Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA 16802, USA.
Proc Biol Sci. 2011 Dec 22;278(1725):3703-12. doi: 10.1098/rspb.2011.0522. Epub 2011 May 11.
Anthropogenic environmental change is often implicated in the emergence of new zoonoses from wildlife; however, there is little mechanistic understanding of these causal links. Here, we examine the transmission dynamics of an emerging zoonotic paramyxovirus, Hendra virus (HeV), in its endemic host, Australian Pteropus bats (fruit bats or flying foxes). HeV is a biosecurity level 4 (BSL-4) pathogen, with a high case-fatality rate in humans and horses. With models parametrized from field and laboratory data, we explore a set of probable contributory mechanisms that explain the spatial and temporal pattern of HeV emergence; including urban habituation and decreased migration-two widely observed changes in flying fox ecology that result from anthropogenic transformation of bat habitat in Australia. Urban habituation increases the number of flying foxes in contact with human and domestic animal populations, and our models suggest that, in addition, decreased bat migratory behaviour could lead to a decline in population immunity, giving rise to more intense outbreaks after local viral reintroduction. Ten of the 14 known HeV outbreaks occurred near urbanized or sedentary flying fox populations, supporting these predictions. We also demonstrate that by incorporating waning maternal immunity into our models, the peak modelled prevalence coincides with the peak annual spill-over hazard for HeV. These results provide the first detailed mechanistic framework for understanding the sporadic temporal pattern of HeV emergence, and of the urban/peri-urban distribution of HeV outbreaks in horses and people.
人为环境变化常常与野生动物中新出现的人畜共患病有关;然而，对于这些因果关系，我们的了解甚少。在这里，我们研究了一种新兴的人畜共患病副粘病毒亨德拉病毒（HeV）在其地方性宿主澳大利亚狐蝠（果蝠或飞狐）中的传播动态。HeV 是一种生物安全 4 级（BSL-4）病原体，对人类和马具有很高的病死率。我们利用来自现场和实验室的数据对一组可能的促成机制进行了建模，这些机制解释了 HeV 出现的时空模式；包括城市驯化和减少迁徙——这是澳大利亚蝙蝠栖息地因人类活动而改变所导致的两种广泛观察到的飞狐生态学变化。城市驯化增加了与人类和家畜接触的狐蝠数量，我们的模型表明，此外，蝙蝠迁徙行为的减少可能导致种群免疫力下降，从而导致在当地病毒重新引入后爆发更强烈的疫情。已知的 14 次 HeV 爆发中有 10 次发生在城市化或定居的狐蝠种群附近，这支持了这些预测。我们还表明，通过将母体免疫衰减纳入我们的模型，模型预测的流行率峰值与 HeV 的年度溢出风险峰值相吻合。这些结果为理解 HeV 间歇性出现的时间模式以及 HeV 在马和人类中的城市/城郊分布提供了第一个详细的机制框架。
