Tuesday, September 10, 2013

Review and Updates of the USDA-APHIS Veterinary Services (VS) National Chronice Wasting Disease (CWD) Program 2012-2013

Review and Updates of the USDA-APHIS Veterinary Services (VS) National Chronice Wasting Disease (CWD) Program


Dr. Patrice Klein




CWD Rule Update


CWD Interim Final Rule was published on June 8, 2012, establishing a national voluntary CWD herd certification program (HCP) and consistent minimum interstate movement requirements. The rule became effective on August 13, 2012. Enforcement of the interstate movement regulations is delayed until December 10, 2012 to give States time to apply to APHIS to become an Approved State CWD HCP.


After reviewing the public comments, the APHIS will issue a final rule, and if needed, incorporate any changes made in response to comments on preemption. Comments received on other topics will be held for future rulemaking. The goal of the CWD Program is to assist States, Tribes, and the cervid industry to prevent and control spread of CWD in farmed and wild cervid populations through establishment of a national CWD HCP and interstate movement requirements.


APHIS provides federal oversight of the voluntary national CWD HCP with program activities conducted by the Approved State CWD HCPs. APHIS will serve in an advisory capacity to Approved States for epidemiological investigations on CWD positive findings, development of herd plans, and assist (where possible) with herd inspections and inventories.


APHIS will continue to fund confirmatory testing on any presumptive CWD-positive samples from farmed and wild cervids, conducted by the National Veterinary Services Laboratories (NVSL).


Farmed/captive cervid surveillance testing


Through FY2012, CWD surveillance testing was conducted on approximately 22,585 farmed /captive cervids by the immunohistochemistry (IHC) standard protocol. This reflects testing that was funded by APHIS through December 2011 and the transition to these laboratory costs paid directly by the cervid owner beginning in January 2012 as a result of CWD program budget reductions in FY2012.


Farmed/captive cervid CWD status


To date, 60 farmed/captive cervid herds have been identified in 13 states: Colorado, Iowa, Kansas, Michigan, Minnesota, Missouri, Montana, Nebraska, New York, Oklahoma, Pennsylvania, South Dakota and Wisconsin. Forty were elk herds, 19 were whitetail deer (WTD) herds, and one was the red deer herd. At this time, 15 CWD positive herds remain – seven elk herds in Colorado, three elk herds in Nebraska, three WTD herds in Iowa, one WTD herd in Pennsylvania, and one red deer herd in Minnesota.


On October 11, 2012, Pennsylvania reported a CWD positive three and one-half year old female white-tailed deer (WTD) in a farmed cervid herd in Adams County, Pennsylvania. NVSL conducted the confirmatory CWD testing and this represents the first report of CWD in PA. The index herd is under state quarantine, and an epidemiological investigation and trace outs are in progress to identify epidemiologically-linked premises in Pennsylvania and other states.


In July, 2012, Iowa reported a CWD positive six year old male WTD in a hunt facility in Davis County, Iowa that was sourced from a deer breeding farm under the same ownership in Cerro Gordo County, Iowa. Trace outs identified several other premises that purchased deer from the index herd. CWD testing of the traced out animals has begun. To date, one CWD positive doe was identified in the source herd that had direct contact with the index animal, and four additional CWD positive deer (including two purchased deer) have been identified on separately owned premises.


In May 2012, Minnesota reported CWD in a two and one-half year old male red deer from a breeding farm in Ramsey County, Minnesota. This represents the first report of CWD in red deer (Cervus elaphus) in the United States. During the epidemiological investigation, 56 pen mates (cohorts) were tested and CWD was not detected in any of those animals. No point source of introduction yet has been determined. The herd remains under state imposed quarantine which is allowing for some animals to be transported directly to a slaughter facility. All slaughtered animals have been CWD tested and reported as ‘not detected’.


Wild Cervid surveillance


In FY2011, cooperative agreements were awarded to 46 State wildlife agencies (approximately $4.2 M) and 34 Native American Tribes (approximately $340,000). The Native American Fish and Wildlife Society received approximately $175,000 to support CWD outreach and education activities Cooperative agreement funds were eliminated in FY2012 due to federal budget reductions.


FY2010 funding supported surveillance in approximately 74,900 wild cervids in 46 cooperating States. Wild cervid CWD surveillance totals are pending for FY2011 due to seasonal surveillance activities and completion of final cooperative agreement reporting to APHIS. To date, approximately 60,890 wild cervids have been tested in fiscal year 2011.


Budget: Commodity Health Line Structure


In FY2011, APHIS received approximately $15.8 million in appropriated funding for the CWD Program. In the FY2012 budget, livestock commodities regulated by USDA were organized into ‘Commodity Health Line’ structures or groupings. APHIS’ Equine, Cervid and Small Ruminant (ECSR) Health line supports efforts to protect the health and thereby improve the quality and productivity of the equine, cervid and small ruminant industries. In FY2012 approximately $1.925 million of ECSR funding was allocated for CWD program activities to provide Federal oversight of the national CWD herd certification program (HCP). The President’s FY2013 budget proposes further funding reductions.









2012 Resolution












It has been stated by the United States Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services that (1) the goal of the Chronic Wasting Disease (CWD) program in the United States has now changed from eradication to controlling its spread, (2) there is no longer federal funding available to pay for CWD testing or to pay indemnity for CWD infected or exposed animals, and (3) depopulation of infected herds will no longer be required or expected.


With this major change in objectives, it is critical that we change the way we implement the CWD program in the United States. We now need a program that minimizes the risk of spreading CWD in farmed and wild cervidae without putting farmed cervidae producers out of business if their herds become CWD infected or exposed. We need a CWD control program that includes plans for how to (1) handle infected or exposed herds, (2) clean up infected herds without depopulation, and (3) provide outlets so producers can continue to sell velvet antler and live animals to slaughter or specified terminal facilities.




The United States Animal Health Association urges the United States Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services and state animal health regulatory officials to develop protocols for the Chronic Wasting Disease (CWD) control program that mitigate the risk of the spread of CWD and allow producers with CWD infected or exposed herds to continue operations under quarantine and which allow (1) addition of cervidae from CWD certified herds, (2) participation in herd plans such as test and removal, and (3) movement of velvet antler and live animals to slaughter or other approved terminal facilities.




2012 Resolution






The U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services (VS) recognizes the concerns of the United States Animal Health Association and appreciates the opportunity to respond. In conjunction with the publication of the chronic wasting disease (CWD) final rule in June 2012, VS prepared a set of program standards governing the voluntary national herd certification program. The standards provide further explanation and guidance on how participating States and cervid owners can meet the program requirements to certify herds as low risk for CWD.


The standards are divided into two parts. Part A covers herd certification program participation requirements; registration, identification, and recordkeeping; surveillance and sampling; and diagnostics and testing. It also describes the requirements for interstate movement of cervids in accordance with the rule. Part B provides guidance to States for responding to findings of CWD in farmed cervids, in accordance with the national CWD herd certification program. This section also provides suggested best management practices that may be used by States and by herd owners to investigate and manage CWD-affected herds, including development of herd plans and factors affecting continuity of business. VS will continue to serve in an advisory capacity to assist States and herd owners with these mitigation efforts. VS has convened a working group to review the program standards (see Resolution 24).








2012 Resolution












It has been stated by the United States Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), Veterinary Services (VS) that the goal of the Chronic Wasting Disease (CWD) program in the United States has now changed from eradication to controlling its spread.


The document entitled, "Chronic Wasting Disease Program Standards" was published by USDA-APHIS-VS in July 2012. It was developed before the shift of the CWD program from eradication to control and without adequate input from state wildlife and animal health officials or farmed cervidae producers. Sections of the document suggest placing restrictions on farmed cervidae producers that do nothing to further the effort to control the spread of CWD. The restrictions are not based on current scientific knowledge and could undermine the success of CWD control programs that have been in place in many states for more than a decade.




The United States Animal Health Association urges the United States Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), Veterinary Services (VS) to revise the document entitled, "Chronic Wasting Disease Program Standards", and establish a Chronic Wasting Disease (CWD) Program Standards Committee to review and rewrite the document within 90 days so that it more appropriately reflects the needs of producers and regulatory officials charged with implementation of a program to control, not eradicate, CWD in the United States.


The United States Animal Health Association suggests that the CWD Program Standards Committee should be made up of representatives from and appointed by each of the following organizations: (1) the Exotic Wildlife Association, (2) the North American Elk Breeders Association, (3) the North American Deer Farmers Association, (4) the Association of Fish and Wildlife Agencies, (5) the National Assembly of State Animal Health Officials, and (6) the USDA-APHIS-VS.




2012 Resolution






The U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services (VS) recognizes the concerns of the United States Animal Health Association (USAHA) and appreciates the opportunity to respond. To address a number of concerns voiced at the 2012 USAHA meeting, VS established a CWD Program Standards Working Group. The goal of the working group is to discuss stakeholder concerns with the CWD program standards and to recommend revisions as necessary. The group is composed of three representatives each from the National Assembly, the Association of Fish and Wildlife Agencies, and the cervid industry; two representatives from the American Association of Veterinary Laboratory Diagnosticians; and experts from VS.


The working group first met on November 28, 2012, and continues to have weekly teleconferences. We expect revisions to the program standards to be completed by the first week of March. The revised program standards will then be made available for public comment through a notice in the Federal Register.



















Wednesday, September 04, 2013


cwd - cervid captive livestock escapes, loose and on the run in the wild...





Thursday, August 08, 2013




Characterization of the first case of naturally occurring chronic wasting disease in a captive red deer (Cervus elaphus) in North America





Sunday, August 25, 2013




Prion2013 Chronic Wasting Disease CWD risk factors, humans, domestic cats, blood, and mother to offspring transmission








HD.13: CWD infection in the spleen of humanized transgenic mice


Liuting Qing and Qingzhong Kong


Case Western Reserve University; Cleveland, OH USA


Chronic wasting disease (CWD) is a widespread prion disease in free-ranging and captive cervid species in North America, and there is evidence suggesting the existence of multiple CWD strains. The susceptibility of human CNS and peripheral organs to the various CWD prion strains remains largely unclear. Current literature suggests that the classical CWD strain is unlikely to infect human brain, but the potential for peripheral infection by CWD in humans is unknown. We detected protease-resistant PrpSc in the spleens of a few humanized transgenic mice that were intracerebrally inoculated with natural CWD isolates, but PrpSc was not detected in the brains of any of the CWD-inoculated mice. Our ongoing bioassays in humanized Tg mice indicate that intracerebral challenge with such PrpSc-positive humanized mouse spleen already led to prion disease in most animals. These results indicate that the CWD prion may have the potential to infect human peripheral lymphoid tissues.






HD.12: Comparative study of the distribution of the prion protein in the squirrel monkey (Saimiri sciureus) following experimental challenge with variant and sporadic CJD


Diane L. Ritchie,1 Paul Brown,2 Susan Gibson,3 Thomas R. Kreil,4 Christian Abee3 and James W. Ironside1


1National CJD Surveillance Unit; Edinburgh, UK; 2Bethesda; Bethesda, MD USA; 3Deparment of Comparative Medicine; University of South Alabama; Mobile, AL USA; 4Baxter Bioscience; Vienna, Austria


Introduction, Reports suggest that the number of tissues and organs showing the presence of the abnormal prion protein (PrPTSE) in variant CJD (vCJD) patients may be greater than previously thought. A limited peripheral involvement in some cases of sporadic CJD (sCJD) has also been reported. This accumulation of PrPTSE outside the brain has raised concerns about the possible iatrogenic transmission risk of vCJD. The squirrel monkey (Saimiri sciureus) has been shown to be highly susceptible to experimental challenge with human prion disease. Neuropathological and biochemical analyses of CNS tissue have shown that sCJD and vCJD can be distinguished in the squirrel monkey and that many of the strain characteristics that define these agents are conserved after transmission. Following on from these initial studies, immunohistochemistry and western blot analysis were performed on a wide range of peripheral tissues including, lymphoreticular tissues and peripheral neural tissue to establish the full-body distribution of PrPTSE in this primate animal model.


Materials and Methods. Brain homogenates from sCJD or vCJD patients were inoculated into the frontal cortex of squirrel monkeys. Animals were kept under constant clinical surveillance. At post-mortem, formalin fixed CNS tissue and a wide range of peripheral tissues were taken for immunohistochemical analysis together with frozen tissues taken for the biochemical detection of PrPTSE.


Results. Immunohistochemical analysis showed no evidence of PrPTSE deposition in peripheral tissues in either variant or sporadic CJD-infected animals. However, western blot assays detected PrPTSE in the spleen of a proportion of the vCJD- infected animals. The PrPTSE isotype resembled that detected in CNS tissue from the vCJD- infected animals and from human vCJD cases. ***In addition, western blot analysis detected PrPTSE in the spleen of a single animal following challenge with sporadic CJD. The PrPTSE type in this animal resembled that found in CNS tissue from the same animal, with a PrPTSE type similar to that found in human sCJD type 1 cases.


Conclusion. This study confirms the accumulation of PrPTSE in the CNS and spleen of a proportion of squirrel monkeys infected intra-cerebrally with human vCJD. Furthermore, this study extends the evidence that there may be a peripheral involvement in some cases of sCJD. PrPTSE typing confirms the conservation of PrPTSE type on transmission to the squirrel monkey and suggests that there are no tissue-specific adaptations in the biochemical phenotype of the agent strain following primate-to-primate transmission.






Oral.15: Molecular barriers to zoonotic prion transmission: Comparison of the ability of sheep, cattle and deer prion disease isolates to convert normal human prion protein to its pathological isoform in a cell-free system


Marcelo A.Barria,1 Aru Balachandran,2 Masanori Morita,3 Tetsuyuki Kitamoto,4 Rona Barron,5 Jean Manson,5 Richard Kniqht,1 James W. lronside1 and Mark W. Head1


1National CJD Research and Surveillance Unit; Centre for Clinical Brain Sciences; School of Clinical Sciences; The University of Edinburgh; Edinburgh, UK; 2National and OIE Reference Laboratory for Scrapie and CWD; Canadian Food Inspection Agency; Ottawa Laboratory; Fallowfield. ON Canada; 3Infectious Pathogen Research Section; Central Research Laboratory; Japan Blood Products Organization; Kobe, Japan; 4Department of Neurological Science; Tohoku University Graduate School of Medicine; Sendai. Japan; 5Neurobiology Division; The Roslin Institute and R(D)SVS; University of Edinburgh; Easter Bush; Midlothian; Edinburgh, UK


Background. Bovine spongiform encephalopathy (BSE) is a known zoonotic prion disease, resulting in variant Creurzfeldt- Jakob disease (vCJD) in humans. In contrast, classical scrapie in sheep is thought to offer little or no danger to human health. However, a widening range of prion diseases have been recognized in cattle, sheep and deer. The risks posed by individual animal prion diseases to human health cannot be determined a priori and are difficult to assess empirically. The fundamemal event in prion disease pathogenesis is thought to be the seeded conversion of normal prion protein (PrPC) to its pathological isoform (PrPSc). Here we report the use of a rapid molecular conversion assay to test whether brain specimens from different animal prion diseases are capable of seeding the conversion of human PrPC ro PrPSc.


Material and Methods. Classical BSE (C-type BSE), H-type BSE, L-type BSE, classical scrapie, atypical scrapie, chronic wasting disease and vCJD brain homogenates were tested for their ability to seed conversion of human PrPC to PrPSc in protein misfolding cyclic amplification (PMCA) reactions. Newly formed human PrPSc was detected by protease digestion and western blotting using the antibody 3F4.


Results. C-type BSE and vCJD were found to efficiently convert PrPC to PrPSc. Scrapie failed to convert human PrPC to PrPSc. Of the other animal prion diseases tested only chronic wasting disease appeared to have the capability ro convert human PrPC to PrPSc. The results were consistent whether the human PrPC came from human brain, humanised transgenic mouse brain or from cultured human cells and the effect was more pronounced for PrPC with methionine at codon 129 compared with that with valine.


Conclusion. Our results show that none of the tested animal prion disease isolates are as efficient as C-type BSE and vCJD in converting human prion protein in this in vitro assay. However, they also show that there is no absolute barrier ro conversion of human prion protein in the case of chronic wasting disease.






Invited.16: Studies of chronic wasting disease transmission in cervid and non-cervid species


Edward A, Hoover,1 Candace K. Mathiason,1 Davin M. Henderson,1 Nicholas J. Haley,1 Davis M. Seelig,1 Nathaniel D. Denkers,1 Amy V. Nalls,1 Mark D. Zabe,1 Glenn C. Telling,1 Fernando Goni2 and Thomas Wisniewski,2


1Prion Research Center; Colorado State University; Fort Collins, CO USA; 2New York University School of Medicine; New York, NY USA


How and why some misfolded proteins become horizontally transmitted agents and occasionally cross species barriers are issues fundamental to understanding prion disease. Chronic wasting disease (CWD) of cervids is perhaps a prototype of horizontal prion transmission, encompassing efficient mucosal uptake, lymphoid amplification, neuroinvasion, peripheralization, and dissemination via mucosal excretion. Efficient mucosal transmission of CWD in deer has been demonstrated by oral, nasal, aerosol, and indirect contact exposure. In addition, other studies (Mathiason CK, et al.) reported at the symposium support a significant role for pre- and/or postnatal transmission of CWD from doe to offspring. Accumulating, yet still incomplete, evidence also suggests that the period of relatively covert CWD infection may be longer than originally thought. Given the above, minimally invasive sensitive assays based on body fluids from live animals would aid substantially in understanding the biology of CWD. We have been applying seeded realtirne quaking-induced amplification of recombinant PrP substrates (i.e., RT-QuIC methodology) to: (1) investigate antemortem CWD detection, and (2) model PrP-based species barriers and trans-species adaptation-topics we previously explored using sPMCA and in vivo bioassays. At this symposium, we report sensitive and specific detection CWD prions in saliva, urine, blood (Mathiason lab), and rectal and pharyngeal lymph node samples (Haley NJ, et al.) from pre-symptomatic and symptomatic experimentally and naturally exposed deer. Other ongoing studies are employing RT-QuIC methodology to model amplification barriers among CWD, FSE, BSE, and CJD prions using cervine, feline, bovine, human, and promiscuous rPrP substrates and the above species prion seeds, cellular co-factors, and transgenic mice. Finally, in collaboration with the Wisniewski laboratory, we are conducting of experimental CWD vaccination studies in deer employing oral administration of an attenuated Salmonella vector expressing cervid PrP epitopes.






AD.06: Detecting prions in the brain and blood of TSE-infected deer and hamsters


Alan Elder,1 Davin Henderson,1 Anca Selariu,1 Amy Nalls,1 Byron Caughey,2 Richard Bessen,1 Jason Bartz3 and Candace Mathiason1


1Colorado State University; Fort Collins, CO USA; 2NIH Rocky Mountain Laboratories; Hamilton, MT USA; 3Creighton University; Omaha, NE USA


While large quantities of protease resistant prion protein (PrPres) can be demonstrated by western blot or IHC in lymphoid biopsies or post-mortem brain tissues harvested from prion-infected animals, these conventional assays are less reliable as means to detect the small quantities of prions thought to be present in bodily fluids or associated with early and asymptomatic phases of TSE disease. The Real Time-Quaking Induced Conversion (RT-QuIC) assay is capable of detecting prions at concentrations below the level of sensitivity of conventional assays and provides a real-time fluorescent readout negating the use of proteases. We have made modifications to the RT-QuIC assay to utilize it for the detection of PrPres in brain and blood harvested from various species infected with prions. In this study, we analyzed CWD-infected deer and CWD/TME-infected hamster whole blood to determine the effect of:


(1) various anticoagulants,


(2) freezing and


(3) NaPTA precipitation.


Brain tissue and blood collected from naive deer and hamsters served as negative controls.


We were able to demonstrate amplifiable prions in


(1) brain and blood samples harvested from CWD/TME-infected animals,


(2) heparinized blood,


(3) frozen vs. fresh blood and


(4) NaPTA treated samples.


The RT-QuIC assay is able to detect PrPres in various species of animals and shows promise as an antemortem diagnostic tool for blood-borne TSEs.






Oral.08: Mother to offspring transmission of chronic wasting disease in Reeve's Muntjac deer


Amy Nalls,1 Erin McNulty,1 Jenny Powers,2 Davis Seelig,1 Clare Hoover,1 Nicholas Haley,1 Jeanette Hayes-Klug,1 Kelly Anderson,1 Paula Stewart,3 Wilfred Goldmann,3 Edward A. Hoover1 and Candace K. Mathiason1


1Colorado State University; Fort Collins, CO USA; 2National Park Service; Fort Collins, CO USA; 3The Roslin Institute and Royal School of Veterinary Studies; Edinburgh, UK


To investigate the role mother to offspring transmission plays in chronic wasting disease (CWD), we have developed a cervid model employing the Reeve's muntjac deer (Muntiacus reevesi). Eight muntjac doe were orally inoculated with CWD and tested PrPCWD lymphoid positive by 4 mo post infection. Fourteen fawns were born to these eight CWD-infected doe-3 were born viable, 6 were born non-viable and 5 were harvested as fetuses from early or end-stage CWD-infected doe. All three viable fawns have demonstrated CWD IHC lymphoid biopsy positivity between 43 d post birth and 11 mo post birth. Two of these three CWD positive viable offspring have developed clinical signs consistent with TSE disease (28-33 mo post birth). Moreover, CWD prions have been detected by sPMCA in 11 of 16 tissues harvested from 6 full-term non-viable fawns and in 7 of 11 fetal tissues harvested in utero from the second and third trimester fetuses. Additional tissues and pregnancy related fluids from doe and offspring are being analyzed for CWD prions. In summary, using the muntjac deer model we have demonstrated CWD clinical disease in offspring born to CWD-infected doe, and in utero transmission of CWD from mother to offspring. These studies provide basis to further investigate the mechanisms of maternal transfer of prions.






AD.63: Susceptibility of domestic cats to chronic wasting disease


Amy V.Nalls,1 Candace Mathiason,1 Davis Seelig,2 Susan Kraft,1 Kevin Carnes,1 Kelly Anderson,1 Jeanette Hayes-Klug1 and Edward A. Hoover1


1Colorado State University; Fort Collins, CO USA; 2University of Minnesota; Saint Paul, MN USA


Domestic and nondomestic cats have been shown to be susceptible to feline spongiform encephalopathy (FSE), almost certainly caused by consumption of bovine spongiform encephalopathy (BSE)-contaminated meat. Because domestic and free-ranging nondomestic felids scavenge cervid carcasses, including those in areas affected by chronic wasting disease (CWD), we evaluated the susceptibility of the domestic cat (Felis catus) to CWD infection experimentally. Cohorts of 5 cats each were inoculated either intracerebrally (IC) or orally (PO) with CWD-infected deer brain. At 40 and 42 mo post-inoculation, two IC-inoculated cats developed signs consistent with prion disease, including a stilted gait, weight loss, anorexia, polydipsia, patterned motor behaviors, head and tail tremors, and ataxia, and progressed to terminal disease within 5 mo. Brains from these two cats were pooled and inoculated into cohorts of cats by IC, PO, and intraperitoneal and subcutaneous (IP/SC) routes. Upon subpassage, feline-adapted CWD (FelCWD) was transmitted to all IC-inoculated cats with a decreased incubation period of 23 to 27 mo. FelCWD was detected in the brains of all the symptomatic cats by western blotting and immunohistochemistry and abnormalities were seen in magnetic resonance imaging, including multifocal T2 fluid attenuated inversion recovery (FLAIR) signal hyper-intensities, ventricular size increases, prominent sulci, and white matter tract cavitation. Currently, 3 of 4 IP/SQ and 2 of 4 PO inoculared cats have developed abnormal behavior patterns consistent with the early stage of feline CWD. These results demonstrate that CWD can be transmitted and adapted to the domestic cat, thus raising the issue of potential cervid-to- feline transmission in nature.








snip...see full text ;



Sunday, August 25, 2013




Prion2013 Chronic Wasting Disease CWD risk factors, humans, domestic cats, blood, and mother to offspring transmission




Sunday, July 21, 2013


*** As Chronic Wasting Disease CWD rises in deer herd, what about risk for humans?




remember that healthy looking deer ?


sub-clinical CWD !



Research Article


Detection of Sub-Clinical CWD Infection in Conventional Test-Negative Deer Long after Oral Exposure to Urine and Feces from CWD+ Deer


Nicholas J. Haley, Affiliation: Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America


X Candace K. Mathiason, Affiliation: Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America


X Mark D. Zabel, Affiliation: Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America


X Glenn C. Telling, Affiliation: Department of Molecular Biology and Genetics, University of Kentucky, Lexington, Kentucky, United States of America


X Edward A. Hoover mail * E-mail: Edward.Hoover@colostate.edu


Affiliation: Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America




Abstract Background Chronic wasting disease (CWD) of cervids is a prion disease distinguished by high levels of transmissibility, wherein bodily fluids and excretions are thought to play an important role. Using cervid bioassay and established CWD detection methods, we have previously identified infectious prions in saliva and blood but not urine or feces of CWD+ donors. More recently, we identified very low concentrations of CWD prions in urine of deer by cervid PrP transgenic (Tg[CerPrP]) mouse bioassay and serial protein misfolding cyclic amplification (sPMCA). This finding led us to examine further our initial cervid bioassay experiments using sPMCA.


Objectives We sought to investigate whether conventional test-negative deer, previously exposed orally to urine and feces from CWD+ sources, may be harboring low level CWD infection not evident in the 19 month observation period. We further attempted to determine the peripheral PrPCWD distribution in these animals.


Methods Various neural and lymphoid tissues from conventional test-negative deer were reanalyzed for CWD prions by sPMCA and cervid transgenic mouse bioassay in parallel with appropriate tissue-matched positive and negative controls.


Results PrPCWD was detected in the tissues of orally exposed deer by both sPMCA and Tg[CerPrP] mouse bioassay; each assay revealed very low levels of CWD prions previously undetectable by western blot, ELISA, or IHC. Serial PMCA analysis of individual tissues identified that obex alone was positive in 4 of 5 urine/feces exposed deer. PrPCWD was amplified from both lymphoid and neural tissues of positive control deer but not from identical tissues of negative control deer.


Discussion Detection of subclinical infection in deer orally exposed to urine and feces (1) suggests that a prolonged subclinical state can exist, necessitating observation periods in excess of two years to detect CWD infection, and (2) illustrates the sensitive and specific application of sPMCA in the diagnosis of low-level prion infection. Based on these results, it is possible that low doses of prions, e.g. following oral exposure to urine and saliva of CWD-infected deer, bypass significant amplification in the LRS, perhaps utilizing a neural conduit between the alimentary tract and CNS, as has been demonstrated in some other prion diseases.


Citation: Haley NJ, Mathiason CK, Zabel MD, Telling GC, Hoover EA (2009) Detection of Sub-Clinical CWD Infection in Conventional Test-Negative Deer Long after Oral Exposure to Urine and Feces from CWD+ Deer. PLoS ONE 4(11): e7990. doi:10.1371/journal.pone.0007990


Editor: Jiyan Ma, Ohio State University, United States of America


Received: September 29, 2009; Accepted: October 29, 2009; Published: November 24, 2009


Copyright: © 2009 Haley et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Funding: This work was supported by NIH/NCRR Ruth L. Kirschstein Institutional T32 R07072-03 and NIH/NIAID NO1-AI-25491-02 (EAH, GCT). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.


Competing interests: The authors have declared that no competing interests exist.








Tuesday, June 16, 2009


Infectious Prions in Pre-Clinical Deer and Transmission of Chronic Wasting Disease Solely by Environmental Exposure






Friday, August 09, 2013




CWD TSE prion, plants, vegetables, and the potential for environmental contamination




Sunday, September 01, 2013


hunting over gut piles and CWD TSE prion disease




Sunday, June 09, 2013


Missouri House forms 13-member Interim Committee on the Cause and Spread of Chronic Wasting Disease CWD




Wednesday, August 21, 2013






Saturday, September 07, 2013


Georgia House Bill 1043 and Chronic Wasting Disease CWD


Greetings Honorable Representatives of the House, Game, Fish, & Parks,




Tuesday, October 23, 2012


PA Captive deer from CWD-positive farm roaming free





USDA TO PGC ONCE CAPTIVES ESCAPE "it‘s no longer its business.”



Sunday, January 06, 2013


USDA TO PGC ONCE CAPTIVES ESCAPE "it‘s no longer its business.”




Tuesday, May 28, 2013


Chronic Wasting Disease CWD quarantine Louisiana via CWD index herd Pennsylvania Update May 28, 2013


6 doe from Pennsylvania CWD index herd still on the loose in Louisiana, quarantine began on October 18, 2012, still ongoing, Lake Charles premises.




Monday, June 24, 2013


The Effects of Chronic Wasting Disease on the Pennsylvania Cervid Industry Following its Discovery




Saturday, June 29, 2013






Friday, August 02, 2013


The Fight to Keep Chronic Wasting Disease Out of Florida




FWC passes rule prohibiting importation of deer News Release


Friday, September 06, 2013


Media contact: Susan Smith, 850-488-8843


(Back to Commission meeting news)


The Florida Fish and Wildlife Conservation Commission (FWC) at its Pensacola commission meeting today, Sept. 6, passed a rule prohibiting the importation of live captive deer into Florida from out-of-state sources.


The rule was passed in an effort to reduce the chances of chronic wasting disease (CWD) being introduced into the state. Eighteen other states, including Georgia and Alabama, also prohibit the importation of live cervids (deer, elk and moose).


CWD is not known to affect people but is a contagious neurological disease affecting cervids. It is always fatal, and there is no known cure or vaccine. So far, the disease has been discovered in 22 states, two Canadian provinces and in South Korea.


To implement the decision immediately, the FWC also issued an executive order prohibiting importation of cervids effective today, Sept. 6, 2013. The order includes limited exemptions for reindeer and zoos.


The Commission also directed the executive director to create a working group to include the industry to develop other measures to safeguard the state from CWD. If these other measures are determined to be sufficient to adequately reduce risk, the Commission gives the executive director authority to then allow importation.


Since the beginning of May, the FWC has received much public comment on this and answered questions and concerns. During this process, those who have deer farms and hunting preserves , hunters and conservationists provided suggestions for additional prevention measures to consider. The Commission used this important feedback to guide its decision making.


For more information on chronic wasting disease, this rule and the CWD Alliance, go to MyFWC.com/CWD. To see the executive order, go to MyFWC.com/About and select “Inside FWC” then “Executive Director.”










Sunday, August 11, 2013


Creutzfeldt-Jakob Disease CJD cases rising North America updated report August 2013


Creutzfeldt-Jakob Disease CJD cases rising North America with Canada seeing an extreme increase of 48% between 2008 and 2010





Friday, August 16, 2013


*** Creutzfeldt-Jakob disease (CJD) biannual update August 2013 U.K. and Contaminated blood products induce a highly atypical prion disease devoid of PrPres in primates





Sunday, September 08, 2013


Iatrogenic Creutzfeldt-Jakob disease via surgical instruments and decontamination possibilities for the TSE prion





*** The potential impact of prion diseases on human health was greatly magnified by the recognition that interspecies transfer of BSE to humans by beef ingestion resulted in vCJD. While changes in animal feed constituents and slaughter practices appear to have curtailed vCJD, there is concern that CWD of free-ranging deer and elk in the U.S. might also cross the species barrier. Thus, consuming venison could be a source of human prion disease. Whether BSE and CWD represent interspecies scrapie transfer or are newly arisen prion diseases is unknown. Therefore, the possibility of transmission of prion disease through other food animals cannot be ruled out. There is evidence that vCJD can be transmitted through blood transfusion. There is likely a pool of unknown size of asymptomatic individuals infected with vCJD, and there may be asymptomatic individuals infected with the CWD equivalent. These circumstances represent a potential threat to blood, blood products, and plasma supplies.









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