DOW continues CWD management research

DOW continues CWD management research

April 5, 2001

DENVER — The Colorado Division of Wildlife will begin several management and research projects this spring and summer as part of its ongoing effort to learn more about chronic wasting disease (CWD) and reduce its prevalence and distribution.

To help achieve its goal of maintaining deer populations at or below current levels and preventing the diseases spread, division biologists will remove a total of 100 to 200 deer on private and public property in two areas in northeastern Colorado where wasting disease occurs. Researchers will also conduct tests in two separate deer herds to determine if CWD can be detected in live animals. And an ongoing research project north of Fort Collins, to test the relationship between deer density and disease prevalence, will continue as planned.

"Protecting the health of Colorado’s wildlife is a cornerstone of this agency’s mission," said DOW Director Russ George. "Chronic wasting disease is a serious wildlife concern that threatens the welfare of deer herds in portions of northeastern Colorado. These efforts are part of our measured approach to manage herds affected by this disease."

As part of the upcoming management project, wildlife biologists in eastern Colorado will reduce deer populations in two specific areas along the South Platte River where infected deer have been found.

The project will occur on public and private land during a four-week period ending in early May. Biologists will time their reduction efforts to not interfere with turkey hunting, and all deer taken on private property will be done with prior permission from landowners. Similar reductions in deer herds in Game Management Units 19 and 191, northwest of Fort Collins, will occur.

"Our short term goal is to not allow the deer population in the chronic wasting disease endemic areas to grow above the 1999 post-hunt levels," said Rick Kahn, manager of terrestrial field programs for the Division. "By removing animals in specific locations where the disease has been found, we hope to reduce the sources of infection and keep the disease from spreading."

Every deer collected will be tested and examined by Division researchers to further learn about disease distribution, prevalence and transmission.

In the Estes Park Valley and in areas west of Fort Collins, Division of Wildlife researchers will attempt to take tonsillar biopsies from about 200 deer to learn if early detection of chronic wasting disease is feasible in live animals. To date, a live-animal test for chronic wasting disease does not exist. Research has indicated that prions, aberrant proteins thought to cause chronic wasting disease in deer and elk, accumulate in the tonsils during the early, mid and late stages of the disease, making tonsillar biopsies a possible detection tool.

In Game Management Unit 9, which is located directly north of Fort Collins, DOW researchers will continue their ongoing management study to measure the relationship between deer density and disease prevalence. During a two- to three-year period, the deer population in the unit will be reduced by half and then monitored to detect if levels of infection change. An adjacent area in Wyoming just north of the state border where similar infection rates have been found will serve as a control.

A special late hunting season was held in January and February to allow public hunters the opportunity to harvest animals and reduce the size of the herd in unit 9. Hunters killed more than 200 deer, but few animals were taken on some portions of Game Management Unit 9. In those areas, Division officers will consult with private property owners about removing additional deer.

CWD is a degenerative neurological disease of deer and elk. It attacks the brains of infected animals, causing them to become emaciated, display abnormal behavior, and lose control of bodily functions and die. Division of Wildlife surveillance during the past six years has found CWD in 4 percent to 5 percent of the animals tested in a portion of northeastern Colorado. In Game Management Unit 9, the incidence is about 15 percent in deer. The incidence is far lower in other units and the disease is relatively rare in wild elk, with less than one percent of the elk in the affected area being infected.

Epidemiologists with the federal Centers for Disease Control and Prevention in Atlanta and at the Colorado Department of Public Health and Environment have found no link between CWD and any human neurological disorders. In addition, ongoing research indicates that the likelihood of CWD being passed to cattle or any animal other than deer or elk is extremely low.

Wasting disease is found in an endemic area encompassing 13 game management units in northeastern Colorado east of the Continental Divide – about 7 percent of the state’s entire area. It has also been found in wild mule and white tail deer and elk in southeastern Wyoming. A single deer infected with CWD was recently found in extreme southwestern Nebraska. CWD has also been found in captive elk herds in several states and Saskatchewan.

Extensive monitoring conducted as part of the division’s ongoing surveillance program indicates that chronic wasting disease is not found outside the endemic area in the state.

"The prevalence has stayed essentially the same since we began our surveillance work, and the disease has not spread appreciably during that time," said Division veterinarian Mike Miller, one of the foremost authorities on CWD. "We want to do all we can to reduce the incidence of this disease and to prevent its spread outside the endemic area."