Abstract

Since 1996 tissue samples have been collected from deer killed in vehicle collisions throughout Colorado as part of a monitoring program for detecting chronic wasting disease (CWD) in free-ranging populations. We estimated CWD prevalence among vehicle-killed mule deer statewide and compared the estimate to CWD prevalence among the surrounding mule deer population to determine if CWD-infected mule deer are more vulnerable to vehicle collision. Overall prevalence was 66% higher in the vehicle-kill population; prevalence for vehicle-killed deer was 0.101 (95% confidence interval [CI]=0.064–0.139) compared to 0.061 (95% CI=0.051–0.072) for mule deer harvested or culled in the vicinity of vehicle-kills. The probability of detecting a CWD-infected, vehicle-killed deer, given that there is at least one other CWD-infected deer within a 3-km radius of the vehicle-kill site, was 16.67%. Our data suggest increased susceptibility of CWD-infected individuals to vehicle collisions. It follows that using vehicle-kill mule deer may be exploited in designing surveillance programs for detecting new foci of infection but that this differential vulnerability also may bias estimates of CWD prevalence in natural populations. Evidence of increased susceptibility to vehicle collisions may aid in understanding vulnerability of CWD-infected individuals to other forms of death, particularly predation.