Chronic Wasting Disease

Trucking CWD TSE Prion

“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

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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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/

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

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

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.

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.