Managing landscapes for conservation and human health: the role of deer and non-native hedgehogs in tick-borne disease emergence in the Western Isles

关键词：生物多样性，人畜共患病，传染病，媒介，莱姆病摘要：随着生物群落的变化，例如物种的增加，消失或变得更加丰富，这改变了物种之间的相互作用。从人类的角度来看，改变的物种相互作用可能是负面的，例如当改变的群落为危险病原体的传播和传播给人类宿主提供更好的条件时。这个项目在苏格兰西部群岛的尤斯特岛调查了这个问题。两种哺乳动物，欧洲刺猬和马鹿，在美国的数量比历史上多得多。刺猬不是岛上的原生物种，但自20世纪70年代以来被引入了几次。从那时起，它们变得非常丰富，并因捕食地面筑巢的鸟类而造成了严重的问题。在过去的几十年里，马鹿的数量也显著增加。与此同时，蜱虫和人类莱姆病病例（由受感染的蜱虫叮咬引起）在乌斯特群岛的发病率上升，远高于邻近岛屿或苏格兰大陆。蜱虫的增加很可能与鹿的增加有关，因为鹿是已知的大量蜱虫的宿主，但鹿不能传播导致莱姆病的伯氏疏螺旋体。另一方面，刺猬可以携带很高的蜱虫负担，通常感染伯氏疏螺旋体。这使得刺猬和本地的小型哺乳动物很可能在维持和目前感染伯氏疏螺旋体的蜱虫数量的增加中发挥了作用。因此，我们假设是高鹿和高刺猬数量的结合导致了该系统中莱姆病的风险增加。我们的项目将检验这一假设，并通过建立一个由学术研究人员、保护团体、蜱虫专家和公共卫生官员组成的跨学科团队，为管理提供急需的信息。该项目将持续四年，主要有三个目标：首先，我们将测试鹿的空间分布和丰度与蜱虫密度和莱姆病风险之间的关系。我们将在uist上发现的鹿的全部密度范围内对环境中的蜱虫进行取样，并测试感染病原体的比例。其次，我们将通过活体诱捕和采样刺猬（以及本地小型哺乳动物）来确定引进刺猬作为蜱虫和蜱传疾病宿主的作用，并对蜱虫进行测试。第三，我们将把我们的实地数据纳入数学模型，以检验预测去除刺猬和鹿对莱姆病风险的影响。这项工作代表了格拉斯哥大学、苏格兰自然遗产（向苏格兰政府提供建议）和西部群岛国家卫生服务之间的独特伙伴关系。共同努力将确保我们的研究满足不同合作伙伴的需求，并确保所有合作伙伴之间有效地共享数据和发现。此外，我们将与当地土地管理者、组织和社区密切合作，确保他们同样能够从这项工作中受益。我们的项目将是一个极好的机会来测试重要的生态假设，并影响土地管理，以减少蜱传疾病的风险。

Studentship strategic priority area:Environment, pollution and human healthKeywords: biodiversity, zoonosis, infectious disease, vector, Lyme diseaseAbstract: As biological communities change, for example because species are added, lost, or become more abundant, this changes how species interact. Altered species interactions can be negative from a human point of view, such as when modified communities provide better conditions for dangerous pathogens to circulate and to be transmitted to the human host. This project investigates this problem on the islands of Uist, in the western Isles of Scotland. Two mammal species, the European hedgehog and red deer, have become much more abundant on the Uists than they historically were. Hedgehogs are not native to the islands but were introduced several times since the 1970s. Since then, they have become highly abundant and are causing serious problems by predating on ground nesting birds. Red deer have also increased markedly in abundance over the past decades. Over the same time, ticks and human cases of Lyme disease, which is caused by the bite of an infected tick, have increased on the Uists to a level that is much higher than on neighbouring islands or on the Scottish mainland. The increase in ticks is most likely linked to that in deer, since deer are known to support high numbers of ticks, but deer are not able to transmit Borrelia, the bacterial agent causing Lyme disease. Hedgehogs on the other hand can carry high tick burdens and are commonly infected with Borrelia. This makes it probable that hedgehogs, along with native small mammals, are playing a role in the maintenance and current rise in ticks infected with Borrelia. We therefore hypothesise that it is the combination high deer and high hedgehog numbers that is causing an increased risk of Lyme disease in this system. Our project will test this hypothesis and provide much needed information for management by forging an interdisciplinary team of academic researchers, conservation groups, tick specialists, and public health officials. The project will run over four years and has three major aims: First, we will test how the spatial distribution and abundance of deer relates to the density of questing ticks and Lyme disease risk. We will sample ticks in the environment across the full range of deer densities found on the Uists, and test what proportion is infected with the pathogen. Secondly, we will establish the role of introduced hedgehogs as hosts for ticks and tick-borne diseases by live-trapping and sampling hedgehogs (and native small mammals) for ticks, which are also tested. Thirdly, we will incorporate our field data into mathematical models to examine what effect the removal of hedgehogs and deer is predicted to have on Lyme disease risk. This work represents a unique partnership between the University of Glasgow, Scottish Natural Heritage (providing advice to the Scottish Government), and the National Health Service - Western Isles. Working jointly will ensure that our research addresses the needs of the different partners and that data and findings are shared efficiently among all of them. In addition, we will work closely with local land managers, organisations, and communities to make sure that they are equally able to benefit from this work. Our project will be an excellent opportunity to test important ecological hypotheses and to influence land management with the aim of reducing the risk of tick-borne disease.