U.S. Department of the InteriorU.S. Geological Survey

Fact Sheet 2019-3034July 2019Printed on recycled paper

U.S. Geological Survey Response to Chronic Wasting DiseaseThe USGS is focused on the development  of early detection and effective response tools that promote an adaptive management  approach to Chronic Wasting Disease.

OverviewChronic wasting disease (CWD), a fatal contagious 

neurological disease, affects free-ranging and captive cervids (members of the deer family) such as elk (Cervus elaphus), moose (Alces alces), white-tailed deer (Odocoileus virginianus), and mule deer (Odocoileus hemionus). It is transmitted directly through animal-to-animal contact, and indirectly through contact with objects or an environment contaminated with infectious material (including saliva, urine, feces, and carcasses of CWD-infected animals). CWD is not known to affect humans or livestock. CWD, similar to scrapie in sheep and bovine spongiform encephalopathy (mad cow disease) in cows, is caused by prions—pathogenic agents that mostly consist of an abnormal, infectious form of a host protein primarily found in the brain and central nervous system tissues of mammals. 

CWD was initially identified in captive animals in the late 1960s and in free-ranging animals in the 1980s. Since its initial identification in Colorado, CWD continues to spread and has affected cervids in 26 States in the United States and 3 Provinces in Canada, as well as in Finland, Norway, South Korea, and Sweden. 

Importance of CervidsHealthy cervid populations are critical 

to biodiversity—these species serve as a middle link in the food chain between the plants they consume and the predators that prey on them. Cervids are also a popular game species providing avaluable food source for many an

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considered Tribal cultural resources and traditional food sources across the United States (Great Lakes Indian Fish and Wildlife Commission, 2018).

Cervids are an integral and charismatic presence in the fabric of the U.S. landscape and an important element in the Nation’s economy. Elk and deer are coveted among hunters and wildlife watchers throughout the country. According to the Outdoor Industry Association (2017), hunting and fishing contributed $63 billion to U.S. retail spending in 2017, and sales of permits and licenses for hunting and fishing support State wildlife agency budgets.   

In 2016, according to the U.S. Fish and Wildlife Service and U.S. Census Bureau (2018), 9.2 million hunters pursued big game such as deer and elk, with deer being the most popular and attracting  8.1 million hunters across the United States. Deer were also among the most popular land mammals observed or photographed by  14 million people. 

In areas of Colorado, Wisconsin, and Wyoming heavily affected by CWD, more than 40 percent of free-ranging cervids are infected. Scientists at the U.S. Geological Survey (USGS) Wyoming Cooperative Fish and Wildlife Research Unit (CRU) and their collaborators have documented CWD-associated population declines in white-tailed deer and mule deer. The effects of CWD on these biologically, culturally, and economically valuable animals could be devastating if measures  are not taken to prevent its spread and persistence  in wildlife and the environment.

A white-tailed deer displaying clinical signsof chronic wasting disease including weight loss, poor body condition, and hypersalivation.

Mule deer 

Elk grazing.

Mapping the Spread of Chronic Wasting Disease

The USGS National Wildlife Health Center (NWHC) maintains an online map (https://go.usa.gov/xmDTH; Richards, 2019) for North America that documents the expanding distribution of CWD. Map data originate from State wildlife agencies, the U.S. Department of Agriculture, and the Canadian Food Inspection Agency and represent best-available information. This map is used and cited by Federal, State, and academic partners to monitor the spread of the disease.

USGS ResearchUSGS scientists across the United States are working to 

understand the biology of CWD; assess and predict the spread and persistence of CWD in wildlife and the environment; and develop tools for early detection and control.

Early Detection

The USGS has been instrumental in conducting risk assessments and developing CWD surveillance strategies for early detection.

Scientists at the USGS NWHC, in collaboration with those at the National Park Service, Wisconsin Department of Natural Resources, and Minnesota Department of Natural Resources, have recently developed a new statistical application  (https://popr.cfc.umt.edu/CWD/) that allows scientists and managers to conduct surveillance of white-tailed deer populations by targeting animals at highest risk of CWD. Use of this application may improve the early detection of CWD in white-tailed deer and allow management agencies to mitigate the emerging wildlife threat, saving valuable time  and resources. 

Scientists at the USGS NWHC, in collaboration with those at the State wildlife agencies in Iowa, Michigan, and Minnesota, Kansas State University, the University of Wisconsin, and the U.S. Department of Agriculture, are developing advanced mathematical models that provide robust, data-driven tools capable of forecasting CWD spread based on historical trends. The tools will provide information for managers to target surveillance and management efforts in areas of high CWD risk and fastest spread.  

CWD in captive facilities(depopulated)

CWD in captive facilities(current)

All locations are approximations based on best-available information

Distribution of Chronic Wasting Diseasein North America

Known distribution prior to 2000(free-ranging)

CWD in free-ranging populations

EXPLANATION

CWD in captive facilities (depopulated)

CWD in captive facilities (current)

Distribution of Chronic Wasting Disease (CWD)    in North America as of June 2019.

Known distribution prior to 2000 (free-ranging)

CWD in free-ranging populations

EXPLANATION