Potential First Case of Chronic Wasting Disease in Washington Mule deer Under Examination

SPOKANE, WA – January 7, 2026 – The Washington Department of Fish and Wildlife (WDFW) is investigating a potential case of chronic wasting disease (CWD) in a mule deer harvested in Ferry County. While initial testing by a private company came back positive, subsequent testing by WDFW yielded inconclusive results, prompting further investigation.

What is Chronic Wasting Disease?

Chronic wasting disease (CWD) is a fatal, neurological disease affecting cervids – animals like deer, elk, and moose. It’s caused by misfolded proteins called prions, which damage the brain and other tissues. According to the Centers for Disease Control and Prevention (CDC), CWD has been found in 31 states, as well as Canada, Norway, South Korea, Sweden, Finland, and Russia.

The Recent Case in Washington

In October, a hunter harvested a mule deer in Game Management Unit (GMU) 101. Instead of submitting the required samples to WDFW for testing, the hunter sent a muscle tissue sample to a private laboratory. This lab reported a positive result for CWD. WDFW Police persistent the hunter acted in good faith and did not intentionally violate CWD regulations.

The hunter preserved brain tissue, which WDFW then submitted to the washington Animal Disease Diagnostic Laboratory (WADDL).However, WADDL’s testing was inconclusive because the sample lacked the brainstem, which is crucial for official CWD diagnosis. WDFW does not recognize tests from commercial laboratories as officially validated for CWD detection due to concerns about accuracy and the type of tissue sampled.

Why Official Testing Matters

According to WDFW, reliable CWD detection requires testing specific lymph nodes or the brainstem by USDA-approved laboratories like WADDL. These labs use standardized procedures to ensure accurate results. Hunters are legally required to submit samples from harvested animals in areas where sampling is mandatory, currently all 100-series GMUs in Washington.

While hunters can utilize third-party testing, it does not supersede the requirement for official WDFW submission.Dr. Kristin Mansfield, WDFW’s state wildlife veterinarian, emphasized, “This case underscores how vital it is for hunters to follow the department’s CWD sampling requirements and transport restrictions. These rules are necessary to provide managers with credible and actionable details, limit the disease’s spread, and ultimately minimize its impact to our state’s deer, elk, and moose populations.”

WDFW’s Response and Ongoing Monitoring

WDFW is communicating with tribal partners and officials in British Columbia due to the proximity of this potential case to their jurisdictions. To date, WDFW has confirmed eight cases of CWD in Washington. Information on confirmed cases and CWD regulations can be found on the WDFW CWD webpage.

Key Takeaways

• A potential case of CWD in a mule deer is under investigation in Ferry County,Washington.
• Initial testing by a private lab was positive, but WDFW testing was inconclusive.
• Official CWD testing requires specific tissue samples (lymph nodes or brainstem) analyzed by USDA-approved laboratories.
• Hunters are required to submit samples to WDFW in mandatory sampling areas.
• WDFW is working with partners to monitor and manage CWD in the state.