With the firearm deer season complete, the Michigan Department of Natural Resources has now identified a total of 30 free-ranging white-tailed deer that are confirmed or suspected to have chronic wasting disease. Several thousand additional samples are awaiting testing by Michigan State University, so numbers for this deer season could still change.
Since May 2015 when the first CWD deer was found, the DNR has tested approximately 23,000 deer. Of those tested, 30 cases of CWD have been suspected or confirmed in deer from Clinton, Ingham, Kent and Montcalm counties. “CWD suspect” means that the deer tested positive on an initial screening test, but has not yet been confirmed through additional testing. It is very rare that a CWD suspect will not be confirmed as a CWD-positive animal, but it is possible.
From 2015 to 2016, a total of four deer (in DeWitt, Eagle and Watertown townships) in Clinton County tested positive. So far in 2017, a single CWD suspect has been identified in Westphalia Township, also in Clinton County. In Ingham County, five deer from Meridian Township tested positive from 2015 to 2016; since then, no deer from Ingham County have tested positive for CWD.
In Montcalm County, a total of 17 deer from the following townships are suspected or confirmed to be positive for CWD: Cato, Douglass, Fairplain, Maple Valley, Montcalm, Pine, Reynolds, Sidney and Winfield. In Kent County, three CWD-positive deer were found in Nelson and Spencer townships. This is the first year any CWD-suspect free-ranging deer were found in Montcalm or Kent counties.
“The fact that we have likely found so many additional CWD-positive deer is a major concern for Michigan’s deer population,” said Chad Stewart, DNR deer specialist. “However, Michigan has a comprehensive CWD response and surveillance plan to guide our actions, and we will continue working with hunters and taking proactive measures to contain this disease.”
To date, the DNR has:
Established a CWD Core and Management Zone where CWD has been detected. Implemented deer feeding and baiting bans throughout entire CWD Core and Management Zones. Intensified surveillance of free-ranging deer in CWD Management Zones, including mandatory check and testing of all hunter-harvested deer within Core CWD Areas. Opened and staffed additional deer check stations to better accommodate hunters within Core CWD Areas.
The DNR encourages hunters throughout the state to continue to hunt responsibly and submit their deer for CWD surveillance and testing.
“Hunters are our best ally in understanding the magnitude of chronic wasting disease in Michigan,” said Stewart. “It’s vital for hunters throughout the state to continue to bring in their deer for testing, and to talk to one another about the seriousness of the situation and the actions they can take right now to help limit the spread of CWD.”
High rates of CWD in a deer population could significantly affect the number of deer, and also could significantly depress the potential for older age classes, especially the more mature bucks.
Michigan welcomes approximately 600,000 deer hunters each year who, over the past decade, harvest an average of 340,000 deer. Overall, hunting generates more than $2.3 billion a year for Michigan’s economy, with approximately $1.9 billion of that stemming from deer hunting.
“There’s no question that a healthy deer herd across the state is critical to Michigan’s economy and to a thriving hunting tradition that spans generations of friends and family,” Stewart said.
The DNR strongly recommends that hunters who harvest deer in Clinton, Ingham, Kent and Montcalm counties have their deer tested by bringing them to a deer check station.
Hunters who have submitted their deer heads for CWD testing should process their deer as needed, but wait for test results before consumption.
To date, there have been no reported cases of CWD infection in humans. However, as a precaution, the U.S. Centers for Disease Control and the World Health Organization recommend that infected animals not be consumed as food by either humans or domestic animals.
Chronic wasting disease is a fatal neurological disease that affects white-tailed deer, mule deer, elk and moose. It is caused by the transmission of infectious, self-multiplying proteins (prions) contained in saliva and other body fluids of infected animals. Susceptible animals can acquire CWD by direct exposure to these fluids, from environments contaminated with these fluids, or from the carcass of a diseased animal.
Some CWD-infected animals will display abnormal behaviors, progressive weight loss and physical debilitation; however, deer can be infected for many years without showing internal or external symptoms. There is no cure for a deer once it is infected with CWD.
To learn more about CWD, and the current known distribution of CWD in Michigan, visit michigan.gov/cwd. Results are updated weekly.
When will the state ban urine based scent lures?
Leading biologists and disease experts and a variet y of state game agencies, including the Michigan DNR, have suggested that the mechanism of yearling buck dispersal increases the risk for the spread of comm unicable diseases like CWD an bTB. This is a well accepted concept and a number o f states including Missouri, Minnesota and Arkansas have removed APR's that prot ect yearling bucks and increase the number which disperse, in areas where CWD is present, to try and minimize the risk of it's spread. Most APR's in Michigan offer protection to approx. 7 0% of yearling bucks. The concept of QDM is built on the premise that protect ing younger bucks, often with an APR, will allow them to advance to older age cla sses, so it's contradictory to suggest, as some on social media have done, that r emoving such protections will have no impact on how many yearling bucks are kille d as yearlings, which in turn has a direct bearing on the number of bucks dispers ing. Another incorrect assumption promoted on social me dia is that disease mitigation only occurs if yearling bucks are killed prior to dispersing. Some have suggested that killing yearling bucks after dispersal is "too late". From an epidemiological standpoint, that premise is false, which is easily demonstrated with a simple analogy. Anyone who has been a parent knows 8 elementary age kids spread germs readily and that c lassrooms can be hot zones for spreading colds. Ideally, if a child has the flu, a parent would not send them to school. That would be analogous to killing an infected yearling buck p rior to dispersal occurring. Unfortunately, a lot of parents send sick kids to s chool. If that sick child sits in the class room and spreads the disease to an averag e of 1 other child for every day they attend school while sick, it's abundantly clea r that the longer that they keep coming to school while sick, the more children will be infected, who in turn infect other children, causing a multiplier effect. If th e teacher notices that the child is sick after the first hour or two and sends them hom e, (analogous to killing an infected yearling buck after dispersal has occurred), then the incidence of the disease spreading in the classroom is substantially reduced. The idea that as soon as that child steps into the classroom, "it's too late" to stop the child from spreading germs, is obviously a fal se one. The suggestion that having the sick child (or the infected yearling buc k) continue to attend school for another 10 months while sick, ignores the potential that exists for the child to continue to spread his germs, infecting other child ren, during that time period. The claim that focusing harvest pressure on yearlin g bucks is "too late" because most yearlings have already dispersed by the time f all hunting season occurs, is also highly questionable. The fact is that a subst antial number of yearling bucks have not dispersed prior to the beginning of fall h unting seasons in October and as such are vulnerable to harvest prior to dispersal. In the QDMA Chesapeake Farms study authored by Dr. Jonathon Shaw, Shaw stated tha t approx. 25% of the yearling bucks in that study dispersed during the s pring fawning season (Apr. - June) at 10 - 12 months of age and 75% dispersed du ring the fall hunting season (Sep - Nov.) at 15 - 17 months of age. While killing yearling bucks prior to dispersal is certainly preferable, killing yearling bucks which have already dispersed is anot her vital piece of the CWD mitigation puzzle, as the longer those bucks surviv e in their new range as "sparks", the more contact they have with other deer, the mor e Prions they shed while feeding in food plots, the more rubbing and scrapin g they engage in and the more potential there is for them facilitating CWD becomi ng entrenched in a new area. This graphic from the Wisconsin DNR shows a typical dispersal pattern. In this graphic, the red star indicates where this particul ar buck was radio collared as an 8 month old button buck on February 4th. Around Oc tober 20th, he started the dispersal process and left his natal range. In Mic higan, he would have already been vulnerable for harvest for almost a month prio r to dispersing, (unless protected by an APR). Over the course of the next m onth he continued to disperse farther from where he was born. He was harvested ( indicated by the red X) on November 20th after having dispersed around 3 miles from where he had spent most of his life. If he had been infected with CWD, any contacts that he had with other deer and any Prion shedding that could occur, ended with his harvest. Imagine the difference in potential disease impact, if this yearling had been protected by an APR and had continued to disperse a nd spread disease for another 10 months, participating in breeding, joining bache lor groups, defecating in food plots where other deer are feeding, engaging in scr aping & rubbing, etc. To suggest that there is no benefit to removing a pote ntially infected yearling buck from the population during or after dispersal has a lready occurred, ignores reality. 9 Imagine the difference in potential disease impact, if this yearling had been protected by an APR and had continued to disperse a nd spread disease for another 10 months, participating in breeding, joining bache lor groups, defecating in food plots where other deer are feeding, engaging in scr aping & rubbing, etc. To suggest that there is no benefit to removing a pote ntially infected yearling buck from the population during or after dispersal has a lready occurred, ignores reality. Figure 7 It has also been suggested that focusing on herd re duction by employing a female focused harvest strategy will reduce dispersal beca use after a number of years, theoretically fewer numbers of male fawns will be b orn, resulting in there being fewer to disperse as yearlings. There are two prim ary problems which this essentially ignores, however. It completely ignore s the immediate negative impact, in terms of the spread of disease, which r esults from protecting yearling bucks with APR's, as they will survive to disperse and spread disease or survive after having dispersed. Under such a model much hi gher numbers of yearling bucks would disperse than would occur under a male focused harvest plan without regulatory protections for yearling bucks. You may eventually lower the number of yearlings dispersing on an annual basis but duri ng the 4 or 5 years that it takes to realize any actual population reductions, 70% of the protected yearlings are dispersing and the disease has spread over a much l arger geographic region, while you are waiting for the impact of fewer yearlings d ue to herd reduction. From a practical disease mitigation standpoint, that is no t a trade off worth making.
Banning deer farms should be in order. Those have proven to be a culprit in WI.
If they ever banned baiting in the UP, I believe loads of people and businesses would be up in arms. I am amazed at the amount of bait I see sold at our local coop in Esky.
"To a large degree, it is a hidden economy. The best guesstimate: A $30 million to $40 million market, saids Ken Nye, a commodities specialist for Michigan Farm Bureau.
A Newaygo sport shop owner said he knows people who spend $10,000 a year on bait."
The latest zones to get CWD were basically from positive tests in enclosures. Now of course the farming operations have not been shut down.
One time when I was at our local coop in Esky, the guy told me that an average day near or in deer season was for them to sell 500 100# bags of corn per day. They go through loads of apples, beets, and carrots too. I know it is big money for this coop.
I have no answers, but I will go along with real science not political science
Seventy new cases of chronic wasting disease have been found in Arkansas since deer season opened in September, according to samples collected by Arkansas Game and Fish Commission biologists, taxidermists and veterinarians. Although the number of positive cases is high, no samples from new areas of the state have been found so far. The disease has been found in Boone, Carroll, Madison, Marion, Newton, Pope and Searcy counties since September.
Cory Gray, manager of the AGFC’s Research, Education and Compliance Division, says overall the results have been as good as can be expected.
“We have taken more than 2,400 samples so far this season, and we have several batches of samples still at the laboratory,” Gray said. “But most of the positive cases are reinforcing where we believe the disease is most prevalent. Once we have completed this year’s sampling, we hopefully will have a clearer picture of disease distribution.”
Gray says hunters who turn in samples that come back positive for CWD are being notified as soon as possible, and any hunter can check www.arkansascwd.com to look up their sample’s status to have some added piece of mind. Biologists will work with hunters to collect and dispose of any meat from CWD-positive animals and reinstate their game tag if possible.
“If a positive sample is returned from a county which doesn’t currently have CWD, we will follow our standard protocol and confirm that sample through an additional test,” Gray said. “If that test also comes back positive, we will issue a release to make sure hunters in that area are informed.”
Gray says the AGFC’s partnership with taxidermists around the state continues to be invaluable to both the hunters and the agency.
“Last year we worked with taxidermists to gather samples from deer turned in to be mounted, but this year we’ve really tried to advertise to people that any deer can be taken to one of our participating taxidermists to have a CWD sample pulled for free,” Gray said. “We don’t have the manpower to pull samples all over the state throughout the entire deer season, so this partnership really helps give hunters peace of mind about their deer and helps us continue to monitor for the disease outside the focal area, where we know we have it.”
Any hunter who harvests a deer still can have the animal tested by taking the head with about 6 inches of neck attached to one of the participating taxidermists listed on www.arkansascwd.com.
CWD is a fatal neurological disease that affects members of the deer/elk family. It was first described in 1967 in Colorado and since has spread to 23 additional states, Canada, South Korea, and Norway. It was discovered in Arkansas in February 2016, and has since been found in 288 deer or elk in Arkansas after thousands of deer have been tested from across the state.
It is similar to “mad cow disease” in cattle. These diseases are caused by misshapen proteins called prions, which accumulate in the tissues of affected animals, especially the brain, spinal cord, and lymph nodes. Infected animals will not show signs of disease at first, but late in the disease process, they will be thin and may demonstrate weakness, abnormal behavior, excessive thirst or drooling.
There has been no confirmed case of CWD affecting humans or livestock, but with an abundance of caution, the Centers for Disease Control recommends hunters test their harvested game and warns that people should not consume any deer or elk known to have CWD.
1. The abnormal prions shed by an infected deer has been shown to be able to be incorporated into plants, creating a new source of infection. (as is pouring urine scent lures from farmed cervids)
2. There has been a strong link to the spread of CWD and cervid farming. Transfer of breeding animals across the Mississippi River may well be the initial source of CWD in the east (that and urine scent lures). There is NO test that will certify that a deer is CWD negative. The live tonsular assay will only provide information that a deer does not have CWD prions at a detectable level. The gold standard (which verifies the ELIZA assay used by the DNR on heads tested) is an immuno staining of brain tissue done at AMES IA lab.
3. CWD is spread by contact with body fluids (saliva, urine, feces), which would indicate that the higher concentration of deer, the greater chance that an infected deer can spread it to others (this was shown in genetic studies in the first cases seen in Ingham County). Obviously, there comes a conflict between maintaining a herd level that satisfies the hunting population and deer densities that limit the spread of CWD.
4. Although we still see that canned statement about CWD being transferred to humans, recent research has shown that eating CWD prion contaminated meat has infected non-human primates with the disease. Ergo, like scrapie and BSE, it appears that CWD can be transferred between species (numerous factors are known contributors). Off hand, I believe that the report said that what the primates were fed was the equivalent of eating an 8oz venison steak every week?/day? for a number of years. This was CWD prion contaminated meat.
4. Knowing what we know about the disease, it is probably wise to change how we handle the deer we harvest. It is probably safer to process ones deer by self rather than taking it to a processor who will use a bandsaw in processing. Far better to debone and filet the carcass rather than cutting through bones which exposes the flesh to particles of marrow where prions can be found. This also means that highly lymphatic tissue should be avoided (liver, spleen, marrow) and of course, brains.
CWD is here, it is spreading and we are just going to have to learn to deal with it. At present, I don't think there is a great danger of it crossing into cattle, but the possibility does exist.
The other mode of possible transmission I recently heard about is shoes and boots. If someone's footwear comes in contact with an infected animal and those shoes/boots go back into the woods with the prions on them, they could then spread the prions to wherever the shoes/boots go. That theory made alot of sense to me as I can see it happening.
The longevity of prions in the environment was aptly demonstrated in sheep studies where scrapie (a ovine prion disease)positive sheep were removed from a farm. The land was left fallow and exposed to the elements (sun, heat, cold, rain, snow) for over a year, topsoil removed and chemically treated. Scrapie negative sheep were reintroduced to the land and animals came down with scrapie within a year.
Historical note: CWD was first observed in a research herd of whitetail deer that were kept in a penned in area that had been previously used with sheep and scrapie research.
Here's something to think about:
The BSE (mad cow) episode in Great Britain showed that downer cattle that was rendered into supplemental protein feed could spread the disease. The abnormal prions are not destroyed or degraded by the process of turning a carcass into protein supplements. The rendering process actually concentrates the abnormal prions. That is why regulation now prohibit downer cattle to be processed into feed for bovines.
However, they can be processed into feed for fish, hogs, chickens, cervids, etc. And the offal from those species can be used for cattle supplemental feeds.
The occurrence of BSE in humans in Great Britain has also been linked to their culinary tastes whose recipes included parts of cattle where BSE prions were concentrated (marrow, blood, and brains). Like the non-human primates that came down with CWD, the British fed on prion loaded foodstuffs.
Hmmmm....maybe that is why there is so much fascination with the upcoming zombie apocalypse: BRAINS!
""CWD Update As most of you are probably aware, recent testing in Montcalm County has detected a significant presence of CWD in the herd in that County. On Tuesday I received a list of CWD positives to date from Chad Stewart, which included 29 deer, 20 of them from this recent finding in Montcalm & Kent Counties. Yesterday Russ Mason said that they have added another 13 suspect deer from Montcalm & Kent Counties to that list, bringing the current total up to 42 suspected or confirmed positives for CWD and both he and Chad said that they expected a whole bunch more to be added to that total by the end of deer season.""
There is a new comment on the post "Boone and Crockett - Situational Overview of Chronic Wasting Disease". https://www.ammoland.com/2018/04/boone-and-crockett-situational-overview-of-chronic-wasting-disease/
Author: Terry S. Singeltary Sr. Comment: thank you Boone and Crocket!
APHIS USDA CFIA CWD TSE Prion Herd Certifications Update
FRIDAY, MARCH 30, 2018
Docket No. APHIS-2018-0011 Chronic Wasting Disease Herd Certification Program Standards Singeltary Submission March 30, 2018
Terry S. Singeltary Sr., Bacliff, Texas USA 77518 email@example.com Attachments (1) Docket No. APHIS-2018-0011 Chronic Wasting Disease Herd Certification Program Standards Singeltary View Attachment:View as format pdf
WEDNESDAY, APRIL 04, 2018
Canada Chronic Wasting Disease Voluntary Herd Certification Program Updated
''Caribou concerns Alberta’s threatened woodland caribou could also be at risk, said University of Alberta researcher Debbie McKenzie, who is among a group of scientists funded by the Alberta Prion Research Institute. “That’s one thing that we’re very concerned about,” she said, adding at least four CWD strains have been confirmed.''
AT LEAST FOUR STRAINS OF CHRONIC WASTING DISEASE CWD TSE PRION HAS BEEN CONFIRMED!
Province of Alberta
The 29th Legislature Fourth Session Alberta Hansard
Thursday afternoon, March 15, 2018 Day 5 The Honourable Robert E. Wanner, Speaker
Chronic Wasting Disease
Dr. Swann: Mr. Speaker, we learned nothing from the BSE crisis. Mad cow disease, an incurable and rapidly fatal infectious prion disease of the brain, devastated our cattle industry 15 years ago at roughly a cost of $10 billion in lost markets. Conventional wisdom at the time assured us that this could not be transmitted to humans. This proved wrong, and variant CJD cost over 200 human lives.
CWD, chronic wasting disease, is a similar, decades-old prion disease which began in deer and elk farms and is now growing across western Canada in the wild. It is spread easily from body fluids, not only from eating the meat, across the deer family, with weak and inconsistent provincial and federal control measures. Both game farming and wildlife management are provincial issues, but the federal food inspection agency, CFIA, sets the standards for meat safety and just last year relaxed the regulations for controlling this disease.
Paul Glover, the CFIA director, wrote the following: since 2010 CWD has spread and become firmly established in wild cervids in Saskatchewan and Alberta and cannot be eradicated with the tools currently available. End quote. This highlights the failure of cooperation between federal and provincial governments in control measures.
Recent U of C studies on CWD showed that it can be transmitted to experimental monkeys after they eat the flesh of infected deer. This is mobilizing the wildlife and hunting community, especially indigenous communities who depend on wild game. It’s also the agricultural community’s worst nightmare. We know that a significant number of infected deer and elk are consumed without being properly tested.
Dr. Neil Cashman, a noted neurobiologist and prion scientist from UBC, recently said, quote, we appear to be waiting till CWD is found in humans, end quote, before taking serious action on control and elimination of the disease.
This provincial government is negligent. We have learned nothing from . . .
The Speaker: Thank you, hon. member
MONDAY, APRIL 02, 2018
Canada Liberal MLA David Swann quoted, This provincial government is negligent, spread of CWD reminiscent of the onset of Canada’s mad cow disease crisis
10. ZOONOTIC, ZOONOSIS, CHRONIC WASTING DISEASE CWD TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHY TSE PRION AKA MAD DEER ELK DISEASE IN HUMANS, has it already happened, that should be the question...
''In particular the US data do not clearly exclude the possibility of human (sporadic or familial) TSE development due to consumption of venison. The Working Group thus recognizes a potential risk to consumers if a TSE would be present in European cervids.'' Scientific opinion on chronic wasting disease (II)
EFSA Panel on Biological Hazards (BIOHAZ) Antonia Ricci Ana Allende Declan Bolton Marianne Chemaly Robert Davies Pablo Salvador Fernández Escámez ... See all authors
First published: 17 January 2018 https://doi.org/10.2903/j.efsa.2018.5132 ;
also, see; 8. Even though human TSE?exposure risk through consumption of game from European cervids can be assumed to be minor, if at all existing, no final conclusion can be drawn due to the overall lack of scientific data. In particular the US data do not clearly exclude the possibility of human (sporadic or familial) TSE development due to consumption of venison. The Working Group thus recognizes a potential risk to consumers if a TSE would be present in European cervids. It might be prudent considering appropriate measures to reduce such a risk, e.g. excluding tissues such as CNS and lymphoid tissues from the human food chain, which would greatly reduce any potential risk for consumers. However, it is stressed that currently, no data regarding a risk of TSE infections from cervid products are available.
The tissue distribution of infectivity in CWD?infected cervids is now known to extend beyond CNS and lymphoid tissues. While the removal of these specific tissues from the food chain would reduce human dietary exposure to infectivity, exclusion from the food chain of the whole carcass of any infected animal would be required to eliminate human dietary exposure.
zoonosis zoonotic cervid tse prion cwd to humans, preparing for the storm
***An alternative to modeling the species barrier is the cell-free conversion assay which points to CWD as the animal prion disease with the greatest zoonotic potential, after (and very much less than) BSE.116***
***> However, to date, no CWD infections have been reported in people.
key word here is 'reported'. science has shown that CWD in humans will look like sporadic CJD. SO, how can one assume that CWD has not already transmitted to humans? they can't, and it's as simple as that. from all recorded science to date, CWD has already transmitted to humans, and it's being misdiagnosed as sporadic CJD. ...terry
LOOKING FOR CWD IN HUMANS AS nvCJD or as an ATYPICAL CJD, LOOKING IN ALL THE WRONG PLACES $$$
*** These results would seem to suggest that CWD does indeed have zoonotic potential, at least as judged by the compatibility of CWD prions and their human PrPC target. Furthermore, extrapolation from this simple in vitro assay suggests that if zoonotic CWD occurred, it would most likely effect those of the PRNP codon 129-MM genotype and that the PrPres type would be similar to that found in the most common subtype of sCJD (MM1).***
To date there is no direct evidence that CWD has been or can be transmitted from animals to humans.
However, initial findings from a laboratory research project funded by the Alberta Prion Research Institute (APRI) and Alberta Livestock Meat Agency (ALMA), and led by a Canadian Food Inspection Agency (CFIA) scientist indicate that CWD has been transmitted to cynomolgus macaques (the non-human primate species most closely related to humans that may be used in research), through both the intracranial and oral routes of exposure.
Both infected brain and muscle tissues were found to transmit disease.
Health Canada’s Health Products and Food Branch (HPFB) was asked to consider the impact of these findings on the Branch’s current position on CWD in health products and foods.
Summary and Recommendation:
Health Portfolio partners were recently made aware of initial findings from a research project led by a CFIA scientist that have demonstrated that cynomolgus macaques can be infected via intracranial exposure and oral gavage with CWD infected muscle.
These findings suggest that CWD, under specific experimental conditions, has the potential to cross the human species barrier, including by enteral feeding of CWD infected muscle.
*** WDA 2016 NEW YORK ***
We found that CWD adapts to a new host more readily than BSE and that human PrP was unexpectedly prone to misfolding by CWD prions.
In addition, we investigated the role of specific regions of the bovine, deer and human PrP protein in resistance to conversion by prions from another species.
***We have concluded that the human protein has a region that confers unusual susceptibility to conversion by CWD prions.
Student Presentations Session 2
The species barriers and public health threat of CWD and BSE prions
Ms. Kristen Davenport1, Dr. Davin Henderson1, Dr. Candace Mathiason1, Dr. Edward Hoover1 1Colorado State University
Chronic wasting disease (CWD) is spreading rapidly through cervid populations in the USA. Bovine spongiform encephalopathy (BSE, mad cow disease) arose in the 1980s because cattle were fed recycled animal protein.
These and other prion diseases are caused by abnormal folding of the normal prion protein (PrP) into a disease causing form (PrPd), which is pathogenic to nervous system cells and can cause subsequent PrP to misfold. CWD spreads among cervids very efficiently, but it has not yet infected humans. On the other hand, BSE was spread only when cattle consumed infected bovine or ovine tissue, but did infect humans and other species.
The objective of this research is to understand the role of PrP structure in cross-species infection by CWD and BSE. To study the propensity of each species’ PrP to be induced to misfold by the presence of PrPd from verious species, we have used an in vitro system that permits detection of PrPd in real-time.
We measured the conversion efficiency of various combinations of PrPd seeds and PrP substrate combinations.
We observed the cross-species behavior of CWD and BSE, in addition to feline-adapted CWD and BSE. We found that CWD adapts to a new host more readily than BSE and that human PrP was unexpectedly prone to misfolding by CWD prions. In addition, we investigated the role of specific regions of the bovine, deer and human PrP protein in resistance to conversion by prions from another species.
***We have concluded that the human protein has a region that confers unusual susceptibility to conversion by CWD prions. CWD is unique among prion diseases in its rapid spread in natural populations. BSE prions are essentially unaltered upon passage to a new species, while CWD adapts to the new species. This adaptation has consequences for surveillance of humans exposed to CWD. Wildlife Disease Risk Communication Research Contributes to Wildlife Trust Administration Exploring perceptions about chronic wasting disease risks among wildlife and agriculture professionals and stakeholders
PRION 2016 TOKYO Zoonotic Potential of CWD Prions:
Chronic wasting disease (CWD) is a widespread and highly transmissible prion disease in free-ranging and captive cervid species in North America. The zoonotic potential of CWD prions is a serious public health concern, but the susceptibility of human CNS and peripheral organs to CWD prions remains largely unresolved. We reported earlier that peripheral and CNS infections were detected in transgenic mice expressing human PrP129M or PrP129V. Here we will present an update on this project, including evidence for strain dependence and influence of cervid PrP polymorphisms on CWD zoonosis as well as the characteristics of experimental human CWD prions.
PRION 2016 TOKYO In Conjunction with Asia Pacific Prion Symposium 2016 PRION 2016 Tokyo Prion 2016
Cervid to human prion transmission
Kong, Qingzhong Case Western Reserve University, Cleveland, OH, United States
Prion disease is transmissible and invariably fatal. Chronic wasting disease (CWD) is the prion disease affecting deer, elk and moose, and it is a widespread and expanding epidemic affecting 22 US States and 2 Canadian provinces so far.
CWD poses the most serious zoonotic prion transmission risks in North America because of huge venison consumption (>6 million deer/elk hunted and consumed annually in the USA alone), significant prion infectivity in muscles and other tissues/fluids from CWD-affected cervids, and usually high levels of individual exposure to CWD resulting from consumption of the affected animal among often just family and friends.
However, we still do not know whether CWD prions can infect humans in the brain or peripheral tissues or whether clinical/asymptomatic CWD zoonosis has already occurred, and we have no essays to reliably detect CWD infection in humans. We hypothesize that:
(1) The classic CWD prion strain can infect humans at low levels in the brain and peripheral lymphoid tissues;
(2) The cervid-to-human transmission barrier is dependent on the cervid prion strain and influenced by the host (human) prion protein (PrP) primary sequence;
(3) Reliable essays can be established to detect CWD infection in humans; and
***(4) CWD transmission to humans has already occurred.
We will test these hypotheses in 4 Aims using transgenic (Tg) mouse models and complementary in vitro approaches.
Aim 1 will prove that the classical CWD strain may infect humans in brain or peripheral lymphoid tissues at low levels by conducting systemic bioassays in a set of "humanized" Tg mouse lines expressing common human PrP variants using a number of CWD isolates at varying doses and routes. Experimental "human CWD" samples will also be generated for Aim 3.
Aim 2 will test the hypothesis that the cervid-to-human prion transmission barrier is dependent on prion strain and influenced by the host (human) PrP sequence by examining and comparing the transmission efficiency and phenotypes of several atypical/unusual CWD isolates/strains as well as a few prion strains from other species that have adapted to cervid PrP sequence, utilizing the same panel of humanized Tg mouse lines as in Aim 1.
Aim 3 will establish reliable essays for detection and surveillance of CWD infection in humans by examining in details the clinical, pathological, biochemical and in vitro seeding properties of existing and future experimental "human CWD" samples generated from Aims 1-2 and compare them with those of common sporadic human Creutzfeldt-Jakob disease (sCJD) prions.
Aim 4 will attempt to detect clinical CWD-affected human cases by examining a significant number of brain samples from prion-affected human subjects in the USA and Canada who have consumed venison from CWD-endemic areas utilizing the criteria and essays established in Aim 3.
The findings from this proposal will greatly advance our understandings on the potential and characteristics of cervid prion transmission in humans, establish reliable essays for CWD zoonosis and potentially discover the first case(s) of CWD infection in humans. Public Health Relevance There are significant and increasing human exposure to cervid prions because chronic wasting disease (CWD, a widespread and highly infectious prion disease among deer and elk in North America) continues spreading and consumption of venison remains popular, but our understanding on cervid-to-human prion transmission is still very limited, raising public health concerns.
This proposal aims to define the zoonotic risks of cervid prions and set up and apply essays to detect CWD zoonosis using mouse models and in vitro methods. The findings will greatly expand our knowledge on the potentials and characteristics of cervid prion transmission in humans, establish reliable essays for such infections and may discover the first case(s) of CWD infection in humans.
Prion Infectivity in Fat of Deer with Chronic Wasting Disease?
Brent Race#, Kimberly Meade-White#, Richard Race and Bruce Chesebro* + Author Affiliations
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.
Prions in Skeletal Muscles of Deer with Chronic Wasting Disease
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.
Terry S. Singeltary Sr.