DNR tests Iowa deer for wasting disease

The 2025 deer tags had not yet gone on sale when Iowa received its first positive case of chronic wasting disease for the 2025 survey season — a buck from Lucas County.

The Iowa Department of Natural Resources has been sampling deer from every county, every year since 2002, and while hunting season is when most samples are collected, collecting samples year-round helps to avoid gaps in surveillance.

Chronic wasting disease is an always fatal disease affecting deer, elk, moose and caribou. It is spread through direct contact and blood, urine and saliva left on the landscape.

“These latest positives are a good example of why we collect samples throughout the year — in these cases three road kills outside of hunting season — which is important because it allows us to implement management actions before hunting season, if necessary,” said Tyler Harms, biometrician with the Iowa DNR.

Initially, the Iowa DNR targeted areas with higher risk of finding the disease, which was Northeast Iowa, close to Southwest Wisconsin and Northwest Illinois where the disease had been found. The goal is to detect the disease as early as possible, providing the best chance to slow the spread through management practices.

“Detecting the disease as early as possible in new areas has always been the goal of our management. It's never changed,” Harms said. “We believe we’ve found it early in most places, with the exception being Marshall and Tama Counties, where the disease trajectory has indicated it's been there longer.”

The Iowa DNR built an online dashboard at iowadnr.gov/cwd to make surveillance data available to hunters providing large amounts of data since sample collection began in 2002. It is viewable by year, showing samples by counties along with where positive deer were found. This followed the initial ability for hunters who provided samples to look up their license information for their test results.

“Hunters care, they’re passionate, they want to do what they can to slow the spread of the disease,” Harms said. “We want to inform our hunters on the disease status in the state so they can make decisions for themselves, like whether or not they want to get their deer tested.”

Initially, tests were conducted on the brain stem, but as more was learned about the disease tests shifted to the lymph nodes, which were much more accessible than the brain stem.

“We made the change because science demonstrated lymph tissue was equally as sensitive or more so than the brain stem, and that increased the efficiency of our sampling,” Harms said.

Recently, the Iowa DNR shifted from a sample-based approach to a risk-based approach that considers factors like where samples are collected and the age or sex of the deer, reflecting advancing knowledge in how the disease spreads through a deer population.

“Sample collection is expensive, and we are working to make it as efficient as possible, collecting only the samples we need, to get the same information with fewer samples,” Harms said.

“In the end, the goal is to provide information to hunters so they can make an informed decision and to inform management actions to slow the spread of the disease.”

Harms, along with other staff at the DNR and Iowa State University Extension, have been holding classes, mostly in areas impacted by the disease, to educate a core group of interested hunters who will help to keep other hunters and landowners informed on the disease and to reduce misinformation.

Hunters interested in becoming more involved may consider attending a chronic wasting disease ambassador class.

More information is available on the ISU Natural Resources Extension website naturalresources.extension.iastate.edu/programs/chronic-wasting-disease-ambassadors.