With 2 CWD-positive deer, California becomes 34th state to report fatal disease

doe-oakridge, Lynn Freeny / Flickr cc

California has become the 34th state to detect chronic wasting disease (CWD), the California Department of Fish and Wildlife (CDFW) announced yesterday.

On May 6, officials received confirmation of the fatal prion disease after submitting samples collected from two deer, one in Madera County near Yosemite Lakes in central California and the other in Inyo County near Bishop, southeast of Madera County. The Madera County deer was found dead of unknown causes, and the Inyo County deer had died after being hit by a vehicle.

CWD likely undetected for some time

The CDFW has been monitoring elk and deer for CWD using lymph node testing of more than 6,500 cervids since 2000 and has been working with hunters, taxidermists, and meat processors to boost disease surveillance since 2018. But given that the affected counties don't share a border and the CWD incubation period can be months to years, officials said CWD has probably been in the state for some time.

CWD infected animals can excrete infectious prions before clinical signs appear and these prions can persist in the environment for years, making it very difficult to prevent or control the spread once it has been introduced.

Brandon Munk, DVM

"CWD infected animals can excrete infectious prions before clinical signs appear and these prions can persist in the environment for years, making it very difficult to prevent or control the spread once it has been introduced," Brandon Munk, DVM, of the CDFW, said in an agency news release.

"The public can help limit the spread of CWD by reporting any signs of illness in deer and elk populations, and hunters should strongly consider testing their harvested deer or elk," added Munk, who oversees the agency's CWD efforts. The CDFW provides surveillance, response, long-term management plans, and public outreach and education through its "No Time to Waste" campaign.

Illness so far known to infect only cervids

CWD, a neurologic disease caused by misfolded proteins called prions, affects cervids such as deer, elk, moose, and reindeer. The disease poses an ongoing threat to cervids, because it can spread from animal to animal and through environmental contamination.

It has also been confirmed in five Canadian provinces and in Norway, Finland, Sweden, and South Korea.

Signs of the disease include weight loss, uncoordinated movement, listlessness, excessive thirst or urination, drooling, drooping ears, and behavioral changes.

While CWD isn't known to infect people, the World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC) recommend against eating meat from an infected animal and urge taking precautions when field-dressing or butchering cervids.