Download the full Chronic Wasting Disease and Cervidae Regulations in North America. [PDF]
The number one objective in the management of CWD is to prevent its spread into new areas. One theoretical mode of disease transmission is via infected carcasses. Therefore, in an effort to minimize the risk of disease spread, a number of states have adopted regulations affecting the transportation of hunter-harvested deer and elk.
Since the suspected infective agent (prion) is concentrated in the brain, spinal cord and lymph glands, the most common regulation is the prohibition of the importation of whole carcasses harvested from CWD areas. Some states, like Colorado, also have established regulations addressing the transport of deer and elk out of CWD areas. Generally, states that have adopted carcass transportation regulations do not allow the importation of any brain or spinal column tissue and allow transport of only the following:
A summary of state-by-state carcass transportation regulations is provided in Column J of the regulations on each state page (accessible from the home page) or on the map. Since these regulations are continually evolving, it is recommended that before hunting you check the CWD regulations in your home state, the state in which you will be hunting and states in which you will travel through en route home from your hunting area. Most state wildlife agencies provide regulations information on their websites, and may be accessed via the clickable map on the home page.
The Carcass Transport and Disposal Working Group of the Association of Fish and Wildlife Agencies (AFWA) Fish and Wildlife Health Committee developed the following guidelines for regulatory and non-regulatory approaches to carcass transport and disposal. The intent of the working group is to encourage states to adopt policies that minimize risk; do not hinder hunting, wild cervid population management, or disease control; are easily understood; and promote compliance because they are consistent and well-justified. The recommendations are based on current knowledge of CWD and may be updated when new information becomes available. The Working Group recognizes state wildlife management agencies will tailor their approach to fit individual concerns and situations, and asks that agency directors, through AFWA, give serious and urgent consideration to this matter so that this potential risk of CWD spread can be minimized.
Senate Environment and Public Works Subcommittee on Fisheries, Wildlife and Water
April 6, 2004
U.S. House of Representatives
House Resources Committee
Subcommittees on Forests and Forest Health, and
Fisheries Conservation, Wildlife and Oceans
Thursday, June 19, 2003
To establish a National Chronic Wasting Disease Task Force, and for other purposes.
HR2431 Word document
To amend the Fish and Wildlife Coordination Act to coordinate and strengthen scientific research and monitoring, and to promote public outreach, education, and awareness, of Chronic Wasting Disease affecting free-ranging populations of deer and elk, and for other purposes.
HR2430 Word document
To authorize the Secretary of the Interior to make grants to State and tribal governments to assist State and tribal efforts to manage and control the spread of chronic wasting disease in deer and elk herds, and for other purposes.
S1366 PDF document | Word document
To authorize the Secretary of the Interior to make grants to State and tribal governments to assist State and tribal efforts to manage and control the spread of chronic wasting disease in deer and elk herds, and for other purposes.
HR2636 PDF document | Word document
24 organizations sign letter requesting funding for National CWD Plan- April 18, 2003
Letter Word document
U.S. House of Representatives
House Resources Committee
Subcommittees on Forests and Forest Health, and
Fisheries Conservation, Wildlife and Oceans
May 16, 2002
CWD Alliances’ Testimony PDF document | Word document
-The sick female reindeer (Rangifer tarandus tarandus) was detected in the middle of March 2016 in connection with capture for GPS-collaring using helicopter performed by the Norwegian Institute for Nature Research (NINA. It died and the carcass was submitted to the Norwegian Veterinary Institute in Oslo for necropsy and laboratory examinations. It was an adult animal, says wildlife pathologist Turid Vikøren at Norwegian Veterinary Institute, who performed the necropsy.
The body condition of the reindeer was below medium, but it had still some adipose tissue left. In cervids older than 18 months, we routinely collect sample of the brain for CWD examination as part of the national surveillance program for CWD, and that was also done in this reindeer, Vikøren continues.
The head of the Norwegian Reference Laboratory for animal prion diseases at Norwegian Veterinary Institute, Sylvie Benestad, states that the brain sample from the reindeer was positive for the detection of prions both by the first routine test (ELISA-test) and in two supplementary tests (Western Blotting, Immunohistochemistry).
Chronic Wasting Disease is a contagious neurological disease that attacks the brain of cervids. CWD belongs to a group of diseases known as Transmissible Spongiform Encephalopathies (TSEs), in which the infectious agents are known to be the prion protein, a normal protein that misfolds and destroys the brain. The development of the disease is slow and affected cervids show loss of body condition and altered behaviour. Death is inevitable once clinical disease occurs.
CWD is an endemic disease in North America, in which natural infections occurs in mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), elk (Cervus elaphus nelsoni) og moose (Alces alces shirasi).The reindeer from Norway represents the first detection of CWD in Europe. Also, this is the first detection of a natural infection in reindeer worldwide.
Turid Vikøren (Wildlife Health)
Kjell Handeland (Wildlife Health)
Sylvie Benestad (Prions Diseases)
Jorun Jarp, Head of Dep. of Health Surveillance Mobile: 90056216.
Asle Haukaas, Communication Director Mobile: 92080877.
State and Provincial Updates
Texas The following press release was issued on July 1, 2015 by the Texas Parks & Wildlife Department
Chronic Wasting Disease Detected in Medina County Captive Deer
AUSTIN – A two-year-old white-tailed deer in a Medina County deer breeding facility has been confirmed positive for Chronic Wasting Disease (CWD). This is the first case of CWD detected in captive white-tailed deer in Texas. CWD was first detected in Texas in 2012 in free-ranging mule deer in the Hueco Mountains in far West Texas.
The Medina County tissue samples submitted by the breeder facility in early June as part of routine deer mortality surveillance revealed the presence of CWD during testing at the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) in College Station. The National Veterinary Services Laboratory in Ames, Iowa, confirmed the findings on Tuesday, June 30. An epidemiological investigation to determine the extent of the disease, assess risks to Texas’ free ranging deer and protect the captive deer and elk breeding industry is being led by the Texas Animal Health Commission (TAHC), in coordination with the Texas Parks and Wildlife Department (TPWD) and U.S. Department of Agriculture’s Animal and Plant Health Inspection Service Veterinary Services (USDA/APHIS/VS).
Officials have taken immediate action to secure all cervids at the Medina County breeder facility with plans to conduct additional investigation for CWD. In addition, those breeder facilities that have received deer from the Medina County facility or shipped deer to that facility during the last two years are under movement restrictions and cannot move or release cervids at this time. TPWD is disallowing liberation of captive deer from all breeder facilities into the wild at this time pending further review. Additional measures to further minimize risk of CWD spreading into Texas’ free-ranging white-tailed deer herd, and to protect the captive deer breeding industry, will be considered.
“This is a terribly unfortunate development that we are committed to addressing as proactively, comprehensively, and expeditiously as possible. The health of our state’s wild and captive deer herds, as well as affiliated hunting, wildlife, and rural based economies, are vitally important to Texas hunters, communities, and landowners. As such, our primary objectives are to determine the source of the disease and to identify other deer breeding facilities and release sites that may have received deer from affected facilities,” said Carter Smith, TPWD Executive Director. “Working collaboratively with experts in the field we have developed protocols to address CWD, and our implementation efforts are already well under way.”
The TPWD and the TAHC CWD Management Plan will guide the State’s response to this incident. The plan was developed by the State’s CWD Task Force, which is comprised of deer and elk breeders, wildlife biologists, veterinarians and other animal-health experts from TPWD, TAHC, TVMDL, Department of State Health Services, Texas A&M College of Veterinary Medicine, and USDA.
Since 2002, the state has conducted surveillance throughout Texas for the disease. More than 34,000 samples collected from hunter-harvested and road kill deer have been tested for CWD. Although animal health and wildlife officials cannot say how long or to what extent the disease has been present in the Medina County deer breeding facility, the breeder has had an active CWD surveillance program since 2006 with no positives detected until now.
“We are working with experts at the local, state and federal level, to determine the extent of this disease, and respond appropriately to limit further transmission,” said Dr. Andy Schwartz, TAHC Epidemiologist and Assistant Executive Director. “Strong public awareness and the continued support of the cervid industry is paramount to the success of controlling CWD in Texas.”
The disease was first recognized in 1967 in captive mule deer in Colorado. CWD has also been documented in captive and/or free-ranging deer in 23 states and 2 Canadian provinces. CWD among cervids is a progressive, fatal disease that commonly results in altered behavior as a result of microscopic changes made to the brain of affected animals. An animal may carry the disease for years without outward indication, but in the latter stages, signs may include listlessness, lowering of the head, weight loss, repetitive walking in set patterns, and a lack of responsiveness. To date there is no evidence that CWD poses a risk to humans or non-cervids. However, as a precaution, the U.S. Centers for Disease Control and the World Health Organization recommend not to consume meat from infected animals.
More information on CWD can be found on TPWD’s website, www.tpwd.texas.gov/CWD or at the Chronic Wasting Disease Alliance website, www.cwd-info.org.
More information about the TAHC CWD program may be found at http://tahc.state.tx.us/animal_health/cwd/cwd.html.
Wisconsin The following press release was issued by the Wisconsin Department of Agriculture, Trade and Consumer Protection on June 24, 2015
CWD-positive white-tailed deer found on Eau Claire County farm MADISON – A white-tailed deer from a breeding farm in Eau Claire County has tested positive for chronic wasting disease (CWD), Wisconsin State Veterinarian Dr. Paul McGraw announced today. The National Veterinary Services Laboratory in Ames, Iowa, confirmed the test results.
The 7-year-old Eau Claire County doe, which died on the farm, was one of about 167 deer reported to be on the 12 acre farm, according to the farm’s March 2015 registration.
Samples were taken from the doe on June 8 in accordance with Wisconsin Department of Agriculture, Trade and Consumer Protection’s (DATCP’s) rules, which require testing of farm-raised deer and elk when they die or are killed.
McGraw quarantined the Eau Claire County herd, which stops movement of live deer from the property, except to slaughter. Disposition of the remaining deer will depend upon the outcome of the investigation. The DATCP Animal Health Division’s investigation will also examine the animal’s history and trace movements of deer onto and off the property to determine whether other herds may have been exposed to the CWD test-positive deer.
Recent Publications Quantitative assessment of prion infectivity in tissues and body fluids by real-time quaking-induced conversion Davin M. Henderson, Kristen A. Davenport, Nicholas J. Haley, Nathaniel D. Denkers, Candace K. Mathiason and Edward A. Hoover Journal of General Virology (2015) 96, 210-219. doi: 10.1099/vir.0.069906-0
Abstract: Prions are amyloid-forming proteins that cause transmissible spongiform encephalopathies through a process involving the templated conversion of the normal cellular prion protein (PrPC) to a pathogenic misfolded conformation. Templated conversion has been modelled in several in vitro assays, including serial protein misfolding amplification, amyloid seeding and real-time quaking-induced conversion (RT-QuIC). As RT-QuIC measures formation of amyloid fibrils in real-time, it can be used to estimate the rate of seeded conversion. Here, we used samples from deer infected with chronic wasting disease (CWD) in RT-QuIC to show that serial dilution of prion seed was linearly related to the rate of amyloid formation over a range of 10?3 to 10?8 ?g. We then used an amyloid formation rate standard curve derived from a bioassayed reference sample (CWD+ brain homogenate) to estimate the prion seed concentration and infectivity in tissues, body fluids and excreta. Using these methods, we estimated that urine and saliva from CWD-infected deer both contained 1–5 LD50 per 10 ml. Thus, over the 1–2 year course of an infection, a substantial environmental reservoir of CWD prion contamination accumulates.
Immediate and Ongoing Detection of Prions in the Blood of Hamsters and Deer following Oral, Nasal, or Blood Inoculations Alan M. Elder, Davin M. Henderson, Amy V. Nalls, Edward A. Hoover, Anthony E. Kincaid, Jason C. Bartz and Candace K. Mathiason
Journal of Virology 89:7421–7424 doi:10.1128/JVI.00760-15. Abstract: Infectious prions traverse epithelial barriers to gain access to the circulatory system, yet the temporal parameters of transepithelial transport and persistence in the blood over time remain unknown. We used whole-blood real-time quaking-induced conversion (wbRT-QuIC) to analyze whole blood collected from transmissible spongiform encephalopathy (TSE)-inoculated deer and hamsters throughout the incubation period for the presence of common prion protein-conversion competent amyloid (PrPC-CCA). We observed PrPC-CCA in the blood of TSE-inoculated hosts throughout the disease course from minutes postexposure to terminal disease. http://jvi.asm.org/content/early/2015/04/24/JVI.00760-15.abstract
State and Provincial Updates
Michigan The following press release was issued on May 26, 2015 by the Michigan Department of Natural Resources
Michigan confirms first case of CWD in free-ranging white-tailed deer
The Michigan departments of Natural Resources (DNR) and Agriculture and Rural Development (MDARD) today confirmed that a free-ranging deer in Meridian Township (Ingham County) has tested positive for chronic wasting disease (CWD), a fatal neurological disease that affects white-tailed deer, mule deer, elk and moose. This is the first time the disease has been found in Michigan’s free-ranging deer population. In 2008 a white-tailed deer from a privately owned cervid (POC) facility in Kent County tested positive for CWD. The animal was observed last month wandering around a Meridian Township residence and showing signs of illness. The homeowner contacted the Meridian Township Police Department, who then sent an officer to euthanize the animal. The deer was collected by a DNR wildlife biologist and delivered for initial testing to the DNR Wildlife Disease Laboratory at the Michigan State University Diagnostic Center for Population and Animal Health in Lansing, Michigan.
After initial tests were positive, samples were forwarded to the U.S. Department of Agriculture’s National Veterinary Services Laboratory in Ames, Iowa, for final confirmation. The Michigan DNR received that positive confirmation last week. To date, there is no evidence that chronic wasting disease presents any risk to non-cervids, including humans, either through contact with an infected animal or from handling contaminated venison. 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. “This is the first case of chronic wasting disease to be confirmed in a free-ranging Michigan white-tailed deer,” said DNR Director Keith Creagh. “While it is a disappointing day for Michigan, the good news is that we are armed with a thoughtfully crafted response plan,” Creagh said. “We are working with other wildlife experts at the local, regional, state and federal level, using every available resource, to determine the extent of this disease, respond appropriately to limit further transmission, and ultimately eradicate the disease in Michigan if possible.” The confirmed positive finding triggers several actions in the state’s surveillance and response plan for chronic wasting disease. The plan was developed in 2002 through cooperation between the DNR and MDARD, and was updated in 2012.
Actions the DNR will take include: 1. Completing a population survey in the area where the CWD-positive deer was found. 2. Establishing a Core CWD Area consisting of Alaiedon, Delhi, Lansing, Meridian, Wheatfield and Williamstown townships in Ingham County; Bath and DeWitt townships in Clinton County; and Woodhull Township in Shiawassee County. Unlimited antlerless deer hunting licenses will be available. Mandatory checking of deer will be required in this area during hunting seasons and restrictions will apply to the movement of carcasses and parts of deer taken in this area. 3. Creating a CWD Management Zone, which will include Clinton, Ingham and Shiawassee counties. 4. Implementing a deer and elk feeding and baiting ban, which will include the Core CWD Area and the larger three-county CWD Management Zone. 5. Prohibiting the possession or salvage of deer killed by collision with a motor vehicle within the Core CWD Area. Also, residents are asked to call in the locations of road-killed deer within this area so DNR staff can pick up for testing. Research shows CWD-infected deer are more likely to be hit by vehicles because of their illness.
DNR Director Creagh will issue an interim order approving immediate implementation of these actions. “MDARD is working with the state’s privately owned cervid facilities within a 15-mile surveillance zone to ensure compliance with CWD testing requirements,” said MDARD State Veterinarian James Averill. “For POC facilities located outside of the surveillance zone, there will be no impact. We are, however, encouraging all POCs to continue to be our partners in the state’s CWD testing program.” Chronic wasting disease first was identified in 1967 as a clinical disease in captive mule deer at the Colorado Division of Wildlife Foothills Wildlife Research Facility in Fort Collins, Colorado. Since then, most CWD cases have occurred in western states, but in the past 15 years it has spread to some midwestern and eastern states. The disease 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 or from environments contaminated with these fluids or the carcass of a diseased animal. Once contaminated, research shows that soil can remain a source of infection for long periods of time, making CWD a particularly difficult disease to eradicate. Some chronically CWD-infected animals will display abnormal behaviors, progressive weight loss and physical debilitation. There is no cure; once a deer is infected with CWD, it will die. Although this is the first positive CWD finding in the state’s free-ranging deer population, it is important to note that from Jan. 1, 1998, through Dec. 31, 2014, tens of thousands of free-ranging Michigan deer were tested and no evidence was found of chronic wasting disease in this population. In fact, that testing included 34,207 deer, 1,607 elk and 70 moose – a large sample of animals with no positive finding. In privately owned deer populations, approximately 21,000 samples have to date been tested for CWD. All of those have been negative as well, with the exception of the 2008 Kent County case. MDARD conducts ongoing surveillance of Michigan’s 365 registered, privately owned cervid facilities.
Public awareness, support “Strong public awareness and cooperation from residents and hunters are critical for a rapid response to evaluate any deer suspected of having chronic wasting disease,” said Steve Schmitt, veterinarian-in-charge at the DNR Wildlife Disease Lab. “We’d like to thank the resident who called local authorities, as well as the Meridian Township Police Department for its swift response.” The DNR asks help from the public and hunters in reporting deer that are: ?
To report a suspicious-looking deer, call the DNR Wildlife Disease Lab at 517-336-5030 or fill out and submit the online observation report found on the DNR website. To report road-kills found in the Core CWD Area call the Wildlife Disease Hotline at 517-614-9602 during office hours. Leave a voicemail with location information and staff will attempt to pick up carcasses on the next open business day. Additionally, Schmitt said hunters will play a key role in helping the state manage this new wildlife challenge. “Michigan has a long tradition of hunter support and conservation ethics. Now, with the CWD finding, that support is needed more than ever,” Schmitt said. “Historically, areas where chronic wasting disease has been found have experienced a decline in hunter numbers. Because hunters are often familiar with the deer herd locally, one of the best things they can do to help manage this disease is to continue hunting and bring their deer to check stations this season.” Once the DNR has conducted targeted surveillance in the CWD Management Zone, staff will have a better understanding of needed changes in hunting regulations for upcoming deer hunting seasons. Despite the CWD finding, Schmitt said there is reason for optimism. “When it comes to chronic wasting disease, Michigan isn’t alone. A total of 23 states and two Canadian provinces have found CWD in either free-ranging or privately owned cervids, or both,” he said. “Michigan will take full advantage of the collective expertise and experience of those who have for years now dealt with chronic wasting disease on a daily basis.” Get more information on CWD – including Michigan’s CWD surveillance and response plan, FAQs and a link to the CWD Alliance website where more photos and video are available – at www.michigan.gov/cwd.
Chronic Wasting Disease (CWD) Surveillance Update: April 10, 2015 We have completed all of the 2014 fall CWD surveillance samples received to date. In 2014 we tested 4,163 heads and detected 86 cases of CWD (2.1%). CWD was confirmed in 74 mule deer (59 males, 15 females; 72 adults, 2 yearlings) and 12 white-tails (all males; 10 adults, 2 yearlings). However in the 2014 data the extraordinarily large number of elk heads tested (n= 909, all negative) many of which were harvested in conjunction with hunting opportunities at Canadian Forces Base Suffield in January and February 2015, provides a confounding factor in comparison to previous years. Thus, to allow valid comparisons among years, the proportion of infected animals is presented in the context of the number of heads tested for each species.
In breaking down the identified 2014 sample, CWD was detected in: ? 3.61% of 2048 mule deer
? 1.13% of 1062 white-tailed deer
? 0 of 131 moose
? 0 of 909 elk
An overview of the 2014 results reveals both expected and unexpected patterns in the data. As in previous years, mule deer remain the species at greatest risk of CWD (74 of 86 (86.0%) cases detected in 2014). However the ratio of infected males to females wherever CWD occurs generally is ~2:1; but in 2014 the ratio in the Alberta sample was ~5:1 (71 males, 15 females). The reason for the unexpected increase in the proportion of infected males is unknown, particularly since almost equal numbers of male and female mule deer, the species at greatest risk, were tested in 2014 (n = 1040 and 1065, respectively).
Overall number (86 cases) and rate (2.1%) of CWD positive deer in 2014 are significantly higher than in previous years. Similarly the geographic distribution of CWD in eastern Alberta continues to expand. The disease now occurs in local areas from the Battle River watershed in the north to the Milk River in the south. We detected the first evidence of CWD in the Hand Hills area northeast of Drumheller in WMU 160, first evidence of the disease in the Bow River watershed (east of Lake Newell), and further evidence of the disease in the vicinity of Canadian Forces Base (CFB) Suffield and the Cypress Hills. However no CWD was found in elk harvested from CFB Suffield, despite testing over 870 elk heads from WMU 732.
The disease remains well established in areas directly adjacent to the Saskatchewan border and continues to expand into WMUs further up the affected watersheds, primarily the Battle, Red Deer, and South Saskatchewan rivers.
The following press release was issued by the Missouri Department of Conservation on March 10, 2015
MDC reports 11 new cases of CWD in Missouri deer JEFFERSON CITY, Mo. — The Missouri Department of Conservation (MDC) reports that 11 new cases of Chronic Wasting Disease (CWD) have recently been found in deer harvested in Macon, Adair, and now Cole counties. A buck harvested near the village of Centertown in Cole County is the first case of the disease to be found outside of the Department’s six-county CWD Containment Zone of Adair, Chariton, Linn, Macon, Randolph, and Sullivan counties. All previous cases have been limited to Macon, Linn, and Adair counties.
These 11 new cases bring the total number of Missouri free-ranging deer that have tested positive for CWD to 14 for this past season and 24 overall since the disease was first discovered in the state in 2010 at a private hunting preserve in Linn County. CWD has also been found in 11 captive deer in Macon and Linn counties.
The Department has collected more than 43,000 tissue samples since it began testing for the emerging disease in 2001. MDC has collected more than 3,400 tissue samples for CWD testing from harvested and other free-ranging deer this season. Results for about 330 tissue samples are still in the process of being tested by an independent, outside laboratory.
“We will provide an update of final results once all testing has been completed for the season,” said MDC Deer Biologist Jason Sumners. “We will continue to monitor the spread of the disease through more CWD testing this coming fall and winter. We are also updating our efforts to help contain the spread of the disease and will be working out the details over this spring and summer.”
Chronic Wasting Disease infects only deer and other members of the deer family by causing degeneration of the brain. The disease has no vaccine or cure and is 100-percent fatal. Missouri offers some of the best deer hunting in the country, and deer hunting is an important part of many Missourians’ lives and family traditions. Infectious diseases such as CWD could reduce hunting and wildlife-watching opportunities for Missouri’s nearly 520,000 deer hunters and almost two million wildlife watchers. Deer hunting is also an important economic driver in Missouri and gives a $1 billion annual boost to state and local economies.
Lower deer numbers from infectious diseases such as CWD could hurt 12,000 Missouri jobs and many businesses that rely on deer hunting as a significant source of revenue, such as meat processors, taxidermists, hotels, restaurants, sporting goods stores, and others. CWD also threatens the investments of thousands of private landowners who manage their land for deer and deer hunting, and who rely on deer and deer hunting to maintain property values.
For more information on CWD in Missouri, visit the MDC website at http://mdc.mo.gov/hunting-trapping/deer-hunting/deer-diseases/chronic-wasting-disease.
Survival and Population Growth of a Free-Ranging Elk Population with a Long History of Exposure to Chronic Wasting Disease Ryan J. Monello, Jenny G. Powers, N. Thompson Hobbs, Terry R. Spraker, Mary Kay Watry and Margaret A. Wild The Journal of Wildlife Management 78(2):214–223; 2014; DOI: 10.1002/jwmg.665
Abstract: Investigations of chronic wasting disease (CWD), a fatal, contagious prion disease of free ranging cervids, suggest the disease can cause long-term population declines in deer (Odocoileus spp.). However, the implications of CWD for elk (Cervus elaphus nelsoni) populations are less certain. During 2008–2010, we used rectal biopsies and telemetry to observe disease transmission and survival in adult female elk from a high-density herd in Rocky Mountain National Park (RMNP) that had been infected by CWD for over 25 years. We studied a cohort of 123 adult female elk that were determined to be free of CWD by rectal biopsy in 2008. Annual incidence of CWD was 0.08 [95% Bayesian credible interval (BCI)?0.05, 0.12]. Annual survival probabilities of the cohort excluding harvest declined from 0.97 in 2008 (BCI?0.93, 0.99) to 0.85 in 2010 (BCI?0.75, 0.93). Declines in survival were attributed almost entirely to CWD; the proportion of radiocollared elk that died of CWD increased from 0.02 in 2008 (BCI?0.00, 0.05) to 0.11 in 2010 (BCI?0.04, 0.21). We attributed the increase to the time lag required for development of new CWD cases. We used survival rates of susceptible and infected elk to develop a projection matrix for a discrete time, female only model that estimated the intrinsic population growth rate (l) of this elk herd to be 1.00 (BCI?0.93, 1.05) using the prevalence of CWD (12.9%) and calf:cow ratios (24:100) observed during this study. Population declines were predicted to occur when prevalence of CWD exceeded 13% (BCI?0, 35). However, this estimate was contingent on calf:cow ratios and harvest. Greater recruitment will offset some of the effects of CWD, whereas the inclusion of female harvest, which was excluded from this study, would likely result in lower l values than those observed in this study. We conclude that CWD can exceed natural rates of mortality, reduce survival of adult females, and decrease population growth of elk herds. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. http://onlinelibrary.wiley.com/doi/10.1002/jwmg.665/abstract Human prion protein sequence elements impede cross-species chronic wasting disease transmission
Timothy D. Kurt, Lin Jiang, Natalia Fernández-Borges, Cyrus Bett, Jun Liu, Tom Yang, Terry R. Spraker, Joaquín Castilla, David Eisenberg, Qingzhong Kong, and Christina J. Sigurdson The Journal of Clinical Investigation. 2015. doi:10.1172/JCI79408
Chronic wasting disease (CWD) is a fatal prion disease of North American deer and elk and poses an unclear risk for transmission to humans. Human exposure to CWD occurs through hunting activities and consumption of venison from prion infected animals. Although the amino acid residues of the prion protein (PrP) that prevent or permit human CWD infection are unknown, NMR-based structural studies suggest that the ?2-?2 loop (residues 165–175) may impact species barriers. Here we sought to define PrP sequence determinants that affect CWD transmission to humans. We engineered transgenic mice that express human PrP with four amino acid substitutions that result in expression of PrP with a ?2-?2 loop (residues 165–175) that exactly matches that of elk PrP. Compared with transgenic mice expressing unaltered human PrP, mice expressing the human-elk chimeric PrP were highly susceptible to elk and deer CWD prions but were concurrently less susceptible to human Creutzfeldt-Jakob disease prions. A systematic in vitro survey of amino acid differences between humans and cervids identified two additional residues that impacted CWD conversion of human PrP. This work identifies amino acids that constitute a substantial structural barrier for CWD transmission to humans and helps illuminate the molecular requirements for cross-species prion transmission.
http://www.jci.org/articles/view/79408 Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions
Sandra Pritzkow, Rodrigo Morales, Fabio Moda, Uffaf Khan, Glenn C. Telling, Edward Hoover, and Claudio Soto Cell Reports 11, 1–8, May 26, 2015. doi:10.1016/j.celrep.2015.04.036
Prions are the protein-based infectious agents responsible for prion diseases. Environmental prion contamination has been implicated in disease transmission. Here, we analyzed the binding and retention of infectious prion protein (PrPSc) to plants. Small quantities of PrPSc contained in diluted brain homogenate or in excretory materials (urine and feces) can bind to wheat grass roots and leaves. Wild-type hamsters were efficiently infected by ingestion of prion-contaminated plants. The prion-plant interaction occurs with prions from diverse origins, including chronic wasting disease. Furthermore, leaves contaminated by spraying with a prion-containing preparation retained PrPSc for several weeks in the living plant. Finally, plants can uptake prions from contaminated soil and transport them to aerial parts of the plant (stem and leaves). These findings demonstrate that plants can efficiently bind infectious prions and act as carriers of infectivity, suggesting a possible role of environmental prion contamination in the horizontal transmission of the disease.
Circulation of prions within dust on a scrapie affected farm Kevin C Gough, Claire A Baker, Hugh A Simmons, Steve A Hawkins and Ben C Maddison
Veterinary Research (2015) 46:40 DOI 10.1186/s13567-015-0176-1
Prion diseases are fatal neurological disorders that affect humans and animals. Scrapie of sheep/goats and Chronic Wasting Disease (CWD) of deer/elk are contagious prion diseases where environmental reservoirs have a direct link to the transmission of disease. Using protein misfolding cyclic amplification we demonstrate that scrapie PrPSc can be detected within circulating dusts that are present on a farm that is naturally contaminated with sheep scrapie. The presence of infectious scrapie within airborne dusts may represent a possible route of infection and illustrates the difficulties that may be associated with the effective decontamination of such scrapie affected premises. http://www.biomedcentral.com/content/pdf/s13567-015-0176-1.pdf
“Gut vaccine” strategy may work for similar brain infections in humans
Researchers at NYU Langone Medical Center and elsewhere say that a vaccination they have developed to fight a brain-based, wasting syndrome among deer and other animals may hold promise on two additional fronts: Protecting U.S. livestock from contracting the disease, and preventing similar brain infections in humans.
The study, to be published in Vaccine online Dec. 21, documents a scientific milestone: The first successful vaccination of deer against chronic wasting disease (CWD), a fatal brain disorder caused by unusual infectious proteins known as prions. Prions propagate by converting otherwise healthy proteins into a disease state.
Equally important, the researchers say, this study may hold promise against human diseases suspected to be caused by prion infections, such as Creutzfeldt-Jakob disease, kuru, familial insomnia, and variably protease-sensitive prionopathy. Some studies also have associated prion-like infections with Alzheimer’s disease. “Now that we have found that preventing prion infection is possible in animals, it’s likely feasible in humans as well,” says senior study investigator and neurologist Thomas Wisniewski, MD, a professor at NYU Langone.
CWD afflicts as much as 100 percent of North America’s captive deer population, as well as large numbers of other cervids that populate the plains and forests of the Northern Hemishpere, including wild deer, elk, caribou and moose. There is growing concern among scientists that CWD could possibly spread to livestock in the same regions, especially cattle, a major life stream for the U.S. economy, in much the same manner that bovine spongiform encephalopathy, or Mad Cow Disease, another prion-based infection, spread through the United Kingdom almost two decades ago.
According to Dr. Wisniewski and his research team, if further vaccine experiments prove successful, a relatively small number of animals (as few as 10 percent) could be inoculated to induce herd immunity, in which disease transmission is essentially stopped in a much larger group.
For the study, five deer were given the vaccine; another six were given a placebo. All of the deer were exposed to prion-infected brain tissue; they also were housed together, engaging in group activities similar to those in the wild. Scientists say this kept them in constant exposure to the infectious prions. The animals receiving the vaccine were given eight boosters over 11 months until key immune antibodies were detectable in blood, saliva, and feces. The deer also were monitored daily for signs of illness, and investigators performed biopsies of the animals’ tonsils and gut tissue every three months to search for signs of CWD infection. Within two years, all of the deer given the placebo developed CWD. Four deer given the real vaccine took significantly longer to develop infection — and the fifth one continues to remain infection free.
Wisniewski and his team made the vaccine using Salmonella bacteria, which easily enters the gut, to mirror the most common mode of natural infection — ingestion of prion-contaminated food or feces. To prepare the vaccine, the team inserted a prion-like protein into the genome of an attenuated, or no longer dangerous, Salmonella bacterium. This engineered the Salmonella to induce an immune response in the gut, producing anti-prion antibodies.
“Although our anti-prion vaccine experiments have so far been successful on mice and deer, we predict that the method and concept could become a widespread technique for not only preventing, but potentially treating many prion diseases,” says lead study investigator Fernando Goni, PhD, an associate professor at NYU Langone.
Funding for the study was provided by the National Institutes of Health grants NIH NS047433, ARRA NS047433-06S1 and the Seix Dow Foundation.
In addition to Wisniewski and Goni, other NYU investigators involved in the study were Kinlung Wong, BSc; Daniel Peyser, MSc; and Jinfeng Zu, PhD. Research support was also provided by Candace Mathiason, PhD; Jeanette Hayes-Klug; Amy Nalls; Kelly Anderson; and Edward Hoover, DVM, MS, of the College of Colorado State University in Fort Collins, where the deer were kept; Lucia Yim, PhD; Veronica Estevez, MSc; and Jose A. Chabalgoity, PhD, at the University of Uruguay in Montevideo, where the vaccine was developed; and David R. Brown, MD, at the University of Bath in the United Kingdom.
For more information, go to: http://adc.med.nyu.edu/researchers/affiliated-labs/dr-thomas-wisniewski www.elsevier.com/locate/vaccine
CHEYENNE – A ten-year study conducted by the University of Wyoming and the Wyoming Game and Fish Department suggests that the effects of chronic wasting disease (CWD) on elk populations may not be as devastating as once believed.
Research has shown that genes play a role in elk susceptibility to CWD. Some elk have genes that prolong the time between exposure to the CWD prion, the infectious agent of CWD, and the onset of the disease. These genes become dominant over many decades, greatly reducing the impact of CWD on the population. Elk with these genes live longer even when heavily exposed to CWD and therefore have more opportunity to reproduce than elk with other genes.
Some people have feared that winter feedgrounds for elk would concentrate the disease resulting in much higher incidence of CWD.
“This study model essentially represents the worst-case scenario that would face feedground elk,” said Dr. Terry Kreeger, retired state wildlife veterinarian for the Wyoming Game and Fish Department. “We predict a genetic shift over several decades favoring genes that prolong the incubation time of CWD resulting in elk populations that are able to persist in the face of the disease.”
Scott Edberg, Deputy Chief of the Wyoming Game and Fish Wildlife Division states, “It helps to know that based on this research, if CWD should become established on feedgrounds, we won’t see a devastating effect on populations as many have feared. This research also looked at how hunting would affect populations, and it appears, Game and Fish would still need to have hunting seasons to manage elk populations even if faced with CWD on feedgrounds.”
The full study was published in an issue of Ecospohere, an online, open-access, peer-reviewed scientific publication of the Ecological Society of America and can be accessed at www.esajournals.org