【摘要】 在潜伏期和感染期是常数的情况下,给出了一个具有两个时滞和脉冲免疫的SEIR流行病模型.利用频闪映射的离散动力系统,得到了无病周期解的表达式以及全局吸引的条件是■~*<1.此外,还证明了疾病一致持续的条件是■_*>1.结论表明较短的脉冲接种间隔或较大的脉冲接种率将导致疾病的灭绝.结论还表明潜伏期和感染期是导致地方病的主要因素.更多还原

【Abstract】 Assuming the incubation period and infected period of the disease to be constant, a disease transmission model of SEIR type with two delays and pulse vaccination is formulated.Using the discrete dynamical system determined by the stroboscopic map,the authors obtain the exact periodic infection-free solution of the impulsive epidemic system and prove that the infection-free periodic solution is globally attractive if R~*<1.Moreover, it is obtained that the disease is uniformly persistent if R_*>1.The results indicate that a short interpulse time or a large pulse vaccination rate will lead to eradication of the disease, and also indicate that the incubation and infected periods of an epidemic are important factors in these whether or not this disease becomes endemic.更多还原