Chronic Wasting Disease Surveillance

CWD is a fatal neurologic disease of cervids (e.g., deer, elk, moose, reindeer). It is caused by a misfolded form of a normal protein, known as a prion. The misfolded proteins aggregate in tissues, particularly the brain, causing progressive damage. CWD belongs to a group of human and animal diseases called transmissible spongiform encephalopathies (TSE). Examples of TSEs in animals include bovine spongiform encephalopathy (BSE) in cattle, also known as “mad cow disease,” and scrapie in sheep and goats, which has been known to veterinary medicine for over 200 years. Creutzfeldt-Jakob disease (CJD), a sporadic prion disease arising in 1:1,000,000 people, and variant Creutzfeldt-Jakob disease (vCJD), which has been linked to the consumption of infected cattle during the “mad cow disease” outbreak in Great Britain and Europe in the 1990s, are examples of TSEs in humans.

The misfolded prion that causes CWD is infectious to other cervids and can be spread through direct contact with infected individuals or through contact with a contaminated environment. Infectious prions can be excreted in urine, feces, and saliva of infected animals, even before they show any signs of the disease. Carcasses and tissues, especially brain, spinal cord, and lymph nodes, of infected animals contain infectious prions and may spread the disease if left out on the landscape. Prions are very stable and difficult to disinfect, persisting for years in a contaminated environment able to infect a susceptible deer or elk.

Chronic wasting disease (CWD) was first described in mule deer at a captive facility in Colorado in 1967. Since then, CWD has been diagnosed in free-ranging deer, elk, and moose populations in 34 states (now including California) and four Canadian provinces. It has also been found in captive elk and Sika deer in South Korea, free-ranging moose and reindeer in Norway, and free-ranging moose in Finland. For a map of current known CWD infected populations in North America, please visit the United States Geological Survey (USGS) CWD page. A timeline of the spread of CWD can be found by visiting the Chronic Wasting Disease Alliance website.

The progression of chronic wasting disease (CWD) in an infected animal is very slow. It takes months or even years following infection for clinical signs of CWD to appear. Infected animals gradually become skinnier, emaciated or “wasted” despite continuing to eat. They may show abnormal behaviors such as a wide stance, staggering gait, or inability to keep their head up.

Chronic wasting disease has now been detected in California’s deer/elk populations. If you see a sick or dead deer that could be due to CWD, please use our online mortality reporting form (preferred) or contact the CDFW  Wildlife Health Laboratory directly at (916) 358-2790. It is important to note that many other conditions that affect deer in California can produce similar clinical signs. However, the Department’s Wildlife Health Laboratory investigates sick or dead wildlife and is particularly interested in deer and elk that display clinical signs consistent with CWD: skinny or “wasted,” abnormal behavior, staggering gait, head and ears lowered. Testing these animals for CWD is an integral part of ongoing CWD surveillance efforts in California, and we rely on members of the public to report sick and dead animals. 

Prevention: Legislation and regulations enacted since the 1990's help keep the risk of importing the disease to a minimum. These include severely limiting the importation of captive deer and elk (and other cervids) into California (CCR Title 14, Section 671)), limiting what hunters can bring in from out-of-state hunts (no skull, no backbone) (CCR Title 14, Section 712)), and banning the feeding of wildlife to prevent artificially congregating susceptible animals (CCR Title 14, Section 251.3).

Surveillance: Since 1999, California has tested over 6,500 deer and elk for CWD, the majority from hunter-harvested animals. In 2017, CDFW developed and implemented a statewide CWD surveillance plan, renewing our active CWD surveillance program and increasing yearly CWD testing goals. 

Management: CDFW initiated an interagency CWD Task Force to develop and implement a CWD management plan. The surveillance portion of that has been implemented and the task force is working to finalize the management plan.

There are no documented cases of CWD affecting a human. However, the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recommend that hunters do not eat meat from deer that test positive for CWD or otherwise appear sick. In addition, CDFW recommends that hunters wear latex or nitrile gloves when field-dressing and processing animals, and that hunters wash their hands and disinfect tools after processing.

Currently, the only approved tests for CWD require lymph node or brainstem samples, taken after death, to detect the prion associated with CWD. However, this is an area of considerable research and we hope additional rapid and live-animal tests become available in the future. 

• Check the “CDFW Sampling Station” page before you go hunting to look for a voluntary CWD sampling station near you. This is updated before and during the hunt season.
• Call or email the Wildlife Health Laboratory about other testing options for your harvested deer or elk at (916) 358-2790 or cwd@wildlife.ca.gov

• Check the "Find Your CWD Testing Results" tab, use the document number on your deer tag to find your results.
• With the recent detection of CWD in California's deer population, hunters should now consider the possibility of infected meat. It's advisable to wait for test results before consuming harvested animals to ensure safety.

• Baits artificially congregate wildlife, can change their normal behaviors, and increase the likelihood of spreading diseases, including CWD.

• These scent lures are produced using deer urine, which can contain infectious CWD prions. It is one way CWD can be imported into California.
• Best practices are to avoid using any urine or other biologically based scent lures for hunting in California to protect against inadvertently importing CWD prions.

Field dress your harvest and leave everything you can at the site of harvest, especially brain and spinal cord, unless taking head for sampling or taxidermy.

• Remember CCR Title 14, Section 712 regulations import restrictions and Section 2353 Fish & Game Code declaration requirements when bringing any harvested cervid parts back to California.
• Check the CWD status of state you are planning to hunt in and review the regulations concerning CWD for that state.
• If the state you plan to hunt has CWD, visit the web page or call the Fish and Wildlife agency for the state you plan to hunt to understand local distribution of CWD where you plan to hunt, whether there are any statewide or hunt zone specific CWD testing requirements, and how to get your harvest tested.
• The Chronic Wasting Disease Alliance maintains a great up to date resource about the latest news regarding this disease and its spread.
• CWD-Related Hunting Regulations
• CWD in North America

• CCR Title 14, Section 712 regulations. Restriction of Importation of Hunter-Harvested Deer and Elk Carcasses.
  • It is unlawful to import, or possess any hunter harvested deer or elk (cervid) carcass or parts of any cervid carcass imported into the State, except for the following body parts:
    • (a) portions of meat with no part of the spinal column, brain or head attached (other bones, such as legs and shoulders, may be attached).
    • (b) hides and capes (no spinal column, brain tissue or head may be attached).
    • (c) clean skull plates (no brain tissue may be present) with antlers attached.
    • (d) antlers with no meat or tissue attached, except legally harvested and possessed antlers in the velvet stage are allowed, if no meat, brain or other tissue is attached.
    • (e) finished taxidermy mounts with no meat or tissue attached (antlers in the velvet stage are allowed if no meat, brain or other tissue is attached).
    • (f) upper canine teeth (buglers, whistlers, ivories).
• Basically, “no skull, no backbone” to avoid importing the highest risk tissues for carrying prion.
• Best practice and best recommendation is to only bring back packaged meat and/or finished taxidermy mounts.

• CDFW cannot test “meat” for CWD. While it is possible to test for and detect CWD prions in meat and other tissues, these tests are currently only available in specialized research labs and not for diagnostic or consumer use. 
• There is no “meat safety” test for CWD. For current testing options, results are reported as “Detected” or “Not Detected” for CWD and other prion diseases. That means we can be certain an animal is positive for CWD if the prions are “detected” but we cannot be certain the animal did not have CWD if the results are “not detected.” This is one of the major issues surrounding CWD and other prion diseases and is in large part because of the attributes of the pathogen itself (the prion) and the sensitivities of the currently available tests 
• Furthermore, if you brought back only the parts allowed by  CCR Title 14, Section 712 regulations, then the samples needed to perform an official CWD test are not available. These are the retropharyngeal lymph nodes or brainstem.
• Best practice is to have your animal tested for CWD in the state you are hunting, especially if that state or region has CWD. As such we recommend doing some research before hunting out-of-state to determine 1) CWD status of the state you are hunting in and 2) how to get an animal tested for CWD in the state it was harvested.
• Some labs such as Colorado State University Diagnostic Veterinary Laboratory or the Texas A&M Veterinary Medical Diagnostic Laboratory allow hunting public to submit samples themselves for testing for a fee.

• Any harvested animal, or parts of, brought into California must be declared using CDFW’s Declaration/Importation of Fish and Wildlife entry form (PDF).
• Best practice is to bring your animal into compliance with CCR Title 14, Section 712 regulations in the state you hunted as surrounding states have similar importation regulations for harvested deer and elk. Additionally, removing the skull and backbone at the CA border may bring you into compliance with California’s regulations, but it risks introducing CWD to our neighboring states.
• Many states have all passed similar rules to CCR Title 14, Section 712 regulations making it unlawful to move the banned parts of harvested cervids from outside states into California or any of its neighbors.
• If the checkpoint is closed or unmanned when you return to California you are still required to submit your Declaration for Entry Form to Department of Fish & Wildlife, 1416 9th Street, Law Enforcement Division, Sacramento CA 95814 within 24 hours after entering the state.
• Keep in mind other states along the way may also have regulations and checkpoints regarding the movement of wildlife across their state lines. Some states will not let you leave a CWD positive area without first removing the skull and backbone. 

• Best recommendation is to have the animal taxidermied in the state it was harvested.
• However, if you have a specific taxidermist you use in California or want to do your own taxidermy, then the CCR Title 14, Section 712 regulations still need to be followed. Only: 
  • “(b) hides and capes (no spinal column, brain tissue or head may be attached).
  • (c) clean skull plates (no brain tissue may be present) with antlers attached.
  • (d) antlers with no meat or tissue attached, except legally harvested and possessed antlers in the velvet stage are allowed, if no meat, brain or other tissue is attached.
  • (e) finished taxidermy mounts with no meat or tissue attached (antlers in the velvet stage are allowed if no meat, brain or other tissue is attached).
  • (f) upper canine teeth (bulgers, whistlers, ivories).” 
• If you would like to make a European mount, keep in mind that without completing the full preparation it is inevitable that infectious material associated with residual brain matter and the lining of the skull will be returned to California with the skull. Simply boiling the skull or pressure washing the skull will not destroy the prion and will not remove all the tissue. To comply with  CCR Title 14, Section 712 regulations no meat or tissue can remain on the skull.

• Both the U.S. Centers for Disease Control (CDC) and the World Health Organization (WHO) recommend not consuming any tissues from CWD-infected animals.
• Improper disposal of meat or other parts  from CWD-positive animals is believed to be the greatest risk for introducing CWD into different/ undetected areas of California’s deer and elk herds. Please do no bury, throw in the trash, leave out for scavengers, feed to your dog, or take to a landfill potentially contaminated meat or other tissues.
• Prions can survive in the environment for 10+ years, and can be absorbed by roots and distributed in growing forage. 
• Incineration is the safest disposal method for contaminated meat or tissues.
• Please call your local CDFW office or the Wildlife Health Laboratory at (916) 358-2790, and we will arrange for the meat or tissues to be picked up and/or destroyed at no cost to you. Be prepared to provide the following information:
  • State of harvest
  • CWD test results
  • Location of harvest
  • Location of processing
  • Weight of meat to be destroyed
  • Contact information
• If your CWD positive animal was processed by a meat processor in California please be sure to inform your processor so that they can take the proper decontamination procedures.