MADISON — A deadly neurological disease impacting Wisconsin’s deer population for decades continues to plague the state’s official wildlife animal.
10 percent of Wisconsin deer sampled for chronic wasting disease tested positive for the disease, according to new data from the Department of Natural Resources.
17,399 deer were sampled throughout the state during the 2024 CWD year, with 1,786 samples testing positive. Of those positive results, nearly 90 percent were located in what’s known as the “Southern Farmland Zone” of Wisconsin, particularly in Richland, Sauk, and Iowa Counties in the southwest part of the state.
The 242 sampling locations included self-sampling kiosks and staffed sites, and carcass-disposal sites including dumpsters, landfills, and transfer stations.
The 1,786 positive samples is the most in the state’s history since records began in 1999. The state has recorded over 1,000 positive tests from its sample population of deer every year since 2018.
Chippewa, Pierce, Manitowoc and Menominee Counties all had their first wild CWD-positive detection in 2024. One deer tested in Milwaukee County of the over 500 sampled yielded a positive result.
“Although we have detected CWD in new areas of the state in recent years, many of these areas are at a low prevalence rate, and opportunities still remain to slow the spread and growth of the disease statewide,” said Erin Larson, DNR deer herd health specialist.
When it comes to the 2024 Wisconsin deer harvest, there were 321,844 total whitetails harvested by hunters in the state. The Southern Farmland Zone accounted for 71,106 of deer harvested.
How did CWD end up in Wisconsin’s deer herd?
CWD is a neurological disorder that has no cure and is always fatal in deer. It is caused by infectious misfolded proteins called prions and spreads from deer to deer through direct contact, bodily fluids and environmental contamination. While there have been no reported cases of CWD infection in humans to date, the Centers for Disease Control recommends that people avoid eating venison from CWD-infected animals.
Larson tells WTMJ we’ll likely never know the answer to what sequence of events led to the disease’s arrival in Wisconsin, though we do know where the disease originated in the United States.
“It was first seen in a captive facility in Colorado. It was then detected in the wild in Colorado and Wyoming in about the mid-1980s. So it was decades later that we found it in Wisconsin,” says Larson. Specifically, CWD was first noted in 1967 within captive mule deer at the Fort Collins, Colorado facility where the deer were used for nutrition research. CWD was then first detected in three Dane County deer after the 2001 hunting season, though Larson noted it was likely first in the state years before that.
The National Deer Association says as of May 2024, CWD has been identified in 35 U.S. states.
What can be done to mitigate the spread of CWD?
One of the ways Wisconsin has regurlarly attempted to contain CWD’s spread is through the practice of bait banning, which the DNR says reduces the frequency and intensity of interactions between deer. 63 of the state’s 72 counties have some form of baiting ban to prevent the spread of the disease. The DNR says none of the 63 counties will be removed from the baiting and feeding ban through June 2025.
Another way to slow the spread, Larson says, is by increasing the number of deer hunters each year.
“We encourage you to bring somebody new who’s maybe not hunted before, introduce them to this sport to help keep our herd healthy, not only from chronic waste and disease, but by just having a more responsible level of deer in an area,” says Larson.
State data indicates sales for deer hunting privileges covering gun, archery, crossbow, conservation patron, and sports licenses reached 791,023 in 2024, up slightly from 788,697 in 2023.
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