DNR anticipates ‘significant rise’ in fatal deer disease as hunting season begins

Since the Iowa Department of Natural Resources held its last public meeting about chronic wasting disease one year ago, the agency has seen an increase in the number of confirmed cases. And they’re anticipating more in the next year as the fatal disease continues to spread among the state’s deer population.

“Unfortunately, a lot has changed in the state of Iowa,” said Rachel Ruden, a wildlife veterinarian with the DNR.

Chronic wasting disease, a “uniformly fatal” and highly contagious disease, is caused when “prions,” or misfolded proteins, attack the brain and nervous system of animals as it accumulates in their tissues. It predominately occurs in white-tailed deer, elk, moose and reindeer, and has been growing in Iowa and other Midwest and northern states.

During the 2023-24 surveillance season — April 1, 2023 to March 30, 2024 — the DNR recorded 128 positive cases, up from 96 the previous season, and 52 the season before that.

The disease also has spread to new counties. In 2023-24 it was confirmed in eight more counties than it had been found in during the 2022-23 surveillance season. In total, as of last year, deer in 25 of Iowa’s 99 counties had tested positive for chronic wasting disease.

According to the DNR’s chronic wasting disease surveillance page, so far in the 2024-2025 surveillance season, there have been 17 confirmed cases of the disease in seven Iowa counties. Two of those seven counties are new: Davis in southern Iowa, and Shelby in western Iowa.

With Iowa’s first shotgun deer hunting season opening Saturday, DNR officials expect that number to rise.

“Unfortunately, it's very likely that we will see a significant rise in CWD detections this season as the bulk of our sampling effort occurs during the firearm deer seasons, which are set to begin tomorrow,” Jace Elliott, white-tailed deer biologist for the DNR, said Friday.

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Ruden said although more Iowa counties are seeing cases of the disease, many of those counties have just one confirmed case of CWD.

The highest incidence of the disease is in northeast and south central Iowa. In Eastern Iowa, three counties — Dubuque, Jones and Muscatine — have reported positive cases of CWD since the state began testing for the disease in 2002.

There have been no reports of humans contracting chronic wasting disease.

‘A decade behind’

Iowa began testing deer for chronic wasting disease in 2002, when two of its neighboring states — Illinois and Wisconsin — reported their first positive detections. Iowa’s first positive case came in 2013.

Ruden said Iowa’s chronic wasting disease rates are still “pretty low” compared to other states. But she said the state is about a “decade behind” in testing for and managing the disease.

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In Iowa County, Wisconsin — where chronic wasting disease was first confirmed in 2002 — Ruden said an adult buck has about a 50 percent chance of testing positive for the disease each year.

Wisconsin reports about 1,000 cases of chronic wasting disease each year, while Iowa has about 100 a year.

“If we've learned anything from other states' experience with CWD, it's very probable that we will continue to see CWD increase in geographic spread and prevalence, though we can hope to slow that increase through selective management efforts,” Elliott said.

The disease’s progression

Chronic wasting disease can be passed from one animal to another before the positive animal starts showing symptoms of the disease.

Ruden said infected deer can start shedding contagious saliva as soon as three months after infection, but it takes, on average, 18 to 36 months for a deer to start showing symptoms.

Chronic wasting disease can spread in two ways: direct and indirect transmission.

Direct transmission occurs from deer to deer through bodily fluids like saliva, mucus and urine. Indirect transmission can occur through soil and feeding areas contaminated with the disease.

Ruden said symptoms of chronic wasting disease infection include:

What hunters can do

To help slow the spread of CWD, the DNR is encouraging hunters to limit carcass movement of infected deer.

Ruden said positive deer carcasses can still infect other deer. She recommends hunters dispose of CWD-positive carcasses by either taking them to a landfill, burying them, or leaving them at the harvest site.

The Centers for Disease Control and Prevention recommend against humans consuming the meat of deer that are either positive for chronic wasting disease, or suspected of being infected. The meat should be disposed of instead.

Ruden also is encouraging hunters to report sick deer or roadkill to the DNR. She said it costs $25 for a hunter to drop off a deer to have the animal’s lymph nodes tested for the disease. Hunters can coordinate a drop-off time for a deer sample at the DNR’s website.

Hunters reporting sick deer and roadkill “is an important source for sure in our surveillance program,” Ruden said.

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; olivia.cohen@thegazette.com