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Contact information
For information on CWD, contact:
Timothy Marien
CWD wildlife biologist
Bureau of Wildlife Management
608-264-6046

Prevalence & surveillance

Prevalence is the proportion or percentage of a population that tests positive for a disease. Chronic wasting disease (CWD) prevalence is influenced by the sex and age of the deer and geographic location. CWD prevalence tends to be higher in males than in females and higher in adults than yearlings.

CWD prevalence in Wisconsin

There appears to be two central areas of CWD infection in Wisconsin. One is centered in western Dane and eastern Iowa counties. The other is located in northern Illinois and extends into southeastern Wisconsin. Analyses of the geographic distribution of disease show that the disease is not evenly distributed throughout the affected area. Disease prevalence is much higher near the centers of each infection and declines with increasing distance from the center as would be expected with this introduced disease which is now endemic in southern Wisconsin.

CWD prevalence has also changed over time. Since 2002, CWD prevalence within our western monitoring area has shown an overall increasing trend in all sex and age classes. During the past 13 years, the trend in prevalence in adult males has risen from 8-10 percent to over 25 percent and in adult females from about 3-4 percent to more than 10 percent. During that same time, the prevalence trend in yearling males has increased from about 2 percent to about 8 percent and in yearling females from roughly 2 percent to about 7 percent.

Surveillance and result maps

Map of sampling areas for 2014  Photo

In 2014 the department continued surveillance in several areas throughout the state. Hunter service testing was provided, free of charge, for adult deer in other areas of the state.


CWD Positive Locations  Photo

Number of cumulative CWD positives of wild white-tailed deer by PLSS Section. Updated 3/24/2015.


Wisconsin/Illinois CWD Positive Locations  Photo

Locations of cumulative CWD positives of wild white-tailed deer in Wisconsin and Illinois. Updated 3/24/2015.


CWD prevalence  Photo

Prevalence of CWD by PLSS Township. Prevalence is the percentage of yearling and adult male and female deer that tested positive for CWD. Results from deer sampled 2010-2013.

Interactive CWD mapping application

A CWD results mapping application is available for users to explore CWD results in all areas of the state as well as create maps. This application shows harvest locations of all deer tested for CWD including the positive test results.

CWD prevalence trends

Trends in CWD prevalence have been estimated for a number of study areas in southern Wisconsin. These areas included in the map were selected based on the geographic distribution of disease and the number of deer that have been tested.

The points on the map include prevalence graphs. The graphs for these study area show estimates of trend curves for yearling and adult males (blue) and females (yellow) during 2002-2014. These annual monitoring data are important for Wisconsin's understanding of CWD distribution and prevalence.

Last revised: Thursday June 11 2015