Comparative vector competence of North American Lyme disease vectors
Comparative vector competence of North American Lyme disease vectors
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DOI：
10.1186/s13071-020-3893-x
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发表时间：
2020-01-14
影响因子：
3.2
通讯作者：
Swei, Andrea
中科院分区：
文献类型：
--
作者：
Couper, Lisa I.;Yang, Youyun;Swei, Andrea
背景了解大空间尺度上莱姆病发病率的驱动因素对于预测和减轻人类疾病风险至关重要。以前的研究已经确定了媒介物候和行为，宿主群落组成和景观特征作为莱姆病风险的驱动因素。然而，虽然莱姆病在美国东部和西部的传播周期涉及不同的媒介物种（分别为肩突硬蜱和太平洋硬蜱），但媒介特异性差异在传播效率中的作用尚未得到直接研究。通过比较这两个物种之间与载体能力相关的性状的表现，本研究旨在确定载体能力如何影响不同的莱姆病风险。方法采用一系列实验室试验，比较两种美国莱姆病媒介的感受态相关性状的表现。对于每一个物种，我们测量了附着到一个共同的啮齿类动物宿主，充血重量，病原体收购（主机蜱）和病原体传播（蜱到主机）从实验室小鼠的效率。在测定病原体的获得和传播中，我们使用了两种不同的病原体菌株，一种与I.肩胛肌1例，与I. pacificus，以评估传播动力学中媒介-病原体共同进化史的重要性。结果发现I.与I. pacificus相比，pacificus的寄主附着成功率和饱腹体重显著较高，但病原体传播效率显著较低。肩胛肌这两个物种之间的蜕皮成功和病原体收购没有差异。然而，病原体收购效率显着高于同域载体和病原体菌株比异域配对。结论本研究确定了物种特异性媒介性状作为美国莱姆病风险大规模变化的潜在驱动因素。特别是，极低的病原体传播率从蜱宿主观察到的I。pacificus可能限制莱姆病在美国西部的传播效率。此外，所观察到的变化，在病原体收购同域和异域之间的媒介-病原体菌株表明，媒介-病原体共同进化的历史可能在传播动力学中发挥关键作用。这些发现强调了需要考虑媒介性状和媒介-病原体共同进化作为控制区域莱姆病风险的重要因素。
Background Understanding the drivers of Lyme disease incidence at broad spatial scales is critical for predicting and mitigating human disease risk. Previous studies have identified vector phenology and behavior, host community composition, and landscape features as drivers of variable Lyme disease risk. However, while the Lyme disease transmission cycles in the eastern and western USA involve different vector species (Ixodes scapularis and Ixodes pacificus, respectively), the role of vector-specific differences in transmission efficiency has not been directly examined. By comparing the performance of traits involved in vector competence between these two species, this study aims to identify how vector competence contributes to variable Lyme disease risk. Methods We used a suite of laboratory experiments to compare the performance of traits related to vector competence for the two USA Lyme disease vectors. For each species, we measured the rate of attachment to a common rodent host, the engorgement weight, and the efficiency of pathogen acquisition (host to tick) and pathogen transmission (tick to host) from laboratory mice. In measuring pathogen acquisition and transmission, we used two different pathogen strains, one sympatric with I. scapularis and one sympatric with I. pacificus, to assess the importance of vector-pathogen coevolutionary history in transmission dynamics. Results We found I. pacificus had significantly higher host attachment success and engorgement weights, but significantly lower pathogen transmission efficiency relative to I. scapularis. Molting success and pathogen acquisition did not differ between these two species. However, pathogen acquisition efficiency was significantly higher for both sympatric vector and pathogen strains than the allopatric pairings. Conclusions This study identified species-specific vector traits as a potential driver of broad scale variation in Lyme disease risk in the USA. In particular, the exceedingly low rates of pathogen transmission from tick to host observed for I. pacificus may limit Lyme disease transmission efficiency in the western USA. Further, observed variation in pathogen acquisition between sympatric and allopatric vector-pathogen strains indicate that vector-pathogen coevolutionary history may play a key role in transmission dynamics. These findings underscore the need to consider vector traits and vector-pathogen coevolution as important factors governing regional Lyme disease risk.