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

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.

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
CWD sampling areas for 2014 [PDF] The department will continue surveillance in the former CWD Management Zone within the western and eastern monitoring areas, north central Iowa County and focused sampling in Dane, Jefferson, southern Dodge, Columbia and eastern Sauk counties. We will utilize select taxidermists in Crawford and Vernon counties for weighted surveillance sampling. We will sample in the 10 mile radius around locations where CWD positive deer were detected in Washburn, Adams, Juneau, southern Portage, northern Portage and Marathon counties. We will also continue to provide hunter service testing, free of charge, for adult deer in other areas of the state.

CWD Positive Locations
CWD positive deer locations [PDF] Updated 03/24/2015.

Wisconsin/Illinois CWD Positive Locations
Wisconsin/Illinois Positive Locations [PDF] Updated 03/24/2015.

CWD prevalence
Prevalence of CWD by PLSS Township [PDF] 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: Wednesday March 25 2015