Wildlife in Wyoming / More Wildlife / Wildlife Health / Chronic Wasting Disease in Wyoming Wildlife

Chronic Wasting Disease (CWD) in Wyoming Wildlife


What is Chronic Wasting Disease?

Chronic wasting disease (CWD) is a chronic, fatal disease of the central nervous system in mule deer, white-tailed deer, elk, and moose. CWD belongs to the group of rare diseases called transmissible spongiform encephalopathies (TSEs). These disorders are caused by abnormally folded proteins called “prions.”

What do deer and elk with CWD look like?

Early in disease, animals may show no clinical signs. Later on, affected animals show progressive weight loss, reluctance to move, excessive salivation, droopy ears, increased drinking and urinating, lethargy, and eventually death. Animals will test positive for the disease long before these clinical signs appear and the majority of CWD positive animals that are harvested appear completely normal and healthy.

How is CWD transmitted?

Evidence suggests that CWD is transmitted via saliva, urine, feces, or even infected carcasses. Animals may also be infected through the environment via contamination of feed or pasture with CWD prions (which can persist for many years). The most likely route of exposure is through ingestion.

Where is CWD found in Wyoming?

CWD was first identified in free-ranging mule deer in southeastern Wyoming in 1985, followed by elk in 1986. Based on early surveillance data and prevalence estimates, a small area in southeastern Wyoming containing the Laramie Mountain mule deer herd, South Converse mule deer herd, Goshen Rim mule deer herd and Laramie Peak elk herd was termed the “core endemic area” where we believe that CWD has been present for the longest period of time. Over the past 20 years, surveillance data has shown an increase in prevalence and distribution of CWD in Wyoming, particularly in deer.  CWD is now found across the majority of the state, with new detections suggesting continued westward spread of the disease.

Click map for interactive CWD map

How does CWD impact deer, elk, and moose populations?

Recent research in Wyoming has demonstrated declines in both mule and white-tailed deer populations in deer hunt area 65 due to CWD (see below for citations). These declines are in the core endemic area where prevalence is highest. In areas with lower prevalence, effects of CWD are poorly understood but are considered additive along with other factors that can negatively affect deer populations in Wyoming (i.e. habitat loss, predation, other diseases). 
The distribution and prevalence of CWD in Wyoming elk is less than that of deer.  Currently there are no documented direct population impacts in Wyoming elk from CWD; however, research from Rocky Mountain National Park suggests that CWD could impact elk populations at higher prevalence (13%). While CWD has been found in free ranging moose, there have been few detections, and there is no evidence that CWD is currently having an impact on moose populations.

Is it safe to eat a CWD infected animal?  What precautions should I take?
To date, there have been no cases of CWD in humans and no direct proof that humans can get CWD.  However, animal studies suggest CWD poses a risk to some types of non-human primates, like monkeys, that eat meat from CWD-infected animals. These experimental studies raise the concern that CWD may pose a risk to humans and suggest that it is important to prevent exposures to CWD.  Therefore, the Centers for Disease Control and the World Health Organization recommend that CWD positive animals not be consumed.  The Wyoming Health Department has also compiled info on human health and prion diseases.  For recommendations for simple handling precautions when processing your harvested animal, see this link…..Handling Precautions
What can you do to help?

• Have your harvested animal tested for CWD to help with our statewide surveillance program. See this link for information on having your harvested animal tested, and sampling guides for collecting your own sample….Sample and Testing Info

• Report sick deer, elk, and moose. Contact the Wyoming Game and Fish Department to report sick animals. Removing CWD positive animals from the landscape can help to minimize transmission of the disease.

• Be aware of carcass transport regulations that apply to animals harvested in hunt areas where CWD is known to occur. See this link for further information on carcass transport…..Proper Carcass Disposal and Transport

Information and Reports Regarding Chronic Wasting Disease in Wyoming's Wildlife

Wyoming CWD Management Plan

WGFD Chronic Wasting Disease Surveillance Report (2022)

WGFD Chronic Wasting Disease Surveillance Report (2021)

WGFD Chronic Wasting Disease Surveillance Report (2020)

WGFD Chornic Wasting Disease Surveillance Report (2018-2019)

WGFD Chronic Wasting Disease Surveillance Report (2017)

WGFD Chronic Wasting Disease Surveillance Report (2016)

Chronic Wasting Disease Article - Wyoming Wildlife - April-2018

CWD in Wyoming Publications

     LaCava ME, Malmberg JL, Edwards WH, Johnson LN, Allen SE, Ernest HB. Spatio-temporal analyses reveal infectious disease-driven selection in a free-ranging ungulate. Royal Society Open Science. 2021 Aug 11;8(8):210802.

      Monello RJ, Galloway NL, Powers JG, Madsen-Bouterse SA, Edwards WH, Wood ME, O’Rourke KI, Wild MA. Pathogen-mediated selection in free-ranging elk populations infected by chronic wasting disease. Proceedings of the National Academy of Sciences. 2017 Oct 30:201707807.

     DeVivo MT, Edmunds DR, Kauffman MJ, Schumaker BA, Binfet J, Kreeger TJ, Richards BJ, Sch√§tzl HM, Cornish TE. Endemic chronic wasting disease causes mule deer population decline in Wyoming. PloS one. 2017 Oct 19;12(10):e0186512.

     Edmunds DR, Kauffman MJ, Schumaker BA, Lindzey FG, Cook WE, Kreeger TJ, Grogan RG, Cornish TE. Chronic Wasting Disease Drives Population Decline of White-Tailed Deer. PLoS One. 2016 Aug 30;11(8):e0161127.


Below are some links for more information on CWD

Chronic Wasting Disease Alliance website
World Health Organization
Center for Disease Control

CWD Monitoring and Surveillance
CWD Carcass Disposal and Transport

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