Epidemiological investigation of emerging infectious diseases of farmed fish in Canada

加拿大养殖鱼类新发传染病流行病学调查

• 批准号: RGPIN-2022-03501
• 负责人: Thakur, Krishna
• 金额: $ 2.11万
• 依托单位: University of Prince Edward Island
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=756998
• 关键词: Epidemiological; investigation; emerging; infectious; diseases

The increase in demand for seafood has led to rapid growth of aquaculture industry, including netpen based salmon production. Canada's Blue Economy Strategy 2040 envisions Canada to be top three best sustainable producer of seafood. However, the industry is challenged by an increase in the emergence, severity, and prevalence of infectious diseases in the marine ecosystem. Many aquatic animal diseases are associated with pronounced shifts in microbial community structures or genetic and functional changes in reservoir non-virulent progenitor variants. Mouthrot (MR; tenacibaculosis), and infectious salmon anemia (ISA) are emerging diseases in Atlantic salmon aquaculture in Canada, the most important bacterial and viral diseases threatening the sustainability of salmon aquaculture. Tenacibaculum maritimum is the principal causative agent of MR; however, other Tenacibaculum spp are also likely involved. The non-virulent strains of the ISA virus are likely the reservoir present in the farm environment, from which the virulent strains emerge. However, the epidemiology and factors associated with outbreaks and severity of disease are mostly unknown for Canadian aquaculture. We surmise that infectious agents involved in these diseases are present on the farms as opportunistic agents and that a multifactorial etiology is involved in their outbreaks. We also hypothesize that outbreaks result from changes in the genetic make-up of the agent and, or microbial community structure in the affected fish due to stressors, such as increased water temperature, management, etc. The short-term goal of my on-farm observational research is to elucidate the interactions between host, pathogen(s), and environment to understand the occurrence, transmission, and risk factors associated with these emerging infectious diseases in salmon aquaculture in Canada using MR and ISA as example cases. The long-term goal of my research program is to understand the effects of changing ecosystems, and farm and wild interactions to enhance the aquatic epidemiology research program for sustainable aquaculture and fishery. Some of the questions this research will answer are: how abundant are non-virulent strains of infectious agents, and how likely are they to convert to virulent strains and result in clinical outbreaks? To what extent do the environmental and other factors interact with these microbial and genetic shifts? Key results on the genomic characteristics of the infectious agents and the identification of factors involved in the emergence of disease will help in efficient management of the disease by formulating mitigation strategies in the short term and reducing antibiotic use, providing informed guidance for outbreak prevention and help achieve Canada's Blue Economy Strategy 2040 sustainable sea food production target in the long term. Knowledge gained on the epidemiology of these diseases in farmed fish can potentially be applied to mitigate their impact on wild salmon.

对海产品需求的增加导致了水产养殖业的快速增长，包括网箱三文鱼生产。加拿大的蓝色经济战略2040设想加拿大将成为最好的可持续海鲜生产国前三名。然而，海洋生态系统中传染病的出现、严重程度和流行率的增加对该行业构成了挑战。许多水生动物疾病与微生物群落结构的显著变化或水库非毒力前体变种的遗传和功能变化有关。Mouthrot(顽固性杆状杆菌病)和传染性鲑鱼贫血(ISA)是加拿大大西洋鲑鱼养殖业的新出现的疾病，是威胁鲑鱼养殖可持续性的最重要的细菌和病毒疾病。Maritimum是引起MR的主要病原体，但也可能涉及其他Tenacbaculum spp。ISA病毒的无毒株很可能是农场环境中存在的蓄水池，强毒株就是从这里产生的。然而，对于加拿大水产养殖来说，与疾病暴发和严重程度相关的流行病学和因素大多是未知的。我们推测，涉及这些疾病的传染病病原体在农场中作为机会性病原体存在，并且它们的暴发涉及多因素病原学。我们还假设暴发是由于压力因素导致受影响鱼类中微生物群落结构的改变和/或病原体的遗传组成的变化，如水温升高，管理等。我在养殖场观察研究的短期目标是阐明宿主、病原体(S)和环境之间的相互作用，以MR和ISA为例了解加拿大鲑鱼养殖中这些新出现的传染病的发生、传播和风险因素。我的研究计划的长期目标是了解生态系统变化的影响，以及农场和野生动物的相互作用，以加强可持续水产养殖和渔业的水生流行病学研究计划。这项研究将回答的一些问题是：非致病毒株的数量有多多，以及它们转化为致病毒株并导致临床暴发的可能性有多大？环境和其他因素在多大程度上与这些微生物和基因转移相互作用？传染病病原体基因组特征的关键结果和疾病出现相关因素的确定将有助于通过制定短期缓解战略和减少抗生素使用来有效管理疾病，为疫情预防提供知情指导，并有助于实现加拿大2040年蓝色经济战略的长期可持续海产品生产目标。在养殖鱼类中获得的这些疾病的流行病学知识可能被用于减轻它们对野生三文鱼的影响。