Annual migration is common across animal taxa and can dramatically shape the spatial and temporal patterns of infectious disease. Although migration can decrease infection prevalence in some contexts, these energetically costly long-distance movements can also have immunosuppressive effects that may interact with transmission processes in complex ways. Here, we develop a mechanistic model for the reactivation of latent infections driven by physiological changes or energetic costs associated with migration (i.e. ‘migratory relapse’) and its effects on disease dynamics. We determine conditions under which migratory relapse can amplify or reduce infection prevalence across pathogen and host traits (e.g. infectious periods, virulence, overwinter survival, timing of relapse) and transmission phenologies. We show that relapse at either the start or end of migration can dramatically increase prevalence across the annual cycle and may be crucial for maintaining pathogens with low transmissibility and short infectious periods in migratory populations. Conversely, relapse at the start of migration can reduce the prevalence of highly virulent pathogens by amplifying culling of infected hosts during costly migration, especially for highly transmissible pathogens and those transmitted during migration or the breeding season. Our study provides a mechanistic foundation for understanding the spatio-temporal patterns of relapsing infections in migratory hosts, with implications for zoonotic surveillance and understanding how infection patterns will respond to shifts in migratory propensity associated with environmental change. Further, our work suggests incorporating within-host processes into population-level models of pathogen transmission may be crucial for reconciling the range of migration–infection relationships observed across migratory species.

中文翻译：

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潜伏感染的重新激活与迁移塑造了人口水平的疾病动态

每年的迁移在动物类群中很常见，并且可以极大地影响传染病的空间和时间模式。尽管在某些情况下迁移可以降低感染率，但这些耗能巨大的长距离移动也可能具有免疫抑制作用，可能以复杂的方式与传播过程相互作用。在这里，我们开发了一种机制模型，用于重新激活由生理变化或与迁移相关的能量成本驱动的潜伏感染（即“迁移复发”）及其对疾病动态的影响。我们确定在何种条件下迁移性复发可以放大或减少病原体和宿主特征（例如感染期、毒力、越冬存活、复发时间）和传播物候的感染流行。我们表明，在迁徙开始或结束时的复发可以显着增加整个年度周期的患病率，并且可能对于维持迁徙人群中低传播性和短传染期的病原体至关重要。相反，迁移开始时的复发可以通过在代价高昂的迁移过程中扩大对受感染宿主的扑杀来降低高毒力病原体的流行，特别是对于高度传播的病原体以及在迁移或繁殖季节传播的病原体。我们的研究为理解迁徙宿主中复发性感染的时空模式提供了机制基础，对人畜共患病监测和了解感染模式将如何应对与环境变化相关的迁徙倾向的变化有影响。更远，