Chronic Wasting Disease – Amidst the Gloom and Doom, There Are Things We Can Do
There is a growing consensus amongst representatives from conservation organizations and wildlife agencies that the single greatest threat to North America’s deer herds and deer hunting is chronic wasting disease (CWD). The threat is daunting and ominous, so it is critically important for MDHA and its members to be engaged and active in doing everything possible to protect Minnesota’s deer herd.
What is CWD?
This year marks the 50th anniversary of the discovery of CWD by wildlife biologists at Colorado State University, who observed captive mule deer developing a new disease which caused weight loss, loss of awareness of their surroundings and ultimately, death. Years later researchers discovered that CWD is caused by prions. Prions are not like bacteria or viruses – they are actually deformed proteins. When ingested, prions force normal proteins in the animal’s body to become deformed as well. Over the course of months, prions gradually destroy the animal’s central nervous system, ultimately killing it. It is always fatal.
CWD affects cervids, which are deer, elk, moose and reindeer. As a prion-based disease, it is similar to Bovine Spongiform Encephalopathy (BSE), also known as “mad cow disease” in cattle, scrapie in sheep, and Creutzfeldt-Jakob Disease (CJD) in humans.
How is CWD spread?
Prions causing CWD can be spread through saliva, urine, feces, spinal and brain fluid and anything from the animal’s central nervous system. Direct contact is not the only way in which CWD can be spread. Sick and dead animals spread prions on the landscape. Some studies suggest these prions end up in the soil and on grass and other plants. It’s possible that animals may pick up these prions when they eat the contaminated plants or soil.
There are many theories about how CWD originated, but it is clear that once it exists in an area, movement of infected animals spreads the disease. This can be most clearly seen by what happened in Saskatchewan. In 1996, the first known instance of CWD in Canada was discovered in a captive herd of elk in the province. Between 1996 and 2002, 39 captive herds of elk in Saskatchewan were found to have CWD. The Saskatchewan source herd is believed to have become infected via importation of animals from a game farm in South Dakota where CWD was subsequently diagnosed. CWD has now spread to wild populations of animals in both Saskatchewan and Alberta.
CWD has now been found in 24 states and two Canadian provinces. It was surprisingly discovered in a reindeer herd in Norway last year. Many of Minnesota’s neighbors are facing circumstances where CWD has become endemic in their states. In Wisconsin, 43 counties are now in a deer feeding ban due to concerns over the spread of CWD. Missouri recently expanded its deer feeding ban to 41 counties in response to CWD. In Wyoming, where CWD has been endemic for decades, up to 40% of some herds are infected and white-tailed deer populations are declining by 10% per year.
Is CWD a Threat to Human Health?
According to the Centers for Disease Control and Prevention’s website, “to date, no strong evidence of CWD transmission to humans has been reported.” It’s fair to say that most deer hunters have generally assumed that CWD cannot be transferred to humans. Yet a recently released study by the Canadian Food Inspection Agency and the University of Calgary may cause hunters to look at the issue more closely. The study, started in 2009, found that five of 18 macaque monkeys exposed to CWD contracted the disease. Three became sick from eating CWD-infected materials – two from meat and one from brain matter. The other two became sick after their brains were injected with CWD-infected materials. Results are not yet in on the other 13 macaques.
As a result of this study, Health Canada recently updated its CWD risk advisories, noting that although extensive disease surveillance in Canada and elsewhere has not found direct evidence that CWD has infected humans, its potential for transmission to humans can’t be ruled out. Health Canada said Canadians should consider that CWD has the potential to infect humans.
So What Can MDHA and Its Members Do in the Face of All of This Negative Information?
MDHA will continue its support of aggressive measures to address the discovery of CWD near Preston. When CWD was discovered near Preston during the 2016 deer season, the Minnesota Department of Natural Resources (DNR) implemented a response plan that created CWD zone 603, established a five-county feeding ban and led to the removal of more than 1,000 adult deer through a special season, landowner shooting permits and sharpshooting. A total of 11 CWD-positive deer were identified in this effort, 10 of which were taken in a very small geographic area. This effort is critical as DNR attempts to fully understand and best-contain this localized outbreak.
These efforts do not come cheap and MDHA will continue to push for funding beyond those provided by deer license dollars. In fact, due in part to the advocacy of DNR, MDHA and others, the Legislature appropriated an additional $500,000 to DNR specifically for planning and response to disease outbreaks like CWD.
MDHA will continue to push for a thorough review by the Legislative Auditor of the Board of Animal Health’s (BAH) oversight of captive cervid farms. In March of 2017, MDHA wrote to the Legislative Auditor requesting a review of BAH’s oversight and enforcement of Minnesota’s captive cervid law. The letter stated in part: “Minnesota’s deer hunters and DNR are doing their part to protect the state’s wild deer. . . . Minnesota cannot afford to have these efforts undermined by ineffective administration or enforcement of Minnesota’s farmed cervidae statute.” The Legislative Auditor has now agreed to conduct such a review. This is great news, but we must make sure that the audit is thorough and addresses all of the areas where MDHA has concerns, such as escaped animals.
Additionally, MDHA will be working to ensure that the Legislature considers tighter restrictions on captive cervid operations such as double-fencing, better recording keeping, and other measures to protect the wild deer population.
MDHA will be at the forefront of an effort to make readily available, inexpensive CWD-testing for deer harvested by Minnesota’s deer hunters. To the extent that any hunter might be less likely to hunt deer due to human health concerns over CWD, a readily available CWD test may remove those concerns. Currently, testing is already available through Veterinary Diagnostic Lab at the University of Minnesota, but that is not widely known to most hunters. MDHA will work with DNR, the University of Minnesota and others to explore the feasibility of widely expanding the availability of quick, relatively inexpensive CWD testing for harvested deer. If you are interested in having your harvested deer tested, this link from DNR provides a video of how to remove the lymph nodes of a deer and it also provides a link to the University’s Veterinary Diagnostic Lab:
http://www.dnr.state.mn.us/cwdcheck/index.html You can help too – If you observe a deer acting strangely in the wild or appearing to be sick, please report your observations to the local DNR conservation officer.
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Topic: CWD information (Read 2143 times)
