CWD Rule Would Continue Deer Baiting Ban

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Three days in March will be very important for Wisconsin hunters, wildlife watchers, farmers and anyone interested in the health of Wisconsin’s white-tailed deer herd. From March 17-19 the Department of Natural Resources will hold hearings at 17 locations across the state to gather comment on proposed chronic wasting disease management rules and an associated Environmental Impact Statement (EIS).

"Wisconsin is at a CWD threshold," says Tom Hauge, director of wildlife management at DNR. "The disease is here, but from the data we’ve collected so far it appears to be in a small area and there’s a chance we can eradicate it. We also have to take aggressive steps to prevent further spread. The steps we take now will likely determine whether or not we can rid ourselves of this disease or if we have to learn to live with it.

"Quite a few other states have CWD management rules in place or are developing them. To my knowledge, Wisconsin is the only state that has written an environmental impact statement analyzing the effects of their rules"

The EIS provides an extensive review of the science pertinent to the proposed rules, a number of alternatives and the potential environmental, social and economic effects of the rules. The environmental impact statement is available on the DNR Web site, by request in writing from the Department of Natural Resources, Bureau of Wildlife Management, PO Box 7921, 101 S. Webster St., Madison, WI 53707-7921, and for reading at libraries and DNR service centers.

Hearing locations are listed in the DNR Meeting and Hearing Calendar.

Among the preferred alternative identified in the EIS on the proposed CWD rules is continuation of the prohibition of baiting and feeding deer currently in place under the emergency CWD rules.

"Research on bovine tuberculosis indicates that feeding and baiting spread disease," says Tim VanDeelen, Ph.D. wildlife ecologist and DNR deer specialist. "From a science and animal health standpoint one of the most important aspects of CWD management is what we choose to do with baiting and feeding. Baiting and feeding unnaturally congregate deer and increase the risk of spreading disease among animals,"

In the north, deer may congregate seasonally in deer yards if winter conditions are severe. However, VanDeelen says, the potential for close animal to animal contact over a supplemental feed pile is fundamentally different than the contact deer experience in yards.

"Under natural conditions most deer food is widely scattered over a wide area, limiting animal to animal contact. Supplemental feeding reduces their normal home range and leads to increased animal concentrations," he says.

The EIS documents that there is a real risk associated with artificially bringing deer together when there is a known occurrence of a transmissible disease like CWD or bovine tuberculosis, according to Sarah Shapiro-Hurley, a DNR veterinarian and land division deputy administrator.

"Researchers who have studied CWD epidemics in both captive and free-ranging deer populations have determined that CWD is both contagious and self sustaining," Shapiro-Hurley says. "In other words, CWD won’t disappear on its own."

Wildlife director Hauge points out that while researchers believe CWD is caused by prions, which are abnormal proteins, they don’t know the exact way that prions are shared between sick and healthy deer.

"We do know that for the last few months of the deer’s life, they excessively urinate, drool and slobber making it likely they’ll contaminate a site with bodily fluids. When deer concentrate in an area, such as around bait or feed piles, their feces also builds up. Natural feeding spreads the deer out so a sick deer isn’t as likely to contaminate any food remaining in the area with the disease-causing prion," he says.

There is good evidence that deer can get CWD by eating something contaminated with the CWD prion, Hauge says.

Researchers fed one group of fawns a daily dose of brain tissue from CWD-negative deer. A second group was fed the same brain tissue but from CWD-positive deer. After 42 days, all fawns fed the CWD-positive tissues tested positive for CWD prions in lymph tissues associated with their digestive tracts.

"Wildlife veterinarians have also observed that contaminated pastures appear to have served as sources of infection in some CWD epidemics. The observational evidence on this is strong based on the experience of the researchers but this hasn’t been proven experimentally at this time," Hauge says.

While the proposed rules and the EIS focus on chronic wasting disease, Hauge says wildlife health specialists say baiting and feeding can put Wisconsin’s deer herd at risk to other serious diseases as well.

"We know bovine tuberculosis is spread from animal to animal over feed and bait piles and for this reason, bait piles are especially worrisome because this disease can cross over into dairy cattle," he says. The Wisconsin Department of Agriculture Trade and Consumer Protection has also recommended the ban be continued, he notes.

Taking steps to limit the amount of contact between infected and healthy deer is a major factor in predicting the spread of CWD in a deer population according to Shapiro-Hurley. Scientists using real-world data taken from CWD outbreaks in mule deer have built computer models to predict rates of new infections. The models show that small reductions in animal to animal contact rates can dramatically reduce the rate of new infection during an epidemic.

"Under a baiting and feeding ban, disease outbreaks are more likely to be smaller in scale and more apt to be contained or eliminated," says VanDeelen. "The long incubation period before CWD is observable in an animal and other factors make discovery of new CWD outbreaks difficult."

FOR MORE INFORMATION CONTACT: Tom Hauge - (608) 266-2193, Tim VanDeelen - (715) 356-8599 or local wildlife biologists