How long has CWD been in Wisconsin?
The exact year that CWD came to Wisconsin is not known. It is most likely an introduced disease, however, and has not always been in our deer herd. Surveillance for infected deer has detected two focal areas of high prevalence surrounded by a zone where prevalence drops off rapidly; this is a pattern of a recently introduced disease. Given that CWD spreads slowly--a trend of prion diseases--the current best estimate is that it has been in Wisconsin for at least 20 years and likely longer.