Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Mathematics and Statistics

Committee Chair(s)

James Powell


James Powell


Brynja Kohler


Noelle Beckman


Chronic Wasting Disease (CWD) is a fatal, untreatable neurodegenerative disease that infects deer and related species. It is highly contagious and caused by abnormal malfunction and assembly of normal cellular proteins into aggregation-prone proteins. The Centers for Disease Control and prevention report that the prevalence of CWD in free-ranging deer in the US is still relatively low. However, in several states the infection rates exceed 1 deer in 10. Deer may uptake CWD from direct interaction with infected individuals or from the environment. Infected individuals shed CWD into the environment through feces, urine, saliva or carcasses, and long-distance dispersal of infected deer poses a danger of spreading CWD to new regions. We propose a mathematical model to capture CWD dynamics and the consequences of long-distance dispersal behavior of White-Tailed Deer (WTD), since there are no dispersal models available to describe the long-distance dispersal behavior of WTD juveniles. Our aim is to characterize long-distance dispersal of WTD juveniles and assess how it may affect CWD spread. We introduce a long-distance dispersal model, based on models of seed transport which accommodate a variety of hypothetical WTD dispersal behaviors. Four dispersal models were obtained by finding the approximate solutions of the seed transport models tweaked to mimic deer dispersal and settling behavior. We used GPS collar data collected in Wisconsin, US to test the accuracy of the models we developed. By calculating the prediction errors made by the models, we adjusted the model parameters, and assessed the competency of models relative to each other. Sensitivity of results was estimated by changing the data randomly to account for the effect of changing data on the results. The settling rate function that resulted in the most supported long-distance dispersal kernel reflects deer preference to not settle down soon after they start dispersal. Then, the impact of long-distance dispersal on CWD spread was quantified using the mathematical model for CWD dynamics we proposed earlier. Our results show that long-distance dispersal can magnify the CWD spread by a factor of 4. Therefore, controlling the total population density and fraction of long-distance dispersers will assist CWD management facilities in managing disease spread.



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