<p>The spread of disease may be subject to stochastic perturbations. In order to quantitatively investigate a stochastic infectious disease model for two competing diseases, we develop a five-dimensional mathematical model, which can be used to analyze the dynamics of an SIS epidemic model with or without mean-reverting Ornstein-Uhlenbeck process. The results manifest that the long-time dynamic behavior of the stochastic epidemic model is determined by a threshold that depends on the random noise. Specifically, infectious diseases will persist if the threshold is positive; Otherwise, epidemics will become extinct. In addition, the threshold provides the basic guidelines for disease control and suggests that stochastic noise may be beneficial to control epidemics. The validity of our results is supported by numerical simulations.</p>