Duncan S R, Scott S, Duncan C J
Department of Electrical Engineering and Electronics UMIST, UK.
Demography. 1993 Aug;30(3):405-23.
Time-series analysis, a valuable tool in studying population dynamics, has been used to determine the periodicity of smallpox epidemics during the seventeenth and eighteenth centuries in two contrasting representative situations: 1) London, a large city where smallpox was endemic, and 2) Penrith, a small rural town. The interepidemic period was found to be two years in London and five years in Penrith. Equations governing the dynamics of epidemics predict 1) a two-year periodicity and 2) that oscillatory epidemics die out quickly. It is suggested that epidemics were maintained by a periodic variation in susceptibility linked either to a five-year cycle of malnutrition or to an annual cycle. Computer modeling shows how the very different patterns of epidemics are related to population size and to the magnitude of the oscillation in susceptibility.
时间序列分析是研究种群动态的一种有价值的工具，已被用于确定17和18世纪天花流行在两种截然不同的典型情况下的周期性：1）伦敦，一个天花为地方病的大城市，以及2）彭里斯，一个小乡村小镇。发现伦敦的流行间期为两年，彭里斯为五年。控制流行病动态的方程预测：1）两年的周期性，以及2）振荡性流行病会迅速消失。有人提出，流行病是由易感性的周期性变化维持的，这种变化要么与五年的营养不良周期有关，要么与年度周期有关。计算机建模展示了非常不同的流行病模式如何与种群规模以及易感性振荡的幅度相关。
