讨论了一类具有非线性传染率的随机SIS传染病模型。证明了该模型全局惟一正解的存在性;研究了模型解的长期渐近行为:当R0≤1时,证明了模型的无病平衡点是随机全局渐近稳定的;当R0〉1时,证明了随机系统的解围绕确定性模型的地方病平衡点震荡,进而得到了疾病平均持续存在以及疾病随机灭绝的充分条件。数值仿真验证了文中主要结论的正确性。
A stochastic SIS epidemic model with nonlinear incidence is investigated. First, the existence of global posi- tive solution is obtained; Next, the asymptotic behaviors of the model are studied that is if R0 ≤ 1, the disease-free equi- librium is stochastically asymptotical stability, and if R0 〉 1 the solution is oscillating around the endemic equilibrium of the deterministic model. Furthermore, the sufficient conditions of persistence in the mean and stochastic extinction are obtained. Finally, the theoretical results are illustrated by numerical simulations.