Lisovski Simeon, van Dijk Jacintha G B, Klinkenberg Don, Nolet Bart A, Fouchier Ron A M, Klaassen Marcel
Deakin University, School of Life and Environmental Sciences, Centre for Integrative Ecology, Geelong, Australia.
Swiss Ornithological Institute, Seerose 1, CH-6204 Sempach, Switzerland.
J Appl Ecol. 2018 Nov;55(6):2963-2975. doi: 10.1111/1365-2664.13154. Epub 2018 Mar 26.
Migratory birds are an increasing focus of interest when it comes to infection dynamics and the spread of avian influenza viruses (AIV). However, we lack detailed understanding migratory birds' contribution to local AIV prevalence levels and their downstream socio-economic costs and threats.To explain the potential differential roles of migratory and resident birds in local AIV infection dynamics, we used a susceptible-infectious-recovered (SIR) model. We investigated five (mutually non- exclusive) mechanisms potentially driving observed prevalence patterns: 1) a pronounced birth pulse (e.g. the synchronised annual influx of immunologically naïve individuals), 2) short-term immunity, 3) increase of susceptible migrants, 4) differential susceptibility to infection (i.e. transmission rate) for migrants and residents, and 5) replacement of migrants during peak migration.SIR models describing all possible combinations of the five mechanisms were fitted to individual AIV infection data from a detailed longitudinal surveillance study in the partially migratory mallard duck (). During autumn and winter, the local resident mallard community also held migratory mallards that exhibited distinct AIV infection dynamics.Replacement of migratory birds during peak migration in autumn was found to be the most important mechanism driving the variation in local AIV infection patterns. This suggests that a constant influx of migratory birds, likely immunological naïve to locally circulating AIV strains, is required to predict the observed temporal prevalence patterns and the distinct differences in prevalence between residents and migrants.. Our analysis reveals a key mechanism that could explain the amplifying role of migratory birds in local avian influenza virus infection dynamics; the constant flow and replacement of migratory birds during peak migration. Aside from monitoring efforts, in order to achieve adequate disease management and control in wildlife - with knock-on effects for livestock and humans, - we conclude that it is crucial, in future surveillance studies, to record host demographical parameters such as population density, timing of birth and turnover of migrants.
在禽流感病毒（AIV）的感染动态和传播方面，候鸟越来越受到关注。然而，我们对候鸟在当地AIV流行水平中的作用以及由此产生的下游社会经济成本和威胁缺乏详细了解。为了解释候鸟和留鸟在当地AIV感染动态中可能存在的不同作用，我们使用了易感-感染-恢复（SIR）模型。我们研究了可能导致观察到的流行模式的五种（相互不排斥）机制：1）明显的出生脉冲（例如，免疫未成熟个体的同步年度涌入），2）短期免疫，3）易感候鸟增加，4）候鸟和留鸟对感染的易感性差异（即传播率），以及5）迁徙高峰期候鸟的替代。将描述这五种机制所有可能组合的SIR模型拟合到来自部分迁徙的绿头鸭详细纵向监测研究的个体AIV感染数据。在秋季和冬季，当地的留鸟绿头鸭群落中也有表现出不同AIV感染动态的候鸟。研究发现，秋季迁徙高峰期候鸟的替代是驱动当地AIV感染模式变化的最重要机制。这表明，需要持续有可能对当地流行的AIV毒株免疫未成熟的候鸟涌入，才能预测观察到的时间流行模式以及留鸟和候鸟之间流行率的明显差异。我们的分析揭示了一个关键机制，可以解释候鸟在当地禽流感病毒感染动态中的放大作用；即迁徙高峰期候鸟的持续流动和替代。除了监测工作外，为了在野生动物中实现充分的疾病管理和控制，并对家畜和人类产生连锁反应，我们得出结论，在未来的监测研究中，记录宿主人口统计学参数，如种群密度、出生时间和候鸟更替情况至关重要。
