Wisconsin Department of Natural Resources
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Deer Health - Disease
 
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   CWD:
Chronic Wasting Disease (CWD) was first detected in Wisconsin in 2002. Since then sampling has been conducted every year in various places throughout the state.

Total # Sampled Deer Graph
The top graph on this page represents the number of deer that have been sampled for CWD per year as well as the number of CWD positive results.

Sick Deer Tested for CWD Graph
Landowners and citizens are encouraged to contact the department when a deer showing clinical signs is seen. These reports are recorded. In low CWD prevalence counties, these deer are dispatched and sampled for CWD, if possible. Not all sick deer in higher prevalence counties are tested for CWD.

More information about CWD in Wisconsin can be found on the department website. For additional Information….
 
   Non-CWD:
In mid-September 2021, epizootic hemorrhagic disease virus (EHDV) was confirmed in a deer in La Crosse County. The DNR will monitor the distribution of the disease and the number of deer impacted by the EHD outbreak. Information will be made available on the wildlife diseases webpage on the Wisconsin DNR website.


EHD History
Epizootic hemorrhagic disease (EHD) is an acute, infectious, viral disease spread by biting insects (especially midges) that affects white-tailed deer and some other hoofed animals. In white-tailed deer the severity of the disease depends upon the deer’s previous exposure to the virus and strain of the virus. At this time, it does not appear that EHD is endemic (always found) in Wisconsin which means that when the virus does appear here, it is more likely to be fatal to deer.

The disease was diagnosed for the first time in Wisconsin deer in the fall of 2002 when approximately 14 deer were found suddenly dead in Iowa County. In the fall of 2012, deer found dead in eight southern Wisconsin counties tested positive for EHD. In the fall of 2019, EHD was detected in deer found dead in southwestern Wisconsin. In the fall of 2020, there were small outbreaks of less than 50 deer each in Oconto and Buffalo counties.
 
  
 
Background
CWD was first detected in Wisconsin in 2002 when three deer taken by hunters in the fall of 2001 near the village of Mount Horeb, about 10 miles southwest of Madison, tested positive. Since that time an intensive surveillance effort has been undertaken to better understand the geographic distribution of the disease, the prevalence of the disease where it occurs and changes in the prevalence over time.
 
Collection and analysis methods
Sampling stations were set up at previous registration stations which allowed for the collection of biological samples for CWD testing. Age, sex and kill location (deer management unit, county and Public Land Survey System [PLSS] township/section) are collected from harvested deer. Retro-pharyngeal lymph nodes are collected for CWD testing by the Wisconsin Veterinary Diagnostic Laboratory.
 
Using the metric
The graphs on this page show the number of deer tested and the number positive for CWD per year. A subset of these sampled deer are sick deer that were showing clinical signs for CWD. Often these deer are reported to the department by a landowner or citizen in the area. The landowner may get permission to dispatch the deer if the deer can be put down safely or a department employee will put the deer down. The deer is then tested for CWD, if possible. Not all sick deer in higher prevalence counties are tested for CWD.
 
Limitations and precautions
Limited statewide CWD program funding precludes sampling everywhere each year. Because sample sizes are limited, estimation of the geographic distribution of disease requires pooling data over multiple years. Likewise, estimation of changes in time require combining data over multiple areas (e.g., townships).
 
Future needs
It will be important to develop ways to cost-effectively assess CWD prevalence and geographic distribution with limitations in budgets and resources.
 
Additional background materials related to this metric
Additional information on deer health can be found on the department website.

 
Total # Sampled Deer
2021 CWD positive deer count: 1295 2020 CWD positive deer count: 1578 2019 CWD positive deer count: 1338 2018 CWD positive deer count: 1064 2017 CWD positive deer count: 603 2016 CWD positive deer count: 448 2015 CWD positive deer count: 300 2014 CWD positive deer count: 331 2013 CWD positive deer count: 357 2012 CWD positive deer count: 339 2011 CWD positive deer count: 239 2010 CWD positive deer count: 219 2009 CWD positive deer count: 179 2008 CWD positive deer count: 181 2007 CWD positive deer count: 135 2006 CWD positive deer count: 205 2005 CWD positive deer count: 181 2004 CWD positive deer count: 145 2003 CWD positive deer count: 117 2002 CWD positive deer count: 205

 
Sick Deer Tested for CWD
2021 Sick Deer Positive Count: 12 2020 Sick Deer Positive Count: 25 2019 Sick Deer Positive Count: 42 2018 Sick Deer Positive Count: 52 2017 Sick Deer Positive Count: 30 2016 Sick Deer Positive Count: 55 2015 Sick Deer Positive Count: 44 2014 Sick Deer Positive Count: 29 2013 Sick Deer Positive Count: 13 2012 Sick Deer Positive Count: 17 2011 Sick Deer Positive Count: 8 2010 Sick Deer Positive Count: 6 2009 Sick Deer Positive Count: 8 2008 Sick Deer Positive Count: 7 2007 Sick Deer Positive Count: 3 2006 Sick Deer Positive Count: 8 2005 Sick Deer Positive Count: 6 2004 Sick Deer Positive Count: 3 2003 Sick Deer Positive Count: 0 2002 Sick Deer Positive Count: 3
For questions on this deer metric data contact:
Bob Nack 608-264-6137 RobertR.Nack@wisconsin.gov
Timothy Marien 608-264-6046 Timothy.Marien@wisconsin.gov