Contributions to the Mathematical Theory of Epidemics. II. The Problem of Endemicity

摘要: In a previous communication an attempt was made to investigate mathe­matically the course of epidemic in closed population susceptible individuals. order simplify problem certain definite assumptions were made, namely, that all individuals equally susceptible, and death resulted, or complete immunity conferred, as result attack. The infectivity individual his chances recovery represented by arbitrary functions, chance new infection occurring assumed be proportional product infected members population. spite introduction it shown general critical density existed, such if actual less than this, no could occur, but exceeded this n would appear on focus infection, further small relative density, size 2 per unit area. It these conclusions readily extended case metaxenous disease, is, one which transmission takes place through intermediate host. is purpose present paper consider effect continuous fresh into appeared desirable point, since might make possible interpret aspects incidence disease not only human communities where there usually influx either immigration birth, also animal experiments carried out Topley others—where animals introduced at constant rate cages cases already present—from results obtained.