chronic wasting disease

States in the Midwest are continuing efforts to combat chronic wasting disease in deer populations. 

As of March 6, 2019, there were 270 counties in 24 states with reported CWD in free-ranging cervids. This map is based on the best-available information from multiple sources, including state wildlife agencies and the United States Geological Survey (USGS).

State officials remain concerned over chronic wasting disease being found in an additional Iowa county earlier this year.

Dubuque County was added to the list that already included Allamakee and Clayton counties in northeast Iowa and Wayne County in south central Iowa. CWD was first discovered in 2013 in Iowa.

“We are always watching where cases are confirmed in Wisconsin or Illinois,” said Terry Haindfield, a wildlife biologist with the Iowa DNR who oversees the CWD program. “Deer have been known to swim across the Mississippi River or walk across the frozen river into Iowa.”

The disease has also been detected near the border in Missouri and southeast Minnesota.

CWD is a neurological disease appearing in deer, elk, moose and other members of the cervid family. It is always fatal. The disease cannot be transmitted to other species, and there is no evidence of CWD being transmitted to humans.

Haindfield said the number of deer found with CWD is very small when compared to Iowa’s deer population.

The DNR implemented a special collection program, using hunters to help gauge the disease’s distribution.

“We wanted to target animals that didn’t look healthy,” he said. “We found none with CWD, which is very good news.”

He said hunters are encouraged to report any suspicious deer they see or harvest.

Learning from states with more cases of CWD could help limit numbers in Iowa, said Julie Blanchong, a wildlife ecologist with Iowa State University.

“The best thing to do is to look at other states and provinces that have found CWD in their free-ranging deer and see what happened,” Blanchong said in a news release. “In most instances, you find more cases over time.”

She said symptoms in infected deer include severe weight loss, as well as stumbling and disorientation. However, visible symptoms may take a year and a half or longer to appear.

Blanchong said the disease spreads from one deer to another via physical contact and through secretions such as saliva, blood, feces and urine. Secretions that contain infected prions can contaminate the environment for lengthy periods of time and facilitate transmission of the disease.

She said there is no vaccine or treatment for CWD.

Some localized areas in Wisconsin indicate nearly 50% of adult male deer are likely infected, and Blanchong said the transient nature of deer can quickly spread CWD. Variables such as availability of habitat, the presence of roads or waterways and other factors can influence how far deer travel.

Blanchong said while there is no risk to livestock such as cattle and sheep, a diseased deer population could lead to changes in hunting and conservation practices. A large outbreak could deeply impact the rural environment, she adds.

“Deer are an important part of their ecosystems,” Blanchong said. “When we start forecasting far into the future, it’s hard to know exactly what changes CWD could cause, but it’s possible we could see changes in deer populations and how we manage those populations.”

Jeff DeYoung is livestock editor for Iowa Farmer Today, Missouri Farmer Today and Illinois Farmer Today.