A team of national and state experts in public health, wildlife diseases, prion research and laboratory diagnosis is calling for a comprehensive national strategy to reduce the risk for human exposure to chronic wasting disease and to limit the risk of transmission among wildlife.
The University of Minnesota reported on the call for strategy Tuesday, July 23, in a news release.
CWD is a prion-related transmissible spongiform encephalopathy of animals in the cervid family including deer, elk, reindeer, sika deer and moose. CWD has been confirmed in at least 26 U.S. states, three Canadian provinces, South Korea, Finland, Norway and Sweden, with a notable increase in the past five years.
On Jan. 23, a dead wild deer infected with CWD was located by Upper Mission Lake north of Merrifield, in close proximity to a game farm in which seven confirmed cases of CWD have been reported in captive deer as of 2018.
Following the Feb. 14 confirmation of CWD in the wild deer near Merrifield, landowners of 10 acres or more within a 2-mile radius of the game farm were permitted to kill deer to be tested for CWD. Federal wildlife specialists also killed deer to be tested in a 2-mile radius around where the infected deer was found. Those distances were selected as a deer's average home range is about 1 mile.
While no CWD was found in any of the deer taken by landowners, state or federal officials near Merrifield, the announcement of CWD in the one wild deer spurred efforts and proposals in the Minnesota Legislature for short-term and long-term solutions, including the creation of CWD task forces, buyout programs for game farms, funding for testing, moratoriums on possessing captive deer and creating a carcass disposal program. The Merrifield deer farm accepted a buyout and has closed.
Now there’s a national effort to combat CWD.
The continued geographic spread of this disease increases the frequency of exposure to CWD prions among deer and related animals, humans and other animal species. Although CWD has not yet been found to cause infections in humans, numerous health agencies advise people should not consume CWD-positive animals.
The team of experts from the Center for Infectious Disease Research and Policy at the University of Minnesota, as part of its Chronic Wasting Disease Response, Research and Policy Program; the Prion Research Center at Colorado State University; the National Prion Disease Pathology Surveillance Center at Case Western Reserve University; and the Minnesota Department of Health recommends several immediate steps that need to be taken to address this potential health crisis.
The steps were published Tuesday in the journal mBio by the American Society for Microbiology.
“We have learned a lot about CWD in deer and elk over the past several decades, but we now realize how much more we need to know to control its rapid spread and devastating impact in cervids,” said lead author Michael T. Osterholm, University of Minnesota regents professor, McKnight Presidential Endowed Chair in Public Health, and director of the infections disease center in a news release. “And we must understand the risk of transmission of CWD prions to humans with the ever increasing consumption of infected venison and how we reduce the possibility that one day we may have a tragic replay of a bovine spongiform encephalopathy or mad cow disease-like scenario in North America.”
The steps include:
Investing in CWD research. This includes adequate federal support allows state wildlife, animal health and public health agencies to enhance hunter education and better develop and conduct comprehensive CWD management plans.
Enhancing mandatory CWD testing. Mandatory testing of killed or dead deer and related species in all areas in which the disease is prevalent and establishing associated monitoring systems that can be shared across states would provide more accurate data for wildlife managers and public policy makers. Improved surveillance would also foster more efficient responses and help prevent disease spread among deer, elk and more. Additionally, mandatory testing results could assist in hunters knowing if consumption will expose them to CWD prions.
“Adoption of more sensitive, next generation diagnostic tests could identify early stage and nonclinical ‘carrier’ animals that likely contribute to direct and indirect transmission and environmental contamination that may be accelerating CWD spread,” stated co-author Mark Zabel, professor in the College of Veterinary Medicine & Biomedical Sciences and associate director of the Prion Research Center at Colorado State University, in a news release. “Identifying infected animals earlier could reduce environmental prion loads and save additional animals from this deadly disease.”
Improving deer and related species management. The Association of Fish and Wildlife Agencies has published best CWD management practices based on current science. These practices, including the movement of live animals, carcass disposal and feeding/baiting, need to be implemented by states as soon as possible to improve the health of wild and farm-raised animals and protect the nearly $40 billion annual contribution of hunting of wild deer, elk and more in the United States, the U of M stated.
Heightened surveillance of human prion diseases to determine if CWD is transmissible to humans. It is imperative the U.S. Centers for Disease Control and Prevention continues its epidemiologic surveillance of human prion disease, especially in CWD endemic states, the U of M stated. The only way to determine the origin of prion disease in humans is via post-mortem analyses of brain tissue. Hence, it is crucial to continue neuropathological surveillance of patients with suspected prion disease to help determine whether or not CWD is transmissible to humans.
“Properly addressing CWD will require a multidisciplinary approach. Engagement with the animal and hunter community, as well as continued long-term funding for human prion disease surveillance, will be required to address the many questions that CWD raises,” stated co-author Brian Appleby, an associate professor in the School of Medicine and director of the National Prion Disease Pathology Surveillance Center at Case Western Reserve University, in the release.