The effect of predation on the dynamics of Chronic Wasting Disease in deer

Abstract

Chronic Wasting Disease (CWD) is a neurological disease impacting deer, elk, moose, and other cervid populations and is caused by a misfolded protein known as a prion. CWD is difficult to control due to the persistence of prions in the environment. Prions can remain infectious for more than a decade and have been found in soil as well as other environmental vectors, such as ticks and plants. Here, we provide a bifurcation analysis of a simple mathematical model of CWD spread in a cervid population and use a modification of the Gillespie algorithm to explore if predators can be used as an ecological control strategy to limit the spread of the disease in several relevant scenarios. We then use several analytical probabilistic arguments to show that lowering the susceptible population is also beneficial to controlling CWD outbreaks. Finally, we consider a more complex model of CWD spread in a cervid population in which predators are assumed to be dynamic. Here, we find that, again, predators may be used to control CWD outbreaks, assuming they selectively prey upon infected cervids at a sufficiently high rate. From our analysis, we conclude that wolves may be used as an effective control strategy to limit the spread of CWD in cervid populations, and hunting or other means of lowering the susceptible population are beneficial to controlling CWD.