Tuesday, May 31, 2011

Chronic Wasting Disease DOI: 10.1007/128_2011_159 # Springer-Verlag Berlin Heidelberg 2011

Top Curr Chem (2011) DOI: 10.1007/128_2011_159 # Springer-Verlag Berlin Heidelberg 2011

Chronic Wasting Disease

Sabine Gilch, Nandini Chitoor, Yuzuru Taguchi, Melissa Stuart, Jean E. Jewell, and Hermann M. Sch€atzl


Chronic wasting disease (CWD) is a prion disease of free-ranging and farmed ungulates (deer, elk, and moose) in North America and South Korea. First described by the late E.S. Williams and colleagues in northern Colorado and southern Wyoming in the 1970s, CWD has increased tremendously both in numerical and geographical distribution, reaching prevalence rates as high as 50% in freeranging and >90% in captive deer herds in certain areas of USA and Canada. CWD is certainly the most contagious prion infection, with significant horizontal transmission of infectious prions by, e.g., urine, feces, and saliva. Dissemination and persistence of infectivity in the environment combined with the appearance in wildliving and migrating animals make CWD presently uncontrollable, and pose extreme challenges to wild-life disease management. Whereas CWD is extremely transmissible among cervids, its trans-species transmission seems to be restricted, although the possible involvement of rodent and carnivore species in environmental transmission has not been fully evaluated. Whether or not CWD has zoonotic potential as had Bovine spongiform encephalopathy (BSE) has yet to be answered. Of note, variant Creutzfeldt–Jakob disease (vCJD) was only detected because clinical presentation and age of patients were significantly different from classical CJD. Along with further understanding of the molecular biology and pathology of CWD, its transmissibility and species restrictions and development of methods for preclinical diagnosis and intervention will be crucial for effective containment of this highly contagious prion disease.

Keywords Cervid prions Chronic wasting disease Prion containment Wild-life prion disease Zoonotic

S. Gilch, N. Chitoor, Y. Taguchi, M. Stuart, J.E. Jewell, and H.M. Sch€atzl (*) Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA and Department of Molecular Biology, University of Wyoming, 1000 E. University Ave., Laramie, WY 82071, USA e-mail: hschatzl@uwyo.edu


While several initial state cases have been identified in captive herds, there is no epidemiological evidence that can point to an origin for CWD. Numerous hypotheses have been suggested including mutation/modification of scrapie strains to affect cervids, or spontaneous conversion of normal cervid PrP into PrPSc that is transmissible to other elk and deer. No clear cut origin for the disease may be discovered.


7 Natural and Experimental Transmission and Strains CWD prions are highly contagious, at least for transmission within and between deer and elk populations. However, it is also of great interest to analyze the interspecies transmissibility or species barriers of CWD for several reasons. Such studies may enable determination of (1) the source of the CWD agent, (2) the possible distribution to carnivores feeding on infected carcasses and rodents as reservoir hosts, and (3) finally, the most important reason for such studies is to predict whether CWD might be transmissible to humans.


7.4 CWD Strains The occurrence of different CWD strains, which are characterized by different incubation periods, diverse brain regions affected by spongiform lesions, or the glycoform pattern of PrPSc, was unclear for many years. Transgenic mice expressing cervid PrP were used for inoculation with elk or mule deer derived CWD prions, and in this model no evidence for CWD strains was revealed [40]. In contrast, when elk PrP expressing tg mice were inoculated with mule deer or elk CWD, differences in incubation time, clinical disease, and histopathology indicated the existence of different CWD strains in primary infected mice and upon passage [99]. In a recent study, the existence of at least two distinct CWD strains (CWD1 and CWD2) has been confirmed [72]. Interestingly, deer appear to harbor a mixture of CWD1 and CWD2, whereas elk are affected by either CWD1 or CWD2, which may be dictated by differences in the primary structures of deer and elk (Q226 vs E226; [72]). However, it is not clear by what means prion propagation in elk is restricted to either one strain or the other if infected with a mixture of CWD1 and CWD2, such as would be present in an inoculum from mule deer. Whether this reflects a stochastic choice of dominant path early in amplification of a selfpropagating strain, or an incompatibility between the two strains that does not allow their coexistence in elk, are among issues remaining to be investigated. In light of these findings, the different stabilities of those strains, and the influence of residue 226, it will be important to re-assess tissue distribution and zoonotic potential of these isolates.

8 Zoonotic Potential Deer hunting is a popular sport in the USA; venison is usually consumed by hunters and their families, and this raises reasonable concerns about the transmissibility of CWD to humans, as exemplified by the zoonotic transmission of BSE. Epidemiological studies have not revealed an increased incidence of CJD in CWD endemic areas. Suspicious case reports about persons having consumed venison and succumbed to neurological disorders turned out to be classical or familial CJD and a causal link to the consumption of contaminated meat could not be proven [109]. In vitro conversion assays were performed to assess the convertibility of human PrPc into PK resistant PrP using CWD derived from elk, mule deer, and white-tailed deer as a template. Only a very low conversion rate could be demonstrated, indicative of a considerable species barrier [110]. In a very recent study employing protein misfolding cyclic amplification (PMCA), a highly sensitive method for in vitro amplification conversion of human PrPc was successful, albeit with the restriction that CWD prions had to be adapted by PMCA or in vivo passage through cervidized tg mice. Passaged CWD template gave rise to a new form of human PrPSc, and its infectivity is currently under investigation. Of note, when field isolates of CWD Chronic Wasting Disease brains were used as a template, no conversion of human PrPc was achieved, which again questions the relevance of the in vitro data [111]. Studies using humanized tg mouse inoculated with CWD furthermore argue against transmissibility to humans since mice did not develop prion disease [112–114]. The best possible animal models to study transmission of animal prion diseases to humans probably are non-human primates. For instance, inoculation of BSE prions into Cynomolgus macaques provided the first hints that BSE might be transmissible to humans [115]. However, oral or i.c. challenge with CWD of macaques did not cause disease [116]. On the other hand, squirrel monkeys (Saimiri sciureus) were susceptible to i.c. inoculation with CWD prions [116, 117], and after oral exposure PrPSc was detectable in brain, spleen, and lymph nodes of 2/15 squirrel monkeys [116]. This shows that CWD can be transmitted to certain non-human primates, although results in Cynomolgus macaques might be of higher relevance since they are evolutionary closer relatives of humans than squirrel monkeys. Overall, there is no compelling evidence that CWD can be transmitted to humans with high efficiency.

snip...see full text ;


Oral Infection of Squirrel Monkeys To test a more natural route of infection, we exposed squirrel monkeys orally to CWD. Of the 15 exposed squirrel monkeys, 1 (no. 345) was found dead in its cage at 69 mpi; it had shown no neurologic signs or weakness. Western blot results indicated PrPres in brain, spleen, and lymph nodes (Figure 2, panel D). The level of PrPres in the brain of monkey 345 was comparable with that in endstage intracerebrally inoculated monkeys; body weight at necropsy indicated a 33% decrease over the final 10 months. The high levels of PrPres and the severe wasting indicate that CWD infection could have been the cause of death. A second monkey, 303, was euthanized at 69 mpi because of suspicion of TSE after 2 weeks of progressive weakness, wasting, and eventual anorexia. PrPres analysis confirmed PrPres in brain (Figure 2, panel D), spleen, and lymph nodes. For monkeys 303 and 345, levels of PrPres in the lymph nodes and spleens were 10–100-fold lower than those in brain.

Two other orally infected monkeys were euthanized during the first 69 mpi (Table 2). Monkey 301 was euthanized at 39 mpi, after rapid onset of lethargy and anorexia that led to severe dehydration. Results of Western blot analysis for PrPres were negative in brain (Figure 1, panel B), spleen, lymph nodes, heart, skeletal muscle, duodenum, jejunum, ileum, colon, salivary gland, kidney, lung, and tonsil. However, immunohistochemical analysis detected PrPres in the spleen and 1 mesenteric lymph node from this monkey, indicating a low level of infection (Figure 3, panels J, K). Monkey 614 was euthanized at 44 mpi because it did not recover from anesthesia related to routine tuberculosis screening. Neither Western blot nor immunohistochemical analysis detected PrPres in brain, spleen, or lymph nodes of this monkey.

Infection of Cynomolgus Macaques

We inoculated cynomolgus macaques both orally and intracerebrally with 3 CWD inocula representing elk, mule deer, and white-tailed deer (Table 3). Of the cynomolgus macaques, 1 (no. 609) was euthanized at 48 mpi after it became aggressive. Brain (Figure 2, panel B), spinal cord, spleen, and lymph nodes were negative for PrPres by Western blot and immunohistochemical analysis. All remaining CWD-inoculated cynomolgus monkeys are currently (at 70 mpi) neurologically asymptomatic and have stable or increased body weights.


Amino acid substitutions in PrP can alter susceptibility to TSE agents, including CWD (18,29,30). To determine whether the lack of susceptibility in several intracerebrally inoculated squirrel monkeys (Table 1) was caused by PrP gene polymorphisms, we sequenced the PrP genes from 23 squirrel monkeys. When compared with published squirrel monkey sequences (28,31), variation was seen at residue 164, in the number of octapeptide repeats, and at residue 19 of the signal peptide (Table 4). However, these genetic differences in PrP did not appear to account for the lack of susceptibility of monkey 310, which was genotype A, because this genotype was also found in 5 of the CWDpositive monkeys. Because we were not able to sequence PrP of monkey 628, we could not assess the role of PrP variation in the lack of disease.


As new CWD foci continue to emerge among cervid populations, the risk for CWD transmission to humans needs to be assessed. We used 2 monkey species and 2 routes of inoculation to test the susceptibility of primates to 8 different pools of CWD. To date, we have verified CWD in 11 of 13 intracerebrally inoculated squirrel monkeys; average incubation period was 41 months (range 33.53 months). Using a single CWD pool, Marsh et al. noted infection in 2 of 2 squirrel monkeys 31.34 months after intracerebral inoculation (13). Intracerebral inoculation of squirrel monkeys with other TSE agents, including agents of kuru, variant CJD, sporadic CJD, and sheep scrapie, had incubation periods of .24 months and attack rates of .100% (14,15,32). The extended incubation periods and lower attack rates for our squirrel monkeys may result from a partial species barrier to CWD.

The signs of wasting syndrome in CWD-infected monkeys were similar to those of CWD infection in cervids, in which loss of body condition is nearly always a major component of infection and neurologic deficits vary (2). The correlation of clinical signs between CWD in cervids and squirrel monkeys suggests that CWD might affect a common brain region in each species. We observed PrPres deposition in squirrel monkeys primarily in the frontal lobe of the cerebral cortex, claustrum, putamen, and thalamus. Cervids typically have the most abundant and predictable PrPres in the dorsal motor vagus nucleus (obex), olfactory cortex, and diencephalon (including thalamus, hypothalamus, metathalamus, and epithalamus) (2,33).

A plausible hypothesis could be that disruption of regions within the hypothalamus and thalamus leads to a metabolic imbalance, resulting in a severe wasting syndrome.

We did not observe a strong correlation between infectivity titer inoculated and attack incidence or incubation period (Table 1). One potential explanation is that the variation in speed of disease progression might not be relevant given the low number of animals in each group. A second possibility is that our squirrel monkeys varied at PrP alleles that may affect CWD susceptibility. However, analysis of 23 squirrel monkeys showed no PrP sequence differences correlating with susceptibility to CWD (Tables 1, 2, 4). A third possibility is that genes other than the gene for PrP might influence CWD susceptibility.

For humans, eating infected or contaminated tissue is a likely route of CWD exposure. In other animal models, oral transmission of TSE is generally 1,000-fold less effective than direct intracerebral challenge and results in longer incubation periods and lower efficiency of disease transmission. In our oral transmission experiments, we found evidence of CWD infection in 3 monkeys; 2 at 69 mpi had abundant PrPres in brain and lower levels in spleen and lymph nodes, and 1 euthanized at 39 mpi had PrPres in lymphatic tissues only. Thus, transmission seems to be slower by the oral route than by the intracerebral route, and other orally infected monkeys may be affected in the future.

Cynomolgus macaques are evolutionarily closer to humans than are squirrel monkeys (17). At nearly 6 years postinoculation, no macaques have shown clinical signs of CWD. Intracerebral inoculation of cynomolgus macaques with BSE causes disease in 3 years; human variant CJD requires 2–3 years, and human sporadic CJD requires 5 years (16,34). However, oral inoculation of cynomolgus macaques with BSE agent required a minimum of 5 years before clinical disease was observed (35). There-fore, we cannot rule out CWD transmission to cynomolgus macaques.

The PrP gene sequence can influence cross-species transmission of prion disease. Therefore, we compared squirrel monkey and cynomolgus macaque PrP gene sequences to look for differences that might account for different susceptibilities of these monkeys to CWD. In the PrP gene excluding the signal peptide, deer differed from squirrel monkeys at 17 residues and from cynomolgus macaques at 16 residues, but 14 of these differing residues were identical in squirrel monkeys and macaques (Figure 4). Therefore, there are only 2 residues in cynomolgus macaques (100 and 108) and 3 residues in squirrel monkeys (56, 159 and 182) at which these monkeys differ from deer and also from each other. These residues might play a role in susceptibility differences seen in our study.

Human exposure to CWD-infected cervids in past decades is likely. The highest levels of prion infectivity are present in the central nervous system and lymphatic tissues of CWD-infected cervids; contamination of knives, saws, and muscles with these tissues can easy occur when processing game. Despite the likelihood of exposures, epidemiologic studies of humans living in CWD-endemic areas of Colorado and Wyoming during 1979–2001 have not shown any increases in human TSE cases (36,37). Ongoing studies by the Colorado Department of Public Health and Environmental Human Prion Disease Surveillance Program, in conjunction with the University of Colorado School of Medicine, have also concluded that no convincing cases of CWD transmission to humans have been detected in Colorado (38).

However, if CWD in humans appears like a wasting syndrome similar to that observed in the squirrel monkeys in our study, affected persons might receive a diagnosis of a metabolic disorder and never be tested for TSE. Fortunately, additional laboratory data are consistent with the epidemiologic data, and these results support the conclusion that a species barrier protects humans from CWD infection (11–13,20,36,37).


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.


*** twenty-seven CJD patients who regularly consumed venison were reported to the Surveillance Center***,


full text ;


2003 The Pathological Protein

The Fort Collins facility became a CWD death trap. Between 1970 and 1981, 90 percent of the deer that stayed more than two years died from the disease or had to be euthanized. In 1980 the scourge emerged outside Colorado, at the Sybille Research Unit in southeastern Wyoming, 120 miles northwest of Fort Collins. The two facilities had exchanged deer for breeding purposes, thus indicating that the disease was infectious--even to a different species: soon the elk at the facilities contracted the disease. (Deer and elk both belong to the cervid family.)

For years, researchers thought CWD resulted from nutritional deficiencies, poisoning, or stress from confinement. But in 1977 Elizabeth S. Williams, studying for her doctorate at Colorado State University, discovered that this view was mistaken. When Williams looked at brain slices from infected animals, she saw that the tissue was full of microscopic holes. "I happened to be taking a course in neuropathology and had studied a lot of brain lesions," she recalls. The holes were unmistakably like scrapie, the sheep sickness that was the first documented spongiform encephalopathy.


In fact, CWD appears to have originated from scrapie. Richard E. Race of the National Institutes of Health Rocky Mountain Laboratories in Hamilton, Mont., conducted test tube studies that revealed no distinction between the malformed PrP of scrapie sheep and CWD cervids. Consistent with this discovery, Amir Hamir of the U.S. Department of Agriculture's National Animal Disease Center in Ames, Iowa, found no difference in the appearance of brain samples from elk with CWD and elk experimentally infected with scrapie. (BSE also probably arose from scrapie, after cows ate feed derived from infected sheep.)



By 1985 veterinarians discovered CWD in free-ranging deer and elk, generally within about 30 miles of the two wildlife facilities. Whether the disease originated in the wild and spread to the captives, or vice versa, is not known. The two populations had plenty of time to mingle. Especially during mating season, wild cervids nosed up to captives through the chain-link fences. Incubating deer could also have escaped or been released.

Both facilities tried hard to eradicate CWD. The Sybille center killed all the deer and elk in the affected area and waited a year to introduce new animals; four years later deer and elk started coming down with CWD. The Fort Collins facility acted more aggressively. Officials first killed off all the resident deer and elk; then they turned several inches of soil and repeatedly sprayed structures and pastures with swimming-pool chlorine, which readily wipes out bacteria and viruses. After waiting a year, they brought in 12 elk calves, but a few years afterward two of those elk contracted CWD.


Philip Yam is Scientific American's news editor. This article is adapted from his book, The Pathological Protein: Mad Cow, Chronic Wasting, and Other Deadly Prion Diseases, published in June.


also, see ;



Perceptions of unconventional slow virus diseases of animals in the USA

Spraker suggested an interesting explanation for the occurrence of CWD. The deer pens at the Foot Hills Campus were built some 30-40 years ago by a Dr. Bob Davis. At or about that time, allegedly, some scrapie work was conducted at this site. When deer were introduced to the pens they occupied ground that had previously been occupied by sheep. Whether they were scrapie infected sheep or not is unclear.






October 1994

Mr R.N. Elmhirst Chairman British Deer Farmers Association Holly Lodge Spencers Lane BerksWell Coventry CV7 7BZ

Dear Mr Elmhirst,


Thank you for your recent letter concerning the publication of the third annual report from the CJD Surveillance Unit. I am sorry that you are dissatisfied with the way in which this report was published.

The Surveillance Unit is a completely independant outside body and the Department of Health is committed to publishing their reports as soon as they become available. In the circumstances it is not the practice to circulate the report for comment since the findings of the report would not be amended. In future we can ensure that the British Deer Farmers Association receives a copy of the report in advance of publication.

The Chief Medical Officer has undertaken to keep the public fully informed of the results of any research in respect of CJD. This report was entirely the work of the unit and was produced completely independantly of the the Department.

The statistical results reqarding the consumption of venison was put into perspective in the body of the report and was not mentioned at all in the press release. Media attention regarding this report was low key but gave a realistic presentation of the statistical findings of the Unit. This approach to publication was successful in that consumption of venison was highlighted only once by the media ie. in the News at one television proqramme.

I believe that a further statement about the report, or indeed statistical links between CJD and consumption of venison, would increase, and quite possibly give damaging credence, to the whole issue. From the low key media reports of which I am aware it seems unlikely that venison consumption will suffer adversely, if at all.


and why do we not want to do TSE transmission studies on chimpanzees $


5. A positive result from a chimpanzee challenged severly would likely create alarm in some circles even if the result could not be interpreted for man. I have a view that all these agents could be transmitted provided a large enough dose by appropriate routes was given and the animals kept long enough. Until the mechanisms of the species barrier are more clearly understood it might be best to retain that hypothesis.




Saturday, May 14, 2011

Modeling Routes of Chronic Wasting Disease Transmission: Environmental Prion Persistence Promotes Deer Population Decline and Extinction


Thursday, April 28, 2011

Chronic Wasting Disease Testing and Prevalence Wisconsin April 2011



Wednesday, September 08, 2010



Tuesday, January 25, 2011

Generation of a new form of human PrPSc in vitro by inter-species transmission from cervids prions


Wednesday, April 06, 2011

Presence and Seeding Activity of Pathological Prion Protein (PrPTSE) in Skeletal Muscles of White-Tailed Deer Infected with Chronic Wasting Disease


Wednesday, January 5, 2011



David W. Colby1,* and Stanley B. Prusiner1,2




Wednesday, April 06, 2011

Presence and Seeding Activity of Pathological Prion Protein (PrPTSE) in Skeletal Muscles of White-Tailed Deer Infected with Chronic Wasting Disease


Generation of a new form of human PrPSc in vitro by inter-species transmission from cervids prions

Marcelo A. Barria1, Glenn C. Telling2, Pierluigi Gambetti3, James A. Mastrianni4 and Claudio Soto5,* + Author Affiliations

1 University of Texas Medical School at Houston, United States; 2 University of Kentucky, United States; 3 Case Western Reserve University, United States; 4 University of Chicago, United States; 5 University of Texas Medical School, United States * Corresponding author; email: claudio.soto@uth.tmc.edu

Received October 28, 2010. Accepted January 4, 2011. Copyright © 2011, The American Society for Biochemistry and Molecular Biology


Our findings demonstrate that cervid PrPSc, upon strain adaptation by serial passages in vitro or in cervid transgenic mice, is capable of converting human PrPC to produce PrPSc with unique biochemical properties, likely representing a new human prion strain. The newly generated CWD-huPrPSc material has been inoculated into transgenic mice expressing human PrP to study infectivity and disease phenotype and this data will be published elsewhere. ...end


Generation of a new form of human PrPSc in vitro by inter-species transmission from cervids prions

Marcelo A. Barria1, Glenn C. Telling2, Pierluigi Gambetti3, James A. Mastrianni4 and Claudio Soto5,* + Author Affiliations

1 University of Texas Medical School at Houston, United States; 2 University of Kentucky, United States; 3 Case Western Reserve University, United States; 4 University of Chicago, United States; 5 University of Texas Medical School, United States * Corresponding author; email: claudio.soto@uth.tmc.edu

Received October 28, 2010. Accepted January 4, 2011. Copyright © 2011, The American Society for Biochemistry and Molecular Biology eneration


Tuesday, January 25, 2011

Generation of a new form of human PrPSc in vitro by inter-species transmission from cervids prions



there are now two documented strains of CWD, and science is showing that indeed CWD could transmit to humans via transmission studies ;



Chad Johnson1, Judd Aiken2,3,4 and Debbie McKenzie4,5 1 Department of Comparative Biosciences, University of Wisconsin, Madison WI, USA 53706 2 Department of Agriculture, Food and Nutritional Sciences, 3 Alberta Veterinary Research Institute, 4.Center for Prions and Protein Folding Diseases, 5 Department of Biological Sciences, University of Alberta, Edmonton AB, Canada T6G 2P5

The identification and characterization of prion strains is increasingly important for the diagnosis and biological definition of these infectious pathogens. Although well-established in scrapie and, more recently, in BSE, comparatively little is known about the possibility of prion strains in chronic wasting disease (CWD), a disease affecting free ranging and captive cervids, primarily in North America. We have identified prion protein variants in the white-tailed deer population and demonstrated that Prnp genotype affects the susceptibility/disease progression of white-tailed deer to CWD agent. The existence of cervid prion protein variants raises the likelihood of distinct CWD strains. Small rodent models are a useful means of identifying prion strains. We intracerebrally inoculated hamsters with brain homogenates and phosphotungstate concentrated preparations from CWD positive hunter-harvested (Wisconsin CWD endemic area) and experimentally infected deer of known Prnp genotypes. These transmission studies resulted in clinical presentation in primary passage of concentrated CWD prions. Subclinical infection was established with the other primary passages based on the detection of PrPCWD in the brains of hamsters and the successful disease transmission upon second passage. Second and third passage data, when compared to transmission studies using different CWD inocula (Raymond et al., 2007) indicate that the CWD agent present in the Wisconsin white-tailed deer population is different than the strain(s) present in elk, mule-deer and white-tailed deer from the western United States endemic region.



Prion Transmission from Cervids to Humans is Strain-dependent

Qingzhong Kong, Shenghai Huang,*Fusong Chen, Michael Payne, Pierluigi Gambetti and Liuting Qing Department of Pathology; Case western Reserve University; Cleveland, OH USA *Current address: Nursing Informatics; Memorial Sloan-Kettering Cancer Center; New York, NY USA

Key words: CWD, strain, human transmission

Chronic wasting disease (CWD) is a widespread prion disease in cervids (deer and elk) in North America where significant human exposure to CWD is likely and zoonotic transmission of CWD is a concern. Current evidence indicates a strong barrier for transmission of the classical CWD strain to humans with the PrP-129MM genotype. A few recent reports suggest the presence of two or more CWD strains. What remain unknown is whether individuals with the PrP-129VV/MV genotypes are also resistant to the classical CWD strain and whether humans are resistant to all natural or adapted cervid prion strains. Here we report that a human prion strain that had adopted the cervid prion protein (PrP) sequence through passage in cervidized transgenic mice efficiently infected transgenic mice expressing human PrP, indicating that the species barrier from cervid to humans is prion strain-dependent and humans can be vulnerable to novel cervid prion strains. Preliminary results on CWD transmission in transgenic mice expressing human PrP-129V will also be discussed.

Acknowledgement Supported by NINDS NS052319 and NIA AG14359.


Generation of a Novel form of Human PrPSc by Inter-species Transmission of Cervid Prions

Marcelo A. Barria,1 Glenn C. Telling,2 Pierluigi Gambetti,3 James A. Mastrianni4 and Claudio Soto1 1Mitchell Center for Alzheimer's disease and related Brain disorders; Dept of Neurology; University of Texas Houston Medical School; Houston, TX USA; 2Dept of Microbiology, Immunology & Molecular Genetics and Neurology; Sanders Brown Center on Aging; University of Kentucky Medical Center; Lexington, KY USA; 3Institute of Pathology; Case western Reserve University; Cleveland, OH USA; 4Dept of Neurology; University of Chicago; Chicago, IL USA

Prion diseases are infectious neurodegenerative disorders affecting humans and animals that result from the conversion of normal prion protein (PrPC) into the misfolded and infectious prion (PrPSc). Chronic wasting disease (CWD) of cervids is a prion disorder of increasing prevalence within the United States that affects a large population of wild and captive deer and elk. CWD is highly contagious and its origin, mechanism of transmission and exact prevalence are currently unclear. The risk of transmission of CWD to humans is unknown. Defining that risk is of utmost importance, considering that people have been infected by animal prions, resulting in new fatal diseases. To study the possibility that human PrPC can be converted into the infectious form by CWD PrPSc we performed experiments using the Protein Misfolding Cyclic Amplification (PMCA) technique, which mimic in vitro the process of prion replication. Our results show that cervid PrPSc can induce the pathological conversion of human PrPC, but only after the CWD prion strain has been stabilized by successive passages in vitro or in vivo. Interestingly, this newly generated human PrPSc exhibits a distinct biochemical pattern that differs from any of the currently known forms of human PrPSc, indicating that it corresponds to a novel human prion strain. Our findings suggest that CWD prions have the capability to infect humans, and that this ability depends on CWD strain adaptation, implying that the risk for human health progressively increases with the spread of CWD among cervids.


Biochemical and Biophysical Characterization of Different CWD Isolates

Martin L. Daus and Michael Beekes Robert Koch Institute; Berlin, Germany

Key words: CWD, strains, FT-IR, AFM

Chronic wasting disease (CWD) is one of three naturally occurring forms of prion disease. The other two are Creutzfeldt-Jakob disease in humans and scrapie in sheep. CWD is contagious and affects captive as well as free ranging cervids. As long as there is no definite answer of whether CWD can breach the species barrier to humans precautionary measures especially for the protection of consumers need to be considered. In principle, different strains of CWD may be associated with different risks of transmission to humans. Sophisticated strain differentiation as accomplished for other prion diseases has not yet been established for CWD. However, several different findings indicate that there exists more than one strain of CWD agent in cervids. We have analysed a set of CWD isolates from white-tailed deer and could detect at least two biochemically different forms of disease-associated prion protein PrPTSE. Limited proteolysis with different concentrations of proteinase K and/or after exposure of PrPTSE to different pH-values or concentrations of Guanidinium hydrochloride resulted in distinct isolate-specific digestion patterns. Our CWD isolates were also examined in protein misfolding cyclic amplification studies. This showed different conversion activities for those isolates that had displayed significantly different sensitivities to limited proteolysis by PK in the biochemical experiments described above. We further applied Fourier transform infrared spectroscopy in combination with atomic force microscopy. This confirmed structural differences in the PrPTSE of at least two disinct CWD isolates. The data presented here substantiate and expand previous reports on the existence of different CWD strains.


Prions in Skeletal Muscles of Deer with Chronic Wasting Disease

Rachel C. Angers1,*, Shawn R. Browning1,*?, Tanya S. Seward2, Christina J. Sigurdson4,?, Michael W. Miller5, Edward A. Hoover4 and Glenn C. Telling1,2,3,§ + Author Affiliations


The emergence of chronic wasting disease (CWD) in deer and elk in an increasingly wide geographic area, as well as the interspecies transmission of bovine spongiform encephalopathy to humans in the form of variant Creutzfeldt Jakob disease, have raised concerns about the zoonotic potential of CWD. Because meat consumption is the most likely means of exposure, it is important to determine whether skeletal muscle of diseased cervids contains prion infectivity. Here bioassays in transgenic mice expressing cervid prion protein revealed the presence of infectious prions in skeletal muscles of CWD-infected deer, demonstrating that humans consuming or handling meat from CWD-infected deer are at risk to prion exposure.

Received for publication 21 November 2005. Accepted for publication 13 January 2006.


Journal of Virology, September 2009, p. 9608-9610, Vol. 83, No. 18 0022-538X/09/$08.00+0 doi:10.1128/JVI.01127-09 Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Prion Infectivity in Fat of Deer with Chronic Wasting Disease

Brent Race,# Kimberly Meade-White,# Richard Race, and Bruce Chesebro* Rocky Mountain Laboratories, 903 South 4th Street, Hamilton, Montana 59840

Received 2 June 2009/ Accepted 24 June 2009


Chronic wasting disease (CWD) is a neurodegenerative prion disease of cervids. Some animal prion diseases, such as bovine spongiform encephalopathy, can infect humans; however, human susceptibility to CWD is unknown. In ruminants, prion infectivity is found in central nervous system and lymphoid tissues, with smaller amounts in intestine and muscle. In mice, prion infectivity was recently detected in fat. Since ruminant fat is consumed by humans and fed to animals, we determined infectivity titers in fat from two CWD-infected deer. Deer fat devoid of muscle contained low levels of CWD infectivity and might be a risk factor for prion infection of other species.


The highest risk of human contact with CWD might be through exposure to high-titer CNS tissue through accidental skin cuts or corneal contact at the time of harvest and butchering. However, the likelihood of a human consuming fat infected with a low titer of the CWD agent is much higher. It is impossible to remove all the fat present within muscle tissue, and fat consumption is inevitable when eating meat. Of additional concern is the fact that meat from an individual deer harvested by a hunter is typically consumed over multiple meals by the same group of people. These individuals would thus have multiple exposures to the CWD agent over time, which might increase the chance for transfer of infection.

In the Rocky Mountain region of North America, wild deer are subject to predation by wolves, coyotes, bears, and mountain lions. Although canines such as wolves and coyotes are not known to be susceptible to prion diseases, felines definitely are susceptible to BSE (9) and might also be infected by the CWD agent. Deer infected with the CWD agent are more likely to be killed by predators such as mountain lions (11). Peripheral tissues, including lymph nodes, muscle, and fat, which harbor prion infectivity are more accessible for consumption than CNS tissue, which has the highest level of infectivity late in disease. Therefore, infectivity in these peripheral tissues may be important in potential cross-species CWD transmissions in the wild.

The present finding of CWD infectivity in deer fat tissue raises the possibility that prion infectivity might also be found in fat tissue of other infected ruminants, such as sheep and cattle, whose fat and muscle tissues are more widely distributed in both the human and domestic-animal food chains. Although the infectivity in fat tissues is low compared to that in the CNS, there may be significant differences among species and between prion strains. Two fat samples from BSE agent-infected cattle were reported to be negative by bioassay in nontransgenic RIII mice (3, 6). However, RIII mice are 10,000-fold-less sensitive to BSE agent infection than transgenic mice expressing bovine PrP (4). It would be prudent to carry out additional infectivity assays on fat from BSE agent-infected cattle and scrapie agent-infected sheep using appropriate transgenic mice or homologous species to determine the risk from these sources.


From: TSS (216-119-163-189.ipset45.wt.net)


Date: September 30, 2002 at 7:06 am PST

From: "Belay, Ermias"


Cc: "Race, Richard (NIH)" ; ; "Belay, Ermias"

Sent: Monday, September 30, 2002 9:22 AM


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-----


Sent: Sunday, September 29, 2002 10:15 AM

To: [log in to unmask]">[log in to unmask]; [log in to unmask]">[log in to unmask]; [log in to unmask]">[log in to unmask]


Sunday, November 10, 2002 6:26 PM ......snip........end..............TSS


full text ;


FDA is not recalling this CWD positive elk meat for the well being of the dead elk ;

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


see full text ;


PLUS, oral transmission between cervids, either infected carcases AND ESPECIALLY FEED THAT HAS ANIMAL PROTEIN, PLEASE SEE ;

PRODUCT Custom deer feed made for a Wisconsin farm. The product was in bags holding about 40 pounds each. Recall # V-122-4. CODE 1-30-04 on the product invoice and mixing record. RECALLING FIRM/MANUFACTURER Crivitz Feed Mill, Crivitz, WI, by telephone on February 20, 2004. Wisconsin State initiated recall is complete. REASON The recalled deer feed contained steamed bone meal which is prohibited material in feed for ruminants.






Experimental oral transmission of chronic wasting disease to red deer (Cervus elaphus elaphus): Early detection and late stage distribution of protease-resistant prion protein

Aru Balachandran, Noel P. Harrington, James Algire, Andrei Soutyrine, Terry R. Spraker, Martin Jeffrey, Lorenzo González, Katherine I. O’Rourke

Abstract — Chronic wasting disease (CWD), an important emerging prion disease of cervids, is readily transmitted by intracerebral or oral inoculation from deer-to-deer and elk-to-elk, suggesting the latter is a natural route of exposure. Studies of host range susceptibility to oral infection, particularly of those species found in habitats where CWD currently exists are imperative. This report describes the experimental transmission of CWD to red deer following oral inoculation with infectious CWD material of elk origin. At 18 to 20 months post-inoculation, mild to moderate neurological signs and weight loss were observed and animals were euthanized and tested using 3 conventional immunological assays. The data indicate that red deer are susceptible to oral challenge and that tissues currently used for CWD diagnosis show strong abnormal prion (PrPCWD) accumulation. Widespread peripheral PrPCWD deposition involves lymphoreticular tissues, endocrine tissues, and cardiac muscle and suggests a potential source of prion infectivity, a means of horizontal transmission and carrier state.

Can Vet J 2010;51:169–178


Journal of General Virology (1999), 80, 2757-2764. © 1999 Society for General Microbiology


Other Agents

Oral transmission and early lymphoid tropism of chronic wasting disease PrPres in mule deer fawns (Odocoileus hemionus ) Christina J. Sigurdson1, Elizabeth S. Williams2, Michael W. Miller3, Terry R. Spraker1,4, Katherine I. O'Rourke5 and Edward A. Hoover1

Department of Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523- 1671, USA1 Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, University of Wyoming, Laramie, WY 82070, USA 2 Colorado Division of Wildlife, Wildlife Research Center, 317 West Prospect Road, Fort Collins, CO 80526-2097, USA3 Colorado State University Veterinary Diagnostic Laboratory, 300 West Drake Road, Fort Collins, CO 80523-1671, USA4 Animal Disease Research Unit, Agricultural Research Service, US Department of Agriculture, 337 Bustad Hall, Washington State University, Pullman, WA 99164-7030, USA5

Author for correspondence: Edward Hoover.Fax +1 970 491 0523. e-mail ehoover@lamar.colostate.edu

Abstract TOP Abstract Introduction Methods Results Discussion References

Mule deer fawns (Odocoileus hemionus) were inoculated orally with a brain homogenate prepared from mule deer with naturally occurring chronic wasting disease (CWD), a prion-induced transmissible spongiform encephalopathy. Fawns were necropsied and examined for PrP res, the abnormal prion protein isoform, at 10, 42, 53, 77, 78 and 80 days post-inoculation (p.i.) using an immunohistochemistry assay modified to enhance sensitivity. PrPres was detected in alimentary-tract-associated lymphoid tissues (one or more of the following: retropharyngeal lymph node, tonsil, Peyer's patch and ileocaecal lymph node) as early as 42 days p.i. and in all fawns examined thereafter (53 to 80 days p.i.). No PrPres staining was detected in lymphoid tissue of three control fawns receiving a control brain inoculum, nor was PrPres detectable in neural tissue of any fawn. PrPres-specific staining was markedly enhanced by sequential tissue treatment with formic acid, proteinase K and hydrated autoclaving prior to immunohistochemical staining with monoclonal antibody F89/160.1.5. These results indicate that CWD PrP res can be detected in lymphoid tissues draining the alimentary tract within a few weeks after oral exposure to infectious prions and may reflect the initial pathway of CWD infection in deer. The rapid infection of deer fawns following exposure by the most plausible natural route is consistent with the efficient horizontal transmission of CWD in nature and enables accelerated studies of transmission and pathogenesis in the native species.


Chronic wasting disease (CWD), an important emerging prion disease of cervids, is readily transmitted by intracerebral or oral inoculation from deer-to-deer and elk-to-elk, suggesting the latter is a natural route of exposure.


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: 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.

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: 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.



----- Original Message -----

From: David Colby

To: flounder9@verizon.net

Cc: stanley@XXXXXXXX

Sent: Tuesday, March 01, 2011 8:25 AM

Subject: Re: FW: re-Prions David W. Colby1,* and Stanley B. Prusiner1,2 + Author Affiliations

Dear Terry Singeltary,

Thank you for your correspondence regarding the review article Stanley Prusiner and I recently wrote for Cold Spring Harbor Perspectives. Dr. Prusiner asked that I reply to your message due to his busy schedule. We agree that the transmission of CWD prions to beef livestock would be a troubling development and assessing that risk is important. In our article, we cite a peer-reviewed publication reporting confirmed cases of laboratory transmission based on stringent criteria. The less stringent criteria for transmission described in the abstract you refer to lead to the discrepancy between your numbers and ours and thus the interpretation of the transmission rate. We stand by our assessment of the literature--namely that the transmission rate of CWD to bovines appears relatively low, but we recognize that even a low transmission rate could have important implications for public health and we thank you for bringing attention to this matter.

Warm Regards, David Colby


David Colby, PhDAssistant ProfessorDepartment of Chemical EngineeringUniversity of Delaware


Wednesday, January 5, 2011



David W. Colby1,* and Stanley B. Prusiner1,2



CWD to cattle figures CORRECTION


I believe the statement and quote below is incorrect ;

"CWD has been transmitted to cattle after intracerebral inoculation, although the infection rate was low (4 of 13 animals [Hamir et al. 2001]). This finding raised concerns that CWD prions might be transmitted to cattle grazing in contaminated pastures."

Please see ;

Within 26 months post inoculation, 12 inoculated animals had lost weight, revealed abnormal clinical signs, and were euthanatized. Laboratory tests revealed the presence of a unique pattern of the disease agent in tissues of these animals. These findings demonstrate that when CWD is directly inoculated into the brain of cattle, 86% of inoculated cattle develop clinical signs of the disease.


" although the infection rate was low (4 of 13 animals [Hamir et al. 2001]). "

shouldn't this be corrected, 86% is NOT a low rate. ...

kindest regards,

Terry S. Singeltary Sr. P.O. Box 42 Bacliff, Texas USA 77518

Thank you!

Thanks so much for your updates/comments. We intend to publish as rapidly as possible all updates/comments that contribute substantially to the topic under discussion.


please see full text of my submission here ;

Wednesday, January 5, 2011



David W. Colby1,* and Stanley B. Prusiner1,2


Thursday, February 17, 2011

Environmental Sources of Scrapie Prions


Monday, February 14, 2011



Journal of Wildlife Diseases, 47(1), 2011, pp. 78-93 © Wildlife Disease Association 2011


Friday, May 13,

2011 EFSA Joint Scientific Opinion on any possible epidemiological or molecular association between TSEs in animals and humans


Tuesday, May 24, 2011 2:24 PM

O.I.E. Terrestrial Animal Health Standards Commission and prion (TSE) disease reporting 2011


Thursday, May 26, 2011

Travel History, Hunting, and Venison Consumption Related to Prion Disease Exposure, 2006-2007 FoodNet Population Survey

Journal of the American Dietetic Association Volume 111, Issue 6 , Pages 858-863, June 2011.



Topics in Current Chemistry, 2011, 1-28, DOI: 10.1007/128_2011_161

Atypical Prion Diseases in Humans and Animals

Michael A. Tranulis, Sylvie L. Benestad, Thierry Baron and Hans Kretzschmar


Although prion diseases, such as Creutzfeldt–Jakob disease (CJD) in humans and scrapie in sheep, have long been recognized, our understanding of their epidemiology and pathogenesis is still in its early stages. Progress is hampered by the lengthy incubation periods and the lack of effective ways of monitoring and characterizing these agents. Protease-resistant conformers of the prion protein (PrP), known as the “scrapie form” (PrPSc), are used as disease markers, and for taxonomic purposes, in correlation with clinical, pathological, and genetic data. In humans, prion diseases can arise sporadically (sCJD) or genetically (gCJD and others), caused by mutations in the PrP-gene (PRNP), or as a foodborne infection, with the agent of bovine spongiform encephalopathy (BSE) causing variant CJD (vCJD). Person-to-person spread of human prion disease has only been known to occur following cannibalism (kuru disease in Papua New Guinea) or through medical or surgical treatment (iatrogenic CJD, iCJD). In contrast, scrapie in small ruminants and chronic wasting disease (CWD) in cervids behave as infectious diseases within these species. Recently, however, so-called atypical forms of prion diseases have been discovered in sheep (atypical/Nor98 scrapie) and in cattle, BSE-H and BSE-L. These maladies resemble sporadic or genetic human prion diseases and might be their animal equivalents. This hypothesis also raises the significant public health question of possible epidemiological links between these diseases and their counterparts in humans.

Keywords Animal - Atypical - Atypical/Nor98 scrapie - BSE-H - BSE-L - Human - Prion disease - Prion strain - Prion type


Monday, May 23, 2011

Atypical Prion Diseases in Humans and Animals 2011

Top Curr Chem (2011)

DOI: 10.1007/128_2011_161

# Springer-Verlag Berlin Heidelberg 2011


Tuesday, April 26, 2011

sporadic CJD RISING Text and figures of the latest annual report of the NCJDRSU covering the period 1990-2009 (published 11th March 2011)


Saturday, March 5, 2011



Wednesday, May 18, 2011

Variably Protease-Sensitive Prionopathy: a Novel Disease of the Prion Protein 17 May 2011

Journal of Molecular Neuroscience DOI: 10.1007/s12031-011-9543-1



Friday, November 30, 2007




The statistical incidence of CJD cases in the United States has been revised to reflect that there is one case per 9000 in adults age 55 and older. Eighty-five percent of the cases are sporadic, meaning there is no known cause at present.




Terry S. Singeltary Sr. P.O. Box 42 Bacliff, Texas USA 77518


Saturday, May 14, 2011

Modeling Routes of Chronic Wasting Disease Transmission: Environmental Prion Persistence Promotes Deer Population Decline and Extinction

Modeling Routes of Chronic Wasting Disease Transmission: Environmental Prion Persistence Promotes Deer Population Decline and Extinction


Emily S. Almberg1,2*, Paul C. Cross1, Christopher J. Johnson3, Dennis M. Heisey3, Bryan J. Richards4

1 Northern Rocky Mountain Science Center, United States Geological Survey, Bozeman, Montana, United States of America, 2 The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America, 3 Prion Research Laboratory, National Wildlife Health Center, United States Geological Survey, Madison, Wisconsin, United States of America, 4 National Wildlife Health Center, United States Geological Survey, Madison, Wisconsin, United States of America


Chronic wasting disease (CWD) is a fatal disease of deer, elk, and moose transmitted through direct, animal-to-animal contact, and indirectly, via environmental contamination. Considerable attention has been paid to modeling direct transmission, but despite the fact that CWD prions can remain infectious in the environment for years, relatively little information exists about the potential effects of indirect transmission on CWD dynamics. In the present study, we use simulation models to demonstrate how indirect transmission and the duration of environmental prion persistence may affect epidemics of CWD and populations of North American deer. Existing data from Colorado, Wyoming, and Wisconsin's CWD epidemics were used to define plausible short-term outcomes and associated parameter spaces. Resulting long-term outcomes range from relatively low disease prevalence and limited host-population decline to host-population collapse and extinction. Our models suggest that disease prevalence and the severity of population decline is driven by the duration that prions remain infectious in the environment. Despite relatively low epidemic growth rates, the basic reproductive number, R0, may be much larger than expected under the direct-transmission paradigm because the infectious period can vastly exceed the host's life span. High prion persistence is expected to lead to an increasing environmental pool of prions during the early phases (i.e. approximately during the first 50 years) of the epidemic. As a consequence, over this period of time, disease dynamics will become more heavily influenced by indirect transmission, which may explain some of the observed regional differences in age and sex-specific disease patterns. This suggests management interventions, such as culling or vaccination, will become increasingly less effective as CWD epidemics progress.

Citation: Almberg ES, Cross PC, Johnson CJ, Heisey DM, Richards BJ (2011) Modeling Routes of Chronic Wasting Disease Transmission: Environmental Prion Persistence Promotes Deer Population Decline and Extinction. PLoS ONE 6(5): e19896. doi:10.1371/journal.pone.0019896

Editor: Andrew Yates, Albert Einstein College of Medicine, United States of America

Received: November 10, 2010; Accepted: April 19, 2011; Published: May 13, 2011

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Funding: This work was funded by the U.S. Geological Survey. 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.

* E-mail: esa5046@psu.edu



Mother to Offspring Transmission of Chronic Wasting Disease

Candace K. Mathiason; Amy Nalls; Kelly Anderson; Jeanette Hayes-Klug; Jenny G. Powers; Nicholas J. Haley; Edward A. Hoover Colorado State University, Fort Collins, CO, USA

We have developed a new cervid model in small Asian muntjac deer (Muntiacus reevesi) to study potential modes of vertical transmission of chronic wasting disease (CWD) from mother to offspring. Eight of eight (8/8) muntjac doe orally infected with CWD tested PrPCWD lymphoid positive by 4 months post infection. Ten fawns were born to these CWD-infected doe— 4 of the fawns were viable, 5 were non-viable, and 1 was a first trimester fetus harvested from a CWD-infected doe euthanized at end-stage disease. The viable fawns have been monitored for CWD infection by immunohistochemistry and sPMCA performed on serial tonsil and rectal lymphoid tissue biopsies. PrPCWD has been detected in one fawn by IHC as early as 40 days of age. Moreover, sPMCA performed on rectal lymphoid tissue has yielded positive results on another fawn at 10 days of age. In addition, sPMCA assays have demonstrated amplifiable prions in fetal placental or spleen tissue of 3 non-viable fawns and mammary tissue of the dams. Additional pregnancy related fluids and tissues from the doe as well as tissue from the nonviable fawns are currently being probed for the presence of CWD. In summary, we have employed the muntjac deer model, to demonstrate for the first time the transmission of CWD from mother to offspring. These studies provide the foundation to investigate the mechanisms and pathways of maternal prion transfer.

2011 Pre-congress Workshop: TSEs in animals and their environment 9



Thursday, April 28, 2011

Chronic Wasting Disease Testing and Prevalence Wisconsin April 2011


Wednesday, April 06, 2011

Presence and Seeding Activity of Pathological Prion Protein (PrPTSE) in Skeletal Muscles of White-Tailed Deer Infected with Chronic Wasting Disease


Thursday, February 17, 2011

Environmental Sources of Scrapie Prions


Friday, May 13,

2011 EFSA Joint Scientific Opinion on any possible epidemiological or molecular association between TSEs in animals and humans


All Other Emerging and Zoonotic Infectious Diseases CDC's FY 2012 request of $52,658,000 for all other emerging and zoonotic infectious disease activities is a decrease of $13,607,000 below the FY 2010 level,

which includes the elimination of Prion activities ($5,473,000),

a reduction for other cross-cutting infectious disease activities, and administrative savings. These funds support a range of critical emerging and zoonotic infectious disease programs such Lyme Disease, Chronic Fatigue Syndrome, and Special Pathogens, as well as other activities described below.


not good news, but something most of us all have predicted. they have floundered to long $$$



Friday, May 13, 2011

Chronic Wasting Disease (CWD) outbreaks and surveillance program in the Republic of Korea

Chronic Wasting Disease (CWD) outbreaks and surveillance program in the Republic of Korea

Hyun-Joo Sohn, Yoon-Hee Lee, Min-jeong Kim, Eun-Im Yun, Hyo-Jin Kim, Won-Yong Lee, Dong-Seob Tark, In- Soo Cho, Foreign Animal Disease Research Division, National Veterinary Research and Quarantine Service, Republic of Korea

Chronic wasting disease (CWD) has been recognized as an important prion disease in native North America deer and Rocky mountain elks. The disease is a unique member of the transmissible spongiform encephalopathies (TSEs), which naturally affects only a few species. CWD had been limited to USA and Canada until 2000. On 28 December 2000, information from the Canadian government showed that a total of 95 elk had been exported from farms with CWD to Korea. These consisted of 23 elk in 1994 originating from the so-called “source farm” in Canada, and 72 elk in 1997, which had been held in pre export quarantine at the “source farm”.Based on export information of CWD suspected elk from Canada to Korea, CWD surveillance program was initiated by the Ministry of Agriculture and Forestry (MAF) in 2001. All elks imported in 1997 were traced back, however elks imported in 1994 were impossible to identify. CWD control measures included stamping out of all animals in the affected farm, and thorough cleaning and disinfection of the premises. In addition, nationwide clinical surveillance of Korean native cervids, and improved measures to ensure reporting of CWD suspect cases were implemented. Total of 9 elks were found to be affected. CWD was designated as a notifiable disease under the Act for Prevention of Livestock Epidemics in 2002. Additional CWD cases - 12 elks and 2 elks - were diagnosed in 2004 and 2005. Since February of 2005, when slaughtered elks were found to be positive, all slaughtered cervid for human consumption at abattoirs were designated as target of the CWD surveillance program. Currently, CWD laboratory testing is only conducted by National Reference Laboratory on CWD, which is the Foreign Animal Disease Division (FADD) of National Veterinary Research and Quarantine Service (NVRQS). In July 2010, one out of 3 elks from Farm 1 which were slaughtered for the human consumption was confirmed as positive. Consequently, all cervid – 54 elks, 41 Sika deer and 5 Albino deer – were culled and one elk was found to be positive. Epidemiological investigations were conducted by Veterinary Epidemiology Division (VED) of NVRQS in collaboration with provincial veterinary services. Epidemiologically related farms were found as 3 farms and all cervid at these farms were culled and subjected to CWD diagnosis. Three elks and 5 crossbreeds (Red deer and Sika deer) were confirmed as positive at farm 2. All cervids at Farm 3 and Farm 4 – 15 elks and 47 elks – were culled and confirmed as negative. Further epidemiological investigations showed that these CWD outbreaks were linked to the importation of elks from Canada in 1994 based on circumstantial evidences. In December 2010, one elk was confirmed as positive at Farm 5. Consequently, all cervid – 3 elks, 11 Manchurian Sika deer and 20 Sika deer – were culled and one Manchurian Sika deer and seven Sika deer were found to be positive. This is the first report of CWD in these sub-species of deer. Epidemiological investigations found that the owner of the Farm 2 in CWD outbreaks in July 2010 had co-owned the Farm 5. In addition, it was newly revealed that one positive elk was introduced from Farm 6 of Jinju-si Gyeongsang Namdo. All cervid – 19 elks, 15 crossbreed (species unknown) and 64 Sika deer – of Farm 6 were culled, but all confirmed as negative. : Corresponding author: Dr. Hyun-Joo Sohn (+82-31-467-1867, E-mail: shonhj@korea.kr)

2011 Pre-congress Workshop: TSEs in animals and their environment 5




Friday, May 13,

2011 EFSA Joint Scientific Opinion on any possible epidemiological or molecular association between TSEs in animals and humans