March 14, 2002 Milwaukee Journal Sentinel by Meg JonesAs hunters head out into woods in southern Wisconsin this week, scientists hope to learn whether a deadly brain disease that has infected wild white-tailed deer is in a small part of the herd or if it's already spread.
Hoping to contain chronic wasting disease before it can get out of control, state officials are asking landowners to get free special permits to shoot a total of 500 deer in a 415-square-mile area in eastern Iowa County and western Dane County. That's the area where officials found the disease -- related to mad cow disease -- in three bucks killed during gun hunting season in November.
Most of the land is privately owned, which is why the state Department of Natural Resources is seeking the help of landowners who know best where deer are located on their property.
Once the deer are killed, their heads will be shipped to a lab in Ames, Iowa, for testing. Scientists examine brain tissue to see if the animal is infected. Like police detectives trying to find a murderer, wildlife biologists will try to track down the source of the infection and determine whether it has spread to other deer.
"It's a large task ahead of us," said Tom Hauge, chief of the DNR Bureau of Wildlife Management.
"It is conceivable that it's only these three deer, but we think that's unlikely," Hauge said. "The whole point of doing the additional sampling is to get a better handle of how prevalent it is."
A 'brave new world'
Whatever the results turn out to be, Wisconsin officials are paddling off into uncharted territory.
The chronic wasting disease infections that have hit wild deer and elk in Colorado, Nebraska and Wyoming were in considerably less dense herds than the animals in Wisconsin, and many of the cases out West were in deer other than whitetails, said Julie Langenberg, a DNR veterinarian.
"We have this brave new world where we've identified infection in a very dense wild whitetail population," said Langenberg, who is helping organize the deer sampling.
Aerial surveys in the area near Mount Horeb where three bucks tested positive for chronic wasting disease showed 50 to 75 white-tailed deer per square mile. Research also showed that an average adult buck in that area travels a maximum distance of 10 miles.
So using a mathematical formula that took into account the number of white-tailed deer in the area, how far they would likely travel and how many should be tested to get an accurate picture of the spread of the disease, scientists came up with the figure of 500.
"Our approach is to take those 500 animals as randomly as possible across that surveillance area," Langenberg said. "Who knows what we're going to find. We may find more positive animals in that circle and they may be at the outer edges of the circle, which would mean we may end up making a bigger concentric circle" to test deer.
What happens once authorities learn how many more animals, if any, are sick is unknown. Considering there are as many as 20,000 deer in the 10-mile circle, it would be quite a task to eradicate the herd to stop the disease from spreading.
That area already has too many deer and is scheduled for a Zone T hunt this fall. Zone T hunts are additional periods in which hunters can kill deer. They were established in 1996 to control growing deer populations in areas where conventional hunting was not keeping the herd within management goals.
"The control options that we'd have to take, we really haven't even begun to start to really lay out those possibilities," Hauge said.
"I guess one end of the spectrum is that you have to take all the deer out if you're going to have any chance to prevent the disease. Maybe another approach is you don't (eliminate every animal in the area), but you try to take it down to a low level. What that low level is, I don't know."
Even if the entire population in that area were eliminated, deer would quickly fill the vacuum, Hauge said, which means officials would have to monitor the situation for a long time.
No danger to humans [There is evidence that CWD prions can infect human brain tissue--BSE coordinator]
Chronic wasting disease results in weight loss and behavioral changes. Although it is still uncertain which infectious agent causes chronic wasting disease, prions -- abnormal forms of protein -- are the most likely suspects.
Because the incubation period can last two years or more, there may be infected animals in Wisconsin that are not yet showing symptoms.
The most widely known prion disorder, mad cow disease, can spread to humans. There are no known cases of chronic wasting disease spreading to humans or other animal species.
But Judd Aikin, a professor of animal health and biomedical sciences at the University of Wisconsin-Madison and an expert on prion diseases, said even though there have been no cases of the disease in humans or cattle, no one can rule that out.
Experts originally thought mad cow disease couldn't be transmitted to humans.
"It tends to move in cervids (deer and elk) more easily," Aikin said Wednesday. "That doesn't mean it can't infect humans. Unfortunately, we just don't know."
Aikin pointed out that cattle have not been infected in chronic wasting disease endemic areas such as Colorado and Wyoming, where deer and elk have been infected for many years.
Somehow, the disease ended up in Wisconsin, and state officials have to deal with the problem, which Aikin said could potentially be "a very, very severe wildlife disease . . . because of its ability to transmit between deer."
That's why the DNR is handing out permits to landowners in the area where the infected deer were shot in November. Interest has been high, with 70 property owners requesting permits even before the DNR publicized a phone number to call, DNR spokesman Bob Manwell said.
Killing could start today
The first permits were being handed out Wednesday, which means landowners could begin shooting deer today. Called scientific collectors permits, they're good for three days, and rifles will be allowed, even though during the gun-deer season, only shotguns can be used in the management unit because of the high density of residents.
"There's a great deal of interest in knowing the situation out there. We're not paying them for the service, but I think most landowners are quite concerned with the health of the land they own," said Manwell, who added that authorities hope to have the operation finished in two to three weeks.
"Many people, whether they're hunters or not, spend a lot of hours and get a lot of pleasure watching deer or hunting," he said. "There's a variety of motivations among people -- desire to help out and find out where and how extensive it is."
In the majority of the sampling area, the DNR will need only one or two deer per section. Landowners are asked to shoot older deer, the animals most likely to be infected due to the long incubation period. At this time of year, deer don't have antlers.
Landowners can designate themselves or another person on the permit. After they shoot a deer, the DNR will pick it up -- either the entire carcass or just the head, if the landowner wants to keep the meat. They're advised to freeze the venison until tests are completed.
Any venison that's not claimed will be available to anyone who contacts the DNR.
The DNR is advising hunters not to eat the brain, spinal cord, eyes, tonsils, spleen or lymph nodes of the animals.
Officials don't know how many hunting permits will be needed to kill 500 deer in the area. If landowners don't harvest enough for testing, U.S. sharpshooters will be called in.