Informing Surveillance through the Characterization of Outbreak Potential of Chronic Wasting Disease in White-Tailed Deer

•We used a Susceptible-Latent-Exposed-Infective (SLEI) compartment model to depict outbreak behavior (R0) of chronic wasting disease (CWD) in white-tailed deer under the influence of a habitat contaminated with infectious prions.•R0 increased when indirect transmission was parameterized to scale with environmental contamination.•CWD can persist in individuals living in a contaminated environment even if transmission between deer is insufficient to sustain circulation.•CWD transmission cannot be exclusively density dependent, and must behave as either a mix between frequency and density dependent, or strictly frequency dependent.•Differential likelihood of disease outbreak can guide state and provincial wildlife managers in the allocation of disease surveillance resources. Understanding the role that an environmental prion reservoir plays in the outbreak dynamics of chronic wasting disease (CWD) in free ranging white-tailed deer (Odocoileus virginianus) is critical for the allocation of disease surveillance resources by state and provincial wildlife agencies. We hypothesized that demographic, ecological, and epidemiological configurations naturally attenuate epidemic risk despite the introduction of infectious prions into a susceptible population of deer, but the magnitude of infectious prions in the environmental prion reservoir complicate outbreak expectations. We developed a Susceptible-Latent-Exposed-Infective (SLEI) compartment model to represent the dynamics of CWD epidemics in free-ranging white-tailed deer, then used the basic reproductive ratio (R0) to pinpoint counties under which pathogenic introduction (transport of infectious bodily fluids, tissues, and carcasses through natural or anthropogenic means) naturally produced (or failed to produce) an epidemic. We found that the outlook for an epidemic hinged on transmission rates, the magnitude of environmental contamination, and system type (density-, frequency-, or density/frequency-dependent). CWD can persistently infect individuals living in a contaminated environment even if direct transmission is insufficient to sustain circulation. Theoretical results show that transmission of CWD cannot be exclusively density dependent, and must behave as either a mix between frequency and density dependent, or strictly frequency dependent. While the compartment model is a simplistic representation of reality and did not contain many complicating biological considerations, it was immediately useful in hypot