Since the discovery in May of a free-ranging deer infected with chronic wasting disease in Ingham County, Michigan, the state’s Department of Natural Resources has been hard at work sampling deer from the immediate area for additional signs of the disease and putting into effect emergency precautions to prevent as much as possible spread of the disease.
So far, no additional infected animals have been found.
wildlife veterinarian working with deer carcassesChronic wasting disease is an unusual neurological disorder that affects members of the deer family. CWD is caused by prions – mutating proteins in the animal’s nervous system – not a bacteria or virus. A form of transmissible spongiform encephalopathy, similar to mad cow disease, CWD causes lesions in the brain. Infected animals exhibit uncharacteristic behavior – they lose their fear of humans, for instance – and gradually waste away. CWD has never been shown to cause illness in humans.
The infected animal in Ingham County showed classic symptoms, said DNR veterinarian Steve Schmitt.
“The animal was found in a subdivision in Meridian Township showing neurological symptoms, standing there, letting people approach it,” Schmitt said. “And it was thin.”
Meridian Township police dispatched the animal and turned it over to the DNR, where it tested positive for CWD. Further testing at the U.S. Department of Agriculture’s National Veterinary Services Laboratory confirmed that the animal was infected.
The DNR went right to work.
“The first step is ramping up our surveillance,” said Chad Stewart, the DNR’s deer and elk specialist. “We’ve determined that the disease exists in Ingham County and now we need to find out how prevalent it is and where else it may exist.
“We’re checking road kills and other samples. If we get on it very quickly, we have a chance to eradicate it. If it gets established, we’re pretty much in containment mode.”
First identified in a captive mule-deer herd at a research facility in Colorado in the late 1960s, CWD has since been found in 23 states and two Canadian provinces.
Michigan’s first case of CWD was in a private, captive herd in Kent County in 2008. Significant monitoring of deer from the county and surrounding area failed to discover another infected animal.
Since CWD was confirmed in Ingham County, 122 deer have been tested. None tested positive for CWD.
The bulk of the deer tested have been road kills, which are excellent test subjects, Schmitt said.
“An animal with neurological disease is more likely to step in front of a car,” he said.
Others have been shot under disease-control permits issued by the DNR and by the USDA’s Wildlife Disease unit, which the DNR contracted to take additional deer.
“This disease can exist in otherwise healthy-looking animals for months or years, but they’re still infectious,” Stewart said. “We’re optimistic that we caught this in time and we can remove enough deer and any infected deer from the population. We obviously won’t know that answer until we test more deer.”
Schmitt said two states that similarly found a single infected deer – Minnesota and New York – were able to prevent the disease from becoming established in their herds by “aggressive management.”
Schmitt said he was pleased that no additional animals have tested positive, but “we’re going to try to get our hands on every deer from the core area – within a 2-mile radius of the infected animal – that we can.”
Prions are passed from infected deer by excrement, saliva or even the dead carcass of an animal. The prions remain active for a lengthy period of time – how long is not fully known – but animals can pick up the disease from a contaminated environment.
“Those prions will bind with soil particles and stay infectious for years,” Schmitt said.
In addition to surveillance, the DNR has issued immediate orders applying to Ingham, Clinton and Shiawassee counties banning feeding deer year-round and baiting during hunting season. All three counties will have an early antlerless hunting season this year.
The DNR has established a nine-township Core CWD Management Area, which includes the townships of Lansing, Meridian, Williamstown, Delhi, Alaiedon and Wheatfield in Ingham County; DeWitt and Bath townships in Clinton County; and Woodhull Township in Shiawassee County. Unlimited antlerless deer licenses will be available in the core area this year.
Hunters will be subject to mandatory deer registration in the core area. They will be required to register their deer at a DNR check station before they take their deer outside the core area and will be instructed on proper carcass disposal.
When the fall deer season arrives, the DNR intends to issue unlimited antlerless deer licenses in the affected area and institute mandatory deer checks. Hunters will be asked not to take the carcass of any deer taken in the area outside the township in which it was harvested, though they will be allowed to have the deer processed by a licensed processor and will be alerted to test results.
CWD has never been known to cause human health effects, but health officials warn against consuming the meat of infected animals or the parts of the central nervous system of any deer, as a precaution.
“We hope the hunters will help by participating in mandatory check-ins, helping restrict carcass movement, and observing the feeding and baiting bans,” Stewart said. “We have to try to stop any potential spread or increase in prevalence on the landscape.
“A lot is going to depend on how much hunter participation we get. We’ve gotten the ball rolling, but we need a lot of samples from our hunters during the season. We need their participation.”
Currently, all deer being tested for CWD are being incinerated.
“We have one chance to try to eradicate this disease, so we have to give it our best shot,” Stewart said. “There are going to be some people who won’t like this – culling deer and unlimited antlerless permits – but it’s the best thing to do.”
People who see animals exhibiting neurological symptoms are asked to call the Report All Poaching (RAP) line at 1-800-292-7800. People who see road-killed deer in the nine-township area are being asked to report them to the Wildlife Disease hotline (517-614-9602) at the DNR Rose Lake Field Office.
For more information on chronic wasting disease, visit www.michigan.gov/cwd.
