Evaluation of a wild white-tailed deer population management program for controlling chronic wasting disease in Illinois, 2003-2008

We evaluated population management programs for controlling chronic wasting disease (CWD) in wild white-tailed deer in Illinois between November 2002 and March 2008. The intervention consisted of measures of deer removal from three deer population control programs: Illinois Department of Natural Resources culling, deer population control permits and nuisance deer removal permits. We included in the analysis a total of 14,650 white-tailed deer CWD test results. These data also included location and demographic data collected from both deer harvested in the interventions as well as deer from hunter harvests and deer vehicle collisions. We quantified intervention pressures as the number of years of intervention, the total number of deer removed and the average number of deer removed per year. We accounted for temporal and spatial variations of intervention by using mixed logistic regression to model the association between intervention pressures and CWD prevalence change. The results showed that deer population management intervention as practiced in Illinois during the study period was negatively associated with CWD prevalence and the strength of association varied depending on age of deer and the measure of intervention pressure. The population management programs showed a more consistent association with reduced CWD prevalence in fawn and yearling white-tailed deer than in adult deer. Our results also suggested that frequent and continuing intervention events with at least moderate intensity of culling were needed to reduce CWD prevalence. A longer study period, however, is needed to make a more definite conclusion about the effectiveness of similar population management programs for controlling CWD in wild white-tailed deer.