Dynamics of a stochastic multi-strain SIS epidemic model driven by Levy noise

A stochastic multi-strain SIS epidemic model is formulated by introducing Levy noise into the disease transmission rate of each strain. First, we prove that the stochastic model admits a unique global positive solution, and, by the comparison theorem, we show that the solution remains within a positively invariant set almost surely. Next we investigate stochastic stability of the disease-free equilibrium, including stability in probability and pth moment asymptotic stability. Then sufficient conditions for persistence in the mean of the disease are established. Finally, based on an Euler scheme for Levy-driven stochastic differential equations, numerical simulations for a stochastic two-strain model are carried out to verify the theoretical results. Moreover, numerical comparison results of the stochastic two-strain model and the deterministic version are also given. Levy noise can cause the two strains to become extinct almost surely, even though there is a dominant strain that persists in the deterministic model. It can be concluded that the introduction of Levy noise reduces the disease extinction threshold, which indicates that Levy noise may suppress the disease outbreak. (C) 2016 Elsevier B.V. All rights reserved.