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Minnesota guards against fatal wildlife disease
By Chris Julin
Minnesota Public Radio
April 2, 2002


Wildlife managers in Wisconsin have found two more deer with chronic wasting disease. It's a relative of bovine spongiform encephalopathy, or "mad cow disease," but it appears that chronic wasting disease attacks only elk and deer.

Chronic wasting disease, or CWD, was detected in Colorado more than 20 years ago, and it seems to be spreading slowly. It's showed up in Wisconsin and South Dakota, but hasn't been detected in Minnesota yet.

Deer with chronic wasting disease
Chronic wasting disease attacks the brains of infected deer and elk, causing the animals to become emaciated, display abnormal behavior, lose bodily functions and die. CWD appears to be caused by an abnormal protein called a prion. Usually, months to years pass from when the animal is infected to when it shows signs of disease.
(Photo courtesy of Wisconsin DNR)

No one is sure how chronic wasting disease spreads, so it's tricky to defend against. Animals might pass it along when they touch noses, or when they share food, but it's not clear. Here's what is certain - deer and elk that get CWD die. Scientists don't think the disease affects cattle or humans.

For years it looked like Minnesota was safe. Chronic wasting disease was limited to a few Rocky Mountain and Great Plains states. It looked like the only way for CWD to get to Minnesota would be for someone to import a captive elk that was sick.

Minnesota has more elk breeders than any other state - and some of those animals come from western states. Breeders transported about 500 elk into Minnesota just last year. But the state doesn't allow elk in if the animals come from areas where CWD has been found.

Kaye Zebarth's family runs an elk farm near Alexandria. She's also the president of the Minnesota Elk Breeders Association. She says it was elk farmers who pushed the state to tighten its regulations on importing elk. She thinks the regulations work. And she says it's not likely a captive elk will bring CWD into Minnesota.

"It's always in the back of your mind," Zebarth says. But she says she's "not real concerned about it. It's a real low incidence, high profile type of disease. One-tenth of one percent, I think, of all the animals that have been slaughtered in Colorado tested positive. They've slaughtered a lot of them because it was found on a couple farms, and they found maybe four positives."

The deer population in Wisconsin is very dense in some areas, making the disease easier to spread. CWD can be spread by close contact between animals, and animals exposed to a CWD-contaminated environment may also become infected.
(Photo courtesy of Wisconsin DNR)

But captive animals aren't the only threat anymore. It's possible wild deer will carry the disease to Minnesota. The state of Wisconsin has found five wild deer with CWD. So far it's been detected only in the southeast corner of the state near Madison.

It's not clear how the disease got to Wisconsin. Biologists suspect that someone imported a captive elk or deer that was infected. Now that CWD is in Wisconsin's wild deer, some people worry it's only a matter of time before it makes its way to Minnesota.

"Let's all get serious about preventing this disease from coming to Minnesota, or lessening its spread if it is here," says Mark Johnson, the executive director of the Minnesota Deer Hunters Association. "Let's not monkey around. We don't have time."

Johnson says CWD will spread among wild deer faster in Minnesota and Wisconsin than it did in western states, because deer are more concentrated here. In much of Colorado and Wyoming there are only six or eight deer per square mile.

"In Minnesota, we're looking at deer densities that are at least in the teens, generally in the 20s," Johnson says. "In Wisconsin we're probably up into 40, 50 maybe even 60 deer per square mile in some areas."

That makes it easier for CWD to spread.

"It's just like people," Johnson says. "When you take your children and put them in a day care, they're in close proximity with more kids. They're bound to catch more illnesses than if you have them at home."

Elk with chronic wasting disease
The elk population is also at risk for chronic wasting disease, although the incidence is higher in deer than in elk. Minnesota elk breeders are concerned that the disease could be carried by an animal imported from a western state. They pushed for tighter restrictions on importing elk from areas where CWD has been found.
(Photo courtesy of Dr. Beth Williams, Wyoming State University Department of Veterinary Science)

That's why Johnson is asking people to stop feeding wild deer in Minnesota. And that's why he's in favor of more testing of wild deer.

Minnesota tested about 50 wild deer for CWD last fall. The Minnesota Deer Hunters Association is lobbying the Department of Natural Resources to do more testing.

Mike DonCarlos, the DNR's manager of wildlife research, says the DNR plans to test more deer during this year's hunting season. The only reliable way to test for the disease is to examine the brain of a dead animal. DonCarlos says the DNR will probably collect hundreds of deer heads from hunters this fall.

DonCarlos says he's been talking with hunting groups, and state lawmakers, and people who raise captive elk and deer.

"Most of the folks that we've talked to are very concerned about this disease," he says, and they "are very supportive of the DNR taking the necessary steps to monitor in Minnesota. (So) we know early if and when it comes into the state, and then aggressively work to eliminate it if we find it."

DonCarlos hopes Minnesota's neighbors succeed in halting the spread of CWD. He says the strategy is to detect the disease early, and then thin the population of wild deer in the area. That way, the deer are less likely to come in contact with each other.

Researchers still don't know if wild animals are infecting captive animals, or the other way around. So another possible strategy to control CWD is to force all elk and deer farmers to build double fences around their captive herds - to keep wild and captive animals away from each other. That's expensive, and some farmers say it isn't necessary yet in Minnesota.

More Information
  • Colorado Department of Natural Resources
  • Wisconsin Department of Natural Resources
  • Minnesota Department of Natural Resources
  • U.S. Department of Agriculture