Joint Research Centre, European Commission, I-21027 Ispra, VA, Italy.
Epidemics. 2013 Jun;5(2):111-21. doi: 10.1016/j.epidem.2013.01.001. Epub 2013 Jan 11.
The annual occurrence of many infectious diseases remains a constant burden to public health systems. The seasonal patterns in respiratory disease incidence observed in temperate regions have been attributed to the impact of environmental conditions on pathogen survival. A model describing the transmission of an infectious disease by means of a pathogenic state capable of surviving in an environmental reservoir outside of its host organism is presented in this paper. The ratio of pathogen lifespan to the duration of the infectious disease state is found to be a critical parameter in determining disease dynamics. The introduction of a seasonally forced pathogen inactivation rate identifies a time delay between peak pathogen survival and peak disease incidence. The delay is dependent on specific disease parameters and, for influenza, decreases with increasing reproduction number. The observed seasonal oscillations are found to have a period identical to that of the seasonally forced inactivation rate and which is independent of the duration of infection acquired immunity.
许多传染病的年发生率仍然是公共卫生系统的一个持续负担。在温带地区观察到的呼吸道疾病发病率的季节性模式归因于环境条件对病原体存活的影响。本文提出了一种通过能够在宿主生物体之外的环境储库中存活的致病状态来描述传染病传播的模型。病原体寿命与传染病状态持续时间的比值被发现是决定疾病动态的关键参数。引入季节性强制病原体失活率可确定峰值病原体存活和峰值疾病发病率之间的时间延迟。该延迟取决于特定的疾病参数，并且对于流感，随着繁殖数的增加而减少。观察到的季节性波动被发现具有与季节性强制失活率相同的周期，并且与获得性感染免疫的持续时间无关。
