CWD Found in Big Horn Basin

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Two mature mule deer bucks harvested in hunt area 127 immediately northwest of Thermopolis have tested positive for chronic wasting disease (CWD), a fatal brain disease that can affect all members of Wyoming’s deer family. CWD had not previously been detected in this area.

Worland Wildlife Biologist Bart Kroger collected lymph nodes from the deer Oct. 17 as part of the Wyoming Game and Fish Department’s CWD surveillance effort. Both samples were tested at the department’s laboratory in Laramie and tested positive for CWD.

CWD testing is a two-pronged approach, according to Cody Region Wildlife Management Coordinator Kevin Hurley. “The first test is an immunologic test called the ELISA. When a sample tests positive, it is termed a ‘presumptive positive’ until the results from a second IHC (immunohistochemistry) test is known,” Hurley said. “In nearly every case, when the ELISA turns up a presumptive positive, it is confirmed positive by the IHC.”

The two samples from area 127 tested positive for first the ELISA test and then the IHC test on Oct. 28.

In an effort to manage the spread of CWD and to understand how widespread it might be in an area, the department considers taking aggressive actions when cases are found in new areas. In this case, Game and Fish Deputy Director Gregg Arthur has instructed personnel in the Cody region to remove up to 50 deer within a five-mile radius of where the area 127 deer were harvested.

“I have asked our Cody personnel to move forward and collect additional samples. This action is consistent with the best science and the department’s CWD Management Plan,” Arthur said. He added that surveillance in other states has shown that it may be possible to slow down the spread of CWD if new cases of CWD are identified early.

According to Arthur, the additional sampling serves three purposes. First, it allows the Game and Fish to determine the prevalence of CWD in an area. Secondly, it may eliminate CWD in an area and prevent its spread to other areas. And thirdly, it may allow the Game and Fish to locate an area of infection that it can manage aggressively.

“Should more positives turn up, we will expand our efforts,” Arthur said.

The Game and Fish will conduct the removal harvesting both adult males and females between Oct. 27 and mid-November during daytime and nighttime hours. Research has demonstrated that samples taken from adult males and adult females are more likely to indicate if CWD is present than taking samples from younger-aged animals.

All of the animals collected will be field dressed and held in cold storage until the absence or presence of CWD in each is known. The meat from deer testing negative will be donated to individuals and families in need. Carcasses testing positive will be disposed of in an approved landfill in accordance with the Game and Fish CWD transportation regulation.

CWD is a fatal neurological disease that has been diagnosed in wild deer and elk in 10 states and two Canadian provinces. Animals show no apparent signs of illness throughout much of disease course. In terminal stages of CWD, animals typically are emaciated and display abnormal behavior.

There is no confirmed link between CWD and any human illness.