An SEIRS epidemic model with two delays and pulse vaccination*

Pulse vaccination is an effective and important strategy to eradicate an infectious disease. The authors investigate an SEIRS epidemic model with two delays and pulse vaccination. By using the discrete dynamical system determined by stroboscopic map, the authors obtain that the infectious population dies out if R _Δ < 1, and the infectious population is uniformly persistent if R ^Δ > 1. The results indicate that a short period of pulse vaccination or a large pulse vaccination rate is a sufficient condition to eradicate the disease. *This research was Supported by the National Natural Science Foundation of China under Grant No. 10471117 and the Emphasis Subject of Guizhou College of Finance & Economics.