INRAE, Oniris, BIOEPAR, 44300, Nantes, France.
INRAE, Oniris, BIOEPAR, 44300, Nantes, France.
Ticks Tick Borne Dis. 2021 Mar;12(2):101625. doi: 10.1016/j.ttbdis.2020.101625. Epub 2020 Dec 13.
Tick-borne diseases have a complex epidemiology that depends on different ecological communities, associating several species of vertebrate hosts, vectors and pathogens. While most studies in Europe are focused on Ixodes ricinus, other Ixodes species may also be involved in the transmission or maintenance of pathogens. This is the case of Ixodes frontalis, a poorly known species associated with different bird species such as blackbirds, thrushes and robins, with a wide distribution covering most European countries. In a previous study, high densities of questing I. frontalis larvae were found during autumn-winter at a site close to Nantes (western France) where a long-term survey focused on I. ricinus was conducted. These I. frontalis were mostly observed under bamboo bushes. In the present study, we investigated the presence of I. frontalis under bamboo bushes at various locations. With that aim in mind, a systematic search for questing I. frontalis was undertaken by the flagging method in public urban parks and private gardens presenting bamboo bushes (32 sites). This survey was carried out during autumn-winter to maximize the probability of finding the most abundant stage, i.e. larvae. We searched for I. frontalis first in the area of Nantes (10 sites), then in other regions of France (21 sites) and at one site in northern Italy. A single visit to each site revealed the presence of I. frontalis at 29 out of 32 sites: larvae were always present, nymphs were frequent (59 % of the positive sites), while adults were found at only 14 % of the sites. Questing stages of this understudied species are thus easy to find, by dragging or flagging under bamboo bushes in autumn or winter. We make the assumption that bamboo offers a favourable place for birds to roost overnight outside their breeding period (i.e. spring), sheltered from both predators and wind. This would explain higher densities of I. frontalis under bamboo, relative to other biotopes. As I. frontalis is known to harbour zoonotic pathogens, the consequences of this discovery on the epidemiology of tick-borne diseases are discussed.
蜱传疾病具有复杂的流行病学特征，取决于不同的生态群落，涉及多种脊椎动物宿主、媒介和病原体。虽然欧洲的大多数研究都集中在蓖子硬蜱上，但其他硬蜱物种也可能参与病原体的传播或维持。这就是前胸硬蜱的情况，它是一种与黑鹂、画眉和知更鸟等不同鸟类有关的了解甚少的物种，分布范围广泛，覆盖了欧洲大部分国家。在之前的一项研究中，在靠近南特（法国西部）的一个地点，在秋季至冬季期间发现了大量的前胸硬蜱幼虫，在那里进行了一项针对蓖子硬蜱的长期调查。这些前胸硬蜱大多在竹丛下被观察到。在本研究中，我们在不同地点调查了竹丛下前胸硬蜱的存在情况。为此，我们通过挂牌法在有竹丛的公共城市公园和私人花园中对前胸硬蜱进行了系统搜索（32 个地点）。这项调查是在秋季至冬季进行的，以最大限度地提高发现最丰富阶段（即幼虫）的可能性。我们首先在南特地区（10 个地点），然后在法国其他地区（21 个地点）和意大利北部的一个地点进行了前胸硬蜱调查。对每个地点的一次访问显示，在 32 个地点中有 29 个地点存在前胸硬蜱：幼虫始终存在，若虫频繁（59%的阳性地点），而成虫仅在 14%的地点发现。因此，通过在秋季或冬季在竹丛下拖动或挂牌，很容易发现这种研究较少的物种的探查阶段。我们假设，竹子为鸟类在繁殖期（即春季）之外过夜栖息提供了一个有利的地方，它们可以躲避捕食者和大风。这可以解释为什么在竹子下发现的前胸硬蜱密度相对较高。由于前胸硬蜱已知携带人畜共患病原体，因此讨论了这一发现对蜱传疾病流行病学的影响。
