Friday, January 21, 2011



Managing Chronic Wasting Disease

A preliminary screening test strongly indicates that a deer harvested by a hunter in November 2010 near Pine Island in southeast Minnesota had Chronic Wasting Disease (CWD), which is fatal to deer, elk and moose but not known to affect human health. If the National Veterinary Services Laboratory in Ames, Iowa, confirms the University of Minnesota's preliminary diagnosis this marks the first time CWD has been found in Minnesota's wild deer herd.

The disease is a serious concern, not only because of the obvious harmful effects on cervid health, but also due to the negative impacts to landowners, hunters and businesses.

The DNR has been actively on the lookout for CWD since 2002, when the disease was first found in a domestic elk farm in central Minnesota. The agency has been conducting surveillance for the disease because an important management strategy is early detection.

Since 2002, the DNR has tested more than 32,000 hunter-harvested or road-killed deer, 60 elk and and 90 moose as part of its early CWD detection strategy. Until now, laboratory analysis had never found a wild deer "presumed positive" for CWD.


The Minnesota Department of Natural Resources has learned that an adult female deer harvested during the 2010 hunting season will likely be diagnosed with Chronic Wasting Disease (CWD), a brain and nervous system disorder found in deer, elk and moose. This is disappointing news but the DNR is well prepared to address it.

The discovery occurred last week during laboratory analysis of more than 500 samples (lymph nodes) taken from hunter-harvested deer taken within a 20-mile radius of Pine Island in southeastern Minnesota. Initial screening of all samples has been completed and this is the only suspect. The DNR collects and evaluates lymph nodes because CWD can be detected through microscopic analysis.

Official confirmation of the disease requires further analysis by the National Veterinary Services Laboratory (NVSL) in Ames, Iowa. The following information answers many common questions.

What is the practical implication of this finding? If the preliminary finding is confirmed by NVSL, this will mark the first time CWD has been found in wild deer in Minnesota. Though the disease has been detected in Minnesota on four previous occasions since 2002, all of the instances involved ?captive cervids,? meaning domestic deer or elk confined to a fenced-in commercial operation.

How did the disease enter Minnesota's wild deer herd? At this point, no one knows. In fact, we may never know. What is known is that the 'presumed positive' deer was harvested about three miles southwest of a former domestic elk farm near Pine Island. The farm's elk herd was depopulated after a seven-year-old female elk tested positive for CWD in January 2008. Three additional elk were found to be infected with CWD during the depopulation effort. The closest wild deer with CWD in Wisconsin is 150 miles from the location this CWD-suspect deer was harvested in Minnesota.

What other states have CWD? CWD is found in wild deer, elk or moose in 13 other states and two Canadian provinces, including the Midwestern states of Wisconsin, Illinois, North Dakota and South Dakota. For specifics, visit the CWD Alliance Website.

What has DNR done to manage CWD? The DNR has done much to prevent CWD from entering Minnesota's wild deer herd. For many years the agency has worked closely with the Minnesota Board of Animal Health (the regulators of domestic deer and elk farms) on policies, procedures, and statutes to protect wild deer from coming into contact with commercially-raised elk and deer. The agency has also worked with the state Legislature to create animal transportation laws that minimize the risk of CWD from entering the state. For example, whole deer, elk, caribou or moose carcasses from other states or provinces may not be brought into Minnesota from areas known to have CWD in the wild.

The DNR has been actively on the lookout for CWD since 2002 when the disease was first found in a domestic elk farm in central Minnesota. The agency has been actively looking for the disease because an important management strategy is early detection. Since 2002, the DNR has tested more than 32,000 hunter-harvested or road-killed deer, 60 elk and and 90 moose in the name of early CWD detection. Until now, laboratory analysis had never found a wild deer "presumed positive" for CWD.

Was DNR specifically looking for CWD in the Pine Island area? Yes. It is a logical place to look because it's an area where CWD was recently discovered. The DNR collected 515 deer lymph node samples during the past deer season. This followed the collection of 934 deer from the same area in 2009. All of these deer were taken within a 25-mile radius of Pine Island. The DNR obtained these samples from hunters who voluntarily allowed DNR staff, University of Minnesota veterinary students and other experts to extract the lymph nodes at deer registration stations. In 2008, the DNR tested the lymph nodes of 500 hunter-harvested deer along the Wisconsin border from Houston County to St. Croix State Park. In 2009, the agency tested a total of 2,685 deer taken in southeastern Minnesota.

If CWD is confirmed, what will DNR do? DNR will implement its CWD response plan. The critical first step is to identify the number and current distribution of deer in the Pine Island area. This will be done using an aerial survey. Once DNR managers compile this data they will make plans to collect additional lymph nodes later this winter. Potential options for collecting these samples include a late winter deer hunting season, landowner shooting permits or sharp-shooting with permission of cooperating landowners. DNR will also implement a deer feeding ban in a CWD management zone surrounding the location of the positive animal, and restrict carcass movements out of the area.

Do you believe other deer in southeastern Minnesota have CWD?

A deer infected with CWD That's possible but it's premature to speculate. The only way to know if other deer have CWD is to continue doing surveillance. Collection of additional samples this winter will be done in a highly targeted way and only with permission of cooperating landowners.

If I harvested a deer from that area, should I be concerned about eating the venison? Based on the fact that only one deer has tested positive for CWD among more than 500 samples, the rate of occurrence is likely low. Still, people with venison in their freezer from this area should know the following:

The National Center for Disease Control (CDC) and the World Health Organization (WHO) have found no scientific evidence that CWD is transferrable from animals to humans; and The CDC advises against eating animals known to have CWD. So, people with venison in their freezer that was harvested from this area will need to make decisions based on the information above. The Minnesota Department of Health – not the DNR – provides guidance to citizens on food consumption issues.

What else can you tell me about CWD? CWD causes a characteristic spongy degeneration of the brains of infected animals resulting in emaciation, abnormal behavior, loss of bodily functions and death. CWD belongs to a group of diseases known as transmissible spongiform encephalopathies (TSEs). Though many observers try to compare CWD with "mad cow disease", the diseases are distinctly different.

What causes CWD? The disease agent is a prion, an abnormal form of cellular protein that is most commonly found in the central nervous system and in lymphoid tissue. The prion "infects" the host animal by promoting conversion of normal cellular protein to the abnormal form.

Where and how did CWD originate? The origin of CWD is unknown, and it may never be possible to definitively determine how or when CWD arose. It was first recognized as a syndrome in captive mule deer held in wildlife research facilities in Colorado in the late 1960s, but it was not identified as a TSE until the 1970s. Computer modeling suggests the disease may have been present in free-ranging populations of mule deer for more than 40 years.

How does CWD spread? It is not known exactly how CWD is transmitted. The infectious agent may be passed in feces, urine or saliva. Transmission is thought to be lateral (from animal to animal). Although maternal transmission (from mother to fetus) may occur, it appears to be relatively unimportant in maintaining epidemics.

Because CWD infectious agents are extremely resistant in the environment, transmission may be both direct and indirect. Concentrating deer and elk in captivity or by artificial feeding probably increases the likelihood of both direct and indirect transmission between individuals. Contaminated pastures appear to have served as sources of infection in some CWD epidemics. The apparent persistence of the infectious agents in contaminated environments represents a significant obstacle to eradication of CWD from either captive or free-ranging cervid populations.

The movement of live animals is one of the greatest risk factors in spreading the disease into new areas. Natural movements of wild deer and elk contribute to the spread of the disease, and human-aided transportation of both captive and wild animals greatly exacerbates this risk factor.

Why should Minnesotans be concerned about CWD? CWD poses serious problems for wildlife managers, and the implications for free-ranging deer, elk and moose are significant:

Ongoing surveillance programs are expensive and draw resources from other wildlife management needs; Impacts of CWD on population dynamics of deer and elk are presently unknown. Computer modeling suggests that CWD could substantially reduce infected cervid populations by lowering adult survival rates and destabilizing long-term population dynamics; Where it occurs, CWD may alter the management of wild deer and elk populations, and it has already begun to do so; and Ultimately, public and agency concerns and perceptions about human health risks associated with all TSE's may erode hunters' confidence and their willingness to hunt in areas where CWD occurs.


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.


Wednesday, September 08, 2010


From: TSS (


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 ;

Wednesday, December 29, 2010

CWD Update 99 December 13, 2010


Labels: , , , , ,


Post a Comment

Subscribe to Post Comments [Atom]

<< Home