Local prevalence of chronic wasting disease concerns state biologists

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As chronic wasting disease continues to move through the state, Wyoming wildlife biologists warn Park County deer herds could see a rise in prevalence within the next few seasons.

“It’s moving across the state,” said Corey Class, wildlife management coordinator for the Cody region.

Biologists manning the check station in Cody tested all deer and elk for the disease from Nov. 1-10. They had several samples come back positive for the disease, which is fatal to all deer species including white-tailed and mule deer, elk and moose. While the prevalence in Park County is currently about 5 percent in deer, some hunt areas in the Big Horn Basin have prevalence rates as high as 40 percent.

“When prevalence gets that high, we worry,” Class said.

Hunt Area 164, just south of Worland, is an area of concern, Class said. The south Bighorn mule deer herd occupies several hunt areas near Worland, including 164. The entire herd has a prevalence rate of about 22 percent, but Hunt Area 164 is nearly double that, which is concerning to area biologists. CWD is more prevalent in mule deer than other species, Class said.

Early results from Park County testing should show a slight increase in the percentage of infected deer, “maybe a percentage point or two,” Class said. The 2018 final report won’t be available until early next year.

The department has received higher participation from hunters in testing this year than in previous years, he said.

“We’re looking harder, so that has to be factored into the equation. But most of our hunt areas had at least one test come back positive.” Class said.

Test results take seven to 14 days. Hunters are notified of results by mail, but they can also check for results online using their sportsman identification number to track the tests. Waiting for tests to come back can be difficult, as many hunters are eager to consume the fresh meat. Class suggests hunters keep the animal hanging and cool until test results are known.

“It’s a different world and it’s up to the hunter to make the choice. We give good information so hunters can make the right decision,” Class said.

Deer have a higher occurrence of contracting the disease than elk in the basin, Class said. Once contracted, the disease usually takes about 18 months before the animal succumbs. CWD progresses slowly and until the end, symptoms aren’t readily apparent.

“Most of our hunters are surprised when [their deer] turns up positive for the disease. We can’t tell [if they are infected] until the tests come back,” Class said.

The disease attacks the brains of affected animals, causing them to become emaciated, display abnormal behavior, lose coordination and eventually die. Signs of the disease include excessive salivation, loss of appetite, progressive weight loss, excessive thirst and urination, listlessness, teeth grinding, a lowered head and drooping ears, according to the U.S. Centers for Disease Control and Prevention.

To date, there have been no reported cases of CWD infection in humans, but recent studies in primates raise concerns that there may be a risk to people. Since 1997, the World Health Organization has recommended that it is important to keep the disease from entering the human food chain. CWD was first detected in northern Colorado and southern Wyoming in the late 70s, Class said.

Despite some regional gains in mule deer populations, numbers have been trending down over the past decades across the west. Class cited disease and competition for habitat — especially with elk — as some of the many possible reasons for the decline in Wyoming. He noted Idaho has yet to find CWD in the state, but is still seeing declines in mule deer populations.

“The take home message for Park County folks is we are going to continue to do surveillance and keep an eye on prevalence to make sure it doesn’t get away from us up here,” he said. “As part of that effort, we need hunters to bring us their samples.”

The department is encouraging hunters to bring in the heads of their harvests for testing and will take samples at regional offices through the end of the season. Hunters can also stop in the office to pick up a kit to collect elk blood for testing as well.

Class said Park County hunters have been very good at responding to requests.

“They are answering the call and I’ve been very impressed with participation levels,” he said.

Class is the newest addition to the department headquarters in Cody and supervises all area wildlife biologists. He transferred to the area from Laramie and is originally from upstate New York.

“I always knew I wanted to be out West and work with wildlife,” Class said.

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