CWD

Wildlife managers want big game hunters to provide lymph nodes, like the one pictured, for chronic wasting disease testing. The Wyoming Game and Fish Department has created “priority herds” that will receive more attention from disease biologists looking to collect such samples.

The Pinedale and Afton elk herds are western Wyoming’s two first “priority herds” that will be exhaustively tested for chronic wasting disease, and wildlife managers want a little help from hunters.

Hunters who kill an elk well away from a road in the backcountry often leave a central nervous system gland called a retropharyngeal lymph node alongside their gut piles out in the field, where it’s nearly impossible to acquire for testing. Now, in hopes of sampling enough of the nodes to determine whether CWD exists in each herd, Wyoming Game and Fish Department personnel like Regional Disease Biologist Ben Wise are asking hunters to learn the extraction process so they can turn over lymph nodes.

“As an agency, we’re looking at ways to improve our sampling, especially in the western side of the state and in these priority herds,” Wise said. “What’s happened is that folks follow our guidelines for CWD, and when they pack an animal out they’re leaving all the stuff that we could use for sampling in the field.”

The retropharyngeal lymph node is a fatty tissue about the size of a gummy bear that’s located near the esophagus of elk and other ungulates. Although brainstems and other bodily matter can also reveal prions, the infectious vector of CWD, the lymph nodes are the preferred tissue for testing. (See a video of Wise extracting one of the nodes posted alongside this story at JHNewsAndGuide.com.)

Invariably fatal, CWD is an condition similar to mad cow disease that has been spreading slowly around Wyoming and the world over the last four decades. It could devastate big game hunting because of its potential to drive down populations of ungulates and render infected animals, which can account for 25% to 50% of specimens in some Wyoming mule deer herds, unsafe to eat.

Prions are nearly indestructible misfolded proteins. CWD reached the region where elk are closely congregated and spreading density-dependent diseases on feedgrounds within the last few years. Its presence became official in Jackson Hole with a road-killed mule deer buck found last fall near Kelly.

Wildlife managers like Wise are trying determine when disease crosses over from deer to elk, and in order to statistically make that determination in elk herds they need hundreds of samples. In some herds, like the Jackson Herd, that’s relatively easy, because hundreds of animals are killed annually in relatively confined late-season hunts on the National Elk Refuge and in Grand Teton National Park.

In other herds, where the hunting is earlier and animals more dispersed, rounding up scores of lymph nodes is much trickier. Designating “priority herds,” Wise said, is an idea born of Game and Fish’s CWD Working Group, and tactic that will allow the agency to overcome manpower and funding limitations.

“The idea is that our lab doesn’t have the capacity nor do we have the capacity on the ground to sample at a statistically significant level throughout the state,” Wise said. “For the Jackson Region, our priority herd for the year is Afton elk.”

Based on where the Afton elk roam, hunters who punch their tags in elk units 88 through 91 are being asked to turn over lymph nodes. Those units cover the entirety of the Salt River Range and Wyoming Range, and also mountainous country along the Idaho state line. Come rifle season on Oct. 15, Game and Fish’s CWD technicians will be working throughout that region.

The “priority herd” in Game and Fish’s Pinedale Region is the Pinedale Herd, which is found in elk hunt units 97 and 98, which sprawl out along the southwest slope of the Wind River Range.

There are no northwest Wyoming priority deer herds this year, but the Sublette Herd, which ranges into Jackson Hole, might be selected next year, Wise said.

Outside of the new priority herd-sampling scheme, hunters can still test their animals through Game and Fish for free. Results come back in about three weeks, though they can be expedited for a $30 fee. With the arrival of CWD to Jackson Hole, hunters often want to know whether their animal is infected.

“It seems like interest has really peaked in CWD,” Wise said, “and people want to get their animals tested.”

Contact Mike Koshmrl at 732-7067 or env@jhnewsandguide.com.

Mike has reported on the Greater Yellowstone Ecosystem's wildlife, wildlands and the agencies that manage them for 7 years. A native Minnesotan, he arrived in the West to study environmental journalism at the University of Colorado.

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