CWD Becoming More Common

Doug Leier

By Doug Leier

Through continued news cycles we hear more and more about chronic wasting disease today. Even so, there are likely people still not familiar with the disease and others who haven’t taken the time to stay current and may have some questions.

What is chronic wasting disease?

Chronic wasting disease is a progressive, fatal disease of the nervous system of white-tailed deer, mule deer, elk and moose. It belongs to a family of diseases known as Transmissible Spongiform Encephalopathies, or prion diseases. Although CWD shares certain features with other TSEs, like bovine spongiform encephalopathy (BSE or mad cow disease), scrapie in sheep and goats, and Creutzfeldt-Jakob disease in humans, it is a distinct disease apparently affecting only deer, elk and moose. It causes damage to portions of the brain; creating holes in the brain cells and causing a sponge-like appearance.

Where is it found?

The origin of CWD is unknown and it may never be possible to definitively determine how or when CWD arose. It was first diagnosed in a Colorado elk research facility in 1967 and a few years later in a similar Wyoming research facility. It was later discovered in wild elk and deer near those facilities in Colorado and Wyoming. The known distribution of CWD in wild deer, elk, and moose includes many states and regions from wild populations in Arkansas and Colorado to Illinois, Iowa, Kansas, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, New

Mexico, New York, North Dakota, Pennsylvania, South Dakota, Texas, Tennessee, Utah, Virginia, West Virginia, Wisconsin, Wyoming, including Canadian provinces of Saskatchewan, and Alberta.

CWD also has been found in farmed elk or deer herds in Colorado, South Dakota, Nebraska, Kansas, Iowa, Missouri, Ohio, Oklahoma, Texas, Montana, Minnesota, Wisconsin, Ontario, Quebec, Saskatchewan, Alberta and South Korea. CWD has also been found in wild moose and reindeer in Scandinavia.

How common is it?

CWD has unfortunately become more prevalent in recent years. In Wisconsin, CWD infects about 25-30% of the deer in its core management zone. In other areas, percentages of infected animals range from 0-30% in deer and wild elk. The number of animals diagnosed with CWD has steadily increased in recent years. It has also been found in numerous new locations where the disease was not previously detected. CWD was first detected in North Dakota in a mule deer buck in the southwestern part of the state more than a decade ago.

What wildlife species are affected by CWD?

Most members of the cervid family are known to be naturally susceptible to CWD: elk, mule deer, white-tailed deer and moose. Susceptibility of other members of the deer family and other wildlife species is variable and depends on the nature of and route of exposure.

With most chronic wasting disease testing completed, the North Dakota Game and Fish Department reports 26 deer tested positive during the 2021 hunting season. Fourteen were from hunting unit 3F2, eight from unit 3A1, and one was found in unit 3B1. Single positive deer were also found in three units (3C, 3D1 and 3E2) where the disease had not been previously detected. CWD is a fatal disease of deer, moose and elk that can cause long-term population declines as infection rates climb. The estimated infection rates in unit 3F2 were 4.9% in mule deer and 3% in whitetail deer. In unit 3A1, the estimated infection rate in mule deer was 6.9%. Approximately 4.9% of hunters turned in heads for testing in units where the Department was

focusing surveillance efforts. Game and Fish will use its 2021 surveillance data to guide its CWD management strategy moving forward. More information about CWD can be found at

Leier is an outreach biologist with the North Dakota Game & Fish Department.

Featured Photo: The number of animals diagnosed with CWD has steadily increased in recent years. NDG&F Photo.

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