建立了具有脉冲接种和总人口变化的时滞SEIR模型.证明了当R~*〈1时染病者消亡即疾病最终消失,当R_*〉1时将发展为地方病.
In this paper, An delayed SEIR epidemic modd with pulse vaccination and varying total population size is considered. We point out, if R* 〈 1, the infections population disappear so the disease dies out, while if R* 〉 1, the infectious persist.