Pulse vaccination in SIRS epidemic model with non-monotonic incidence rate

The impulsive vaccination strategy is applied to an SIRS epidemic model with non-linear incidence rate. The infection free periodic solution of impulsive system has been obtained and is found to be globally asymptotically stable when R-0 < 1. The supercritical bifurcation occurs at the threshold R-0 = 1. The numerical simulations have been carried out to study the influence of other key parameters. The system shows complex dynamical behavior with respect to the parameter p, the fraction of susceptible that are vaccinated. (C) 2006 Elsevier Ltd. All rights reserved.