Third International CWD Symposium July 22-24, 2009 – Park City, Utah ABSTRACTS
Greetings,
I'm posting _some_ of the Third International CWD Symposium July 22-24, 2009 – Park City, Utah ABSTRACTS. In no certain order, just some topics of interest that i read over, and i might have missed some, and other topics might interest others. so, please read through all.........
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Third International CWD Symposium July 22-24, 2009 – Park City, Utah ABSTRACTS
Updates on the Status of Chronic Wasting Disease in Free-Ranging Cervids in Canada and the United States Each province and state has provided a 1-2 page status update on CWD in their area. The Third International Chronic Wasting Disease Symposium Program and Abstracts booklet is distributed to all meeting attendees. These updates were lightly edited to comply with formatting and space limits, but otherwise were printed as submitted. The Utah Division of Wildlife Resources and the organizers for the Symposium do not regard this Symposium Program and Abstracts booklet as a publication, and the status updates published herein should not be cited in scientific literature. Status updates are organized in alphabetical order with Canada appearing first and the states thereafter. Also included is a 1 page summary on the CWD Workshop held in Edmonton, Alberta in 2008.
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Chronic Wasting Disease and the Environment: Contamination, Persistence and Remediation
Christopher J. Johnson1* 1USGS National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin 53711 *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:cjjohnson@usgs.gov
The unique nature of prions, the etiological agents of transmissible spongiform encephalopathies (TSEs) makes them resistant to degradation and inactivation. Such stability leads to unexpected reservoirs of TSE infectivity, such as contaminated medical devices, feed additives, medications, and, under appropriate circumstances, the environment. Transmission of the TSEs scrapie and cervid chronic wasting disease (CWD) can occur both by horizontal and environmental routes. Soil serves as a likely reservoir of infectivity for both diseases. In the case of CWD, multiple scenarios have been proposed for the introduction of CWD into soils, including natural shedding of agent from cervids, deer dying on the landscape and release of agent by hunters. Parameters related to prion-soil binding, persistence and infectivity have been explored by a number of groups with concurring results indicating that prions remain infectious in the environment and can persist for extended periods of time. Other environments may also be subject to contamination with CWD, including run-off water, wastewater and landfills; however, the risks associated with the presence of CWD agent in these environments remain unknown. Further investigation into the fate, mobility, persistence and infectivity of prions in natural and engineered environments will aid in defining risks and containment procedures needed to safeguard human and animal health. Hope exists for remediation of natural and artificial environments contaminated with CWD in the form of soil minerals capable of inactivating prions and in organisms or enzymes with anti-prion activities.
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Evidence for Soil Humic Substances Interaction with Prions
Gabriele Giachin1, Hoang Ngoc Ai Tran1, Alja Margon2, Joanna Narkiewicz1, Giuseppe Legname1, and Liviana Leita2* 1Scuola Internazionale Superiore di Studi Avanzati - International School of Advanced Studies, (SISSA-ISAS), Trieste, Italy 2Agricultural Research Council (CRA) – Research Centre for Soil-Plant System, Gorizia, Italy *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:liviana.leita@entecra.it
A notable feature of scrapie and CWD is the horizontal transmission between grazing animals. Contaminated soil is therefore a good candidate for prion disease propagation. Since grazing animals tend to ingest from tens to hundreds grams of soil per day, either incidentally through the diet, or deliberately in answering salt intake needs. Indeed, several reports indicate that mule deer can develop CWD after grazing in locations that previously housed infected animals. Recent studies have proven that prions can be retained in soil, which could act as a carrier of infectivity even several years after the contamination. However, within the large spread of potentially infected lands, prion diseases have become endemic only in geographically limited regions. Reasons for this geographical distribution remain unknown, but it suggests a role of the different kinds of soil in either enhancing or accumulate prion infectivity. The extent of the prion transmission from a contaminated environment is unknown. Several studies have tried to address the issue of prion interaction with soil, but, at the present, different approaches show several drawbacks and technical difficulties, as soil is a complex, multi-component system of both mineral and organic interacting substances. Most research has focused on the adsorption capacity of clay minerals; however the contribution of soil organic components in adsorption has been neglected, as they represent a minor soil fraction on a weight basis. Among organic molecules, humic substances (HSs) are natural polyanions that result among the most reactive compounds in the soil and possess the largest specific surface area.
This work focuses on the interaction of the recombinant prion protein with a class of refractory natural organic polyanions, humic substances (HSs), polydisperse mixtures of polyphenol-polycarboxylic acids, possessing self associating and colloidal properties, whose precise chemical structure is still unknown. HSs are important refractory components of the natural organic matter in soils, sediments and waters, widely diffused in all climatic environments and naturally accumulated in soil under cool-temperate climates. They are classified as humic acids (HAs), which are soluble only in alkaline solutions, and fulvic acids (FAs), which are soluble in both alkaline and acid solutions. In addition, HAs and HFs display the ability to interact with xenobiotics to form chemical structures of different solubility and chemical and biochemical stability. It is therefore reasonable suppose that the interaction with prion proteins may lead to adducts with peculiar chemical and biophysical characteristics, thus affecting the transport, fixation and toxicity of prion, in particular, in soil and in the ecosystems. Results from our chemical, biophysical and biochemical investigations will be presented.
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Transport of the Pathogenic Prion Protein Through Porous Media
Joel A. Pedersen1*, Kurt H. Jacobson1, Seunghak Lee1, Debbie McKenzie2, and Craig H. Benson3. 1 University of Wisconsin, Madison, WI 53706 2 University of Alberta, Edmonton, AB, Canada 3 University of Washington, Seattle, WA 98195 *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:joelpedersen@wisc.edu
The present understanding of prion fate and transport in soils and subsurface environments is extremely limited. Such knowledge, however, is critical for assessing the risks associated with prions in the natural environment (e.g., from diseased carcasses, animal shedding) and in engineered systems (e.g., landfill disposal of carcasses and waste from eradication programs and meat recalls). We conducted saturated column experiments to examine the transport of the disease-associated prion protein (PrPTSE) through several soils with contrasting properties, green waste residual (a potential burial material), and fresh and aged municipal solid waste (MSW). PrPTSE was retained strongly by fine-textured soils. First-order attachment coefficients, estimated from breakthrough curves and profiles of retained PrPTSE, were > 1.8 h-1 for these soils. In contrast, PrPTSE was more mobile in porous media with higher porosity and organic carbon content (e.g., MSW, green waste residual). The transport parameters derived from the column experiments were used to model PrPTSE migration in a MSW landfill. To the extent that the PrPTSE used mimics that released from decomposing carcasses and the column experiments adequately simulate prion transport through burial soils, burial of CWD-infected materials at MSW landfills could provide secure containment of PrPTSE provided reasonable burial strategies (e.g., encasement in fine-grained soil) are used.
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Prion Protein Adsorption to Soil in a Competitive Matrix
Samuel E. Saunders1*, Jason C. Bartz2, and Shannon L. Bartelt-Hunt1 1Department of Civil Engineering, University of Nebraska-Lincoln, Peter Kiewit Institute, Omaha, Nebraska, United States of America, 2Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:ssaunders@unomaha.edu
It is likely that the soil environment serves as a stable reservoir of infectious CWD and scrapie prions, facilitating a sustained incidence of CWD in free-ranging cervid populations and complicating efforts to eliminate disease in captive livestock herds. Prion adsorption to soil may play an important role in prion mobility, proteolysis, and infectivity. We hypothesized that the competitive matrix in which prions enter the environment (e.g. tissue, excreta) could significantly affect prion interactions with soil, and that these interactions may vary with prion strain and species. We modified previously published methods to quantify adsorbed prions via direct detection and investigated prion adsorption to soil in both kinetic and isothermal studies. Prion-infected brain homogenates from two hamster strains and CWD-elk, were used as complex, relevant prion sources. We determined that maximum PrP adsorption requires days or weeks, depending on the soil or mineral, and is two to five orders of magnitude lower than previous studies using purified PrPSc or recPrP. Because PrP adsorption to soil is slow and less avid in tissue homogenate, the possibility of prion transport in soil environments cannot be excluded and requires further investigation. Our results indicate that binding to soil may protect prions from degradation, consistent with prions’ longevity in the environment. Our data also provide evidence that the N-terminal enhances adsorption of PrPSc to clay but may hinder adsorption to sand. We report strain and species differences in PrP adsorption, indicating that the fate of prions in the environment may vary with the prion strain and species infected. PrP adsorption was maximal at an intermediate aqueous concentration, most likely due to the competitive brain homogenate matrix in which it enters the soil environment.
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Detection of Protease-Resistant Prion Protein in Water from a CWD-Endemic Area
Tracy A. Nichols*1,2, Bruce Pulford1, Christy Wyckoff1,2, Crystal Meyerett1, Brady Michel1, Kevin Gertig3, Jean E. Jewell4, Glenn C. Telling5 and M.D. Zabel1 1Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA 2National Wildlife Research Center, Wildlife Services, United States Department of Agriculture, Fort Collins, Colorado, 80521, USA 3Fort Collins Water and Treatment Operations, Fort Collins, Colorado, 80521, USA 4 Department of Veterinary Sciences, Wyoming State Veterinary Laboratory, University of Wyoming, Laramie, Wyoming, 82070, USA 5Department of Microbiology, Immunology, Molecular Genetics and Neurology, Sanders Brown Center on Aging, University of Kentucky, Lexington, Kentucky, 40536, USA * Corresponding author- mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:tracy.a.nichols@aphis.usda.gov
Chronic wasting disease (CWD) is the only known transmissible spongiform encephalopathy affecting free-ranging wildlife. Experimental and epidemiological data indicate that CWD can be transmitted horizontally and via blood and saliva, although the exact mode of natural transmission remains unknown. Substantial evidence suggests that prions can persist in the environment, implicating it as a potential prion reservoir and transmission vehicle. CWD- positive animals can contribute to environmental prion load via biological materials including saliva, blood, urine and feces, shedding several times their body weight in possibly infectious excreta in their lifetime, as well as through decomposing carcasses. Sensitivity limitations of conventional assays hamper evaluation of environmental prion loads in water. Here we show the ability of serial protein misfolding cyclic amplification (sPMCA) to amplify minute amounts of CWD prions in spiked water samples at a 1:1 x106 , and protease-resistant prions in environmental and municipal-processing water samples from a CWD endemic area. Detection of CWD prions correlated with increased total organic carbon in water runoff from melting winter snowpack. These data suggest prolonged persistence and accumulation of prions in the environment that may promote CWD transmission.
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Effect of Invertebrates on Environmental Prion Contamination
Jay Schneider1* 1University of Wisconsin - Madison *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:jschneider@usgs.gov
Transmissible spongiform encephalopathies (prion diseases) are fatal neurodegenerative diseases affecting a number of mammalian species. The infectious agent is exceptionally resistant to degradation and can persist in the environment for long periods of time, contributing to the maintenance and spread of sheep scrapie and chronic wasting disease in cervids. We investigated what effect two common invertebrates, earthworms and Dermestid beetles, would have on the integrity of prion proteins. As opportunistic feeders, both organisms consumed prion-infected tissue. However, their impact on prion protein after consumption varied. Whereas the earthworm, which possesses strong proteolytic enzymes, demonstrated the ability to degrade prions and reduce infectivity levels; the dermestid beetle larva was more proficient in passing prion into waste (frass). These studies suggest that earthworms may provide a biotic means of decreasing infectivity levels in the environment and serve as a source of enzyme(s) with strong anti-prion activity. Conversely, Dermestids may contribute to the spread and persistence of prions in the environment.
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Chronic Wasting Disease Surveillance in Wild and Farmed Cervids in Alberta.
Margo J. Pybus1*, and Gerald Hauer2 1Fish and Wildlife Division of Alberta Sustainable Resource Development, Edmonton, Alberta 2Alberta Agriculture and Rural Development, Edmonton, Alberta *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:margo.pybus@gov.ab.ca
Alberta has wrestled with CWD surveillance in wild and farmed cervids since 1996. Most of the surveillance in wild cervids is based on hunter samples and road kills in CWD risk areas, supplemented with clinical cases of emaciation or neurologic dysfunction in cervids from throughout the province. Mandatory submission of hunter-killed deer in CWD risk areas is a primary feature of the program. Surveillance of farmed cervids was voluntary for cervid producers from 1996 until August 2002 when it became mandatory to submit heads from all cervids over 1 year of age that die for any reason, including on-farm and commercial slaughter. To date over 26,000 wild cervids and 51,000 farmed cervids have been tested. The first case of CWD in a wild deer was found in 2005; cases in farmed cervids were found in 2002/03. A total of 61 cases of CWD were identified in wild deer (55 mule deer, 6 whitetails) in a limited area in eastern Alberta. A total of three cases of CWD were identified in farmed cervids (1 elk, 2 white-tailed deer) in central Alberta. Ongoing surveillance programs identified 19 (31%) of the wild cases and 2 of the 3 farmed cases. The remaining infected animals were detected in associated disease control programs.
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Detecting Environmental Deposits of Chronic Wasting Disease Prions in Soil
A. Christy Wyckoff1, Traci A. Nichols1, Kurt C. VerCauteren2 and Mark D. Zabel1* 1 Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Co. 2 National Wildlife Research Center, Wildlife Services, United States Department of Agriculture, Fort Collins, Co. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:mark.zabel@colostate.edu
Current research suggests that environmental deposits of Chronic Wasting Disease prions (PrPCWD) play a role in the transmission and persistence of Chronic Wasting Disease (CWD) among captive and wild cervids. Furthermore, studies indicate that the prion molecule forms a close association with certain types of soil such as clays, enhancing its persistence and surprisingly, enhancing the transmissibility of the infectious agent. Aspects of PrPCWD persistence in soil has been a particularly challenging aspect to study due to limited sensitivity of existing laboratory assays. Our objective was to develop an assay that will allow for an increased detection limit of PrPCWD in soil sample. We used PrPCWD positive elk brain homogenate (E2) to spike samples of whole soil from the region. Next we used increasing detergent concentrations of SDS and sarkosyl to help elute PrPCWD off the soil by western blot. Preliminary results indicate a maximum recovery of PrPCWD from spiked soil samples at 0.05% SDS and 0.25% Sarkosyl by electrophoresis. Future directions include the use of protein misfolding cyclic amplification (PMCA) to increase the detection limit of positive soil samples.
Humic Acid Influences Pathogenic Prion Protein Sorption to Clay Particles
Christen M. Bell1, Debbie McKenzie4, Judd M. Aiken4, and Joel A. Pedersen*1,2,3* 1Environmental Chemistry and Technology Program 2Department of Soil Science, 3Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI 53706 4 Alberta Centre for Prions and Protein Folding Diseases, 2-04 Environmental Engineering Building, University of Alberta, Edmonton, Alberta T6G 2M8, Canada *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:japedersen@soils.wisc.edu
Soil may contribute to the horizontal transmission of the prion diseases sheep scrapie and chronic wasting disease of deer, elk and moose by serving as an environmental reservoir for the infectious agent. We previously demonstrated that the disease-associated form of the prion protein (PrPTSE) binds to soil particles and that the PrPTSE interaction with the clay mineral montmorillonite (Mte) is remarkably avid. Here, we investigate the role of natural organic carbon on the interaction of pathogenic prion protein with soil particles by studying PrPTSE sorption to humic acid-montmorillonite (HA-Mte) complexes. We found that HA-Mte complexes have a lower affinity for PrPTSE than Mte alone and that the binding capacity for the protein decreased with increasing HA content. Extraction of humic acid from HA-Mte after PrPTSE sorption suggests that the pathogenic prion protein associates primarily with Mte surfaces and that organic carbon blocks PrPTSE binding sites on Mte. Immunoblot analysis of PrPTSE incubated with dissolved humic acid indicates cleavage of the protein at the N-terminus. The influence of organic carbon on oral disease transmission by soil particle bound prions warrants investigation.
Interaction of a Model Prion Protein with Soil Humic, and Humic-Like Compounds
Maria A. Rao1, Fabio Russo1*, Riccardo Scotti1, Liliana Gianfreda1 1Dipartimento di Scienze del Suolo, della Pianta, dell’Ambiente e delle Produzioni Animali, Università di Napoli Federico II, Via Università 100, 80055 Portici, Italy. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:russofab@unina.it
Infectious prion protein is able to persist in soil for years and likely to propagate the disease to wild animals. While studies were devoted to investigate the role of whole soils or inorganic constituents to bind these agents and affect their infectivity; less information instead is available on the interaction of prion protein with soil organic matter (SOM).
As a part of the processes leading to the formation of humic substances in soil, oxidative coupling reactions of phenolic groups of simple and more complex molecules can occur through the action of enzymes like peroxidases and polyphenoloxidases. Further reorganization of resulting molecules can lead either to higher size molecules or to higher size complexes. Biomacromolecules such as proteins can be involved in these processes, resulting thus associated with SOM.. We report in this study the interaction of an ovine recombinant prion protein with preformed soil humic acids and humic-like substances in formation. Organic synthetic humic like aggregates were produced by using laccase and catechol. Desorption and extraction was investigated by using weak and strong extracting procedures. The percentage of protein bounded by humic acids or humic-like substances in formation as well as the amounts extractable from these complexes indicated more stable interaction between prion protein and SOM in formation.
Overall, the results seem to indicate that entrapment or adsorption phenomena involving prion protein actually occurs with SOM, even if at different degree probably depending on its stage of maturation.
However, elucidating the effect of prions immobilization in SOM on their infectivity and environmental diffusion requires the use of the infectious prion protein.
per lo Studio degli Ecosistemi, CNR Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy. 2Dipartimento di Scienza del Suolo e Nutrizione della Pianta, Università degli Studi di Firenze, Piazzale Cascine 28 50144 Firenze, Italy *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:pucci@ise.cnr.it
The researches carried out on prions adsorption related to soil were generally focused on the soil as a whole or on selected inorganic or organic constituents with equilibrium batch techniques which can not take into account their spatial distribution and/or the relative interrelationships occurring in natural environment. In fact, the sorption processes in the “in situ” conditions are complex phenomena due only partly to the properties of single components but, due also to some "newly born" properties resulting from of the interaction among constituents.
In this work the adsorption of a recombinant protein whose structure mimics the ovine prion (recPrP) was studied on native OM of undisturbed soil aggregates used as a simplified microcosm model system of soil at laboratory scale, and considered as individual adsorption system rather than the summation of single constituents. A Low-Temperature Ashing (LTA) by oxygen plasma has been applied to investigate the contribution of OM to the adsorption of a recPrP on soil aggregates from two different soils before and after OM removal by LTA. This technique allows a controlled removal of OM layer by layer, like a peeling of an onion skin, with minimal disturbance of the mineral matrix.
Soil aggregates were selected as a representative model of the “in situ” conditions. Adsorption from batch vs percolation experiments were compared, and High affinity (H-Type) adsorption isotherms were found , with maximal sorption amounts indicating that native OM has specific adsorption capacity even superior to the mineral matrix.
The coupled LTA-PAS-FTIR approach demonstrated that, albeit OM composition was homogeneous throughout the aggregates, its presence in the most external surfaces of the aggregates affects the diffusion dynamics of RecPrP within the aggregates during percolation by a “filtering out” effect.
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Modeling Lateral CWD Transmission in the Environment Using Cervid and Bovine PrP-Expressing Mice
Theodore Johnson 1*, BA Michel1, B Pulford1 and MD Zabel1 1Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:tejohnso@rams.colostate.edu
Chronic wasting disease (CWD) is efficiently transmitted laterally among wild and captive deer and elk populations. Possible transmission vehicles include saliva, urine and feces shed into the environment. An attempt to model lateral transmission through environmental contamination with a murine model was made using Tg(cerPrP)5037 and Tg(bovPrp)3705 mice. Healthy mice were continuously housed in bedding and water previously used by mice inoculated with CWD-infected or normal brain homogenate. All mice failed to develop clinical disease after over 700 days of continuous exposure, demonstrating limitations of murine models to recapitulate mechanisms of efficient lateral CWD transmission among cervids.
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Pathogenic Prion Protein is Degraded by a Serine Protease in Lichens
Christopher J. Johnson1,2*, James P. Bennett1,3, Steven M. Biro1,3, Camilo Duque-Velasquez4, Richard A. Bessen2 and Tonie E. Rocke1 1 USGS National Wildlife Health Center, Madison WI, USA 2 Montana State University, Bozeman, MT, USA 3 University of Wisconsin, Madison WI, USA 4 Grupo de Investigacion Centauro, Universidad de Antioquia, Medellin, Colombia. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:cjjohnson@usgs.gov
Lichens are unusual, symbiotic organisms formed from a fungus and partner algae or cyanobacteria. The geographic distribution of lichens is extraordinarily wide and many species thrive in extreme environments such as arctic tundra, desert rock, pure sand or toxic slag heaps. Few biological systems have been identified that degrade the pathogenic form of the prion protein (PrPTSE) and the remarkable biology of lichens and their need to capture and conserve nutrients in harsh conditions suggests that lichens may be capable of unique metabolic activities. We tested the hypotheses that lichen extracts and intact lichens can degrade PrPTSE. We found that extracts of three lichen species caused approximately a 100-fold loss of prion protein immunoreactivity in samples of PrPTSE from either hamsters or white-tailed deer. Intact lichens exposed to infected brain homogenate reduced PrPTSE levels approximately 70% following 24h incubation. Some common lichen chemicals were excluded from being the active substance(s) and treatments to interfere with redox reactions or reactive metals were not effective at blocking degradation. Two protease inhibitor cocktails, however, were each partially effective at preventing lichen extract-induced PrPTSE degradation. Screening a panel of individual, specific protease inhibitors revealed that a serine protease of lichens is the likely agent that degrades prion protein. While animal bioassay experiments to determine the effect of lichen extracts on infectious titer are ongoing, these data suggest that lichens could promote prion degradation in the environment and may have utility for prion inactivation in medical or biotechnological settings. Additionally, the role of lichens in prion environmental biology should be investigated.
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Degradation of the Pathogenic Prion Protein by a Manganese Mineral Found in Soils
Joel A. Pedersen1*, Fabio Russo2, Christopher J. Johnson3, Chad J. Johnson1, Debbie McKenzie4 and Judd M. A iken4 1University of Wisconsin, Madison, WI, USA 2Dipartimento di Scienze del Suolo della Pianta dell’Ambiente e delle Produzioni Animali, Università Federico II, Portici (NA), Italy 3USGS National Wildlife Health Center, Madison, WI, USA 4University of Alberta, Edmonton, AB, Canada. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:joelpedersen@wisc.edu
Prions, the etiological agents of transmissible spongiform encephalopathies, exhibit extreme resistance to degradation. Soil can retain prion infectivity in the environment for years. Reactive soil components may, however, contribute to the inactivation of prions in soil. Members of the birnessite family of manganese oxides (MnO2) rank among the strongest natural oxidants in soils. We found a synthetic analog of naturally occurring birnessite minerals to be capable of degrading the pathogenic prion protein (PrPTSE). Aqueous MnO2 suspensions degraded the PrPTSE as evidenced by decreased immunoreactivity and diminished ability to seed protein misfolding cyclic amplification reactions. Birnessite-mediated PrPTSE degradation increased as solution pH decreased, consistent with the pH-dependence of the redox potential of MnO2. Exposure to 5.6 mg·mL-1 MnO2 (PrPTSE:MnO2 = 1:110) decreased PrPTSE levels by =4 orders of magnitude. Manganese oxides may contribute to prion degradation in soil environments rich in these minerals.
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NeuroPrion Cervid Group Activities and Surveillance for TSEs in European Cervids
Michael J. Stack1* 1Veterinary Laboratories Agency, Weybridge, Surrey, UK *Corresponding author e-mail:
In 2004, the European Food Safety Authority published an opinion on the surveillance for TSEs in deer across Europe. Commission officials and an appointed scientist attended the 2nd International CWD Symposium in Madison, Wisconsin, July 2005, where pre-conference tours were arranged of sampling outposts in the hunting area and the USDA diagnostic laboratory. Officials also met with CWD experts from USA and Canada to ascertain the best scientific approaches for surveillance in Europe. In January 2007, several EU countries started to officially monitor farmed and wild deer for TSEs. The survey comes to an end in 2009 when it is hoped that EU Member States will meet their targets designed to detect disease at 0.5% prevalence with 95% confidence. Running in parallel with the build up to the survey, the NeuroPrion initiative in Europe has funded a cervids working group since 2005.
Questions
The NeuroPrion cervid group was set up to answer the following questions:
Are European cervids susceptible to CWD or other TSEs?
Are diagnostic tests developed for CWD hosts in North America suitable for European cervids?
What is the likelihood/risk of CWD occurring in Europe?
Will CWD transmit experimentally to European deer?
Methods
EU countries have been employing rapid tests to screen for TSEs in various species of deer and Western blot and IHC to use as confirmatory and discriminatory techniques. Transgenic mice over expressing CWD PrP have also been imported from the USA for bioassay and strain typing of any positive cases. CWD tissue has also been supplied by North America for proficiency testing in Europe.
Results
No cases of TSE in the European cervid populations have been found.
Conclusion
Although European cervid species are susceptible to TSEs experimentally, no evidence of disease was found in Europe in the cervid populations tested.
Differential Characteristics of Experimental BSE and CWD in European Red Deer (Cervus elaphus elaphus)
Stuart Martin1, Martin Jeffrey1, Lorenzo González1*, Sílvia Sisó1, Hugh W. Reid2, Philip Steele2, Mark P. Dagleish2, Michael Stack3, Melanie Chaplin3 and Aru Balachandran4 1Veterinary Laboratories Agency (VLA-Lasswade), Pentlands Science Park, Midlothian EH26 0PZ, UK. 2Moredun Research Institute, Pentlands Science Park, Midlothian EH26 0PZ, UK. 3VLA-Weybridge, Addlestone KT15 3NB, UK. 4Animal Diseases Research Institute, Canadian Food Inspection Agency, Ottawa, Ontario, Canada K2H 8P9 *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:l.gonzalez@vla.defra.gsi.gov.uk
The cause of the bovine spongiform encephalopathy (BSE) epidemic in the United Kingdom (UK) was the inclusion of contaminated meat and bone meal in the protein rations fed to cattle. Contaminated feedstuffs were also fed to other livestock including farmed and free living deer. BSE has been shown to be naturally or experimentally transmissible to a wide range of different ungulates although to date there are no reported cases of natural BSE infections in European deer. In North America, however, several cervid species are highly susceptible to chronic wasting disease (CWD), an endemic transmissible spongiform encephalopathy. Should BSE infection have been introduced into the UK deer population, the CWD precedent would suggest that there is a danger for spread and maintenance of the disease in both free living and captive UK deer populations. This study compares the immunohistochemical and biochemical characteristics of BSE and CWD in experimentally-infected European red deer (Cervus elaphus elaphus). Six out of six red deer challenged intracerebrally and one of six dosed orally with 25 g of cattle BSE developed TSE-confirmed disease at 26-42 and 58 months post-infection, respectively. Four out of four deer challenged orally with 5 g of elk CWD developed TSE-confirmed disease at 18-20 months post-infection. In terms of abnormal PrP distribution, BSE in red deer more closely resembled natural infection in cattle rather than experimental BSE in small ruminants, due to the lack of accumulation of abnormal PrP in lymphoid tissues. In this respect it was different from CWD, and despite similarities in vacuolation profiles of both diseases, BSE could be clearly distinguished from CWD by immunohistochemical and biochemical methods currently in routine use. Therefore, although red deer are susceptible to BSE infection, they develop a disease with pathological and molecular signatures different from those of CWD in the same species.
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Susceptibility of Domestic Cattle to Chronic Wasting Disease by Oral Inoculation and Natural Exposure: Final Phase of a 10-year Study
Elizabeth S. Williams1, Donal O’Toole1, Matthew M. Hille1, Donald L. Montgomery1, Jean E. Jewell1*, Terry J. Kreeger2, and Michael W. Miller3 1Department of Veterinary Sciences, University of Wyoming, Laramie, WY 82070 2Wyoming Game and Fish Department, Wheatland, WY 82201 3Colorado Division of Wildlife, Fort Collins, Colorado 80526 *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:jjewell@uwyo.edu
The risk of domestic cattle developing a transmissible spongiform encephalopathy (TSE) after oral inoculation followed by a long incubation period, or by long-term natural exposure to cervids infected with chronic wasting disease (CWD) was studied. Ten cattle were given large oral doses of pooled brain material from CWD-infected mule deer in late August 1997 and housed in isolation at the Wyoming State Veterinary Laboratory until September 2007. Two additional groups of cattle were penned outdoors with CWD-infected deer and elk or in CWD-contaminated premises at Colorado Division of Wildlife (n=11) and Wyoming Game and Fish Department (n=10) research facilities during the same ten-year period. These conditions simulated exposure routes that cattle in North America might encounter if they are raised or grazed in areas where free-ranging or captive deer and elk are infected with CWD.
Beginning in July 2007 all exposed and three untreated control cattle were killed, and select tissues were collected at necropsy. Samples from each animal were analyzed for the diagnostic hallmarks of TSEs by immunohistochemistry and Western blot. DNA sequences were determined for the cellular prion protein gene in each animal. No proteinase-K resistant prion protein or anti-PrP immunoreactive IHC signals were detected in any tissues of exposed or control animals. None of these results, taken individually or together, support a diagnosis of TSE in cattle inoculated orally with a high dose of infectious CWD material or continually exposed by cohabitation with infected deer or elk, or transmission from contaminated premises despite an incubation period of up to 10 or 11 years.
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Progressive Accumulation of PrPCWD and Spongiform Encephalopathy in the Obex of Rocky Mountain Elk (Cervus elaphus nelsoni) with Chronic Wasting Disease and its Use as a Means of Scoring the Stage of Disease and Predicting Accumulation of Prion in Peripheral Tissues
Terry R. Spraker1*, Thomas L. Gidlewski2, Jenny Powers3, Scott D. Wright4, Aru Balachandren5, and Katherine I. O’Rourke6 1College State University Diagnostic Laboratory, 300 West Drake Road, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80526 2USDA/APHIS/WS, Fort Collins, CO 80521 3National Park Service, Biological Resources Management Division, Fort Collins, CO 80525 4National Wildlife Health Center/USGS, 6006 Schroeder Road, Madison WI 53711 5National and OIE Reference Laboratory for scrapie and CWD, Canadian Food Inspection Agency, Ottawa, Canada 6USDA/ARS, Pullman, WA 99164 (KO) *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:terry.spraker@colostate.edu
Chronic wasting disease (CWD), a transmissible spongiform encephalopathy, has been reported in captive and free-ranging cervids. An abnormal isoform of a prion protein (PrPCWD) has been associated with CWD in cervids and this prion protein can be detected with immunolabeling. It has been suggested in mule deer that as the disease progresses the degree of accumulation of PrPCWD and severity of spongiform degeneration increases. This communication describes a method to delineate the progressive accumulation of PrPCWD and increase severity of spongiform degeneration in a single section of obex. Ten nuclear areas and white matter tracts including the subependymal area of the fourth ventricle and in the thin subpial astrocytic layer of a section of obex were examined and scored in 75 free-ranging and ranch-raised elk that were positive for naturally occurring CWD. This obex score was divided into ten categories and then each category was compared to the detection of PrPCWD in peripheral tissues (approximately 130) and brain (approximately 100 neuroanatomical locations) in 25 elk with natural occurring CWD. Lymphoid tissues in early cases were at first sporadically affected, but became more uniformly affected as the disease progressed. Spinal cord was commonly affected starting in the dorsal and intermediate horns, but dorsal root ganglia were not. Myoenteric plexuses and mucosa of the entire digestive tract was affected early and remained positive throughout the disease. The prion spread quickly through out the brain and nearly all areas had a degree of detectably prion midway in the disease. Adrenal medulla was affected in what was considered mid disease and then later the adrenal cortex was positive. Prion was found in the retina, nerves of the ethmoid turbinates, circumvallate papillae, heart, placenta and skeletal muscle in later stages of disease. PrPCWD was not detected in the lungs, trachea, kidney, skin and sebaceous glands. Numerous sarcocyst were examined in skeletal muscle and heart and PrPCWD was not detected in them. The obex score was then compared to the obex score in 13 experimental elk representing all three genotypes with known incubation times and this score was compared to the obex scores to the elk with natural occurring CWD. The genetics of the elk play a major role in this process or speed of spread throughout the body and brain. Elk with a 132MM genotype had the lowest obex scored, 132ML had intermediate scores and 132LL had the longest incubation times with comparable obex scores to natural occurring CWD cases. The utility of this method to estimate the distribution of prion throughout the body and brain and to estimate duration of disease will be discussed. Perhaps this data also will give some insight into the pathogenesis of CWD in elk.
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Diagnosis of Pre-Clinical CWD in Farmed White-Tailed Deer in Canada by the Immunohistochemical Examination of Rectal Biopsies
A. Balachandran1* B. Thomsen2, T. Gidlewski3, T. R. Spraker4, G. Mitchell1, A. Soutyrine1, N. Harrington1 R. Munger3 J. McLane5, R. Allen6, D.A. Schneider7 and K.I. O’Rourke7 1Canadian Food Inspection Agency, Ottawa, Ontario, CANADA 2USDA-National Veterinary Services Laboratory, Ames, Iowa, USA 3USDA-APHIS-Veterinary Services, Fort Collins, Colorado, USA 4Colorado State University, Fort Collins, Colorado, USA 5Canadian Food Inspection Agency, Battleford, SK, CANADA 6Canadian Food Inspection Agency, Prince Albert, SK, CANADA 7USDA-Agricultural Research Service, Pullman, Washington, USA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:Aru.Balachandran@inspection.gc.ca
Approved testing for diagnosis of chronic wasting disease (CWD) in cervids includes postmortem detection of disease-associated prion protein (PrPCWD) in lymph nodes or brain. Detection of PrP-CWD in rectoanal mucosa-associated lymphoid tissue (RAMALT) offers the possibility of live animal, preclinical diagnosis; however, recent reports suggest certain factors affect such detection in cervids. The present observational study reports preliminary analysis of two white-tailed deer farm depopulations in Canada. For this analysis deer were considered CWD-positive if PrP-CWD was detected in the brain, retropharyngeal lymph node (RPLN) or tonsil by immunohistochemistry, ELISA or western blot. Farm A included 122 deer with an overall disease prevalence of 31%; Farm B included 385 deer with an overall disease prevalence of 21%. Approximate overall immunohistochemistry test sensitivities were: RPLN = 0.90, tonsil = 0.87, RAMALT = 0.72 and brain = 0.60. In CWD-positive deer from Farm A, PrP-CWD was detected in 55% of RAMALT biopsies from obex grade 0 deer, and in all RAMALT biopsies from deer with obex grades greater than 0. In CWD-positive deer from Farm B, PrP-CWD was detected in 33%, 77%, 96% of RAMALT biopsies respectively from obex grades 0-2 deer, and in all RAMALT biopsies from obex grades 3 and 4 deer. RAMALT follicle count data was currently available for only a subset of biopsies from Farm 2 deer and was highly variable. The proportion positive RAMALT follicles for two wt/G96S deer (both obex grade 0) were lower than six out of eight obex grade-matched wt/wt deer. This preliminary analysis suggests diagnostic evaluation of RAMALT in captive white-tailed deer has an intermediate sensitivity compared to the range associated with currently approved tissue sites. False-negative RAMALT results were most common in deer early in disease progression. Heterozygosity at PRNP codon 96 may be associated with more limited detection of PrP-CWD.
Utility Of Rectal Biopsy For Preclinical Diagnosis Of Chronic Wasting Disease In Free-Ranging Rocky Mountain Elk
Jenny G. Powers1*, Terry R. Spraker2, Mark S. Graham1, Katherine O’Rourke3, Michael W. Miller4, and Margaret A. Wild1 1National Park Service, Fort Collins, CO, USA 2Colorado State University, Fort Collins, CO, USA 3Agricultural Research Services, USDA, Pullman, WA, USA 4Colorado Division of Wildlife, Fort Collins, CO, USA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:Jenny_Powers@nps.gov
Chronic wasting disease (CWD) has not previously been diagnosed using a preclinical ante mortem test in free-ranging elk. In this study, we captured, radio-collared, and collected samples of rectal lymphoid tissue from 136 female elk in Rocky Mountain National Park, Colorado, USA. No clear clinical signs of CWD were observed at the time of capture. Thirteen of 117 diagnostic samples (86% diagnostic using = 5 lymphoid follicles) were positive when examined using immunohistochemistry. Positive animals were removed from the population and complete necropsies performed. All had evidence of PrPCWD in the brain and retropharyngeal lymph nodes. Three months post-capture a single CWD biopsy test negative female began showing subtle behavioral signs of disease. At necropsy she was confirmed CWD positive, and represents an apparent false negative rectal biopsy result. January 2009, 1 year post capture, 20 study animals were observed, darted, repeat rectal biopsies performed then euthanized. None demonstrated clinical signs of CWD at this time. In 2009, 75% of biopsies contained = 5 lymphoid follicles and 1 animal was rectal biopsy and brain/ lymph node CWD positive. Full necropsy results are pending from this cohort.
Genotyping of the PrP gene at codon 132 showed 55% of the entire study population was homozygous for methionine (MM), 40% were heterozygous (ML), and 5% were homozygous for leucine (LL). Proportions of genotypes from CWD infected elk were not significantly different from those of CWD test negative elk (p = 0.23). However, this may be due to the small sample size of CWD positive elk. These results show that while rectal biopsy is an intensive tool, it can be used to diagnose preclinical CWD in free-ranging elk and may provide a method for measuring CWD incidence if repeated at regular intervals.
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The Use of Recto-Anal Mucosa-Associated Lymphoid Tissue (RAMALT) for Diagnosis of CWD in White-Tailed Deer (Odocoileus virginianus).
Delwyn Keane,1* Daniel Barr,1 Rebecca Osborn,2 Julie Langenberg,2 Katherine O’Rourke,3 David Schneider3 and Philip Bochsler1 1University of Wisconsin, Wisconsin Veterinary Diagnostic Laboratory, Madison, WI 2Wisconsin Department of Natural Resources, Madison, WI 3US Department of Agriculture, Agricultural Research Service, Animal Disease Research Unit, Pullman, WA *Corresponding author e-mail:
Diagnosis of CWD is currently generally dependent upon the finding of PrPCWD in obex and/or lymphoid tissues of animals collected post-mortem. Ante-mortem evaluation of tonsillar biopsies has been shown to detect preclinical CWD in deer but collection of tonsillar tissue is not a practical field procedure. Recent studies have shown that scrapie-associated PrP (PrPSC) is deposited in the recto-anal mucosa-associated lymphoid tissues (RAMALT) of infected sheep relatively early in the infection course. In this study we examined RAMALT collected at post-mortem from 210 free-ranging white-tailed deer harvested from an area of Wisconsin in which CWD is enzootic and from 76 white-tailed deer removed from a know infected farm in Wisconsin. Sensitivity of the immunohistochemical staining of RAMALT tissues compared to that of obex, tonsil and/or retropharyngeal lymph node was 91% for the free-ranging animals and 81% for the captive animals. False negatives were usually associated with early infection as evidenced by early or low intensity of PrPCWD staining in the obex and/or a polymorphism at PRNP codon 96 (glycine to serine (G96S)). The number of inadequate RAMALT samples was higher for the free-range deer (21%) than for captive animals (3.9%). Though this study was conducted using RAMALT tissues that had been collected post-mortem, the results suggest that RAMALT tissues collected ante-mortem may be useful as an adjunct to tonsil biopsy and necropsy surveillance for screening of farmed deer.
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Diagnosis of Pre-Clinical CWD in Farmed White-Tailed Deer in Canada by the Immunohistochemical Examination of Rectal Biopsies
A. Balachandran1* B. Thomsen2, T. Gidlewski3, T. R. Spraker4, G. Mitchell1, A. Soutyrine1, N. Harrington1 R. Munger3 J. McLane5, R. Allen6, D.A. Schneider7 and K.I. O’Rourke7 1Canadian Food Inspection Agency, Ottawa, Ontario, CANADA 2USDA-National Veterinary Services Laboratory, Ames, Iowa, USA 3USDA-APHIS-Veterinary Services, Fort Collins, Colorado, USA 4Colorado State University, Fort Collins, Colorado, USA 5Canadian Food Inspection Agency, Battleford, SK, CANADA 6Canadian Food Inspection Agency, Prince Albert, SK, CANADA 7USDA-Agricultural Research Service, Pullman, Washington, USA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:Aru.Balachandran@inspection.gc.ca
Approved testing for diagnosis of chronic wasting disease (CWD) in cervids includes postmortem detection of disease-associated prion protein (PrPCWD) in lymph nodes or brain. Detection of PrP-CWD in rectoanal mucosa-associated lymphoid tissue (RAMALT) offers the possibility of live animal, preclinical diagnosis; however, recent reports suggest certain factors affect such detection in cervids. The present observational study reports preliminary analysis of two white-tailed deer farm depopulations in Canada. For this analysis deer were considered CWD-positive if PrP-CWD was detected in the brain, retropharyngeal lymph node (RPLN) or tonsil by immunohistochemistry, ELISA or western blot. Farm A included 122 deer with an overall disease prevalence of 31%; Farm B included 385 deer with an overall disease prevalence of 21%. Approximate overall immunohistochemistry test sensitivities were: RPLN = 0.90, tonsil = 0.87, RAMALT = 0.72 and brain = 0.60. In CWD-positive deer from Farm A, PrP-CWD was detected in 55% of RAMALT biopsies from obex grade 0 deer, and in all RAMALT biopsies from deer with obex grades greater than 0. In CWD-positive deer from Farm B, PrP-CWD was detected in 33%, 77%, 96% of RAMALT biopsies respectively from obex grades 0-2 deer, and in all RAMALT biopsies from obex grades 3 and 4 deer. RAMALT follicle count data was currently available for only a subset of biopsies from Farm 2 deer and was highly variable. The proportion positive RAMALT follicles for two wt/G96S deer (both obex grade 0) were lower than six out of eight obex grade-matched wt/wt deer. This preliminary analysis suggests diagnostic evaluation of RAMALT in captive white-tailed deer has an intermediate sensitivity compared to the range associated with currently approved tissue sites. False-negative RAMALT results were most common in deer early in disease progression. Heterozygosity at PRNP codon 96 may be associated with more limited detection of PrP-CWD.
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Diagnosis of Pre-Clinical Sheep TSEs in Rectal Biopsies by ELISA: Overcoming “False Negative” Results
Lorenzo González1*, Leigh Thorne2, Sally J. Everest2, Andrew Ramsay2, Mark P. Dagleish, Martin Jeffrey1 and Linda A. Terry2 1Veterinary Laboratories Agency (VLA-Lasswade), Pentlands Science Park, Midlothian EH26 0PZ, UK. 2VLA-Weybridge, Addlestone KT15 3NB, UK. 3Moredun Research Institute, Pentlands Science Park, Midlothian EH26 0PZ, UK. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:l.gonzalez@vla.defra.gsi.gov.uk
Disease-associated prion protein (PrPd) accumulates in the lymphoid tissue of the rectal mucosa of a high proportion of scrapie-infected sheep at clinical and preclinical stages. PrPd can therefore be detected in biopsy specimens of rectal mucosa, with increasing probability proportional to age or incubation period, and with efficiency almost identical to that of tonsil biopsies. Rectal biopsies have the advantages of providing higher numbers of lymphoid follicles and of being simpler to perform, making them suitable for the screening of scrapie in the field. PrPd in biopsy samples can be demonstrated by immunohistochemistry (IHC) and Western blot. More recently, a “rapid test” (HerdChek® CWD Antigen EIA Test) was optimized and evaluated for the diagnosis of scrapie in rectal biopsy samples, providing specificity and sensitivity figures of 99.2% and 93.5%, respectively, compared to IHC results in the same samples obtained at post-mortem. The sensitivity of the assay increased from 82.1% when a single rectal mucosa sample was tested to 99.4% for those sheep in which three or more samples were analyzed. Similarly, sensitivity values of the CWD EIA test on biopsy samples increased from 95% to 100% for sheep subjected to one or two sequential biopsies four months apart, respectively. Thus, preclinical diagnosis of scrapie in live sheep can be achieved by a combination of a simple and repeatable sampling procedure, and a rapid and efficient laboratory method. However, unlike IHC, this method does not allow identification of “false negatives”, i.e. samples that do not contain enough target lymphoid tissue. To overcome this problem we have developed an ELISA for the detection of CD21, a marker expressed by B cells and follicular dendritic cells; these cells are most abundant in secondary lymphoid follicles, i.e. the same site where PrPd accumulates in lymphoid tissues. This sandwich ELISA provides increased signals in rectal mucosa containing lymphoid follicles compared to gut mucosa devoid of lymphoid tissue.
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Chronic Wasting Disease in Wild Deer: Wildlife Agency Responses Across North America.
Margo J. Pybus1*, and Yeen Ten Hwang2 1Fish and Wildlife Division of Alberta Sustainable Resource Development, Edmonton, Alberta 2Saskatchewan Ministry of Environment, Regina, Saskatchewan. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:margo.pybus@gov.ab.ca
In August 2008, Alberta and Saskatchewan wildlife agencies co-hosted a workshop to review wildlife management responses to chronic wasting disease (CWD) in wild deer. The approach was to examine representative current programs, their successes and failures, and use the information in conjunction with participant experiences to offer collective recommendations for future CWD response plans and programs. Workshop presenters focused on CWD response in their jurisdiction. This set the stage for breakout groups to have detailed discussions of the merits of various wildlife agency response activities and their applicability in three CWD risk scenarios: enzootic, newly detected, and at risk (not detected). Overall, the response programs of most jurisdictions are influenced by the availability of financial resources, and most importantly, public and political support. Prevention is the most effective goal in jurisdictions that are at risk of incurring CWD. Ongoing aggressive surveillance, particularly targeting clinical cases, as well as regional planning are most useful. In newly detected areas, timely and consistent response is prudent. CWD management is best served by aggressive targeting of infected individuals and reduction of risk factors. In enzootic areas, ongoing risk evaluation and hunter surveillance, as well as attempts to control disease spread into new areas and new species is best. Developing effective communication plans to inform the public and agency personnel are critical in all risk categories. The workshop final report and presentations are posted at
www.srd.gov.ab.ca/fishwildlife/livingwith/diseases/
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Alberta's CWD One-Two Punch: Seek and Destroy
Margo J. Pybus1*, Mark Ball1, Al Gibson1, and Jim Allen1. 1Fish and Wildlife Division, Alberta Sustainable Resource Development, Edmonton, Alberta *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:margo.pybus@gov.ab.ca
Although Alberta has limited risk factors for CWD, the province began active surveillance in 1996. Upon finding CWD in a wild deer in Alberta in 2005, the province began an aggressive 2-pronged attack on CWD: intensified fall surveillance involving hunters and landowners to find infected deer, followed by targeted disease control delivered in the immediate vicinity of infected deer. Control programs were delivered in winter when deer were concentrated and other land use activities were minimal. Population reduction was applied in roughly 10km radius circles around known positive deer, modified by availability of suitable deer habitat and winter concentrations of deer. Deer were collected from the ground by government sharp-shooters and, at times, from the air by a private contractor. Meat, hides, and antlers were salvaged and this was an important component of maintaining rural and urban public support. Ongoing public education and one-on-one contact with landowners were essential to the success of the program. Of the 53 cases of CWD identified in wild deer prior to the 2008 fall hunting seasons, 40 (77%) were detected as a result of the directed CWD control program. The disease generally occurs along major river valleys with east/west orientation and small clusters in isolated habitats. In Alberta, CWD prevalence remains low, disease distribution is relatively limited (spilling in from infected deer in Saskatchewan), and many infected deer are in early stages of infection, all suggesting the disease is not yet fully established in Alberta. However, the program failed in the crucial area of maintaining support among key politicians and the winter control portion was not delivered in 2009 despite 8 new cases found in the fall programs of 2008.
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The Wisconsin Experience with Chronic Wasting Disease Management: Lessons Learned
Michael D. Samuel1*, Julie A. Langenberg2, and Robert E. Rolley2 1U.S. Geological Survey, Wisconsin Cooperative Wildlife Research Unit, 204 Russell Labs, 1630 Linden Drive, University of Wisconsin, Madison, Wisconsin, USA 2Wisconsin Department of Natural Resources, 2801 Progress Road, Madison, Wisconsin, USA; *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:mdsamuel@wisc.edu
Since 2002, Wisconsin has identified over 1100 cases of chronic wasting disease in free-ranging white-tailed deer (Odocoileus virginianus) distributed over > 2000 mi2. Wisconsin implemented an aggressive chronic wasting disease management program with the goals of controlling the spread of the disease and attempting to eradicate it from both wild and farm-raised cervids in the state. The primary control objectives for free-ranging deer included: 1) drastic population reduction in the CWD affected areas, 2) moderate population reduction in a buffer zone around affected areas, and 3) banning baiting and feeding of deer in these management areas. Strategies to reduce deer populations included extended deer hunting seasons (September - March) with no bag limits, a requirement for hunters to harvest an antlerless deer before harvesting a buck (Earn-a-Buck), focused culling by agency sharpshooters, and financial incentives for deer harvest. Social, political, and budgetary constraints (advocated by deer hunters) have progressively eroded these deer reduction strategies. Based on annual deer population surveys in the CWD eradication zones, there has been little cumulative change over the 6 years of attempted deer population reduction. A change in CWD prevalence in the "core" affected area has been difficult to detect until 2008; analysis of 7 years of surveillance data now suggests increasing prevalence. We will review the results of Wisconsin’s CWD management efforts to increase deer harvests and resulting population trends, social and political factors that influenced CWD management strategies, and temporal/spatial patterns of CWD. Disease modeling and mapping studies indicate that CWD was likely introduced in Wisconsin > 20 years ago and became widely distributed across southern Wisconsin, factors that make CWD control difficult. Management experiences indicate limited public support for drastic deer reduction strategies to affect disease control. We summarize lessons learned from our experiences and speculate about the future of CWD management in Wisconsin.
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Sharpshooting Implementation and Efficacy in Management of CWD in Illinois
Paul A. Shelton1*, Nohra E. Mateus-Pinilla2, Hsin-Yi Weng3, Patrick McDonald1, Marilyn O. Ruiz3, William Brown3, Jan E. Novakofski3, Tom J. Beissel1, Marlis Douglas2, and Michael Douglas2 1Illinois Department of Natural Resources, One Natural Resources Way, Springfield, IL 62702 2Illinois Natural History Survey, 1816 S. Oak St., Champaign, IL 61820 3Departments of Animal Sciences and Pathobiology, University of Illinois, Urbana, IL 61801 *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:paul.shelton@illinois.gov
CWD was first detected in northern Illinois during Fall 2002. The outbreak has a central core with high disease prevalence, diffusing as distance from the core increases. Affected counties consist of highly fragmented forest habitat in a matrix of row-crop agriculture, with rapid urbanization of open spaces.
Illinois’ disease management strategy assumes: (1) disease transmission efficiency and deer density are interrelated, and (2) extent of environmental contamination is a function of the number of disease-positive deer. Thus, our goal is to achieve significant localized reductions in infected deer populations.
Locations in need of intervention (typified by high deer density, high prevalence and low hunter access) are selected based on winter aerial deer censuses and spatial distribution of cases identified by testing hunter-harvested deer. Teams of trained sharpshooters are deployed four nights a week between mid-January and March 31. We evaluated sharpshooting as a CWD management tool using 5 years of data and two related criteria: (1) effects on target population density; and (2) effects on disease prevalence/incidence. Although hunting opportunities increased in CWD counties during the study period, substantial growth in number of deer taken resulted only from post-hunt sharpshooting. Mixed linear regression modeling revealed a significant decrease in deer density when sharpshooting was employed for multiple years (=3) at relatively high intensity (=25 deer/mi2 per year).
A logistic regression model identified temporal changes in CWD prevalence across years (2003 - 2008). A significant decreasing linear trend was found in estimated prevalence rates among fawn/yearlings (p=0.013) but not among adults (p=0.48). This implies that the number of new cases (measured in =1.5 year olds) declined over time where sharpshooting was used between 2003 and 2007. Although preliminary, these results emphasize the importance of continuing CWD surveillance and interventions in an effort to thoroughly evaluate management options.
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Culling as an Approach to Chronic Wasting Disease Management
Lisa L. Wolfe1*, Mary M. Conner2, Daniel Walsh1, Michael W. Miller1 1Wildlife Health Program, Wildlife Research Center, Colorado Division of Wildlife, 317 West Prospect Road, Fort Collins, CO 80526-2097, USA 2Utah Division of Wildlife Resources, Salt Lake City, UT and California Fish and Game Department, Bishop CA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:lisa.wolfe@state.co.us
In the early 2000s, the Colorado Division of Wildlife (CDOW) attempted several approaches for controlling chronic wasting disease (CWD) in free-ranging mule deer (Odocoileus hemionus) in northern Colorado. Harvest of female deer was increased in three Data Analysis Units (DAUs) with a goal of reducing population sizes by 25%; although population reduction goals apparently were achieved, CWD persisted in these areas. Localized culling of deer in “hotspots” of relatively high local CWD prevalence in north central Colorado along the northern Front Range and the South Platte River bottom and tablelands also was attempted; subsequent analyses of data from 16 sites could not demonstrate an overall effect of culling in lowering CWD prevalence compared to adjacent areas where no culling occurred (Conner et al. 2006). In addition, the CDOW also evaluated a “test and cull” strategy for lowering CWD prevalence using a naturally infected, free-ranging, mule deer population wintering in the town of Estes Park and nearby Rocky Mountain National Park (Wolfe et al. 2004); over a 5 year period, prevalence remained static among female deer and declined by about 50% among males. None of the approaches evaluated thus far appear sustainable over the time periods likely necessary to effect control of CWD: both population suppression and culling were extremely unpopular with constituent groups, and cost, labor, private property access, and animal approachability limit the application of test and cull.
References
Conner, M. M., Miller, M. W., Ebinger, M. R., and Burnham, K .P. 2007. A meta-BACI approach for evaluating management intervention on chronic wasting disease in mule deer. Ecological Applications 17 (1): 140-153. Wolfe, L. L., M. W. Miller, and E. S. Williams. 2004. Feasibility of “test-and-cull” for managing chronic wasting disease in urban mule deer populations. Wildlife Society Bulletin 32: 500-505.
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Chronic Wasting Disease Susceptibility of Four North American Rodents
Chad J. Johnson1*, Jay R. Schneider2, Christopher J. Johnson2, Natalie A. Mickelsen2, Julia A. Langenberg3, Philip N. Bochsler4, Delwyn P. Keane4, Daniel J. Barr4, and Dennis M. Heisey2 1University of Wisconsin School of Veterinary Medicine, Department of Comparative Biosciences, 1656 Linden Drive, Madison WI 53706, USA 2US Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison WI 53711, USA 3Wisconsin Department of Natural Resources, 101 South Webster Street, Madison WI 53703, USA 4Wisconsin Veterinary Diagnostic Lab, 445 Easterday Lane, Madison WI 53706, USA *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:cjohnson@svm.vetmed.wisc.edu
We intracerebrally challenged four species of native North American rodents that inhabit locations undergoing cervid chronic wasting disease (CWD) epidemics. The species were: deer mice (Peromyscus maniculatus), white-footed mice (P. leucopus), meadow voles (Microtus pennsylvanicus), and red-backed voles (Myodes gapperi). The inocula were prepared from the brains of hunter-harvested white-tailed deer from Wisconsin that tested positive for CWD. Meadow voles proved to be most susceptible, with a median incubation period of 272 days. Immunoblotting and immunohistochemistry confirmed the presence of PrPd in the brains of all challenged meadow voles. Subsequent passages in meadow voles lead to a significant reduction in incubation period. The disease progression in red-backed voles, which are very closely related to the European bank vole (M. glareolus) which have been demonstrated to be sensitive to a number of TSEs, was slower than in meadow voles with a median incubation period of 351 days. We sequenced the meadow vole and red-backed vole Prnp genes and found three amino acid (AA) differences outside of the signal and GPI anchor sequences. Of these differences (T56-, G90S, S170N; read-backed vole:meadow vole), S170N is particularly intriguing due its postulated involvement in “rigid loop” structure and CWD susceptibility. Deer mice did not exhibit disease signs until nearly 1.5 years post-inoculation, but appear to be exhibiting a high degree of disease penetrance. White-footed mice have an even longer incubation period but are also showing high penetrance. Second passage experiments show significant shortening of incubation periods. Meadow voles in particular appear to be interesting lab models for CWD. These rodents scavenge carrion, and are an important food source for many predator species. Furthermore, these rodents enter human and domestic livestock food chains by accidental inclusion in grain and forage. Further investigation of these species as potential hosts, bridge species, and reservoirs of CWD is required.
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Elk and Deer Use of Mineral Licks: Implications for Disease Transmission
Kurt C. VerCauteren1*, Michael J. Lavelle1, Gregory E. Phillips1, Justin W. Fischer1, and Randal S. Stahl1 1United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, 4101 LaPorte Avenue, Fort Collins, CO 80521-2154, USA *Cooresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:kurt.c.vercauteren@aphis.usda.gov
North American cervids require and actively seek out minerals to satisfy physiological requirements. Minerals required by free-ranging cervids exist within natural and artificial mineral licks that commonly serve as focal sites for cervids. Ingestion of soils contaminated with the agent that causes chronic wasting disease (CWD) may result in risk of contracting CWD. Our objective was to evaluate the extent and nature of use of mineral licks by CWD-susceptible cervid species. We used animal-activated cameras to monitor use of 18 mineral licks between 1 June and 16 October 2006 in Rocky Mountain National Park, north-central Colorado. We also assessed mineral concentrations at mineral licks to evaluate correlations between visitation rates and site-specific characteristics. We collected > 400,000 images of which 991 included elk, 293 included deer, and 6 included moose. We documented elk and deer participating in a variety of potentially risky behaviors (e.g., ingesting soil, ingesting water, defecating, urinating) while at mineral licks. Results from the mineral analyses combined with camera data revealed that visitation was highest at sodium-rich mineral licks. Mineral licks may play a role in disease transmission by acting as sites of increased interaction as well as reservoirs for deposition, accumulation, and ingestion of disease agents.
SNIP...
Potential Venison Exposure Among FoodNet Population Survey Respondents, 2006-2007
Ryan A. Maddox1*, Joseph Y. Abrams1, Robert C. Holman1, Lawrence B. Schonberger1, Ermias D. Belay1 Division of Viral and Rickettsial Diseases, National Center for Zoonotic, Vector-Borne, and Enteric Diseases, Centers for Disease Control and Prevention, Atlanta, GA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:rmaddox@cdc.gov
The foodborne transmission of bovine spongiform encephalopathy to humans, resulting in variant Creutzfeldt-Jakob disease, indicates that humans can be susceptible to animal prion diseases. However, it is not known whether foodborne exposure to the agent causing chronic wasting disease (CWD) in cervids can cause human disease. The United States Foodborne Diseases Active Surveillance Network (FoodNet) conducts surveillance for foodborne diseases through an extensive survey administered to respondents in selected states. To describe the frequency of deer and elk hunting and venison consumption, five questions were included in the 2006-2007 FoodNet survey. This survey included 17,372 respondents in ten states: California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee. Of these respondents, 3,220 (18.5%) reported ever hunting deer or elk, with 217 (1.3%) reporting hunting in a CWD-endemic area (northeastern Colorado, southeastern Wyoming, and southwestern Nebraska). Of the 217 CWD-endemic area hunters, 74 (34.1%) were residents of Colorado. Respondents reporting hunting were significantly more likely to be male than female (prevalence ratio: 3.3, 95% confidence interval: 3.1-3.6) and, in general, older respondents were significantly more likely to report hunting than younger respondents. Venison consumption was reported by more than half (67.4%) of the study population, and most venison consumers (94.1%) reported that at least half of their venison came from the wild. However, more than half (59.1%) of the consumers reported eating venison only one to five times in their life or only once or twice a year. These findings indicate that a high percentage of the United States population engages in hunting and/or venison consumption. If CWD continues to spread to more areas across the country, a substantial number of people could potentially be exposed to the infectious agent.
http://www.cwd-info.org/pdf/3rd_CWD_Symposium_utah.pdf
Tuesday, August 04, 2009
Susceptibilities of Nonhuman Primates to Chronic Wasting Disease
SNIP...
Thursday, April 03, 2008
A prion disease of cervids: Chronic wasting disease
2008 1: Vet Res. 2008 Apr 3;39(4):41
A prion disease of cervids: Chronic wasting disease
Sigurdson CJ.
snip...
*** twenty-seven CJD patients who regularly consumed venison were reported to the Surveillance Center***,
snip...
full text ;
http://chronic-wasting-disease.blogspot.com/2008/04/prion-disease-of-cervids-chronic.html
From: TSS (216-119-163-189.ipset45.wt.net)
Subject: CWD aka MAD DEER/ELK TO HUMANS ???
Date: September 30, 2002 at 7:06 am PST
From: "Belay, Ermias"
To:
Cc: "Race, Richard (NIH)" ; ; "Belay,
Ermias"
Sent: Monday, September 30, 2002 9:22 AM
Subject: RE: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS
Dear Sir/Madam,
In the Archives of Neurology you quoted (the abstract of which was
attached to your email), we did not say CWD in humans will present like
variant CJD.
That assumption would be wrong. I encourage you to read the whole
article and call me if you have questions or need more clarification
(phone: 404-639-3091). Also, we do not claim that "no-one has ever been
infected with prion disease from eating venison." Our conclusion stating
that we found no strong evidence of CWD transmission to humans in the
article you quoted or in any other forum is limited to the patients we
investigated.
Ermias Belay, M.D.
Centers for Disease Control and Prevention
-----Original Message-----
From:
Sent: Sunday, September 29, 2002 10:15 AM
To: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:rr26k@nih.gov; mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:rrace@niaid.nih.gov; mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:ebb8@CDC.GOV
Subject: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG
HUNTERS
Sunday, November 10, 2002 6:26 PM ......snip........end..............TSS
also,
A. Aguzzi - Chronic Wasting Disease (CWD) also needs to be addressed. Most
serious because of rapid horizontal spread and higher prevalence than BSE in
UK, up to 15% in some populations. Also may be a risk to humans - evidence
that it is not dangerous to humans is thin.
http://www.tseandfoodsafety.org/activities/bse_conference_basel_april_02/2summar
SNIP...END...TSS
Chronic Wasting Disease and Potential Transmission to Humans
Ermias D. Belay,* Ryan A. Maddox,* Elizabeth S. Williams,? Michael W. Miller,? Pierluigi Gambetti,§ and Lawrence B. Schonberger*
*Centers for Disease Control and Prevention, Atlanta, Georgia, USA; ?University of Wyoming, Laramie, Wyoming, USA; ?Colorado Division of Wildlife, Fort Collins, Colorado, USA; and §Case Western Reserve University, Cleveland, Ohio, USA
Suggested citation for this article: Belay ED, Maddox RA, Williams ES, Miller MW, Gambetti P, Schonberger LB. Chronic wasting disease and potential transmission to humans. Emerg Infect Dis [serial on the Internet]. 2004 Jun [date cited]. Available from:
http://www.cdc.gov/ncidod/EID/vol10no6/03-1082.htm
Chronic wasting disease (CWD) of deer and elk is endemic in a tri-corner area of Colorado, Wyoming, and Nebraska, and new foci of CWD have been detected in other parts of the United States. Although detection in some areas may be related to increased surveillance, introduction of CWD due to translocation or natural migration of animals may account for some new foci of infection. Increasing spread of CWD has raised concerns about the potential for increasing human exposure to the CWD agent. The foodborne transmission of bovine spongiform encephalopathy to humans indicates that the species barrier may not completely protect humans from animal prion diseases. Conversion of human prion protein by CWD-associated prions has been demonstrated in an in vitro cell-free experiment, but limited investigations have not identified strong evidence for CWD transmission to humans. More epidemiologic and laboratory studies are needed to monitor the possibility of such transmissions.
snip...full text ;
http://www.cdc.gov/ncidod/EID/vol10no6/03-1082.htm
Volume 12, Number 10-October 2006
Research
Human Prion Disease and Relative Risk Associated with Chronic Wasting Disease
Samantha MaWhinney,* W. John Pape,? Jeri E. Forster,* C. Alan Anderson,?§ Patrick Bosque,?¶ and Michael W. Miller#
*University of Colorado at Denver and Health Sciences Center, Denver, Colorado, USA; ?Colorado Department of Public Health and Environment, Denver, Colorado, USA; ?University of Colorado School of Medicine, Denver, Colorado, USA; §Denver Veteran's Affairs Medical Center, Denver, Colorado, USA; ¶Denver Health Medical Center, Denver, Colorado, USA; and #Colorado Division of Wildlife, Fort Collins, Colorado, USA
Suggested citation for this article
The transmission of the prion disease bovine spongiform encephalopathy (BSE) to humans raises concern about chronic wasting disease (CWD), a prion disease of deer and elk. In 7 Colorado counties with high CWD prevalence, 75% of state hunting licenses are issued locally, which suggests that residents consume most regionally harvested game. We used Colorado death certificate data from 1979 through 2001 to evaluate rates of death from the human prion disease Creutzfeldt-Jakob disease (CJD). The relative risk (RR) of CJD for CWD-endemic county residents was not significantly increased (RR 0.81, 95% confidence interval [CI] 0.40-1.63), and the rate of CJD did not increase over time (5-year RR 0.92, 95% CI 0.73-1.16). In Colorado, human prion disease resulting from CWD exposure is rare or nonexistent. However, given uncertainties about the incubation period, exposure, and clinical presentation, the possibility that the CWD agent might cause human disease cannot be eliminated.
snip... full text ;
http://0-www.cdc.gov.mill1.sjlibrary.org/ncidod/EID/vol12no10/06-0019.htm
full text ;
http://chronic-wasting-disease.blogspot.com/2006_12_01_archive.html
SEE FULL TEXT ;
Tuesday, August 04, 2009 Susceptibilities of Nonhuman Primates to Chronic Wasting Disease
http://chronic-wasting-disease.blogspot.com/2009/08/susceptibilities-of-nonhuman-primates.html
Sunday, April 12, 2009
CWD UPDATE Infection Studies in Two Species of Non-Human Primates and one Environmental reservoir infectivity study and evidence of two strains
http://chronic-wasting-disease.blogspot.com/2009/04/cwd-update-infection-studies-in-two.html
Wednesday, March 18, 2009
Detection of CWD Prions in Urine and Saliva of Deer by Transgenic Mouse Bioassay
http://chronic-wasting-disease.blogspot.com/2009/03/detection-of-cwd-prions-in-urine-and.html
Thursday, July 23, 2009
UW Hospital warning 53 patients about possible exposure to rare brain disease
http://creutzfeldt-jakob-disease.blogspot.com/2009/07/uw-hospital-warning-53-patients-about.html
10.3201/eid1505.081458 Suggested citation for this article: Angers RC, Seward TS, Napier D, Green M, Hoover E, Spraker T, et al. Chronic wasting disease prions in elk antler velvet. Emerg Infect Dis. 2009 May; [Epub ahead of print]
Chronic Wasting Disease Prions in Elk Antler Velvet
http://chronic-wasting-disease.blogspot.com/2009/03/chronic-wasting-disease-prions-in-elk.html
Wednesday, March 18, 2009
Noah's Ark Holding, LLC, Dawson, MN RECALL Elk products contain meat derived from an elk confirmed to have CWD NV, CA, TX, CO, NY, UT, FL, OK RECALLS AND FIELD CORRECTIONS: FOODS CLASS II
http://chronic-wasting-disease.blogspot.com/2009/03/noahs-ark-holding-llc-dawson-mn-recall.html
http://chronic-wasting-disease.blogspot.com/2009/02/exotic-meats-usa-announces-urgent.html
NOT only muscle, but now fat of CWD infected deer holds infectivity of the TSE (prion) agent. ...TSS
just follow the different topics and urls to the science and transmission studies. the transmission studies do not lie. only the politicians do. ...
and you don't even want to go to the mad cow issue and or the scrapie issue, and why should you $$$ your a sports writer, and this is much bigger than any of us will ever be, it was said long ago BSE would never be found in the USA. and due to the incubation period, it probably will not. but the BSE issue is just one phenotype. h and l and c BSE have all been found in North America.......... it's a damn political foot ball game, and we loose, and the animals loose $$$
Monday, July 13, 2009
Deer Carcass Decomposition and Potential Scavenger Exposure to Chronic Wasting Disease
http://chronic-wasting-disease.blogspot.com/2009/07/deer-carcass-decomposition-and.html
CWD, GAME FARMS, BAITING, AND POLITICS
http://chronic-wasting-disease.blogspot.com/2009/01/cwd-game-farms-baiting-and-politics.html
NOT only muscle, but now fat of CWD infected deer holds infectivity of the TSE (prion) agent. ...TSS
Monday, July 06, 2009
Prion infectivity in fat of deer with Chronic Wasting Disease
http://chronic-wasting-disease.blogspot.com/2009/07/prion-infectivity-in-fat-of-deer-with.html
Friday, February 20, 2009
Both Sides of the Fence: A Strategic Review of Chronic Wasting Disease
http://chronic-wasting-disease.blogspot.com/2009/02/both-sides-of-fence-strategic-review-of.html
Saturday, September 06, 2008
Chronic wasting disease in a Wisconsin white-tailed deer farm 79% INFECTION RATE
Contents: September 1 2008, Volume 20, Issue 5
snip...see full text ;
http://chronic-wasting-disease.blogspot.com/2008/11/commentary-crimes-hurt-essence-of.html
Tuesday, January 27, 2009
Chronic Wasting Disease found in a farmed elk from Olmsted County ST. PAUL, Minn. FOR IMMEDIATE RELEASE: Monday, January 26, 2009
http://chronic-wasting-disease.blogspot.com/2009/01/chronic-wasting-disease-found-in-farmed.html
Saturday, January 24, 2009
Research Project: Detection of TSE Agents in Livestock, Wildlife, Agricultural Products, and the Environment Location: 2008 Annual Report
http://bse-atypical.blogspot.com/2009/01/research-project-detection-of-tse.html
2008 CWD Laboratory Testing for Wild White-tailed Deer
http://www.michigan.gov/emergingdiseases/0,1607,7-186-25806-202922--,00.html
Wednesday, January 07, 2009
CWD to tighten taxidermy rules Hunters need to understand regulations
http://chronic-wasting-disease.blogspot.com/2009/01/cwd-to-tighten-taxidermy-rules-hunters.html
Thursday, December 25, 2008 Lions and Prions and Deer Demise
http://chronic-wasting-disease.blogspot.com/2008/12/lions-and-prions-and-deer-demise.html
http://chronic-wasting-disease.blogspot.com/
TSS
I'm posting _some_ of the Third International CWD Symposium July 22-24, 2009 – Park City, Utah ABSTRACTS. In no certain order, just some topics of interest that i read over, and i might have missed some, and other topics might interest others. so, please read through all.........
kind regards, terry
Third International CWD Symposium July 22-24, 2009 – Park City, Utah ABSTRACTS
Updates on the Status of Chronic Wasting Disease in Free-Ranging Cervids in Canada and the United States Each province and state has provided a 1-2 page status update on CWD in their area. The Third International Chronic Wasting Disease Symposium Program and Abstracts booklet is distributed to all meeting attendees. These updates were lightly edited to comply with formatting and space limits, but otherwise were printed as submitted. The Utah Division of Wildlife Resources and the organizers for the Symposium do not regard this Symposium Program and Abstracts booklet as a publication, and the status updates published herein should not be cited in scientific literature. Status updates are organized in alphabetical order with Canada appearing first and the states thereafter. Also included is a 1 page summary on the CWD Workshop held in Edmonton, Alberta in 2008.
SNIP...
Chronic Wasting Disease and the Environment: Contamination, Persistence and Remediation
Christopher J. Johnson1* 1USGS National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin 53711 *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:cjjohnson@usgs.gov
The unique nature of prions, the etiological agents of transmissible spongiform encephalopathies (TSEs) makes them resistant to degradation and inactivation. Such stability leads to unexpected reservoirs of TSE infectivity, such as contaminated medical devices, feed additives, medications, and, under appropriate circumstances, the environment. Transmission of the TSEs scrapie and cervid chronic wasting disease (CWD) can occur both by horizontal and environmental routes. Soil serves as a likely reservoir of infectivity for both diseases. In the case of CWD, multiple scenarios have been proposed for the introduction of CWD into soils, including natural shedding of agent from cervids, deer dying on the landscape and release of agent by hunters. Parameters related to prion-soil binding, persistence and infectivity have been explored by a number of groups with concurring results indicating that prions remain infectious in the environment and can persist for extended periods of time. Other environments may also be subject to contamination with CWD, including run-off water, wastewater and landfills; however, the risks associated with the presence of CWD agent in these environments remain unknown. Further investigation into the fate, mobility, persistence and infectivity of prions in natural and engineered environments will aid in defining risks and containment procedures needed to safeguard human and animal health. Hope exists for remediation of natural and artificial environments contaminated with CWD in the form of soil minerals capable of inactivating prions and in organisms or enzymes with anti-prion activities.
62
Evidence for Soil Humic Substances Interaction with Prions
Gabriele Giachin1, Hoang Ngoc Ai Tran1, Alja Margon2, Joanna Narkiewicz1, Giuseppe Legname1, and Liviana Leita2* 1Scuola Internazionale Superiore di Studi Avanzati - International School of Advanced Studies, (SISSA-ISAS), Trieste, Italy 2Agricultural Research Council (CRA) – Research Centre for Soil-Plant System, Gorizia, Italy *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:liviana.leita@entecra.it
A notable feature of scrapie and CWD is the horizontal transmission between grazing animals. Contaminated soil is therefore a good candidate for prion disease propagation. Since grazing animals tend to ingest from tens to hundreds grams of soil per day, either incidentally through the diet, or deliberately in answering salt intake needs. Indeed, several reports indicate that mule deer can develop CWD after grazing in locations that previously housed infected animals. Recent studies have proven that prions can be retained in soil, which could act as a carrier of infectivity even several years after the contamination. However, within the large spread of potentially infected lands, prion diseases have become endemic only in geographically limited regions. Reasons for this geographical distribution remain unknown, but it suggests a role of the different kinds of soil in either enhancing or accumulate prion infectivity. The extent of the prion transmission from a contaminated environment is unknown. Several studies have tried to address the issue of prion interaction with soil, but, at the present, different approaches show several drawbacks and technical difficulties, as soil is a complex, multi-component system of both mineral and organic interacting substances. Most research has focused on the adsorption capacity of clay minerals; however the contribution of soil organic components in adsorption has been neglected, as they represent a minor soil fraction on a weight basis. Among organic molecules, humic substances (HSs) are natural polyanions that result among the most reactive compounds in the soil and possess the largest specific surface area.
This work focuses on the interaction of the recombinant prion protein with a class of refractory natural organic polyanions, humic substances (HSs), polydisperse mixtures of polyphenol-polycarboxylic acids, possessing self associating and colloidal properties, whose precise chemical structure is still unknown. HSs are important refractory components of the natural organic matter in soils, sediments and waters, widely diffused in all climatic environments and naturally accumulated in soil under cool-temperate climates. They are classified as humic acids (HAs), which are soluble only in alkaline solutions, and fulvic acids (FAs), which are soluble in both alkaline and acid solutions. In addition, HAs and HFs display the ability to interact with xenobiotics to form chemical structures of different solubility and chemical and biochemical stability. It is therefore reasonable suppose that the interaction with prion proteins may lead to adducts with peculiar chemical and biophysical characteristics, thus affecting the transport, fixation and toxicity of prion, in particular, in soil and in the ecosystems. Results from our chemical, biophysical and biochemical investigations will be presented.
63
Transport of the Pathogenic Prion Protein Through Porous Media
Joel A. Pedersen1*, Kurt H. Jacobson1, Seunghak Lee1, Debbie McKenzie2, and Craig H. Benson3. 1 University of Wisconsin, Madison, WI 53706 2 University of Alberta, Edmonton, AB, Canada 3 University of Washington, Seattle, WA 98195 *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:joelpedersen@wisc.edu
The present understanding of prion fate and transport in soils and subsurface environments is extremely limited. Such knowledge, however, is critical for assessing the risks associated with prions in the natural environment (e.g., from diseased carcasses, animal shedding) and in engineered systems (e.g., landfill disposal of carcasses and waste from eradication programs and meat recalls). We conducted saturated column experiments to examine the transport of the disease-associated prion protein (PrPTSE) through several soils with contrasting properties, green waste residual (a potential burial material), and fresh and aged municipal solid waste (MSW). PrPTSE was retained strongly by fine-textured soils. First-order attachment coefficients, estimated from breakthrough curves and profiles of retained PrPTSE, were > 1.8 h-1 for these soils. In contrast, PrPTSE was more mobile in porous media with higher porosity and organic carbon content (e.g., MSW, green waste residual). The transport parameters derived from the column experiments were used to model PrPTSE migration in a MSW landfill. To the extent that the PrPTSE used mimics that released from decomposing carcasses and the column experiments adequately simulate prion transport through burial soils, burial of CWD-infected materials at MSW landfills could provide secure containment of PrPTSE provided reasonable burial strategies (e.g., encasement in fine-grained soil) are used.
64
Prion Protein Adsorption to Soil in a Competitive Matrix
Samuel E. Saunders1*, Jason C. Bartz2, and Shannon L. Bartelt-Hunt1 1Department of Civil Engineering, University of Nebraska-Lincoln, Peter Kiewit Institute, Omaha, Nebraska, United States of America, 2Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:ssaunders@unomaha.edu
It is likely that the soil environment serves as a stable reservoir of infectious CWD and scrapie prions, facilitating a sustained incidence of CWD in free-ranging cervid populations and complicating efforts to eliminate disease in captive livestock herds. Prion adsorption to soil may play an important role in prion mobility, proteolysis, and infectivity. We hypothesized that the competitive matrix in which prions enter the environment (e.g. tissue, excreta) could significantly affect prion interactions with soil, and that these interactions may vary with prion strain and species. We modified previously published methods to quantify adsorbed prions via direct detection and investigated prion adsorption to soil in both kinetic and isothermal studies. Prion-infected brain homogenates from two hamster strains and CWD-elk, were used as complex, relevant prion sources. We determined that maximum PrP adsorption requires days or weeks, depending on the soil or mineral, and is two to five orders of magnitude lower than previous studies using purified PrPSc or recPrP. Because PrP adsorption to soil is slow and less avid in tissue homogenate, the possibility of prion transport in soil environments cannot be excluded and requires further investigation. Our results indicate that binding to soil may protect prions from degradation, consistent with prions’ longevity in the environment. Our data also provide evidence that the N-terminal enhances adsorption of PrPSc to clay but may hinder adsorption to sand. We report strain and species differences in PrP adsorption, indicating that the fate of prions in the environment may vary with the prion strain and species infected. PrP adsorption was maximal at an intermediate aqueous concentration, most likely due to the competitive brain homogenate matrix in which it enters the soil environment.
65
Detection of Protease-Resistant Prion Protein in Water from a CWD-Endemic Area
Tracy A. Nichols*1,2, Bruce Pulford1, Christy Wyckoff1,2, Crystal Meyerett1, Brady Michel1, Kevin Gertig3, Jean E. Jewell4, Glenn C. Telling5 and M.D. Zabel1 1Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA 2National Wildlife Research Center, Wildlife Services, United States Department of Agriculture, Fort Collins, Colorado, 80521, USA 3Fort Collins Water and Treatment Operations, Fort Collins, Colorado, 80521, USA 4 Department of Veterinary Sciences, Wyoming State Veterinary Laboratory, University of Wyoming, Laramie, Wyoming, 82070, USA 5Department of Microbiology, Immunology, Molecular Genetics and Neurology, Sanders Brown Center on Aging, University of Kentucky, Lexington, Kentucky, 40536, USA * Corresponding author- mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:tracy.a.nichols@aphis.usda.gov
Chronic wasting disease (CWD) is the only known transmissible spongiform encephalopathy affecting free-ranging wildlife. Experimental and epidemiological data indicate that CWD can be transmitted horizontally and via blood and saliva, although the exact mode of natural transmission remains unknown. Substantial evidence suggests that prions can persist in the environment, implicating it as a potential prion reservoir and transmission vehicle. CWD- positive animals can contribute to environmental prion load via biological materials including saliva, blood, urine and feces, shedding several times their body weight in possibly infectious excreta in their lifetime, as well as through decomposing carcasses. Sensitivity limitations of conventional assays hamper evaluation of environmental prion loads in water. Here we show the ability of serial protein misfolding cyclic amplification (sPMCA) to amplify minute amounts of CWD prions in spiked water samples at a 1:1 x106 , and protease-resistant prions in environmental and municipal-processing water samples from a CWD endemic area. Detection of CWD prions correlated with increased total organic carbon in water runoff from melting winter snowpack. These data suggest prolonged persistence and accumulation of prions in the environment that may promote CWD transmission.
66
Effect of Invertebrates on Environmental Prion Contamination
Jay Schneider1* 1University of Wisconsin - Madison *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:jschneider@usgs.gov
Transmissible spongiform encephalopathies (prion diseases) are fatal neurodegenerative diseases affecting a number of mammalian species. The infectious agent is exceptionally resistant to degradation and can persist in the environment for long periods of time, contributing to the maintenance and spread of sheep scrapie and chronic wasting disease in cervids. We investigated what effect two common invertebrates, earthworms and Dermestid beetles, would have on the integrity of prion proteins. As opportunistic feeders, both organisms consumed prion-infected tissue. However, their impact on prion protein after consumption varied. Whereas the earthworm, which possesses strong proteolytic enzymes, demonstrated the ability to degrade prions and reduce infectivity levels; the dermestid beetle larva was more proficient in passing prion into waste (frass). These studies suggest that earthworms may provide a biotic means of decreasing infectivity levels in the environment and serve as a source of enzyme(s) with strong anti-prion activity. Conversely, Dermestids may contribute to the spread and persistence of prions in the environment.
SNIP...
Chronic Wasting Disease Surveillance in Wild and Farmed Cervids in Alberta.
Margo J. Pybus1*, and Gerald Hauer2 1Fish and Wildlife Division of Alberta Sustainable Resource Development, Edmonton, Alberta 2Alberta Agriculture and Rural Development, Edmonton, Alberta *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:margo.pybus@gov.ab.ca
Alberta has wrestled with CWD surveillance in wild and farmed cervids since 1996. Most of the surveillance in wild cervids is based on hunter samples and road kills in CWD risk areas, supplemented with clinical cases of emaciation or neurologic dysfunction in cervids from throughout the province. Mandatory submission of hunter-killed deer in CWD risk areas is a primary feature of the program. Surveillance of farmed cervids was voluntary for cervid producers from 1996 until August 2002 when it became mandatory to submit heads from all cervids over 1 year of age that die for any reason, including on-farm and commercial slaughter. To date over 26,000 wild cervids and 51,000 farmed cervids have been tested. The first case of CWD in a wild deer was found in 2005; cases in farmed cervids were found in 2002/03. A total of 61 cases of CWD were identified in wild deer (55 mule deer, 6 whitetails) in a limited area in eastern Alberta. A total of three cases of CWD were identified in farmed cervids (1 elk, 2 white-tailed deer) in central Alberta. Ongoing surveillance programs identified 19 (31%) of the wild cases and 2 of the 3 farmed cases. The remaining infected animals were detected in associated disease control programs.
96
Detecting Environmental Deposits of Chronic Wasting Disease Prions in Soil
A. Christy Wyckoff1, Traci A. Nichols1, Kurt C. VerCauteren2 and Mark D. Zabel1* 1 Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Co. 2 National Wildlife Research Center, Wildlife Services, United States Department of Agriculture, Fort Collins, Co. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:mark.zabel@colostate.edu
Current research suggests that environmental deposits of Chronic Wasting Disease prions (PrPCWD) play a role in the transmission and persistence of Chronic Wasting Disease (CWD) among captive and wild cervids. Furthermore, studies indicate that the prion molecule forms a close association with certain types of soil such as clays, enhancing its persistence and surprisingly, enhancing the transmissibility of the infectious agent. Aspects of PrPCWD persistence in soil has been a particularly challenging aspect to study due to limited sensitivity of existing laboratory assays. Our objective was to develop an assay that will allow for an increased detection limit of PrPCWD in soil sample. We used PrPCWD positive elk brain homogenate (E2) to spike samples of whole soil from the region. Next we used increasing detergent concentrations of SDS and sarkosyl to help elute PrPCWD off the soil by western blot. Preliminary results indicate a maximum recovery of PrPCWD from spiked soil samples at 0.05% SDS and 0.25% Sarkosyl by electrophoresis. Future directions include the use of protein misfolding cyclic amplification (PMCA) to increase the detection limit of positive soil samples.
Humic Acid Influences Pathogenic Prion Protein Sorption to Clay Particles
Christen M. Bell1, Debbie McKenzie4, Judd M. Aiken4, and Joel A. Pedersen*1,2,3* 1Environmental Chemistry and Technology Program 2Department of Soil Science, 3Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI 53706 4 Alberta Centre for Prions and Protein Folding Diseases, 2-04 Environmental Engineering Building, University of Alberta, Edmonton, Alberta T6G 2M8, Canada *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:japedersen@soils.wisc.edu
Soil may contribute to the horizontal transmission of the prion diseases sheep scrapie and chronic wasting disease of deer, elk and moose by serving as an environmental reservoir for the infectious agent. We previously demonstrated that the disease-associated form of the prion protein (PrPTSE) binds to soil particles and that the PrPTSE interaction with the clay mineral montmorillonite (Mte) is remarkably avid. Here, we investigate the role of natural organic carbon on the interaction of pathogenic prion protein with soil particles by studying PrPTSE sorption to humic acid-montmorillonite (HA-Mte) complexes. We found that HA-Mte complexes have a lower affinity for PrPTSE than Mte alone and that the binding capacity for the protein decreased with increasing HA content. Extraction of humic acid from HA-Mte after PrPTSE sorption suggests that the pathogenic prion protein associates primarily with Mte surfaces and that organic carbon blocks PrPTSE binding sites on Mte. Immunoblot analysis of PrPTSE incubated with dissolved humic acid indicates cleavage of the protein at the N-terminus. The influence of organic carbon on oral disease transmission by soil particle bound prions warrants investigation.
Interaction of a Model Prion Protein with Soil Humic, and Humic-Like Compounds
Maria A. Rao1, Fabio Russo1*, Riccardo Scotti1, Liliana Gianfreda1 1Dipartimento di Scienze del Suolo, della Pianta, dell’Ambiente e delle Produzioni Animali, Università di Napoli Federico II, Via Università 100, 80055 Portici, Italy. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:russofab@unina.it
Infectious prion protein is able to persist in soil for years and likely to propagate the disease to wild animals. While studies were devoted to investigate the role of whole soils or inorganic constituents to bind these agents and affect their infectivity; less information instead is available on the interaction of prion protein with soil organic matter (SOM).
As a part of the processes leading to the formation of humic substances in soil, oxidative coupling reactions of phenolic groups of simple and more complex molecules can occur through the action of enzymes like peroxidases and polyphenoloxidases. Further reorganization of resulting molecules can lead either to higher size molecules or to higher size complexes. Biomacromolecules such as proteins can be involved in these processes, resulting thus associated with SOM.. We report in this study the interaction of an ovine recombinant prion protein with preformed soil humic acids and humic-like substances in formation. Organic synthetic humic like aggregates were produced by using laccase and catechol. Desorption and extraction was investigated by using weak and strong extracting procedures. The percentage of protein bounded by humic acids or humic-like substances in formation as well as the amounts extractable from these complexes indicated more stable interaction between prion protein and SOM in formation.
Overall, the results seem to indicate that entrapment or adsorption phenomena involving prion protein actually occurs with SOM, even if at different degree probably depending on its stage of maturation.
However, elucidating the effect of prions immobilization in SOM on their infectivity and environmental diffusion requires the use of the infectious prion protein.
per lo Studio degli Ecosistemi, CNR Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy. 2Dipartimento di Scienza del Suolo e Nutrizione della Pianta, Università degli Studi di Firenze, Piazzale Cascine 28 50144 Firenze, Italy *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:pucci@ise.cnr.it
The researches carried out on prions adsorption related to soil were generally focused on the soil as a whole or on selected inorganic or organic constituents with equilibrium batch techniques which can not take into account their spatial distribution and/or the relative interrelationships occurring in natural environment. In fact, the sorption processes in the “in situ” conditions are complex phenomena due only partly to the properties of single components but, due also to some "newly born" properties resulting from of the interaction among constituents.
In this work the adsorption of a recombinant protein whose structure mimics the ovine prion (recPrP) was studied on native OM of undisturbed soil aggregates used as a simplified microcosm model system of soil at laboratory scale, and considered as individual adsorption system rather than the summation of single constituents. A Low-Temperature Ashing (LTA) by oxygen plasma has been applied to investigate the contribution of OM to the adsorption of a recPrP on soil aggregates from two different soils before and after OM removal by LTA. This technique allows a controlled removal of OM layer by layer, like a peeling of an onion skin, with minimal disturbance of the mineral matrix.
Soil aggregates were selected as a representative model of the “in situ” conditions. Adsorption from batch vs percolation experiments were compared, and High affinity (H-Type) adsorption isotherms were found , with maximal sorption amounts indicating that native OM has specific adsorption capacity even superior to the mineral matrix.
The coupled LTA-PAS-FTIR approach demonstrated that, albeit OM composition was homogeneous throughout the aggregates, its presence in the most external surfaces of the aggregates affects the diffusion dynamics of RecPrP within the aggregates during percolation by a “filtering out” effect.
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Modeling Lateral CWD Transmission in the Environment Using Cervid and Bovine PrP-Expressing Mice
Theodore Johnson 1*, BA Michel1, B Pulford1 and MD Zabel1 1Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:tejohnso@rams.colostate.edu
Chronic wasting disease (CWD) is efficiently transmitted laterally among wild and captive deer and elk populations. Possible transmission vehicles include saliva, urine and feces shed into the environment. An attempt to model lateral transmission through environmental contamination with a murine model was made using Tg(cerPrP)5037 and Tg(bovPrp)3705 mice. Healthy mice were continuously housed in bedding and water previously used by mice inoculated with CWD-infected or normal brain homogenate. All mice failed to develop clinical disease after over 700 days of continuous exposure, demonstrating limitations of murine models to recapitulate mechanisms of efficient lateral CWD transmission among cervids.
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Pathogenic Prion Protein is Degraded by a Serine Protease in Lichens
Christopher J. Johnson1,2*, James P. Bennett1,3, Steven M. Biro1,3, Camilo Duque-Velasquez4, Richard A. Bessen2 and Tonie E. Rocke1 1 USGS National Wildlife Health Center, Madison WI, USA 2 Montana State University, Bozeman, MT, USA 3 University of Wisconsin, Madison WI, USA 4 Grupo de Investigacion Centauro, Universidad de Antioquia, Medellin, Colombia. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:cjjohnson@usgs.gov
Lichens are unusual, symbiotic organisms formed from a fungus and partner algae or cyanobacteria. The geographic distribution of lichens is extraordinarily wide and many species thrive in extreme environments such as arctic tundra, desert rock, pure sand or toxic slag heaps. Few biological systems have been identified that degrade the pathogenic form of the prion protein (PrPTSE) and the remarkable biology of lichens and their need to capture and conserve nutrients in harsh conditions suggests that lichens may be capable of unique metabolic activities. We tested the hypotheses that lichen extracts and intact lichens can degrade PrPTSE. We found that extracts of three lichen species caused approximately a 100-fold loss of prion protein immunoreactivity in samples of PrPTSE from either hamsters or white-tailed deer. Intact lichens exposed to infected brain homogenate reduced PrPTSE levels approximately 70% following 24h incubation. Some common lichen chemicals were excluded from being the active substance(s) and treatments to interfere with redox reactions or reactive metals were not effective at blocking degradation. Two protease inhibitor cocktails, however, were each partially effective at preventing lichen extract-induced PrPTSE degradation. Screening a panel of individual, specific protease inhibitors revealed that a serine protease of lichens is the likely agent that degrades prion protein. While animal bioassay experiments to determine the effect of lichen extracts on infectious titer are ongoing, these data suggest that lichens could promote prion degradation in the environment and may have utility for prion inactivation in medical or biotechnological settings. Additionally, the role of lichens in prion environmental biology should be investigated.
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Degradation of the Pathogenic Prion Protein by a Manganese Mineral Found in Soils
Joel A. Pedersen1*, Fabio Russo2, Christopher J. Johnson3, Chad J. Johnson1, Debbie McKenzie4 and Judd M. A iken4 1University of Wisconsin, Madison, WI, USA 2Dipartimento di Scienze del Suolo della Pianta dell’Ambiente e delle Produzioni Animali, Università Federico II, Portici (NA), Italy 3USGS National Wildlife Health Center, Madison, WI, USA 4University of Alberta, Edmonton, AB, Canada. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:joelpedersen@wisc.edu
Prions, the etiological agents of transmissible spongiform encephalopathies, exhibit extreme resistance to degradation. Soil can retain prion infectivity in the environment for years. Reactive soil components may, however, contribute to the inactivation of prions in soil. Members of the birnessite family of manganese oxides (MnO2) rank among the strongest natural oxidants in soils. We found a synthetic analog of naturally occurring birnessite minerals to be capable of degrading the pathogenic prion protein (PrPTSE). Aqueous MnO2 suspensions degraded the PrPTSE as evidenced by decreased immunoreactivity and diminished ability to seed protein misfolding cyclic amplification reactions. Birnessite-mediated PrPTSE degradation increased as solution pH decreased, consistent with the pH-dependence of the redox potential of MnO2. Exposure to 5.6 mg·mL-1 MnO2 (PrPTSE:MnO2 = 1:110) decreased PrPTSE levels by =4 orders of magnitude. Manganese oxides may contribute to prion degradation in soil environments rich in these minerals.
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NeuroPrion Cervid Group Activities and Surveillance for TSEs in European Cervids
Michael J. Stack1* 1Veterinary Laboratories Agency, Weybridge, Surrey, UK *Corresponding author e-mail:
In 2004, the European Food Safety Authority published an opinion on the surveillance for TSEs in deer across Europe. Commission officials and an appointed scientist attended the 2nd International CWD Symposium in Madison, Wisconsin, July 2005, where pre-conference tours were arranged of sampling outposts in the hunting area and the USDA diagnostic laboratory. Officials also met with CWD experts from USA and Canada to ascertain the best scientific approaches for surveillance in Europe. In January 2007, several EU countries started to officially monitor farmed and wild deer for TSEs. The survey comes to an end in 2009 when it is hoped that EU Member States will meet their targets designed to detect disease at 0.5% prevalence with 95% confidence. Running in parallel with the build up to the survey, the NeuroPrion initiative in Europe has funded a cervids working group since 2005.
Questions
The NeuroPrion cervid group was set up to answer the following questions:
Are European cervids susceptible to CWD or other TSEs?
Are diagnostic tests developed for CWD hosts in North America suitable for European cervids?
What is the likelihood/risk of CWD occurring in Europe?
Will CWD transmit experimentally to European deer?
Methods
EU countries have been employing rapid tests to screen for TSEs in various species of deer and Western blot and IHC to use as confirmatory and discriminatory techniques. Transgenic mice over expressing CWD PrP have also been imported from the USA for bioassay and strain typing of any positive cases. CWD tissue has also been supplied by North America for proficiency testing in Europe.
Results
No cases of TSE in the European cervid populations have been found.
Conclusion
Although European cervid species are susceptible to TSEs experimentally, no evidence of disease was found in Europe in the cervid populations tested.
Differential Characteristics of Experimental BSE and CWD in European Red Deer (Cervus elaphus elaphus)
Stuart Martin1, Martin Jeffrey1, Lorenzo González1*, Sílvia Sisó1, Hugh W. Reid2, Philip Steele2, Mark P. Dagleish2, Michael Stack3, Melanie Chaplin3 and Aru Balachandran4 1Veterinary Laboratories Agency (VLA-Lasswade), Pentlands Science Park, Midlothian EH26 0PZ, UK. 2Moredun Research Institute, Pentlands Science Park, Midlothian EH26 0PZ, UK. 3VLA-Weybridge, Addlestone KT15 3NB, UK. 4Animal Diseases Research Institute, Canadian Food Inspection Agency, Ottawa, Ontario, Canada K2H 8P9 *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:l.gonzalez@vla.defra.gsi.gov.uk
The cause of the bovine spongiform encephalopathy (BSE) epidemic in the United Kingdom (UK) was the inclusion of contaminated meat and bone meal in the protein rations fed to cattle. Contaminated feedstuffs were also fed to other livestock including farmed and free living deer. BSE has been shown to be naturally or experimentally transmissible to a wide range of different ungulates although to date there are no reported cases of natural BSE infections in European deer. In North America, however, several cervid species are highly susceptible to chronic wasting disease (CWD), an endemic transmissible spongiform encephalopathy. Should BSE infection have been introduced into the UK deer population, the CWD precedent would suggest that there is a danger for spread and maintenance of the disease in both free living and captive UK deer populations. This study compares the immunohistochemical and biochemical characteristics of BSE and CWD in experimentally-infected European red deer (Cervus elaphus elaphus). Six out of six red deer challenged intracerebrally and one of six dosed orally with 25 g of cattle BSE developed TSE-confirmed disease at 26-42 and 58 months post-infection, respectively. Four out of four deer challenged orally with 5 g of elk CWD developed TSE-confirmed disease at 18-20 months post-infection. In terms of abnormal PrP distribution, BSE in red deer more closely resembled natural infection in cattle rather than experimental BSE in small ruminants, due to the lack of accumulation of abnormal PrP in lymphoid tissues. In this respect it was different from CWD, and despite similarities in vacuolation profiles of both diseases, BSE could be clearly distinguished from CWD by immunohistochemical and biochemical methods currently in routine use. Therefore, although red deer are susceptible to BSE infection, they develop a disease with pathological and molecular signatures different from those of CWD in the same species.
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Susceptibility of Domestic Cattle to Chronic Wasting Disease by Oral Inoculation and Natural Exposure: Final Phase of a 10-year Study
Elizabeth S. Williams1, Donal O’Toole1, Matthew M. Hille1, Donald L. Montgomery1, Jean E. Jewell1*, Terry J. Kreeger2, and Michael W. Miller3 1Department of Veterinary Sciences, University of Wyoming, Laramie, WY 82070 2Wyoming Game and Fish Department, Wheatland, WY 82201 3Colorado Division of Wildlife, Fort Collins, Colorado 80526 *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:jjewell@uwyo.edu
The risk of domestic cattle developing a transmissible spongiform encephalopathy (TSE) after oral inoculation followed by a long incubation period, or by long-term natural exposure to cervids infected with chronic wasting disease (CWD) was studied. Ten cattle were given large oral doses of pooled brain material from CWD-infected mule deer in late August 1997 and housed in isolation at the Wyoming State Veterinary Laboratory until September 2007. Two additional groups of cattle were penned outdoors with CWD-infected deer and elk or in CWD-contaminated premises at Colorado Division of Wildlife (n=11) and Wyoming Game and Fish Department (n=10) research facilities during the same ten-year period. These conditions simulated exposure routes that cattle in North America might encounter if they are raised or grazed in areas where free-ranging or captive deer and elk are infected with CWD.
Beginning in July 2007 all exposed and three untreated control cattle were killed, and select tissues were collected at necropsy. Samples from each animal were analyzed for the diagnostic hallmarks of TSEs by immunohistochemistry and Western blot. DNA sequences were determined for the cellular prion protein gene in each animal. No proteinase-K resistant prion protein or anti-PrP immunoreactive IHC signals were detected in any tissues of exposed or control animals. None of these results, taken individually or together, support a diagnosis of TSE in cattle inoculated orally with a high dose of infectious CWD material or continually exposed by cohabitation with infected deer or elk, or transmission from contaminated premises despite an incubation period of up to 10 or 11 years.
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Progressive Accumulation of PrPCWD and Spongiform Encephalopathy in the Obex of Rocky Mountain Elk (Cervus elaphus nelsoni) with Chronic Wasting Disease and its Use as a Means of Scoring the Stage of Disease and Predicting Accumulation of Prion in Peripheral Tissues
Terry R. Spraker1*, Thomas L. Gidlewski2, Jenny Powers3, Scott D. Wright4, Aru Balachandren5, and Katherine I. O’Rourke6 1College State University Diagnostic Laboratory, 300 West Drake Road, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80526 2USDA/APHIS/WS, Fort Collins, CO 80521 3National Park Service, Biological Resources Management Division, Fort Collins, CO 80525 4National Wildlife Health Center/USGS, 6006 Schroeder Road, Madison WI 53711 5National and OIE Reference Laboratory for scrapie and CWD, Canadian Food Inspection Agency, Ottawa, Canada 6USDA/ARS, Pullman, WA 99164 (KO) *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:terry.spraker@colostate.edu
Chronic wasting disease (CWD), a transmissible spongiform encephalopathy, has been reported in captive and free-ranging cervids. An abnormal isoform of a prion protein (PrPCWD) has been associated with CWD in cervids and this prion protein can be detected with immunolabeling. It has been suggested in mule deer that as the disease progresses the degree of accumulation of PrPCWD and severity of spongiform degeneration increases. This communication describes a method to delineate the progressive accumulation of PrPCWD and increase severity of spongiform degeneration in a single section of obex. Ten nuclear areas and white matter tracts including the subependymal area of the fourth ventricle and in the thin subpial astrocytic layer of a section of obex were examined and scored in 75 free-ranging and ranch-raised elk that were positive for naturally occurring CWD. This obex score was divided into ten categories and then each category was compared to the detection of PrPCWD in peripheral tissues (approximately 130) and brain (approximately 100 neuroanatomical locations) in 25 elk with natural occurring CWD. Lymphoid tissues in early cases were at first sporadically affected, but became more uniformly affected as the disease progressed. Spinal cord was commonly affected starting in the dorsal and intermediate horns, but dorsal root ganglia were not. Myoenteric plexuses and mucosa of the entire digestive tract was affected early and remained positive throughout the disease. The prion spread quickly through out the brain and nearly all areas had a degree of detectably prion midway in the disease. Adrenal medulla was affected in what was considered mid disease and then later the adrenal cortex was positive. Prion was found in the retina, nerves of the ethmoid turbinates, circumvallate papillae, heart, placenta and skeletal muscle in later stages of disease. PrPCWD was not detected in the lungs, trachea, kidney, skin and sebaceous glands. Numerous sarcocyst were examined in skeletal muscle and heart and PrPCWD was not detected in them. The obex score was then compared to the obex score in 13 experimental elk representing all three genotypes with known incubation times and this score was compared to the obex scores to the elk with natural occurring CWD. The genetics of the elk play a major role in this process or speed of spread throughout the body and brain. Elk with a 132MM genotype had the lowest obex scored, 132ML had intermediate scores and 132LL had the longest incubation times with comparable obex scores to natural occurring CWD cases. The utility of this method to estimate the distribution of prion throughout the body and brain and to estimate duration of disease will be discussed. Perhaps this data also will give some insight into the pathogenesis of CWD in elk.
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Diagnosis of Pre-Clinical CWD in Farmed White-Tailed Deer in Canada by the Immunohistochemical Examination of Rectal Biopsies
A. Balachandran1* B. Thomsen2, T. Gidlewski3, T. R. Spraker4, G. Mitchell1, A. Soutyrine1, N. Harrington1 R. Munger3 J. McLane5, R. Allen6, D.A. Schneider7 and K.I. O’Rourke7 1Canadian Food Inspection Agency, Ottawa, Ontario, CANADA 2USDA-National Veterinary Services Laboratory, Ames, Iowa, USA 3USDA-APHIS-Veterinary Services, Fort Collins, Colorado, USA 4Colorado State University, Fort Collins, Colorado, USA 5Canadian Food Inspection Agency, Battleford, SK, CANADA 6Canadian Food Inspection Agency, Prince Albert, SK, CANADA 7USDA-Agricultural Research Service, Pullman, Washington, USA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:Aru.Balachandran@inspection.gc.ca
Approved testing for diagnosis of chronic wasting disease (CWD) in cervids includes postmortem detection of disease-associated prion protein (PrPCWD) in lymph nodes or brain. Detection of PrP-CWD in rectoanal mucosa-associated lymphoid tissue (RAMALT) offers the possibility of live animal, preclinical diagnosis; however, recent reports suggest certain factors affect such detection in cervids. The present observational study reports preliminary analysis of two white-tailed deer farm depopulations in Canada. For this analysis deer were considered CWD-positive if PrP-CWD was detected in the brain, retropharyngeal lymph node (RPLN) or tonsil by immunohistochemistry, ELISA or western blot. Farm A included 122 deer with an overall disease prevalence of 31%; Farm B included 385 deer with an overall disease prevalence of 21%. Approximate overall immunohistochemistry test sensitivities were: RPLN = 0.90, tonsil = 0.87, RAMALT = 0.72 and brain = 0.60. In CWD-positive deer from Farm A, PrP-CWD was detected in 55% of RAMALT biopsies from obex grade 0 deer, and in all RAMALT biopsies from deer with obex grades greater than 0. In CWD-positive deer from Farm B, PrP-CWD was detected in 33%, 77%, 96% of RAMALT biopsies respectively from obex grades 0-2 deer, and in all RAMALT biopsies from obex grades 3 and 4 deer. RAMALT follicle count data was currently available for only a subset of biopsies from Farm 2 deer and was highly variable. The proportion positive RAMALT follicles for two wt/G96S deer (both obex grade 0) were lower than six out of eight obex grade-matched wt/wt deer. This preliminary analysis suggests diagnostic evaluation of RAMALT in captive white-tailed deer has an intermediate sensitivity compared to the range associated with currently approved tissue sites. False-negative RAMALT results were most common in deer early in disease progression. Heterozygosity at PRNP codon 96 may be associated with more limited detection of PrP-CWD.
Utility Of Rectal Biopsy For Preclinical Diagnosis Of Chronic Wasting Disease In Free-Ranging Rocky Mountain Elk
Jenny G. Powers1*, Terry R. Spraker2, Mark S. Graham1, Katherine O’Rourke3, Michael W. Miller4, and Margaret A. Wild1 1National Park Service, Fort Collins, CO, USA 2Colorado State University, Fort Collins, CO, USA 3Agricultural Research Services, USDA, Pullman, WA, USA 4Colorado Division of Wildlife, Fort Collins, CO, USA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:Jenny_Powers@nps.gov
Chronic wasting disease (CWD) has not previously been diagnosed using a preclinical ante mortem test in free-ranging elk. In this study, we captured, radio-collared, and collected samples of rectal lymphoid tissue from 136 female elk in Rocky Mountain National Park, Colorado, USA. No clear clinical signs of CWD were observed at the time of capture. Thirteen of 117 diagnostic samples (86% diagnostic using = 5 lymphoid follicles) were positive when examined using immunohistochemistry. Positive animals were removed from the population and complete necropsies performed. All had evidence of PrPCWD in the brain and retropharyngeal lymph nodes. Three months post-capture a single CWD biopsy test negative female began showing subtle behavioral signs of disease. At necropsy she was confirmed CWD positive, and represents an apparent false negative rectal biopsy result. January 2009, 1 year post capture, 20 study animals were observed, darted, repeat rectal biopsies performed then euthanized. None demonstrated clinical signs of CWD at this time. In 2009, 75% of biopsies contained = 5 lymphoid follicles and 1 animal was rectal biopsy and brain/ lymph node CWD positive. Full necropsy results are pending from this cohort.
Genotyping of the PrP gene at codon 132 showed 55% of the entire study population was homozygous for methionine (MM), 40% were heterozygous (ML), and 5% were homozygous for leucine (LL). Proportions of genotypes from CWD infected elk were not significantly different from those of CWD test negative elk (p = 0.23). However, this may be due to the small sample size of CWD positive elk. These results show that while rectal biopsy is an intensive tool, it can be used to diagnose preclinical CWD in free-ranging elk and may provide a method for measuring CWD incidence if repeated at regular intervals.
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The Use of Recto-Anal Mucosa-Associated Lymphoid Tissue (RAMALT) for Diagnosis of CWD in White-Tailed Deer (Odocoileus virginianus).
Delwyn Keane,1* Daniel Barr,1 Rebecca Osborn,2 Julie Langenberg,2 Katherine O’Rourke,3 David Schneider3 and Philip Bochsler1 1University of Wisconsin, Wisconsin Veterinary Diagnostic Laboratory, Madison, WI 2Wisconsin Department of Natural Resources, Madison, WI 3US Department of Agriculture, Agricultural Research Service, Animal Disease Research Unit, Pullman, WA *Corresponding author e-mail:
Diagnosis of CWD is currently generally dependent upon the finding of PrPCWD in obex and/or lymphoid tissues of animals collected post-mortem. Ante-mortem evaluation of tonsillar biopsies has been shown to detect preclinical CWD in deer but collection of tonsillar tissue is not a practical field procedure. Recent studies have shown that scrapie-associated PrP (PrPSC) is deposited in the recto-anal mucosa-associated lymphoid tissues (RAMALT) of infected sheep relatively early in the infection course. In this study we examined RAMALT collected at post-mortem from 210 free-ranging white-tailed deer harvested from an area of Wisconsin in which CWD is enzootic and from 76 white-tailed deer removed from a know infected farm in Wisconsin. Sensitivity of the immunohistochemical staining of RAMALT tissues compared to that of obex, tonsil and/or retropharyngeal lymph node was 91% for the free-ranging animals and 81% for the captive animals. False negatives were usually associated with early infection as evidenced by early or low intensity of PrPCWD staining in the obex and/or a polymorphism at PRNP codon 96 (glycine to serine (G96S)). The number of inadequate RAMALT samples was higher for the free-range deer (21%) than for captive animals (3.9%). Though this study was conducted using RAMALT tissues that had been collected post-mortem, the results suggest that RAMALT tissues collected ante-mortem may be useful as an adjunct to tonsil biopsy and necropsy surveillance for screening of farmed deer.
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Diagnosis of Pre-Clinical CWD in Farmed White-Tailed Deer in Canada by the Immunohistochemical Examination of Rectal Biopsies
A. Balachandran1* B. Thomsen2, T. Gidlewski3, T. R. Spraker4, G. Mitchell1, A. Soutyrine1, N. Harrington1 R. Munger3 J. McLane5, R. Allen6, D.A. Schneider7 and K.I. O’Rourke7 1Canadian Food Inspection Agency, Ottawa, Ontario, CANADA 2USDA-National Veterinary Services Laboratory, Ames, Iowa, USA 3USDA-APHIS-Veterinary Services, Fort Collins, Colorado, USA 4Colorado State University, Fort Collins, Colorado, USA 5Canadian Food Inspection Agency, Battleford, SK, CANADA 6Canadian Food Inspection Agency, Prince Albert, SK, CANADA 7USDA-Agricultural Research Service, Pullman, Washington, USA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:Aru.Balachandran@inspection.gc.ca
Approved testing for diagnosis of chronic wasting disease (CWD) in cervids includes postmortem detection of disease-associated prion protein (PrPCWD) in lymph nodes or brain. Detection of PrP-CWD in rectoanal mucosa-associated lymphoid tissue (RAMALT) offers the possibility of live animal, preclinical diagnosis; however, recent reports suggest certain factors affect such detection in cervids. The present observational study reports preliminary analysis of two white-tailed deer farm depopulations in Canada. For this analysis deer were considered CWD-positive if PrP-CWD was detected in the brain, retropharyngeal lymph node (RPLN) or tonsil by immunohistochemistry, ELISA or western blot. Farm A included 122 deer with an overall disease prevalence of 31%; Farm B included 385 deer with an overall disease prevalence of 21%. Approximate overall immunohistochemistry test sensitivities were: RPLN = 0.90, tonsil = 0.87, RAMALT = 0.72 and brain = 0.60. In CWD-positive deer from Farm A, PrP-CWD was detected in 55% of RAMALT biopsies from obex grade 0 deer, and in all RAMALT biopsies from deer with obex grades greater than 0. In CWD-positive deer from Farm B, PrP-CWD was detected in 33%, 77%, 96% of RAMALT biopsies respectively from obex grades 0-2 deer, and in all RAMALT biopsies from obex grades 3 and 4 deer. RAMALT follicle count data was currently available for only a subset of biopsies from Farm 2 deer and was highly variable. The proportion positive RAMALT follicles for two wt/G96S deer (both obex grade 0) were lower than six out of eight obex grade-matched wt/wt deer. This preliminary analysis suggests diagnostic evaluation of RAMALT in captive white-tailed deer has an intermediate sensitivity compared to the range associated with currently approved tissue sites. False-negative RAMALT results were most common in deer early in disease progression. Heterozygosity at PRNP codon 96 may be associated with more limited detection of PrP-CWD.
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Diagnosis of Pre-Clinical Sheep TSEs in Rectal Biopsies by ELISA: Overcoming “False Negative” Results
Lorenzo González1*, Leigh Thorne2, Sally J. Everest2, Andrew Ramsay2, Mark P. Dagleish, Martin Jeffrey1 and Linda A. Terry2 1Veterinary Laboratories Agency (VLA-Lasswade), Pentlands Science Park, Midlothian EH26 0PZ, UK. 2VLA-Weybridge, Addlestone KT15 3NB, UK. 3Moredun Research Institute, Pentlands Science Park, Midlothian EH26 0PZ, UK. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:l.gonzalez@vla.defra.gsi.gov.uk
Disease-associated prion protein (PrPd) accumulates in the lymphoid tissue of the rectal mucosa of a high proportion of scrapie-infected sheep at clinical and preclinical stages. PrPd can therefore be detected in biopsy specimens of rectal mucosa, with increasing probability proportional to age or incubation period, and with efficiency almost identical to that of tonsil biopsies. Rectal biopsies have the advantages of providing higher numbers of lymphoid follicles and of being simpler to perform, making them suitable for the screening of scrapie in the field. PrPd in biopsy samples can be demonstrated by immunohistochemistry (IHC) and Western blot. More recently, a “rapid test” (HerdChek® CWD Antigen EIA Test) was optimized and evaluated for the diagnosis of scrapie in rectal biopsy samples, providing specificity and sensitivity figures of 99.2% and 93.5%, respectively, compared to IHC results in the same samples obtained at post-mortem. The sensitivity of the assay increased from 82.1% when a single rectal mucosa sample was tested to 99.4% for those sheep in which three or more samples were analyzed. Similarly, sensitivity values of the CWD EIA test on biopsy samples increased from 95% to 100% for sheep subjected to one or two sequential biopsies four months apart, respectively. Thus, preclinical diagnosis of scrapie in live sheep can be achieved by a combination of a simple and repeatable sampling procedure, and a rapid and efficient laboratory method. However, unlike IHC, this method does not allow identification of “false negatives”, i.e. samples that do not contain enough target lymphoid tissue. To overcome this problem we have developed an ELISA for the detection of CD21, a marker expressed by B cells and follicular dendritic cells; these cells are most abundant in secondary lymphoid follicles, i.e. the same site where PrPd accumulates in lymphoid tissues. This sandwich ELISA provides increased signals in rectal mucosa containing lymphoid follicles compared to gut mucosa devoid of lymphoid tissue.
80
Chronic Wasting Disease in Wild Deer: Wildlife Agency Responses Across North America.
Margo J. Pybus1*, and Yeen Ten Hwang2 1Fish and Wildlife Division of Alberta Sustainable Resource Development, Edmonton, Alberta 2Saskatchewan Ministry of Environment, Regina, Saskatchewan. *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:margo.pybus@gov.ab.ca
In August 2008, Alberta and Saskatchewan wildlife agencies co-hosted a workshop to review wildlife management responses to chronic wasting disease (CWD) in wild deer. The approach was to examine representative current programs, their successes and failures, and use the information in conjunction with participant experiences to offer collective recommendations for future CWD response plans and programs. Workshop presenters focused on CWD response in their jurisdiction. This set the stage for breakout groups to have detailed discussions of the merits of various wildlife agency response activities and their applicability in three CWD risk scenarios: enzootic, newly detected, and at risk (not detected). Overall, the response programs of most jurisdictions are influenced by the availability of financial resources, and most importantly, public and political support. Prevention is the most effective goal in jurisdictions that are at risk of incurring CWD. Ongoing aggressive surveillance, particularly targeting clinical cases, as well as regional planning are most useful. In newly detected areas, timely and consistent response is prudent. CWD management is best served by aggressive targeting of infected individuals and reduction of risk factors. In enzootic areas, ongoing risk evaluation and hunter surveillance, as well as attempts to control disease spread into new areas and new species is best. Developing effective communication plans to inform the public and agency personnel are critical in all risk categories. The workshop final report and presentations are posted at
www.srd.gov.ab.ca/fishwildlife/livingwith/diseases/
81
Alberta's CWD One-Two Punch: Seek and Destroy
Margo J. Pybus1*, Mark Ball1, Al Gibson1, and Jim Allen1. 1Fish and Wildlife Division, Alberta Sustainable Resource Development, Edmonton, Alberta *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:margo.pybus@gov.ab.ca
Although Alberta has limited risk factors for CWD, the province began active surveillance in 1996. Upon finding CWD in a wild deer in Alberta in 2005, the province began an aggressive 2-pronged attack on CWD: intensified fall surveillance involving hunters and landowners to find infected deer, followed by targeted disease control delivered in the immediate vicinity of infected deer. Control programs were delivered in winter when deer were concentrated and other land use activities were minimal. Population reduction was applied in roughly 10km radius circles around known positive deer, modified by availability of suitable deer habitat and winter concentrations of deer. Deer were collected from the ground by government sharp-shooters and, at times, from the air by a private contractor. Meat, hides, and antlers were salvaged and this was an important component of maintaining rural and urban public support. Ongoing public education and one-on-one contact with landowners were essential to the success of the program. Of the 53 cases of CWD identified in wild deer prior to the 2008 fall hunting seasons, 40 (77%) were detected as a result of the directed CWD control program. The disease generally occurs along major river valleys with east/west orientation and small clusters in isolated habitats. In Alberta, CWD prevalence remains low, disease distribution is relatively limited (spilling in from infected deer in Saskatchewan), and many infected deer are in early stages of infection, all suggesting the disease is not yet fully established in Alberta. However, the program failed in the crucial area of maintaining support among key politicians and the winter control portion was not delivered in 2009 despite 8 new cases found in the fall programs of 2008.
82
The Wisconsin Experience with Chronic Wasting Disease Management: Lessons Learned
Michael D. Samuel1*, Julie A. Langenberg2, and Robert E. Rolley2 1U.S. Geological Survey, Wisconsin Cooperative Wildlife Research Unit, 204 Russell Labs, 1630 Linden Drive, University of Wisconsin, Madison, Wisconsin, USA 2Wisconsin Department of Natural Resources, 2801 Progress Road, Madison, Wisconsin, USA; *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:mdsamuel@wisc.edu
Since 2002, Wisconsin has identified over 1100 cases of chronic wasting disease in free-ranging white-tailed deer (Odocoileus virginianus) distributed over > 2000 mi2. Wisconsin implemented an aggressive chronic wasting disease management program with the goals of controlling the spread of the disease and attempting to eradicate it from both wild and farm-raised cervids in the state. The primary control objectives for free-ranging deer included: 1) drastic population reduction in the CWD affected areas, 2) moderate population reduction in a buffer zone around affected areas, and 3) banning baiting and feeding of deer in these management areas. Strategies to reduce deer populations included extended deer hunting seasons (September - March) with no bag limits, a requirement for hunters to harvest an antlerless deer before harvesting a buck (Earn-a-Buck), focused culling by agency sharpshooters, and financial incentives for deer harvest. Social, political, and budgetary constraints (advocated by deer hunters) have progressively eroded these deer reduction strategies. Based on annual deer population surveys in the CWD eradication zones, there has been little cumulative change over the 6 years of attempted deer population reduction. A change in CWD prevalence in the "core" affected area has been difficult to detect until 2008; analysis of 7 years of surveillance data now suggests increasing prevalence. We will review the results of Wisconsin’s CWD management efforts to increase deer harvests and resulting population trends, social and political factors that influenced CWD management strategies, and temporal/spatial patterns of CWD. Disease modeling and mapping studies indicate that CWD was likely introduced in Wisconsin > 20 years ago and became widely distributed across southern Wisconsin, factors that make CWD control difficult. Management experiences indicate limited public support for drastic deer reduction strategies to affect disease control. We summarize lessons learned from our experiences and speculate about the future of CWD management in Wisconsin.
83
Sharpshooting Implementation and Efficacy in Management of CWD in Illinois
Paul A. Shelton1*, Nohra E. Mateus-Pinilla2, Hsin-Yi Weng3, Patrick McDonald1, Marilyn O. Ruiz3, William Brown3, Jan E. Novakofski3, Tom J. Beissel1, Marlis Douglas2, and Michael Douglas2 1Illinois Department of Natural Resources, One Natural Resources Way, Springfield, IL 62702 2Illinois Natural History Survey, 1816 S. Oak St., Champaign, IL 61820 3Departments of Animal Sciences and Pathobiology, University of Illinois, Urbana, IL 61801 *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:paul.shelton@illinois.gov
CWD was first detected in northern Illinois during Fall 2002. The outbreak has a central core with high disease prevalence, diffusing as distance from the core increases. Affected counties consist of highly fragmented forest habitat in a matrix of row-crop agriculture, with rapid urbanization of open spaces.
Illinois’ disease management strategy assumes: (1) disease transmission efficiency and deer density are interrelated, and (2) extent of environmental contamination is a function of the number of disease-positive deer. Thus, our goal is to achieve significant localized reductions in infected deer populations.
Locations in need of intervention (typified by high deer density, high prevalence and low hunter access) are selected based on winter aerial deer censuses and spatial distribution of cases identified by testing hunter-harvested deer. Teams of trained sharpshooters are deployed four nights a week between mid-January and March 31. We evaluated sharpshooting as a CWD management tool using 5 years of data and two related criteria: (1) effects on target population density; and (2) effects on disease prevalence/incidence. Although hunting opportunities increased in CWD counties during the study period, substantial growth in number of deer taken resulted only from post-hunt sharpshooting. Mixed linear regression modeling revealed a significant decrease in deer density when sharpshooting was employed for multiple years (=3) at relatively high intensity (=25 deer/mi2 per year).
A logistic regression model identified temporal changes in CWD prevalence across years (2003 - 2008). A significant decreasing linear trend was found in estimated prevalence rates among fawn/yearlings (p=0.013) but not among adults (p=0.48). This implies that the number of new cases (measured in =1.5 year olds) declined over time where sharpshooting was used between 2003 and 2007. Although preliminary, these results emphasize the importance of continuing CWD surveillance and interventions in an effort to thoroughly evaluate management options.
84
Culling as an Approach to Chronic Wasting Disease Management
Lisa L. Wolfe1*, Mary M. Conner2, Daniel Walsh1, Michael W. Miller1 1Wildlife Health Program, Wildlife Research Center, Colorado Division of Wildlife, 317 West Prospect Road, Fort Collins, CO 80526-2097, USA 2Utah Division of Wildlife Resources, Salt Lake City, UT and California Fish and Game Department, Bishop CA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:lisa.wolfe@state.co.us
In the early 2000s, the Colorado Division of Wildlife (CDOW) attempted several approaches for controlling chronic wasting disease (CWD) in free-ranging mule deer (Odocoileus hemionus) in northern Colorado. Harvest of female deer was increased in three Data Analysis Units (DAUs) with a goal of reducing population sizes by 25%; although population reduction goals apparently were achieved, CWD persisted in these areas. Localized culling of deer in “hotspots” of relatively high local CWD prevalence in north central Colorado along the northern Front Range and the South Platte River bottom and tablelands also was attempted; subsequent analyses of data from 16 sites could not demonstrate an overall effect of culling in lowering CWD prevalence compared to adjacent areas where no culling occurred (Conner et al. 2006). In addition, the CDOW also evaluated a “test and cull” strategy for lowering CWD prevalence using a naturally infected, free-ranging, mule deer population wintering in the town of Estes Park and nearby Rocky Mountain National Park (Wolfe et al. 2004); over a 5 year period, prevalence remained static among female deer and declined by about 50% among males. None of the approaches evaluated thus far appear sustainable over the time periods likely necessary to effect control of CWD: both population suppression and culling were extremely unpopular with constituent groups, and cost, labor, private property access, and animal approachability limit the application of test and cull.
References
Conner, M. M., Miller, M. W., Ebinger, M. R., and Burnham, K .P. 2007. A meta-BACI approach for evaluating management intervention on chronic wasting disease in mule deer. Ecological Applications 17 (1): 140-153. Wolfe, L. L., M. W. Miller, and E. S. Williams. 2004. Feasibility of “test-and-cull” for managing chronic wasting disease in urban mule deer populations. Wildlife Society Bulletin 32: 500-505.
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Chronic Wasting Disease Susceptibility of Four North American Rodents
Chad J. Johnson1*, Jay R. Schneider2, Christopher J. Johnson2, Natalie A. Mickelsen2, Julia A. Langenberg3, Philip N. Bochsler4, Delwyn P. Keane4, Daniel J. Barr4, and Dennis M. Heisey2 1University of Wisconsin School of Veterinary Medicine, Department of Comparative Biosciences, 1656 Linden Drive, Madison WI 53706, USA 2US Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison WI 53711, USA 3Wisconsin Department of Natural Resources, 101 South Webster Street, Madison WI 53703, USA 4Wisconsin Veterinary Diagnostic Lab, 445 Easterday Lane, Madison WI 53706, USA *Corresponding author email: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:cjohnson@svm.vetmed.wisc.edu
We intracerebrally challenged four species of native North American rodents that inhabit locations undergoing cervid chronic wasting disease (CWD) epidemics. The species were: deer mice (Peromyscus maniculatus), white-footed mice (P. leucopus), meadow voles (Microtus pennsylvanicus), and red-backed voles (Myodes gapperi). The inocula were prepared from the brains of hunter-harvested white-tailed deer from Wisconsin that tested positive for CWD. Meadow voles proved to be most susceptible, with a median incubation period of 272 days. Immunoblotting and immunohistochemistry confirmed the presence of PrPd in the brains of all challenged meadow voles. Subsequent passages in meadow voles lead to a significant reduction in incubation period. The disease progression in red-backed voles, which are very closely related to the European bank vole (M. glareolus) which have been demonstrated to be sensitive to a number of TSEs, was slower than in meadow voles with a median incubation period of 351 days. We sequenced the meadow vole and red-backed vole Prnp genes and found three amino acid (AA) differences outside of the signal and GPI anchor sequences. Of these differences (T56-, G90S, S170N; read-backed vole:meadow vole), S170N is particularly intriguing due its postulated involvement in “rigid loop” structure and CWD susceptibility. Deer mice did not exhibit disease signs until nearly 1.5 years post-inoculation, but appear to be exhibiting a high degree of disease penetrance. White-footed mice have an even longer incubation period but are also showing high penetrance. Second passage experiments show significant shortening of incubation periods. Meadow voles in particular appear to be interesting lab models for CWD. These rodents scavenge carrion, and are an important food source for many predator species. Furthermore, these rodents enter human and domestic livestock food chains by accidental inclusion in grain and forage. Further investigation of these species as potential hosts, bridge species, and reservoirs of CWD is required.
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Elk and Deer Use of Mineral Licks: Implications for Disease Transmission
Kurt C. VerCauteren1*, Michael J. Lavelle1, Gregory E. Phillips1, Justin W. Fischer1, and Randal S. Stahl1 1United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, 4101 LaPorte Avenue, Fort Collins, CO 80521-2154, USA *Cooresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:kurt.c.vercauteren@aphis.usda.gov
North American cervids require and actively seek out minerals to satisfy physiological requirements. Minerals required by free-ranging cervids exist within natural and artificial mineral licks that commonly serve as focal sites for cervids. Ingestion of soils contaminated with the agent that causes chronic wasting disease (CWD) may result in risk of contracting CWD. Our objective was to evaluate the extent and nature of use of mineral licks by CWD-susceptible cervid species. We used animal-activated cameras to monitor use of 18 mineral licks between 1 June and 16 October 2006 in Rocky Mountain National Park, north-central Colorado. We also assessed mineral concentrations at mineral licks to evaluate correlations between visitation rates and site-specific characteristics. We collected > 400,000 images of which 991 included elk, 293 included deer, and 6 included moose. We documented elk and deer participating in a variety of potentially risky behaviors (e.g., ingesting soil, ingesting water, defecating, urinating) while at mineral licks. Results from the mineral analyses combined with camera data revealed that visitation was highest at sodium-rich mineral licks. Mineral licks may play a role in disease transmission by acting as sites of increased interaction as well as reservoirs for deposition, accumulation, and ingestion of disease agents.
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Potential Venison Exposure Among FoodNet Population Survey Respondents, 2006-2007
Ryan A. Maddox1*, Joseph Y. Abrams1, Robert C. Holman1, Lawrence B. Schonberger1, Ermias D. Belay1 Division of Viral and Rickettsial Diseases, National Center for Zoonotic, Vector-Borne, and Enteric Diseases, Centers for Disease Control and Prevention, Atlanta, GA *Corresponding author e-mail: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:rmaddox@cdc.gov
The foodborne transmission of bovine spongiform encephalopathy to humans, resulting in variant Creutzfeldt-Jakob disease, indicates that humans can be susceptible to animal prion diseases. However, it is not known whether foodborne exposure to the agent causing chronic wasting disease (CWD) in cervids can cause human disease. The United States Foodborne Diseases Active Surveillance Network (FoodNet) conducts surveillance for foodborne diseases through an extensive survey administered to respondents in selected states. To describe the frequency of deer and elk hunting and venison consumption, five questions were included in the 2006-2007 FoodNet survey. This survey included 17,372 respondents in ten states: California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee. Of these respondents, 3,220 (18.5%) reported ever hunting deer or elk, with 217 (1.3%) reporting hunting in a CWD-endemic area (northeastern Colorado, southeastern Wyoming, and southwestern Nebraska). Of the 217 CWD-endemic area hunters, 74 (34.1%) were residents of Colorado. Respondents reporting hunting were significantly more likely to be male than female (prevalence ratio: 3.3, 95% confidence interval: 3.1-3.6) and, in general, older respondents were significantly more likely to report hunting than younger respondents. Venison consumption was reported by more than half (67.4%) of the study population, and most venison consumers (94.1%) reported that at least half of their venison came from the wild. However, more than half (59.1%) of the consumers reported eating venison only one to five times in their life or only once or twice a year. These findings indicate that a high percentage of the United States population engages in hunting and/or venison consumption. If CWD continues to spread to more areas across the country, a substantial number of people could potentially be exposed to the infectious agent.
http://www.cwd-info.org/pdf/3rd_CWD_Symposium_utah.pdf
Tuesday, August 04, 2009
Susceptibilities of Nonhuman Primates to Chronic Wasting Disease
SNIP...
Thursday, April 03, 2008
A prion disease of cervids: Chronic wasting disease
2008 1: Vet Res. 2008 Apr 3;39(4):41
A prion disease of cervids: Chronic wasting disease
Sigurdson CJ.
snip...
*** twenty-seven CJD patients who regularly consumed venison were reported to the Surveillance Center***,
snip...
full text ;
http://chronic-wasting-disease.blogspot.com/2008/04/prion-disease-of-cervids-chronic.html
From: TSS (216-119-163-189.ipset45.wt.net)
Subject: CWD aka MAD DEER/ELK TO HUMANS ???
Date: September 30, 2002 at 7:06 am PST
From: "Belay, Ermias"
To:
Cc: "Race, Richard (NIH)" ; ; "Belay,
Ermias"
Sent: Monday, September 30, 2002 9:22 AM
Subject: RE: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS
Dear Sir/Madam,
In the Archives of Neurology you quoted (the abstract of which was
attached to your email), we did not say CWD in humans will present like
variant CJD.
That assumption would be wrong. I encourage you to read the whole
article and call me if you have questions or need more clarification
(phone: 404-639-3091). Also, we do not claim that "no-one has ever been
infected with prion disease from eating venison." Our conclusion stating
that we found no strong evidence of CWD transmission to humans in the
article you quoted or in any other forum is limited to the patients we
investigated.
Ermias Belay, M.D.
Centers for Disease Control and Prevention
-----Original Message-----
From:
Sent: Sunday, September 29, 2002 10:15 AM
To: mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:rr26k@nih.gov; mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:rrace@niaid.nih.gov; mhtml:%7B33B38F65-8D2E-434D-8F9B-8BDCD77D3066%7Dmid://00000408/!x-usc:mailto:ebb8@CDC.GOV
Subject: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG
HUNTERS
Sunday, November 10, 2002 6:26 PM ......snip........end..............TSS
also,
A. Aguzzi - Chronic Wasting Disease (CWD) also needs to be addressed. Most
serious because of rapid horizontal spread and higher prevalence than BSE in
UK, up to 15% in some populations. Also may be a risk to humans - evidence
that it is not dangerous to humans is thin.
http://www.tseandfoodsafety.org/activities/bse_conference_basel_april_02/2summar
SNIP...END...TSS
Chronic Wasting Disease and Potential Transmission to Humans
Ermias D. Belay,* Ryan A. Maddox,* Elizabeth S. Williams,? Michael W. Miller,? Pierluigi Gambetti,§ and Lawrence B. Schonberger*
*Centers for Disease Control and Prevention, Atlanta, Georgia, USA; ?University of Wyoming, Laramie, Wyoming, USA; ?Colorado Division of Wildlife, Fort Collins, Colorado, USA; and §Case Western Reserve University, Cleveland, Ohio, USA
Suggested citation for this article: Belay ED, Maddox RA, Williams ES, Miller MW, Gambetti P, Schonberger LB. Chronic wasting disease and potential transmission to humans. Emerg Infect Dis [serial on the Internet]. 2004 Jun [date cited]. Available from:
http://www.cdc.gov/ncidod/EID/vol10no6/03-1082.htm
Chronic wasting disease (CWD) of deer and elk is endemic in a tri-corner area of Colorado, Wyoming, and Nebraska, and new foci of CWD have been detected in other parts of the United States. Although detection in some areas may be related to increased surveillance, introduction of CWD due to translocation or natural migration of animals may account for some new foci of infection. Increasing spread of CWD has raised concerns about the potential for increasing human exposure to the CWD agent. The foodborne transmission of bovine spongiform encephalopathy to humans indicates that the species barrier may not completely protect humans from animal prion diseases. Conversion of human prion protein by CWD-associated prions has been demonstrated in an in vitro cell-free experiment, but limited investigations have not identified strong evidence for CWD transmission to humans. More epidemiologic and laboratory studies are needed to monitor the possibility of such transmissions.
snip...full text ;
http://www.cdc.gov/ncidod/EID/vol10no6/03-1082.htm
Volume 12, Number 10-October 2006
Research
Human Prion Disease and Relative Risk Associated with Chronic Wasting Disease
Samantha MaWhinney,* W. John Pape,? Jeri E. Forster,* C. Alan Anderson,?§ Patrick Bosque,?¶ and Michael W. Miller#
*University of Colorado at Denver and Health Sciences Center, Denver, Colorado, USA; ?Colorado Department of Public Health and Environment, Denver, Colorado, USA; ?University of Colorado School of Medicine, Denver, Colorado, USA; §Denver Veteran's Affairs Medical Center, Denver, Colorado, USA; ¶Denver Health Medical Center, Denver, Colorado, USA; and #Colorado Division of Wildlife, Fort Collins, Colorado, USA
Suggested citation for this article
The transmission of the prion disease bovine spongiform encephalopathy (BSE) to humans raises concern about chronic wasting disease (CWD), a prion disease of deer and elk. In 7 Colorado counties with high CWD prevalence, 75% of state hunting licenses are issued locally, which suggests that residents consume most regionally harvested game. We used Colorado death certificate data from 1979 through 2001 to evaluate rates of death from the human prion disease Creutzfeldt-Jakob disease (CJD). The relative risk (RR) of CJD for CWD-endemic county residents was not significantly increased (RR 0.81, 95% confidence interval [CI] 0.40-1.63), and the rate of CJD did not increase over time (5-year RR 0.92, 95% CI 0.73-1.16). In Colorado, human prion disease resulting from CWD exposure is rare or nonexistent. However, given uncertainties about the incubation period, exposure, and clinical presentation, the possibility that the CWD agent might cause human disease cannot be eliminated.
snip... full text ;
http://0-www.cdc.gov.mill1.sjlibrary.org/ncidod/EID/vol12no10/06-0019.htm
full text ;
http://chronic-wasting-disease.blogspot.com/2006_12_01_archive.html
SEE FULL TEXT ;
Tuesday, August 04, 2009 Susceptibilities of Nonhuman Primates to Chronic Wasting Disease
http://chronic-wasting-disease.blogspot.com/2009/08/susceptibilities-of-nonhuman-primates.html
Sunday, April 12, 2009
CWD UPDATE Infection Studies in Two Species of Non-Human Primates and one Environmental reservoir infectivity study and evidence of two strains
http://chronic-wasting-disease.blogspot.com/2009/04/cwd-update-infection-studies-in-two.html
Wednesday, March 18, 2009
Detection of CWD Prions in Urine and Saliva of Deer by Transgenic Mouse Bioassay
http://chronic-wasting-disease.blogspot.com/2009/03/detection-of-cwd-prions-in-urine-and.html
Thursday, July 23, 2009
UW Hospital warning 53 patients about possible exposure to rare brain disease
http://creutzfeldt-jakob-disease.blogspot.com/2009/07/uw-hospital-warning-53-patients-about.html
10.3201/eid1505.081458 Suggested citation for this article: Angers RC, Seward TS, Napier D, Green M, Hoover E, Spraker T, et al. Chronic wasting disease prions in elk antler velvet. Emerg Infect Dis. 2009 May; [Epub ahead of print]
Chronic Wasting Disease Prions in Elk Antler Velvet
http://chronic-wasting-disease.blogspot.com/2009/03/chronic-wasting-disease-prions-in-elk.html
Wednesday, March 18, 2009
Noah's Ark Holding, LLC, Dawson, MN RECALL Elk products contain meat derived from an elk confirmed to have CWD NV, CA, TX, CO, NY, UT, FL, OK RECALLS AND FIELD CORRECTIONS: FOODS CLASS II
http://chronic-wasting-disease.blogspot.com/2009/03/noahs-ark-holding-llc-dawson-mn-recall.html
http://chronic-wasting-disease.blogspot.com/2009/02/exotic-meats-usa-announces-urgent.html
NOT only muscle, but now fat of CWD infected deer holds infectivity of the TSE (prion) agent. ...TSS
just follow the different topics and urls to the science and transmission studies. the transmission studies do not lie. only the politicians do. ...
and you don't even want to go to the mad cow issue and or the scrapie issue, and why should you $$$ your a sports writer, and this is much bigger than any of us will ever be, it was said long ago BSE would never be found in the USA. and due to the incubation period, it probably will not. but the BSE issue is just one phenotype. h and l and c BSE have all been found in North America.......... it's a damn political foot ball game, and we loose, and the animals loose $$$
Monday, July 13, 2009
Deer Carcass Decomposition and Potential Scavenger Exposure to Chronic Wasting Disease
http://chronic-wasting-disease.blogspot.com/2009/07/deer-carcass-decomposition-and.html
CWD, GAME FARMS, BAITING, AND POLITICS
http://chronic-wasting-disease.blogspot.com/2009/01/cwd-game-farms-baiting-and-politics.html
NOT only muscle, but now fat of CWD infected deer holds infectivity of the TSE (prion) agent. ...TSS
Monday, July 06, 2009
Prion infectivity in fat of deer with Chronic Wasting Disease
http://chronic-wasting-disease.blogspot.com/2009/07/prion-infectivity-in-fat-of-deer-with.html
Friday, February 20, 2009
Both Sides of the Fence: A Strategic Review of Chronic Wasting Disease
http://chronic-wasting-disease.blogspot.com/2009/02/both-sides-of-fence-strategic-review-of.html
Saturday, September 06, 2008
Chronic wasting disease in a Wisconsin white-tailed deer farm 79% INFECTION RATE
Contents: September 1 2008, Volume 20, Issue 5
snip...see full text ;
http://chronic-wasting-disease.blogspot.com/2008/11/commentary-crimes-hurt-essence-of.html
Tuesday, January 27, 2009
Chronic Wasting Disease found in a farmed elk from Olmsted County ST. PAUL, Minn. FOR IMMEDIATE RELEASE: Monday, January 26, 2009
http://chronic-wasting-disease.blogspot.com/2009/01/chronic-wasting-disease-found-in-farmed.html
Saturday, January 24, 2009
Research Project: Detection of TSE Agents in Livestock, Wildlife, Agricultural Products, and the Environment Location: 2008 Annual Report
http://bse-atypical.blogspot.com/2009/01/research-project-detection-of-tse.html
2008 CWD Laboratory Testing for Wild White-tailed Deer
http://www.michigan.gov/emergingdiseases/0,1607,7-186-25806-202922--,00.html
Wednesday, January 07, 2009
CWD to tighten taxidermy rules Hunters need to understand regulations
http://chronic-wasting-disease.blogspot.com/2009/01/cwd-to-tighten-taxidermy-rules-hunters.html
Thursday, December 25, 2008 Lions and Prions and Deer Demise
http://chronic-wasting-disease.blogspot.com/2008/12/lions-and-prions-and-deer-demise.html
http://chronic-wasting-disease.blogspot.com/
TSS
posted by Terry S. Singeltary Sr. at
2:08 PM
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