The nation’s first national park just announced its first-confirmed case of chronic wasting disease (CWD). The deadly neurological disease was found in an adult mule deer buck near the shores of Yellowstone Lake in Yellowstone National Park sometime this fall, and the discovery was made public yesterday. According to the National Park Service (NPS), a team of biologists tracked down a CWD-infected deer after its radio collar began emitting mortality signals back mid-October 2023.

“In coordination with Yellowstone staff, [the Wyoming Game & Fish Department] located the carcass on the Promontory, a landmass that separates the South and Southeast arms of Yellowstone Lake and collected samples for testing,” reads a November 14 statement issued by NPS. “The samples tested positive for CWD based on multiple diagnostic tests performed at WGFD’s Wildlife Health Laboratory.”

NPS said there’s “no effective strategy to eradicate CWD” now that it’s established inside the 2.2 million-acre park. According to its press release, the agency will work with the Wyoming Game and Fish Department (WGFD)—and other wildlife agencies in states that border Yellowstone—to pin-point areas with increased risk for further spread of the disease. That includes monitoring other deer species like elk and moose, which can also contract and transmit always-fatal illness.

The CWD-infected muley was originally captured and fitted with a radio-tracking device in March near Cody, Wyoming, a gateway town about 80 miles east of the Yellowstone Lake area by road. It was part of a population dynamics study being conducted by WGFD biologists. In its recent press release, NPS said that “10-15% of the mule deer near Cody, Wyoming, that migrate into the southeast portion of Yellowstone during summer months are estimated to have CWD.”

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CWD has been spreading across Wyoming since the mid-1980’s and is now found throughout most of the Cowboy State, NPS states. It was first detected in Montana, another state that includes portions of Yellowstone, back in 2017. In neighboring Idaho—which includes a thin sliver of Yellowstone’s far-western border—the disease wasn’t confirmed until 2021.