Chronic wasting disease (CWD) is a fatal prion disease affecting members of the Cervidae family and is present in both wild and captive cervid populations across the United States. CWD continues to spread among captive facilities, with new positive facilities being detected each year. CWD can quickly become established in these facilities due to the close and prolonged contact among deer and repeated exposure to infected individuals or contaminated environments. Early detection is crucial for managing CWD; however, identifying a rare event like CWD introduction in a large population presents significant challenges. Furthermore, the number of samples required to achieve a high level of confidence in detecting CWD increases for low prevalence scenarios, making it particularly difficult to detect a single infected deer in a captive facility. Thus, CWD often remains undetected in the early phase of the outbreak, mainly because of the logistical constraints on wildlife agencies' ability to match the sample size targets. To address these challenges, we developed an agent-based modeling approach that enhances the estimation of CWD detection probability in captive deer facilities. Specifically, we define CWD detection probability as the confidence in identifying the single infected deer within a population, based on a given number of samples tested over the course of a year. Our modeling approach integrates CWD testing records from captive deer facilities, along with herd size, composition, and individual deer transfer histories, to quantify the likelihood of undetected CWD within a facility. These annual detection probability estimates provide a measure of confidence in identifying a single CWD-infected deer within a population, based on the number of deer that tested negative throughout the year. This approach improves the effectiveness of CWD surveillance by enabling the prioritization of surveillance efforts across captive facilities, using the model-derived quantitative metric of detection probability. By refining this estimation process, we provide improved surveillance approach and inform better CWD management strategies in captive cervid populations.
