the probability of at least one person travelling to/from a CWD affected area and, in doing so, contaminating their clothing, footwear and/or equipment prior to arriving in GB is greater than negligible...
UFor deer hunters, specifically, the risk is likely to be greater given the increased contact with deer and their environment. However, there is significant uncertainty associated with these estimates.
snip.....
Therefore, it is considered that farmed and park deer may have a higher probability of exposure to CWD transferred to the environment than wild deer given the restricted habitat range and higher frequency of contact with tourists and returning GB residents.
snip.....
https://web.archive.org/web/20170404125557/http://webarchive.nationalarchives.gov.uk/20130822084033/http://www.defra.gov.uk/animal-diseases/files/qra_chronic-wasting-disease-121029.pdf
Title: Horizontal transmission of chronic wasting disease in reindeer
Submitted to: Emerging Infectious Diseases Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/29/2016 Publication Date: 12/1/2016
Citation: Moore, S., Kunkle, R., Greenlee, M., Nicholson, E., Richt, J., Hamir, A., Waters, W., Greenlee, J. 2016. Horizontal transmission of chronic wasting disease in reindeer.
Emerging Infectious Diseases. 22(12):2142-2145. doi:10.3201/eid2212.160635.
Interpretive Summary: Chronic wasting disease (CWD) is a fatal neurodegenerative disease that occurs in farmed and wild cervids (deer and elk) of North America and was recently diagnosed in a single free-ranging reindeer (Rangifer tarandus tarandus) in Norway. CWD is a transmissible spongiform encephalopathy (TSE) that is caused by infectious proteins called prions that are resistant to various methods of decontamination and environmental degradation. Little is known about the susceptibility of or potential for transmission amongst reindeer. In this experiment, we tested the susceptibility of reindeer to CWD from various sources (elk, mule deer, or white-tailed deer) after intracranial inoculation and tested the potential for infected reindeer to transmit to non-inoculated animals by co-housing or housing in adjacent pens. Reindeer were susceptible to CWD from elk, mule deer, or white-tailed deer sources after experimental inoculation. Most importantly, non-inoculated reindeer that were co-housed with infected reindeer or housed in pens adjacent to infected reindeer but without the potential for nose-to-nose contact also developed evidence of CWD infection. This is a major new finding that may have a great impact on the recently diagnosed case of CWD in the only remaining free-ranging reindeer population in Europe as our findings imply that horizontal transmission to other reindeer within that herd has already occurred. Further, this information will help regulatory and wildlife officials developing plans to reduce or eliminate CWD and cervid farmers that want to ensure that their herd remains CWD-free, but were previously unsure of the potential for reindeer to transmit CWD.
Technical Abstract: Chronic wasting disease (CWD) is a naturally-occurring, fatal prion disease of cervids. Reindeer (Rangifer tarandus tarandus) are susceptible to CWD following oral challenge, and CWD was recently reported in a free-ranging reindeer of Norway. Potential contact between CWD-affected cervids and Rangifer species that are free-ranging or co-housed on farms presents a potential risk of CWD transmission. The aims of this study were to 1) investigate the transmission of CWD from white-tailed deer (Odocoileus virginianus; CWDwtd), mule deer (Odocoileus hemionus; CWDmd), or elk (Cervus elaphus nelsoni; CWDelk) to reindeer via the intracranial route, and 2) to assess for direct and indirect horizontal transmission to non-inoculated sentinels. Three groups of 5 reindeer fawns were challenged intracranially with CWDwtd, CWDmd, or CWDelk. Two years after challenge of inoculated reindeer, non-inoculated negative control reindeer were introduced into the same pen as the CWDwtd inoculated reindeer (direct contact; n=4) or into a pen adjacent to the CWDmd inoculated reindeer (indirect contact; n=2). Experimentally inoculated reindeer were allowed to develop clinical disease. At death/euthanasia a complete necropsy examination was performed, including immunohistochemical testing of tissues for disease-associated CWD prion protein (PrPcwd). Intracranially challenged reindeer developed clinical disease from 21 months post-inoculation (months PI). PrPcwd was detected in 5 out of 6 sentinel reindeer although only 2 out of 6 developed clinical disease during the study period (< 57 months PI). We have shown that reindeer are susceptible to CWD from various cervid sources and can transmit CWD to naïve reindeer both directly and indirectly.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=328261
Conclusions
Potential sources of infectivity for direct contact animals include urine, feces, and saliva from their CWDwtd-challenged pen-mates, as has been shown for CWD-affected white-tailed deer (6,8,9). Pinpointing the source of infectivity in the indirect contact group is more difficult. Infectious prions can travel at least 30 m in airborne particulate (10), but because the negative control reindeer in the pen adjacent to the indirect contact reindeer did not become positive, a more direct route of transmission is likely in this case. Penning, feeding, and watering protocols were designed to prevent exposure of negative control and indirect contact reindeer to potential infectivity on feed and water buckets, bedding, or fencing (6,11). However, reindeer might have had access to bedding from adjacent pens that had spread into the central alleyway.
During the 5-year course of this study, reindeer were moved between pens several times to maintain an optimal number of animals per pen (Technical Appendix Figure 1). Prolonged persistence of prion infectivity in the natural environment has been documented for both CWD (2 years [5]) and scrapie (up to 16 years [12]). In addition, thorough cleaning and disinfection might not be sufficient to remove all infectivity from the environment, leading to persistence of infectivity under experimental housing conditions (13).
In reindeer challenged orally with the agent of CWD, the SS138 genotype (serine/serine at PRNPcodon 138) has been associated with susceptibility to disease and the NS138 (asparagine/serine) genotype with resistance (1). In the study we report, disease developed in reindeer with the NS138 genotype after intracranial inoculation, although the extent of lymphoreticular system involvement was significantly lower than in NN138 and SS138 reindeer. The potential association of the NN138 polymorphism with shorter survival times is interesting. However, as with all potential genotype versus phenotype interactions, care should be taken not to over-interpret these results given the small group sizes and the large number of PRNPgenotype groups in this study.
Our results demonstrate that reindeer are susceptible to the agent of CWD from white-tailed deer, mule deer, and elk sources after intracranial inoculation. Furthermore, naive reindeer are susceptible to the agent of CWD after direct and indirect exposure to CWD-infected reindeer, suggesting a high potential for horizontal transmission of CWD within and between farmed and free-ranging reindeer (and caribou) populations.
https://wwwnc.cdc.gov/eid/article/22/12/16-0635_article
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5189146/
Artificial mineral sites that pre-date endemic chronic wasting disease become prion hotspots
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.
https://int-cwd-sympo.org/wp-content/uploads/2023/06/final-agenda-with-abstracts.pdf
Detection of chronic wasting disease prions in the farm soil of the Republic of Korea
Here, we show that prion seeding activity was detected in extracts from farm soil following 4 years of incubation with CWD-infected brain homogenate.
https://journals.asm.org/doi/10.1128/msphere.00866-24
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
https://www.tandfonline.com/doi/full/10.1080/19336896.2022.2091286
https://intcwdsympo.files.wordpress.com/2023/06/final-agenda-with-abstracts.pdf?force_download=true
***> 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
https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.82011-0
This old study always brings to light the long term effects of a TSE in the environment…
Transmission of Creutzfeldt-Jakob disease to a chimpanzee by electrodes contaminated during neurosurgery
Gibbs CJ Jr, Asher DM, Kobrine A, Amyx HL, Sulima MP, Gajdusek DC.
Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892. Stereotactic multicontact electrodes used to probe the cerebral cortex of a middle aged woman with progressive dementia were previously implicated in the accidental transmission of Creutzfeldt-Jakob disease (CJD) to two younger patients. The diagnoses of CJD have been confirmed for all three cases. More than two years after their last use in humans, after three cleanings and repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were implanted in the cortex of a chimpanzee. Eighteen months later the animal became ill with CJD. This finding serves to re-emphasise the potential danger posed by reuse of instruments contaminated with the agents of spongiform encephalopathies, even after scrupulous attempts to clean them.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8006664&dopt=Abstract
THE CWD TSE Prion aka mad cow type disease is not your normal pathogen.
The TSE prion disease survives ashing to 600 degrees celsius, that’s around 1112 degrees farenheit.
YOU cannot cook the TSE prion disease out of meat.
YOU can take the ash and mix it with saline and inject that ash into a mouse, and the mouse will go down with TSE.
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production as well.
The TSE prion agent also survives Simulated Wastewater Treatment Processes.
IN fact, you should also know that the TSE Prion agent will survive in the environment for years, if not decades.
YOU can bury it and it will not go away.
The TSE agent is capable of infected your water table i.e. Detection of protease-resistant cervid prion protein in water from a CWD-endemic area.
it’s NOT your ordinary pathogen you can just cook it out and be done
New studies on the heat resistance of hamster-adapted scrapie agent: Threshold survival after ashing at 600°C suggests an inorganic template of replication
http://www.pnas.org/content/97/7/3418.full
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2493038/
March 13, 2025
Prion Partitioning and Persistence in Environmental Waters
https://pubs.acs.org/doi/epdf/10.1021/acs.est.4c11497?ref=article_openPDF
Prions in Waterways
https://vimeo.com/898941380?fbclid=IwAR3Di7tLuU-iagCetdt4-CVPrOPQQrv037QS1Uxz0tX3z7BuvPeYlwIp7IY
Detection of protease-resistant cervid prion protein in water from a CWD-endemic area
https://www.ncbi...nlm.nih.gov/pmc/articles/PMC2802782/pdf/prion0303_0171.pdf
A Quantitative Assessment of the Amount of Prion Diverted to Category 1 Materials and Wastewater During Processing
http://onlinelibrary.wiley.com/doi/10.1111/j.1539-6924.2012.01922.x/abstract
Rapid assessment of bovine spongiform encephalopathy prion inactivation by heat treatment in yellow grease produced in the industrial manufacturing process of meat and bone meals
https://bmcvetres.biomedcentral.com/track/pdf/10.1186/1746-6148-9-134.pdf
THURSDAY, FEBRUARY 28, 2019
BSE infectivity survives burial for five years with only limited spread
https://link.springer.com/content/pdf/10.1007%2Fs00705-019-04154-8.pdf
Texas CWD in the Wild
CWD spreads among wild populations at a relatively slow rate, limited by the natural home range and dispersed nature of wild animals. There is evidence that CWD can also be spread when carcasses, specifically brain and spinal material, are transported from CWD areas to other parts of the state.
Since 2012, CWD has been detected in wild deer in just 9 counties in Texas and is only established in the western panhandle and far west Texas.
Texas CWD in Captive Deer
In that same period of time, captive deer breeders have exposed over half of Texas counties to CWD.
Deer held in captive breeding facilities are confined to much tighter spaces, and have intimate contact with many more animals on a daily basis. By far the greatest factor in amplifying the spread of CWD is the artificial movement of these animals, shipped in livestock trailers hundreds of miles, far outside of their natural home range, and ultimately released to co-mingle with wild deer.
https://www.cwdintexas.com/?fbclid=IwZXh0bgNhZW0CMTEAAR0S-yyIu-Lia3irHlKgo539m0ArjzCe6tLp8Hw45_Lwimg4WYGR9_MDCHM_aem_dg5_E-RqPot9tWyvj38Big
Texas CWD Surveillance Positives Tracking Page is still outdated
https://tpwd.texas.gov/huntwild/wild/diseases/cwd/positive-cases/listing-cwd-cases-texas.phtml#texasCWD
My last figures of Texas CWD Totals To Date were 1061 Confirmed, but that is way outdated.
Texas CWD total by calendar years
https://chronic-wasting-disease.blogspot.com/2024/12/texas-cwd-tse-prion-positive-samples-by.html
Counties where CWD Exposed Deer were Released
https://tpwd.texas.gov/documents/257/CWD-Trace-OutReleaseSites.pdf
Number of CWD Exposed Deer Released by County
https://tpwd.texas.gov/documents/258/CWD-Trace-OutReleaseSites-NbrDeer.pdf
CWD Status Captive Herds
https://www.aphis.usda.gov/sites/default/files/status-of-captive-herds.pdf
Texas Game Wardens Bust Illegal Deer Operations Across the State Feb. 27, 2025
Media Contact: TPWD News, Business Hours, 512-389-8030
AUSTIN – A recent investigation by Texas Game Wardens resulted in approximately 1,200 pending charges and 22 suspects from across the state involved in the deer breeding industry and black-market wildlife trade.
The suspects and charges are associated with three deer breeding facilities, ten release sites, one deer management pen and three illegal facilities not registered in the Texas Wildlife Information Management Services (TWIMS) database, meaning they were operating or receiving deer in violation of registration requirements and disease monitoring protocols.
"The hard work and commitment of our Texas Game Wardens to uncover these violations cannot be overstated," said TPWD Executive Director David Yoskowitz. "Their pivotal role in conservation law enforcement helps ensure the health of all deer populations in the state. These violations don’t just break the law—they undermine the very foundation of responsible wildlife management in Texas."
Texas Parks and Wildlife Department (TPWD) has referred the cases to prosecutors’ offices in 11 Texas counties.
The cases stem from a prior investigation involving the illegal smuggling of captive white-tailed deer, ultimately leading wardens to uncover this much larger network of alleged offenders after the arrest and conviction of two individuals that occurred in Montgomery County.
The investigation uncovered approximately 500 Class C charges, 700 Class B charges, 22 Class A charges and multiple state jail felony charges. Due to the ongoing nature of this case, the final number of charges filed may vary.
"I am incredibly proud of the dedication and diligence Texas Game Wardens devoted to this case," said Col. Ronald VanderRoest, TPWD law enforcement director. "An operation of this size and scope did not develop overnight and the widespread violations may have continued unchecked, posing an even greater threat to Texas’ deer populations and the integrity of the deer breeding industry, if not for their hard work.”
TPWD has established science-based regulations and procedures to both manage deer breeding in Texas and prevent major disease outbreak, all with the goal of ensuring the long-term sustainability of native and captive deer in Texas.
Chronic Wasting Disease (CWD) is a fatal neurological disease and can devastate deer populations by silently spreading through direct animal contact and contaminated environments. Without close monitoring, illegal movement of captive deer increases the risk of introducing CWD to areas it is not known to exist, potentially leading to widespread outbreaks which will impact more than just the health of Texas deer.
Yoskowitz also noted that with many rural Texans depending on hunting as their full or supplemental income, a large-scale outbreak of CWD could pose a significant threat to white-tailed deer hunting, which has a $9.6 billion annual economic contribution and could irreversibly alter Texas’ rich outdoor heritage.
By circumventing requirements, disregarding regulations and falsifying official records, the suspects in this case intentionally placed the state’s entire deer population at risk, explained VanderRoest.
"These individuals and ranches operated with impunity, repeatedly violating established laws designed to protect Texas’ natural resources and safeguard the state’s wildlife against disease transmission," VanderRoest said. "Systematic abuse of the regulatory framework governing the deer breeding industry will not be tolerated as we focus on our mission of conservation law enforcement."
Class C pending charges include transferring deer without valid antemortem CWD tests, lack of identifying tattoos or valid transfer permits, failure to report mortality within the required seven-day period following detection and failure to submit CWD samples within seven days of collection. Additional pending charges include illegally selling and purchasing wild white-tailed deer and hunting deer in a closed season to falsify and circumvent CWD testing requirements by submitting samples from free-ranging wild white-tailed deer in place of breeder deer.
Class B pending charges include possession of wild deer in breeder facilities to replace dead breeder deer, multiple Trap, Transport and Transplant (TTT) permit violations and criminal mischief for the destruction of county and state property.
TTT charges stem from the illegal trapping, transporting and transplanting of free-ranging white-tailed deer for release for hunting, trapping previously released wild deer and reselling them, illegal operation of unregistered facilities participating in the same TTT activities and the undocumented and unauthorized transportation and release of unidentified fawns.
Suspects face Class A charges for taking white-tailed deer without landowner consent and for hunting exotic animals from a public roadway or right of way.
Pending state jail felony charges include tampering with government records falsifying information in TWIMS reports, which were certified as accurate. These incidents include falsifying tests through the submission of tissue samples from poached wild deer for CWD testing in place of the samples of breeder deer, tag swapping between breeder deer, and swapping tags between breeder deer and replacement deer captured in the wild.
TPWD remains committed to enforcing these laws and will hold violators accountable. Texas Game Wardens will continue to pursue those who disregard regulations and illegally exploit Texas’ natural resources, putting both captive and native populations at risk.
About Texas Game Wardens
Texas Game Wardens, within the Law Enforcement Division of TPWD, are responsible for enforcing laws related to the conservation and management of natural resources and public safety through community-based law enforcement. Their mission is to provide hunting, fishing and outdoor recreation opportunities for the use and enjoyment of present and future generations. Additionally, they play a crucial role in search and rescue operations during natural disasters, exemplifying their commitment to protecting both the environment and the people of Texas.
If you witness a wildlife violation in progress, please call 1-800-792-GAME (4263) immediately and report it to Operation Game Thief (OGT), Texas’ Wildlife Crime-Stoppers Program. Dispatchers are available 24/7. Reports can be made anonymously, and tipsters may be eligible for rewards up to $1,000 for information leading to a conviction.
https://tpwd.texas.gov/newsmedia/releases/?req=20250227b
https://chronic-wasting-disease.blogspot.com/2025/02/texas-game-wardens-bust-illegal-deer.html
https://chronic-wasting-disease.blogspot.com/2025/02/texas-animal-health-commission-423rd.html
So, this is what we leave our children and grandchildren?
TEXAS ANIMAL HEALTH COMMISSION AGENCY STRATEGIC PLAN FISCAL YEARS 2025 - 2029 CWD
https://www.tahc.texas.gov/agency/pdf/TAHC_Strategic_Plan_2025_2029.pdf
Texas Kimble County Farm Chronic Wasting Disease CWD TSE Prion Approximate Herd Prevalence 12%
SUMMARY MINUTES OF THE 407th COMMISSION MEETING Texas Animal Health Commission
September 22, 2020
Chronic Wasting Disease (CWD):
A new CWD positive breeding herd was disclosed in February 2020 in Kimble County. This herd depopulation was completed in July 2020. Including the two index positive deer, an additional eight more positive deer were disclosed (approximate herd prevalence 12%). Since July 2015 and prior to this discovery, five positive captive breeder herds have been disclosed and four of those are in Medina County. One herd in Lavaca and three herds in Medina County were depopulated leaving one large herd in Medina County that is managed on a herd plan. A new zone was established in Val Verde County in December 2019 as a result of a positive free-ranging White-tailed Deer (WTD). A second positive WTD was also disclosed in February 2020 in the same area.
SUMMARY MINUTES OF THE 407th COMMISSION MEETING – 9/22/2020
Scrapie: The flock identified in April 2016 remains under quarantine in Hartley County.
https://www.tahc.texas.gov/agency/meetings/minutes/SummaryMinutes_CommMtg_2020-09-22
http://web.archive.org/web/20201017124040/https://www.tahc.texas.gov/agency/meetings/minutes/SummaryMinutes_CommMtg_2020-09-22.pdf
Texas CWD Surveillance Positives Tracking Page is outdated
https://tpwd.texas.gov/huntwild/wild/diseases/cwd/positive-cases/listing-cwd-cases-texas.phtml#texasCWD
My last figures of Texas CWD Totals To Date were 1061 Confirmed, but that is way outdated.
Texas CWD total by calendar years
https://chronic-wasting-disease.blogspot.com/2024/12/texas-cwd-tse-prion-positive-samples-by.html
CDC CWD TSE Prion Update 2025
KEY POINTS
Chronic wasting disease affects deer, elk and similar animals in the United States and a few other countries.
The disease hasn't been shown to infect people.
***> However, it might be a risk to people if they have contact with or eat meat from animals infected with CWD.
Prions in Muscles of Cervids with Chronic Wasting Disease, Norway
Volume 31, Number 2—February 2025
Research
Prions in Muscles of Cervids with Chronic Wasting Disease, Norway
Snip…
In summary, the results of our study indicate that prions are widely distributed in peripheral and edible tissues of cervids in Norway, including muscles. This finding highlights the risk of human exposure to small amounts of prions through handling and consuming infected cervids. Nevertheless, we note that this study did not investigate the zoonotic potential of the Norway CWD prions. In North America, humans have historically consumed meat from CWD-infected animals, which has been documented to harbor prions (35,44–47). Despite the potential exposure to prions, no epidemiologic evidence indicates a correlation between the occurrence of CWD cases in animals and the prevalence of human prion diseases (48). A recent bioassay study reported no transmissions from 3 Nordic isolates into transgenic mice expressing human PrP (49). Therefore, our findings should be interpreted with caution in terms of human health implications, and further research is required to determine the zoonotic potential of these CWD strains.
The presence of prions in peripheral tissues indicates that CWD may have a systemic nature in all Norwegian cervid species, challenging the view that prions are exclusively localized in the CNS in sporadic CWD of moose and red deer. Our findings expand the notion of just how widely distributed prions can be in cervids affected with CWD and call into question the capability of emerging CWD strains in terms of infectivity to other species, including humans.
Appendix
Volume 31, Number 2—February 2025
Dispatch
Detection of Chronic Wasting Disease Prions in Raw, Processed, and Cooked Elk Meat, Texas, USA
Rebeca Benavente, Fraser Brydon, Francisca Bravo-Risi, Paulina Soto, J. Hunter Reed, Mitch Lockwood, Glenn Telling, Marcelo A. Barria, and Rodrigo MoralesComments to Author
Snip…
CWD prions have been detected in the muscle of both farmed and wild deer (10), and at concentrations relevant to sustain disease transmission (11). CWD prions have also been identified across several cervid species and in multiple tissues, including lymph nodes, spleen, tongue, intestines, adrenal gland, eyes, reproductive tissues, ears, lungs, and liver, among others (12–14). Those findings raise concerns about the safety of ingesting processed meats that contain tissues other than skeletal muscle (15) (Appendix). https://wwwnc.cdc.gov/eid/article/31/2/24-0906-app1.pdf .
In addition, those findings highlight the need for continued vigilance and research on the transmission risks of prion diseases and for development of new preventative and detection measures to ensure the safety of the human food supply.
Snip…
Overall, our study results confirm previous reports describing the presence of CWD prions in elk muscles (13). The data also demonstrated CWD prion persistence in food products even after processing through different procedures, including the addition of salts, spices, and other edible elements. Of note, our data show that exposure to high temperatures used to cook the meat increased the availability of prions for in vitro amplification. Considering the potential implications in food safety and public health, we believe that the findings described in this study warrant further research. Our results suggest that although the elk meat used in this study resisted different manipulations involved in subsequent consumption by humans, their zoonotic potential was limited. Nevertheless, even though no cases of CWD transmission to human have been reported, the potential for human infection is still unclear and continued monitoring for zoonotic potential is warranted.
Volume 31, Number 1—January 2025
Dispatch
Detection of Prions in Wild Pigs (Sus scrofa) from Areas with Reported Chronic Wasting Disease Cases, United States
Abstract
Using a prion amplification assay, we identified prions in tissues from wild pigs (Sus scrofa) living in areas of the United States with variable chronic wasting disease (CWD) epidemiology. Our findings indicate that scavenging swine could play a role in disseminating CWD and could therefore influence its epidemiology, geographic distribution, and interspecies spread.
Snip…
Conclusions In summary, results from this study showed that wild pigs are exposed to cervid prions, although the pigs seem to display some resistance to infection via natural exposure. Future studies should address the susceptibility of this invasive animal species to the multiple prion strains circulating in the environment. Nonetheless, identification of CWD prions in wild pig tissues indicated the potential for pigs to move prions across the landscape, which may, in turn, influence the epidemiology and geographic spread of CWD.
Although the current U.S. feed ban is based on keeping tissues from TSE infected cattle from contaminating animal feed, swine rations in the U.S. could contain animal derived components including materials from scrapie infected sheep and goats. These results indicating the susceptibility of pigs to sheep scrapie, coupled with the limitations of the current feed ban, indicates that a revision of the feed ban may be necessary to protect swine production and potentially human health.
2. Determined that pigs naturally exposed to chronic wasting disease (CWD) may act as a reservoir of CWD infectivity. Chronic wasting disease is a naturally occurring, fatal, neurodegenerative disease of cervids. The potential for swine to serve as a host for the agent of CWD disease is unknown. The purpose of this study was to investigate the susceptibility of swine to the CWD agent following experimental oral or intracranial inoculation. Pigs were assigned to 1 of 3 groups: intracranially inoculated; orally inoculated; or non-inoculated. At market weight age, half of the pigs in each group were tested ('market weight' groups). The remaining pigs ('aged' groups) were allowed to incubate for up to 73 months post inoculation (MPI). Tissues collected at necropsy were examined for disease-associated prion protein (PrPSc) by multiple diagnostic methods. Brain samples from selected pigs were bioassayed in mice expressing porcine prion protein. Some pigs from each inoculated group were positive by one or more tests. Bioassay was positive in 4 out of 5 pigs assayed. Although only small amounts of PrPSc were detected using sensitive methods, this study demonstrates that pigs can serve as hosts for CWD. Detection of infectivity in orally inoculated pigs using mouse bioassay raises the possibility that naturally exposed pigs could act as a reservoir of CWD infectivity. Currently, swine rations in the U.S. could contain animal derived components including materials from deer or elk. In addition, feral swine could be exposed to infected carcasses in areas where CWD is present in wildlife populations. The current feed ban in the U.S. is based exclusively on keeping tissues from TSE infected cattle from entering animal feeds. These results indicating the susceptibility of pigs to CWD, coupled with the limitations of the current feed ban, indicates that a revision of the feed ban may be necessary to protect swine production and potentially human health.
***> Price of TSE Prion Poker goes up substantially, all you cattle ranchers and such, better pay close attention here...terry <***
Transmission of the chronic wasting disease agent from elk to cattle after oronasal exposure
Justin Greenlee, Jifeng Bian, Zoe Lambert, Alexis Frese, and Eric Cassmann Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA
Aims: The purpose of this study was to determine the susceptibility of cattle to chronic wasting disease agent from elk.
Materials and Methods: Initial studies were conducted in bovinized mice using inoculum derived from elk with various genotypes at codon 132 (MM, LM, LL). Based upon attack rates, inoculum (10% w/v brain homogenate) from an LM132 elk was selected for transmission studies in cattle. At approximately 2 weeks of age, one wild type steer (EE211) and one steer with the E211K polymorphism (EK211) were fed 1 mL of brain homogenate in a quart of milk replacer while another 1 mL was instilled intranasally. The cattle were examined daily for clinical signs for the duration of the experiment. One steer is still under observation at 71 months post-inoculation (mpi).
Results: Inoculum derived from MM132 elk resulted in similar attack rates and incubation periods in mice expressing wild type or K211 bovine PRNP, 35% at 531 days post inoculation (dpi) and 27% at 448 dpi, respectively. Inoculum from LM132 elk had a slightly higher attack rates in mice: 45% (693 dpi) in wild type cattle PRNP and 33% (468) in K211 mice. Inoculum from LL132 elk resulted in the highest attack rate in wild type bovinized mice (53% at 625 dpi), but no K211 mice were affected at >700 days. At approximately 70 mpi, the EK211 genotype steer developed clinical signs suggestive of prion disease, depression, low head carriage, hypersalivation, and ataxia, and was necropsied. Enzyme immunoassay (IDEXX) was positive in brainstem (OD=4.00, but non-detect in retropharyngeal lymph nodes and palatine tonsil. Immunoreactivity was largely limited to the brainstem, midbrain, and cervical spinal cord with a pattern that was primarily glia-associated.
Conclusions: Cattle with the E211K polymorphism are susceptible to the CWD agent after oronasal exposure of 0.2 g of infectious material.
Funded by: This research was funded in its entirety by congressionally appropriated funds to the United States Department of Agriculture, Agricultural Research Service. The funders of the work did not influence study design, data collection and analysis, decision to publish, or preparation of the manuscript.
"Cattle with the E211K polymorphism are susceptible to the CWD agent after oronasal exposure of 0.2 g of infectious material."
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Strain characterization of chronic wasting disease in bovine-PrP transgenic mice
Nuria Jerez-Garrido1, Sara Canoyra1, Natalia Fernández-Borges1, Alba Marín Moreno1, Sylvie L. Benestad2, Olivier Andreoletti3, Gordon Mitchell4, Aru Balachandran4, Juan María Torres1 and Juan Carlos Espinosa1. 1 Centro de Investigación en Sanidad Animal, CISA-INIA-CSIC, Madrid, Spain. 2 Norwegian Veterinary Institute, Ås, Norway. 3 UMR Institut National de la Recherche Agronomique (INRA)/École Nationale Vétérinaire de Toulouse (ENVT), Interactions Hôtes Agents Pathogènes, Toulouse, France. 4 Canadian Food Inspection Agency, Ottawa, Canada.
Aims: Chronic wasting disease (CWD) is an infectious prion disease that affects cervids. Various CWD prion strains have been identified in different cervid species from North America and Europe. The properties of the infectious prion strains are influenced by amino acid changes and polymorphisms in the PrP sequences of different cervid species. This study, aimed to assess the ability of a panel of CWD prion isolates from diverse cervid species from North America and Europe to infect bovine species, as well as to investigate the properties of the prion strains following the adaptation to the bovine-PrP context.
Materials and Methods: BoPrP-Tg110 mice overexpressing the bovine-PrP sequence were inoculated by intracranial route with a panel of CWD prion isolates from both North America (two white-tailed deer and two elk) and Europe (one reindeer, one moose and one red deer).
Results: Our results show distinct behaviours in the transmission of the CWD isolates to the BoPrP-Tg110 mouse model. Some of these isolates did not transmit even after the second passage. Those able to transmit displayed differences in terms of attack rate, survival times, biochemical properties of brain PrPres, and histopathology.
Conclusions: Altogether, these results exhibit the diversity of CWD strains present in the panel of CWD isolates and the ability of at least some CWD isolates to infect bovine species. Cattle being one of the most important farming species, this ability represents a potential threat to both animal and human health, and consequently deserves further study.
Funded by: MCIN/AEI /10.13039/501100011033 and by European Union NextGeneration EU/PRTR
Grant number: PCI2020-120680-2 ICRAD
"Altogether, these results exhibit the diversity of CWD strains present in the panel of CWD isolates and the ability of at least some CWD isolates to infect bovine species. Cattle being one of the most important farming species, this ability represents a potential threat to both animal and human health, and consequently deserves further study."
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MONDAY, OCTOBER 16, 2023
Transmission of the chronic wasting disease agent from elk to cattle after oronasal exposure
Price of TSE Prion Poker goes up substantially, all you cattle ranchers and such, better pay close attention here...
PRION 2023 CONTINUED;
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.
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.”
Detection of chronic wasting disease prions in processed meats
Rebeca Benavente1 , Francisca Bravo1,2, J. Hunter Reed3 , Mitch Lockwood3 , Glenn Telling4 , Rodrigo Morales1,2 1 Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Texas, USA; 2 Universidad Bernardo O’Higgins. Santiago, Chile; 3 Texas Parks and Wildlife Department, Texas, USA. 4 Prion Research Center, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
Aims: identify the presence of CWD prions in processed meats derived from elk.
Materials and Methods: In this study, we analyzed different processed meats derived from a CWD-positive (pre-clinical) free-ranging elk. Products tested included filets, sausages, boneless steaks, burgers, seasoned chili meats, and spiced meats. The presence of CWD-prions in these samples were assessed by PMCA using deer and elk substrates. The same analyses were performed in grilled and boiled meats to evaluate the resistance of the infectious agent to these procedures.
Results: Our results show positive prion detection in all the samples analyzed using deer and elk substrates. Surprisingly, cooked meats displayed increased seeding activities. This data suggests that CWD-prions are available to people even after meats are processed and cooked.
Conclusions: These results suggest CWD prions are accessible to humans through meats, even after processing and cooking. Considering the fact that these samples were collected from already processed specimens, the availability of CWD prions to humans is probably underestimated.
Funded by: NIH and USDA
Grant number: 1R01AI132695 and APP-20115 to RM
Acknowledgement: We would like to thank TPWD personnel for providing us with valuable samples
"Our results show positive prion detection in all the samples analyzed using deer and elk substrates. Surprisingly, cooked meats displayed increased seeding activities."
end...
PRION 2023 CONTINUED;
The detection and decontamination of chronic wasting disease prions during venison processing
Aims: There is a growing concern that chronic wasting disease (CWD) prions in venison pose a risk to human health. CWD prions accumulate in infected deer tissues that commonly enter the human food chain through meat processing and consumption. The United States (US) Food and Drug Administration and US Department of Agriculture now formally consider CWD-positive venison unfit for human and animal consumption. Yet, the degree to which prion contamination occurs during routine venison processing is unknown. Here, we use environmental surface swab methods to:
a) experimentally test meat processing equipment (i.e., stainless steel knives and polyethylene cutting boards) before and after processing CWD-positive venison and
b) test the efficacy of five different disinfectant types (i.e., Dawn dish soap, Virkon-S, Briotech, 10% bleach, and 40% bleach) to determine prion decontamination efficacy.
Materials and Methods: We used a real-time quaking-induced conversion (RT-QuIC) assay to determine CWD infection status of venison and to detect CWD prions in the swabs. We collected three swabs per surface and ran eight technical replicates on RT-QuIC.
Results: CWD prions were detected on all cutting boards (n= 3; replicates= 8/8, 8/8, 8/8 and knives (n= 3; replicates= 8/8, 8/8, 8/8) used in processing CWD-positive venison, but not on those used for CWD-negative venison. After processing CWD-positive venison, allowing the surfaces to dry, and washing the cutting board with Dawn dish soap, we detected CWD prions on the cutting board surface (n= 3; replicates= 8/8, 8/8, 8/8) but not on the knife (n= 3, replicates = 0/8, 0/8, 0/8). Similar patterns were observed with Briotech (cutting board: n= 3; replicates= 7/8, 1/8, 0/8; knife: n= 3; replicates = 0/8, 0/8, 0/8). We did not detect CWD prions on the knives or cutting boards after disinfecting with Virkon-S, 10% bleach, and 40% bleach.
Conclusions: These preliminary results suggest that Dawn dish soap and Briotech do not reliably decontaminate CWD prions from these surfaces. Our data suggest that Virkon-S and various bleach concentrations are more effective in reducing prion contamination of meat processing surfaces; however, surface type may also influence the ability of prions to adsorb to surfaces, preventing complete decontamination. Our results will directly inform best practices to prevent the introduction of CWD prions into the human food chain during venison processing.
Prion 2023 Abstracts
DETECTION OF CHRONIC WASTING DISEASE PRIONS IN PROCESSED MEATS.
Abstract
The zoonotic potential of chronic wasting disease (CWD) remains unknown. Currently, there are no known natural cases of CWD transmission to humans but increasing evidence suggests that the host range of CWD is not confined only to cervid species. Alarmingly, recent experimental evidence suggests that certain CWD isolates can induce disease in non-human primates. While the CDC strongly recommends determining CWD status in animals prior to consumption, this practice is voluntary. Consequently, it is plausible that a proportion of the cervid meat entering the human food chain may be contaminated with CWD. Of additional concern is that traditional diagnostic techniques used to detect CWD have relatively low sensitivity and are only approved for use in tissues other than those typically ingested by humans. In this study, we analyzed different processed meats derived from a pre-clinical, CWD-positive free-ranging elk. Products tested included filets, sausages, boneless steaks, burgers, ham steaks, seasoned chili meats, and spiced meats. CWD-prion presence in these products were assessed by PMCA using deer and elk substrates. Our results show positive prion detection in all products. To confirm the resilience of CWD-prions to traditional cooking methods, we grilled and boiled the meat products and evaluated them for any remnant PMCA seeding activity. Results confirmed the presence of CWD-prions in these meat products suggesting that infectious particles may still be available to people even after cooking. Our results strongly suggest ongoing human exposure to CWD-prions and raise significant concerns of zoonotic transmission through ingestion of CWD contaminated meat products.
***> Products tested included filets, sausages, boneless steaks, burgers, ham steaks, seasoned chili meats, and spiced meats.
***> CWD-prion presence in these products were assessed by PMCA using deer and elk substrates.
***> Our results show positive prion detection in all products.
***> Results confirmed the presence of CWD-prions in these meat products suggesting that infectious particles may still be available to people even after cooking.
***> Our results strongly suggest ongoing human exposure to CWD-prions and raise significant concerns of zoonotic transmission through ingestion of CWD contaminated meat products.
Transmission of prion infectivity from CWD-infected macaque tissues to rodent models demonstrates the zoonotic potential of chronic wasting disease.
Samia Hannaoui1,2, Ginny Cheng1,2, Wiebke Wemheuer3, Walter Schulz-Schaeffer3, Sabine Gilch1,2, Hermann Schatzl1,2 1University of Calgary, Calgary, Canada. 2Calgary Prion Research Unit, Calgary, Canada. 3Institute of Neuropathology, Medical Faculty, Saarland University, Homburg/Saar, Germany
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***> Further passage to cervidized mice revealed transmission with a 100% attack rate.
***> Our findings demonstrate that macaques, considered the best model for the zoonotic potential of prions, were infected upon CWD challenge, including the oral one.
****> The disease manifested as atypical in macaques and initial transgenic mouse transmissions, but with infectivity present at all times, as unveiled in the bank vole model with an unusual tissue tropism.
***> Epidemiologic surveillance of prion disease among cervid hunters and people likely to have consumed venison contaminated with chronic wasting disease
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Transmission of Cervid Prions to Humanized Mice Demonstrates the Zoonotic Potential of CWD
Samia Hannaouia, Irina Zemlyankinaa, Sheng Chun Changa, Maria Immaculata Arifina, Vincent Béringueb, Debbie McKenziec, Hermann M. Schatzla, and Sabine Gilcha
Results: Here, we provide the strongest evidence supporting the zoonotic potential of CWD prions, and their possible phenotype in humans. Inoculation of mice expressing human PrPCwith deer CWD isolates (strains Wisc-1 and 116AG) resulted in atypical clinical manifestations in > 75% of the mice, with myoclonus as leading clinical sign. Most of tg650brain homogenates were positive for seeding activity in RT-QuIC. Clinical disease and presentation was transmissible to tg650 mice and bank voles. Intriguingly, protease-resistant PrP in the brain of tg650 mice resembled that found in a familial human prion disease and was transmissible upon passage. Abnormal PrP aggregates upon infection with Wisc-1 were detectable in thalamus, hypothalamus, and midbrain/pons regions.
Unprecedented in human prion disease, feces of CWD-inoculated tg650 mice harbored prion seeding activity and infectious prions, as shown by inoculation of bank voles and tg650 with fecal homogenates.
Conclusions: This is the first evidence that CWD can infect humans and cause disease with a distinctive clinical presentation, signature, and tropism, which might be transmissible between humans while current diagnostic assays might fail to detect it. These findings have major implications for public health and CWD-management.
The finding that infectious PrPSc was shed in fecal material of CWD-infected humanized mice and induced clinical disease, different tropism, and typical three banding pattern-PrPres in bank voles that is transmissible upon second passage is highly concerning for public health. The fact that this biochemical signature in bank voles resembles that of the Wisc-1 original deer isolate and is different from that of bvWisc-1, in the migration profile and the glyco-form-ratio, is valid evidence that these results are not a product of contamination in our study. If CWD in humans is found to be contagious and transmissible among humans, as it is in cervids [57], the spread of the disease within humans might become endemic.
Transmission of cervid prions to humanized mice demonstrates the zoonotic potential of CWD
Acta Neuropathol 144, 767–784 (2022). https://doi.org/10.1007/s00401-022-02482-9
Published
22 August 2022
Fortuitous generation of a zoonotic cervid prion strain
Aims: Whether CWD prions can infect humans remains unclear despite the very substantial scale and long history of human exposure of CWD in many states or provinces of USA and Canada. Multiple in vitro conversion experiments and in vivo animal studies indicate that the CWD-to-human transmission barrier is not unbreakable. A major long-term public health concern on CWD zoonosis is the emergence of highly zoonotic CWD strains. We aim to address the question of whether highly zoonotic CWD strains are possible.
Materials and Methods: We inoculated several sCJD brain samples into cervidized transgenic mice (Tg12), which were intended as negative controls for bioassays of brain tissues from sCJD cases who had potentially been exposed to CWD. Some of the Tg12 mice became infected and their brain tissues were further examined by Western blot as well as serial passages in humanized or cervidized mice.
Results: Passage of sCJDMM1 in transgenic mice expressing elk PrP (Tg12) resulted in a “cervidized” CJD strain that we termed CJDElkPrP. We observed 100% transmission of the original CJDElkPrP in transgenic mice expressing human PrP. We passaged CJDElkPrP two more times in the Tg12 mice. We found that such second and third passage CJDElkPrP prions retained 100% transmission rate in the humanized mice, despite that the natural elk CWD isolates and CJDElkPrP share the same elk PrP sequence. In contrast, we and others found zero or poor transmission of natural elk CWD isolates in humanized mice.
Conclusions: Our data indicate that highly zoonotic cervid prion strains are not only possible but also can retain zoonotic potential after serial passages in cervids, suggesting a very significant and serious long-term risk of CWD zoonosis given that the broad and continuing spread of CWD prions will provide fertile grounds for the emergence of zoonotic CWD strains over time.
The finding that infectious PrPSc was shed in fecal material of CWD-infected humanized mice and induced clinical disease, different tropism, and typical three banding pattern-PrPres in bank voles that is transmissible upon second passage is highly concerning for public health. The fact that this biochemical signature in bank voles resembles that of the Wisc-1 original deer isolate and is different from that of bvWisc-1, in the migration profile and the glyco-form-ratio, is valid evidence that these results are not a product of contamination in our study. If CWD in humans is found to be contagious and transmissible among humans, as it is in cervids [57], the spread of the disease within humans might become endemic.
Transmission of cervid prions to humanized mice demonstrates the zoonotic potential of CWD
Acta Neuropathol 144, 767–784 (2022). https://doi.org/10.1007/s00401-022-02482-9
Published
22 August 2022
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