Hunters, motorists, taxidermists asked to help monitor chronic wasting disease

The Kansas Department of Wildlife and Parks (KDWP) plans to collect 3,200 samples to test for chronic wasting disease (CWD) in deer and elk during the 2007-08 hunting season. The effort will begin earlier than in previous years.

“We’re starting early this year because we want to have time to collect as many specimens as possible from vehicle-killed deer and from animals submitted to taxidermists,” says Dr. Ruby Mosher, KDWP wildlife disease coordinator. "Those animals are more likely to test positive than those from a random collection of hunter-killed deer."
The reason deer killed on the highway are more likely to have CWD than the average deer is because the disease affects the brain and causes the animal to be unaware of its surroundings. That doesn’t mean that every deer hit on the highway has CWD. To date, none of the vehicle-killed deer tested in Kansas have been positive for CWD, but not many have been tested.

“We want to start testing a higher percentage of deer killed by vehicles,” Mosher says, "especially in counties along borders with Colorado and Nebraska, where CWD is more common than in Kansas.”

However, KDWP doesn't have enough time and manpower to get many of these specimens. That’s where Mosher is asking for help from the public.

“We would like to work with people who are on the road a lot and see the vehicle-killed deer,” she says. "Those people might include highway patrol troopers, rural newspaper carriers, and staff from other state agencies. KDWP has a special grant from the U.S. Department of Agriculture (USDA) that helps us pay contractors for their efforts."

Mosher stresses that in no case should anyone try to collect a sample from a vehicle-killed animal that would put that person’s safety in jeopardy. More information can be obtained by calling 620-342-0658.

Another group of people Mosher wants to hear from is Kansas taxidermists. A number of taxidermists have worked with KDWP since the CWD testing program began, and their participation in the program is greatly appreciated. Samples obtained from deer that are collected from taxidermists are valued for CWD testing because they tend to be from older bucks. Mosher, a veterinarian, says older animals provide desirable samples because they’ve had more contacts with other potentially-infected deer; they’ve traveled more and have had more opportunities to encounter a CWD-contaminated hotspot; and they’ve also had time for the disease to develop.

“CWD has a very long incubation period, so we get more accurate results by testing animals that are at least 18 months old," she explains. "It doesn’t mean that a younger animal couldn’t have picked up the infective prion [the carrier of the disease]; it just means that the animal hasn’t had time for the abnormal prions to start showing up in the brain and lymph tissues that are collected for testing."

CWD is a member of the group of diseases called transmissible spongiform encephalopathies (TSE’s). Other diseases in this group include scrapie in sheep and goats, bovine spongiform encephalopathy (BSE or mad cow disease) in cattle, and Cruetzfeldt-Jacob disease in people.

CWD is a progressive, fatal disease that results in small holes developing in the brain, giving it a sponge-like appearance under the microscope. Decreased brain function causes the animal to display neurological symptoms such as depression, droopy head, staggering, loss of appetite, and a lack of response to man. The continuing deterioration of the brain leads to other symptoms such as weight loss, drooling, and excessive thirst. Caution is advised because of unknown factors associated with prion disease, but no human health risks have been discovered where CWD occurs.

“None of the TSE-related symptoms are CWD-specific,” Mosher says. “They may be the result of other diseases. The only way we can accurately diagnose CWD is to collect and test the appropriate samples.”

Those samples may include the obex portion of the brain, the retropharyngeal lymph nodes, or the tonsils. For CWD testing in elk, KDWP collects the obex and the lymph nodes, but with deer, usually only lymph nodes are collected. That is because in deer (but not elk) the abnormal prion that is associated with CWD shows up first in the lymph tissue. That’s an important point Mosher wants to make sure that taxidermists and meat locker plant operators understand.

“Because we don’t need the brain from deer, we can still get the samples we need if the upper portion of the brain has been removed along with the antlers,” she says. "The lymph node samples we want are located near the lower jaw bones at the back of the throat."

CWD has been detected twice in Kansas. The first case was in 2001 in a captive elk herd in Harper County. The other case of CWD was detected during the 2005-06 hunting season in a free-ranging whitetail doe harvested in Cheyenne County, bordering Colorado and Nebraska.

Although testing of nearly 3,000 animals in Kansas last year resulted in no new cases of CWD, Mosher cautions that this doesn’t mean CWD doesn’t exist here. It only means that CWD wasn’t detected in collected samples.

Although research is underway, there is currently no vaccine or other biological method of preventing the spread of CWD. And there may never be. The only tool is to prevent the spread of CWD to new areas. This is important for the public to realize because once the infective particle (an abnormal prion) is deposited into the environment -- either through an infected carcass or from a live animal -- it may exist for a decade or more, just waiting to infect a healthy deer.

Mosher recommends the following guidelines for hunters and wildlife watchers:

• It is strongly recommended that hunters not transport carcasses into eastern Kansas from western Kansas or from states where CWD is endemic. (Boned meat and antlers with skull cap are not considered a serious threat and may be taken home.) Check the regulations where you hunt. Some states may prohibit you from transporting certain parts of a carcass from areas where CWD occurs. Some states may prohibit carcasses from being brought into their state, and others may have regulations that require certain parts of the carcass to remain attached while the carcass is in transport;
• Dispose of carcasses properly. Especially when a deer is harvested in counties bordering Nebraska or Colorado, it is recommended that the carcass be kept in those counties, or be buried, composted, or disposed of in an approved landfill;
• Don’t train deer to congregate around bait piles. It is highly likely that enticing wild deer to unnaturally congregate around bait piles may increase the chance of spreading CWD once a positive animal has visited the spot. This is true for other transmissible diseases such as tuberculosis. Baiting and using various mineral blocks and lures to attract deer to a site may make that site deadly for deer in the future; and
• Alert local KDWP officials if you notice a deer that is acting abnormally or appears unhealthy.

Currently, the Kansas deer herd is strong and healthy. Kansas residents can help keep it that way by following the above recommendations and by volunteering or contracting with KDWP to collect samples for the surveillance effort.

“Several collection partners -- including taxidermists, meat lockers, and road-kill collectors -- refuse payment for saving the specimens we need for testing,” Mosher says. “They volunteer their time and energy simply because they believe in working toward the conservation of our wildlife resources for future generations. They know that everything they can do to help us get a handle on CWD now will make a positive difference in the quality of life for all Kansans.”

This year, KDWP is able to offer payment to contractors to collect CWD samples, as well as to provide free CWD testing to hunters who present the head from their harvested deer or elk for testing. Although Mosher urges hunters to take advantage of the free CWD testing this year, she cautions that the test is a screening tool used for research purposes; it is not a test of food safety. It also may take a month or two before the results are received and entered into the database. Once that is completed, hunters may obtain the results for their animal by going online at cwd.wp.state.ks.us and entering their hunting license number.

For more information about CWD, write the KDWP Research and Survey Office, 1830 Merchant, Emporia, KS, 66801 or phone 620-342-0658.

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