Separate seasons of infection and reproduction can lead to multi-year population cycles
Separate seasons of infection and reproduction can lead to multi-year population cycles
复制标题
DOI：
10.1016/j.jtbi.2020.110158
复制
发表时间：
2020-03-21
影响因子：
2
通讯作者：
Hamelin, F. M.
中科院分区：
文献类型：
--
作者：
Hilker, F. M.;Sun, T. A.;Hamelin, F. M.
许多宿主-病原体系统的特征在于疾病传播和宿主繁殖的时间顺序。例如，这可能是由于病原体感染昆虫宿主的某些生命周期阶段;在候鸟聚集期间发生传播;或在种植季节之间传播的植物疾病。建立了一个简单的离散时间传染病模型，该模型具有密度依赖的传播和影响宿主繁殖力和存活率的疾病。该模型显示了持续多年的周期在主机人口丰度和疾病的流行，无论是在存在和不存在密度依赖的主机繁殖，大的水平传播，不完善的垂直传播，高毒力，高繁殖能力。多年周期出现在Neimark-Sacker分叉的不变曲线。它们是由结转效应引起的，因为在较早的季节中由于感染而导致的毒性效应会降低个体的生殖适合度，由于感染过程是密度依赖性的，但仅在较晚的季节显示出效果，这产生了典型的二阶振荡的延迟密度依赖性。感染季节和繁殖季节之间的时间间隔在驱动周期方面至关重要;如果这些过程像微分方程模型中那样同时发生，就没有持续的振荡。我们的模型强调了季节间反馈的不稳定影响，是可以产生人口周期的最简单的流行病模型之一。(C)2020爱思唯尔有限公司保留所有权利。
Many host-pathogen systems are characterized by a temporal order of disease transmission and host reproduction. For example, this can be due to pathogens infecting certain life cycle stages of insect hosts; transmission occurring during the aggregation of migratory birds; or plant diseases spreading between planting seasons. We develop a simple discrete-time epidemic model with density-dependent transmission and disease affecting host fecundity and survival. The model shows sustained multi-annual cycles in host population abundance and disease prevalence, both in the presence and absence of density dependence in host reproduction, for large horizontal transmissibility, imperfect vertical transmission, high virulence, and high reproductive capability. The multi-annual cycles emerge as invariant curves in a Neimark-Sacker bifurcation. They are caused by a carry-over effect, because the reproductive fitness of an individual can be reduced by virulent effects due to infection in an earlier season, As the infection process is density-dependent but shows an effect only in a later season, this produces delayed density dependence typical for second-order oscillations. The temporal separation between the infection and reproduction season is crucial in driving the cycles; if these processes occur simultaneously as in differential equation models, there are no sustained oscillations. Our model highlights the destabilizing effects of inter-seasonal feedbacks and is one of the simplest epidemic models that can generate population cycles. (C) 2020 Elsevier Ltd. All rights reserved.