Predicting the rate of invasion of the agent of Lyme disease Borrelia burgdorferi
Predicting the rate of invasion of the agent of Lyme disease Borrelia burgdorferi
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DOI：
10.1111/1365-2664.12050
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发表时间：
2013-04-01
影响因子：
5.7
通讯作者：
Leighton, Patrick A.
中科院分区：
文献类型：
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作者：
Ogden, Nicholas H.;Lindsay, L. Robbin;Leighton, Patrick A.
识别入侵的蜱虫种群为正在扩大其地理范围的新出现的蜱传疾病提供了早期预警。但是蜱传病原体在蜱虫定居后入侵的速度有多快？在加拿大南部，这些物种目前正在入侵的地区，对蜱虫肩胛硬蜱和莱姆病病原体伯氏疏螺旋体的监测数据显示，在魁北克南部，一个时空簇的蜱虫低B.burgdorferi感染流行率，标志着蜱虫种群开始于2004年建立的位置。该集群在2009年消失，表明蜱和B.burgdorferi入侵之间有5年的间隔。肩胛硬蜱种群和伯氏B.burgdorferi传播模型的模拟确定了迁入蜱的数量，而不是宿主密度和多样性，作为蜱建立后病原体入侵速度的关键决定因素。与加拿大东部相比，预计加拿大中部会有更多的移民感染蜱虫，因为美国中西部来源人群中的若虫和幼虫蜱虫在春季很活跃，此时候鸟可以将蜱虫带到北方。而在美国东北部，蜱虫种群是加拿大东部的移民蜱虫的来源，有活跃的蜱虫，但很少有幼虫在春季活跃。因此，我们假设在加拿大东部蜱虫和B.burgdorferi入侵之间存在5年的间隔，但在加拿大中部的间隔要短得多。与这一假设一致，监测数据分析显示，在加拿大东部肩胛硬蜱入侵的地区，蜱的感染流行率低，持续时间为5年，但在加拿大中部肩胛硬蜱入侵的地区，蜱的感染流行率仅为3年。合成与应用。我们已经确定的速度，病原体伯氏疏螺旋体入侵后，蜱肩胛硬蜱的入侵，并在春季蜱幼虫和若虫活动的同步性是一个关键因素，确定蜱和病原体入侵之间的差距。这在解释莱姆病风险的紧迫性时，监测确定新出现的蜱虫种群在加拿大有直接的应用。它也有普遍的应用在预测的速度，新出现的蜱传病原体在世界其他地方的入侵。
Identifying invading tick populations provides early warning for emerging tickborne diseases that are expanding their geographic range. But how fast do tickborne pathogens invade after ticks become established? Surveillance data for the tick Ixodes scapularis and the agent of Lyme disease Borrelia burgdorferi in southern Canada, an area where these species currently are invading, revealed a space-time cluster of ticks of low B.burgdorferi infection prevalence in southern Quebec signalling the location where tick populations became established beginning in 2004. The cluster disappeared in 2009, indicating a 5-year gap between tick and B.burgdorferi invasion. Simulations of a model of I.scapularis populations and B.burgdorferi transmission identified numbers of immigrating ticks, rather than host density and diversity, as key determinants of the speed of pathogen invasion after ticks become established. Greater numbers of immigrating infected nymphs would be expected in Central compared with Eastern Canada because nymphal and larval ticks in source populations in Midwestern USA are active in spring when migratory birds can carry ticks north. Whereas in northeastern USA, tick populations that are sources for immigrating ticks for Eastern Canada have active nymphs, but few larvae are active in spring. Consequently, we hypothesized that a 5-year gap would occur between tick and B.burgdorferi invasion in Eastern Canada, but a much shorter gap would occur in Central Canada. Consistent with this hypothesis, analysis of surveillance data revealed clusters of ticks with low infection prevalence of 5years duration in locations in Eastern Canada where I.scapularis is invading, but a nonsignificant cluster of only 3-year duration in regions of Central Canada where I.scapularis is invading. Synthesis and applications. We have identified the speed at which the pathogen Borrelia burgdorferi invades following the invasion of the tick Ixodes scapularis, and that the synchrony of larval and nymphal tick activity in spring is a key factor determining the gap between tick and pathogen invasion. This has immediate application in interpreting imminence of Lyme disease risk when surveillance identifies emerging tick populations in Canada. It also has general application in predicting of the speed of invasion of emerging tickborne pathogens elsewhere in the world.