Hagenaars T J, Ferguson N M, Donnelly C A, Anderson R M
Wellcome Trust Centre for the Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, United Kingdom.
Epidemiol Infect. 2001 Aug;127(1):157-67. doi: 10.1017/s0950268801005738.
The epidemiology and transmission dynamics of sheep scrapie is as yet poorly understood. Here we present a theoretical analysis of the transmission dynamics within a sheep flock, concentrating on how persistence properties depend on transmission scenario and flock size. Patterns of disease persistence and extinction are studied analytically using branching-process approximations and numerically using stochastic model simulations. For a given basic reproduction number, disease extinction is most likely when late-stage infected animals are responsible for most of the transmission. This effect can be understood in terms of aggregation in the distribution of the number of secondary infections arising from a single primary infection. The presence of an environmental reservoir reduces the probability of extinction.
绵羊瘙痒病的流行病学和传播动力学目前仍知之甚少。在此，我们对羊群内的传播动力学进行了理论分析，重点关注持续性特征如何依赖于传播情形和羊群规模。利用分支过程近似法对疾病的持续和灭绝模式进行了分析研究，并通过随机模型模拟进行了数值研究。对于给定的基本繁殖数，当晚期感染动物导致了大部分传播时，疾病最有可能灭绝。这种效应可以从单个原发感染产生的二代感染数量分布中的聚集现象来理解。环境宿主的存在降低了灭绝的概率。
