摘要：A sharp threshold is established that separates disease persistence from the extinction of small disease outbreaks in an S → E → I → R → S type metapopulation model. The travel rates between patches depend on disease prevalence. The threshold is formulated in terms of a basic replacement ratio (disease reproduction number), ℛ 0 , and, equivalently, in terms of the spectral bound of a transmission and travel matrix. Since frequency-dependent (standard) incidence is assumed, the threshold results do not require knowledge of a disease-free equilibrium. As a trade-off, for ℛ 0 >1, only uniform weak disease persistence is shown in general, while uniform strong persistence is proved for the special case of constant recruitment of susceptibles into the patch populations. For ℛ 0 <1, Lyapunov's direct stability method shows that small disease outbreaks do not spread much and eventually die out.
关键词：Persistence ; Extinction ; Basic reproduction number
