Four new cases of Chronic Wasting Disease (CWD) in the wild deer herd were detected last fall from hunter-provided samples in Vilas and Oneida counties, more proof that the prion disease is slowly spreading statewide.
According to the Department of Natural Resources (DNR), just one of those new detections came from Vilas, where a yearling buck harvested in an area between Spring Meadow and Anvil Lake east of Eagle River tested positive.
That is just the second positive detection in Vilas, the first of which occurred just east of the city of Eagle River in 2021.
In Oneida, where there were previously just four positive cases in the Harrison Hills area near the border of Oneida and Lincoln counties, three new cases were detected.
One of those involved a 3 1/2-year-old doe that was harvested just northwest of Stella Lake and a second was a 3 1/2-year-old doe harvested east of Jennie Webber Lake.
The third case, involving a 3 1/2-year-old buck, was taken in a large block of county-owned land and mixed industrial forest located between Rhinelander and Pelican Lake, about two miles south of the Pelican River.
CWD is a fatal, infectious nervous system disease of deer, moose, elk and reindeer/caribou. It belongs to the family of diseases known as transmissible spongiform encephalopathies (TSEs) or prion diseases.
According to the DNR, CWD occurs only in members of the cervid or deer family, both wild and captive.
For the 2024 season, DNR herd health specialist Erin Larson said the department focused its efforts on increasing sample collection in designated priority areas in northern and central counties where recent positive cases showed in both game farms and the wild herd.
She said additional samples tested from the priority areas helped the DNR better understand disease levels and distribution in areas with recent detections.
There were 272 deer tested in Vilas, one of them positive, and 361 deer tested in Oneida, with three of them positive.
In total, 17,399 deer were sampled throughout the state during the 2024 CWD year, with 1,786 samples testing positive.
Most (89%) of these detections were in the Southern Farmland Zone, with the largest impact in a seven county area west of Madison — the area where CWD was first detected in 2002.
Those counties include Dane, Columbia, Iowa, Richland, Sauk, Vernon and Crawford. There were 1,334 positive CWD cases in those seven counties last year.
A full breakdown of sampled and positive totals by zone and year is available on the DNR’s Summary of CWD Statewide Surveillance webpage. Results by county are also available on the DNR’s CWD Deer Testing Results by County webpage.
The website also includes a new map of the CWD-positive detections in wild deer, showing both the historic detections (2001-2023) and the 2024 detections.
According to Larson, a total of 242 sampling locations were available throughout the state, including 166 self-sampling kiosks and 76 staffed sites. Disposal sites (154 in total), including dumpsters, landfills and transfer stations, were available for deer carcass waste.
She said the average number of days statewide from when a sample was dropped off at a sampling location to when the CWD result was emailed to the hunter was 8.4 days.
“The DNR sincerely thanks all the hunters who submitted a sample for CWD, the business owners who managed a CWD sampling site, and those who participated in the Adopt-a-Kiosk or Adopt-a-Dumpster partnerships this year,” she said.
This year, two counties within the priority sampling areas, Pierce and Menominee, had their first wild CWD-positive detection. In the northern part of the state, Polk and Vilas detected the second wild positive in the county.
Several areas in eastern Wisconsin saw additional positive detections in 2024. Waushara and Fond du Lac had only detected one positive prior to the 2024 season, and each county detected several additional positives. Waupaca detected its third CWD positive. Shawano detected three additional CWD positives, and two of them were in different areas of the county from past detections.
CWD positives were also detected in several of the counties in the west-central or central part of the state including Adams, Buffalo, Dunn, Eau Claire, Jackson, Juneau, Marathon, Monroe, Portage and Trempealeau.
Endemic Area
CWD sampling in southern Wisconsin continues to help measure disease patterns and changes in the disease prevalence over time.
During the 2024 CWD year, 7,680 samples were tested in the Southern Farmland Zone, and 1,583 were positive for CWD.
Additionally, the DNR shares results from a large CWD study on the endemic area, the area of southwest Wisconsin, where CWD was first detected. These results (from the Southwest Wisconsin CWD, Deer and Predator Study) were recently presented to the Natural Resources Board (NRB).
The results showed that CWD substantially reduces deer survival rates, suppresses population growth, and can cause deer populations to decline in areas where CWD prevalence is high. While there are areas of high CWD prevalence in several counties in southern Wisconsin, the prevalence rate is not consistent throughout those counties or the entire state.
Rest Of The State
Two counties (outside of the priority sampling areas and endemic area), Chippewa and Manitowoc, had their first wild positive detection in 2024. Oconto County detected its second wild positive in the center of the county, three years after the first positive was detected.
“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 Larson.
The DNR reminds the public that there have been no reported cases of CWD infection in humans to date. However, public health officials recommend against consuming meat from deer that test positive for CWD and to consider testing deer prior to consumption, especially in areas prevalent with CWD.
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