Assessing the risk of an emerging salmonid disease

肾脏疾病（PKD）是一种新出现的鲑鱼疾病，其严重程度和地理范围正在增加。PKD是由粘虫Tetracapsuloides bryosalmonae（Tb）引起的，并且可以在养殖和野生鱼类种群中产生显著的，有时是灾难性的死亡率。PKD被认为是导致瑞士河流中褐鳟鱼数量下降的原因，冰岛和挪威最近在野生鱼类种群中爆发的疾病增加了该疾病的地理范围。所有鲑鱼都是易感的，爆发和下降与水温和营养水平的增加有关。结核杆菌利用高度克隆的苔藓虫作为主要宿主，释放到水中的孢子对鱼类具有感染性。该项目的目的是通过关注疾病来源来评估英国野生鱼类种群的PKD风险。因此，我们的目标是：1）表征苔藓虫种群动态和Tb在该主机内的动态。2)建立风险因素与结核病患病率和负担苔藓虫和随后的传播到鱼类宿主。3)使用流行病学和实地研究开发的风险模型（在目标1中进行）制定并验证一项对苔藓虫进行采样的方案，作为对野生鱼进行采样的替代品，以评估和监测寄生虫水平，并在环境局（EA）和渔业与水产养殖科学中心（Cefas）制定野生鱼中PKD的风险地图将率先开发统计模型，以确定PKD的风险因素，制定监测PKD风险的标准操作程序，并绘制风险图。学术监督员将监督必要的流行病学研究，以便能够进行风险因素分析。因此，该项目将产生有益于监管机构的实际产出（见下文），并将通过描述野外殖民宿主和体内寄生虫的相互作用以及环境变化对这些相互作用的潜在影响，为宿主和寄生虫进化生态学的基础知识做出重大贡献。学生将获得一系列可转移和技术技能的培训，并在研究期间与CASE合作伙伴，养鱼场合作伙伴和学术机构进行广泛的互动。环境条件如何促进PKD的发展尚不清楚，但这种理解对于确定与疾病爆发和野生鱼类种群易感性相关的风险因素至关重要。由于鲑鱼的价值和褐鳟鱼种群面临的许多压力，监测野生鱼类健康仍然是一个严峻的挑战。使用苔藓虫作为监测PKD的替代品将为管理野生鱼类种群提供一种有价值的新方法，为国家监测和最大限度地减少未来疾病的影响提供基础。

Proliferative kidney disease (PKD) is an emerging disease of salmonid fish that is increasing in severity and geographic range. PKD is caused by the myxozoan Tetracapsuloides bryosalmonae (Tb) and can effect significant and sometimes catastrophic mortality in farmed and wild fish populations. PKD is believed to have contributed to declines in brown trout populations in Swiss rivers and recent outbreaks in wild fish populations in Iceland and Norway have increased the geographic range of the disease. All salmonids are susceptible and outbreaks and declines have been linked with increasing water temperatures and nutrient levels. Tb exploits highly clonal bryozoans as primary hosts and spores released into the water are infective to fish. The aim of this project is to assess the risk of PKD for wild fish populations in the UK by focusing on the disease source. Our objectives are thus to: 1) Characterise bryozoan population dynamics and the dynamics of Tb within this host. 2) Establish risk factors associated with Tb prevalence and burden in bryozoans and subsequent transmission to fish hosts. 3) Use risk models developed from epidemiological and field studies (conducted in Objective 1) to produce and validate a protocol to sample bryozoans as a surrogate for sampling wild fish in order to assess and monitor parasite levels and to produce a risk map for PKD in wild fish CASE Project Partners at the Environment Agency (EA) and Centre for Fisheries & Aquaculture Science (Cefas) will spearhead the development of statistical modelling to identify risk factors for PKD, to develop a standard operating procedure for monitoring PKD risk, and to produce a risk map. Academic supervisors will supervise the requisite epidemiological studies that will enable risk factor analysis. As a result the project will generate practical outputs of benefit to regulatory agencies (see below) and will significantly contribute to fundamental knowledge of the evolutionary ecology of hosts and parasites by characterising the interactions of colonial hosts and endoparasites in the wild and the potential effect of environmental variation on these interactions. The student would gain training in a range of transferable and technical skills and would interact broadly during research with CASE partners, fish farm partners and academic institutes. Drivers for the work How environmental conditions promote the development of PKD is poorly understood but such understanding is crucial for identifying risk factors associated with disease outbreaks and the susceptibility of wild fish populations. Due to the value of salmonid fish and the many pressures facing brown trout populations, monitoring fish health in the wild remains a serious challenge. Using bryozoans as a surrogate for monitoring PKD would provide a valuable and novel approach for managing wild fish populations, affording a basis for national monitoring and minimising future disease impacts.