Different Populations of Blacklegged Tick Nymphs Exhibit Differences in Questing Behavior That Have Implications for Human Lyme Disease Risk
Different Populations of Blacklegged Tick Nymphs Exhibit Differences in Questing Behavior That Have Implications for Human Lyme Disease Risk
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DOI：
10.1371/journal.pone.0127450
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发表时间：
2015-05-21
期刊：
影响因子：
3.7
通讯作者：
Tsao, Jean I.
中科院分区：
文献类型：
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作者：
Arsnoe, Isis M.;Hickling, Graham J.;Tsao, Jean I.
动物行为对病原体的传播和疾病的发生有着深远的影响。我们研究了黑腿硬蜱（Ixodes scapularis）的寻找（=宿主寻找）行为，黑腿硬蜱是美国东部莱姆病的主要媒介。莱姆病在北方很常见，但在南方地区并不常见，先前的生态研究发现，在北方地区收集寻找宿主的莱姆病的标准方法在南方并不成功。这使我们假设，北方和南方的莱姆病之间存在行为差异，这些差异改变了它们被收集的容易程度，以及它们将莱姆病病原体传播给人类的可能性。为了验证这个问题，我们比较了I。源自北方（莱姆病地方病）和两个美国南部（非地方病）地区在威斯康星州、罗得岛、田纳西州和佛罗里达的野外地点的肩胛骨。在含有木钉（模仿林下植被的茎）的圆形0.2 m（2）竞技场中监测人工饲养的未感染蝗虫10（2011）和19（2012）周。在这两年和所有田间试验点，在这些茎（2011年）以及茎、落叶层顶部和竞技场墙壁（2012年）上观察到寄生蜱的概率，北方蜱远高于南方蜱（2011年为19.5倍; 2012年为3.6-11.6倍）。我们的研究结果表明，南方起源I。肩叶海葵很少从落叶中出现，因此不太可能与路过的人接触。我们建议，这种差异的探索行为占观察到的地理差异的标准抽样技术用于收集探索的有效性。这些发现也支持了我们的假设，即莱姆病在南部各州的发病率很低，部分原因是主要莱姆病媒介的南部人群所表现出的宿主寻找行为类型。
Animal behavior can have profound effects on pathogen transmission and disease incidence. We studied the questing (= host-seeking) behavior of blacklegged tick (Ixodes scapularis) nymphs, which are the primary vectors of Lyme disease in the eastern United States. Lyme disease is common in northern but not in southern regions, and prior ecological studies have found that standard methods used to collect host-seeking nymphs in northern regions are unsuccessful in the south. This led us to hypothesize that there are behavior differences between northern and southern nymphs that alter how readily they are collected, and how likely they are to transmit the etiological agent of Lyme disease to humans. To examine this question, we compared the questing behavior of I. scapularis nymphs originating from one northern (Lyme disease endemic) and two southern (non-endemic) US regions at field sites in Wisconsin, Rhode Island, Tennessee, and Florida. Laboratory-raised uninfected nymphs were monitored in circular 0.2 m(2) arenas containing wooden dowels (mimicking stems of understory vegetation) for 10 (2011) and 19 (2012) weeks. The probability of observing nymphs questing on these stems (2011), and on stems, on top of leaf litter, and on arena walls (2012) was much greater for northern than for southern origin ticks in both years and at all field sites (19.5 times greater in 2011; 3.6-11.6 times greater in 2012). Our findings suggest that southern origin I. scapularis nymphs rarely emerge from the leaf litter, and consequently are unlikely to contact passing humans. We propose that this difference in questing behavior accounts for observed geographic differences in the efficacy of the standard sampling techniques used to collect questing nymphs. These findings also support our hypothesis that very low Lyme disease incidence in southern states is, in part, a consequence of the type of host-seeking behavior exhibited by southern populations of the key Lyme disease vector.