The application of epidemiology in aquatic animal health -opportunities and challenges

ABSTRACT: Over recent years the growth in aquaculture, accompanied by the emergence of new and transboundary diseases, has stimulated epidemiological studies of aquatic animal diseases. Great potential exists for both observational and theoretical approaches to investigate the processes driving emergence but, to date, compared to terrestrial systems, relatively few studies exist in aquatic animals. Research using risk methods has assessed routes of introduction of aquatic animal pathogens to facilitate safe trade (e.g. import risk analyses) and support biosecurity. Epidemiological studies of risk factors for disease in aquaculture (most notably Atlantic salmon farming) have effectively supported control measures. Methods developed for terrestrial livestock diseases (e.g. risk-based surveillance) could improve the capacity of aquatic animal surveillance systems to detect disease incursions and emergence. The study of disease in wild populations presents many challenges and the judicious use of theoretical models offers some solutions. Models, parameterised from observational studies of host pathogen interactions, have been used to extrapolate estimates of impacts on the individual to the population level. These have proved effective in estimating the likely impact of parasite infections on wild salmonid populations in Switzerland and Canada (where the importance of farmed salmon as a reservoir of infection was investigated). A lack of data is often the key constraint in the application of new approaches to surveillance and modelling. The need for epidemiological approaches to protect aquatic animal health will inevitably increase in the face of the combined challenges of climate change, increasing anthropogenic pressures, limited water sources and the growth in aquaculture. TABLE OF CONTENTS: 1 Introduction 42 The development of aquatic epidemiology 73 Transboundary and emerging diseases 93.1 Import risk analysis (IRA) 103.2 Aquaculture and disease emergence 113.3 Climate change and disease emergence 133.4 Outbreak investigations 134 Surveillance and surveys 154.1 Investigation of disease prevalence 154.2 Developments in surveillance methodology 164.2.1 Risk-based surveillance and scenario tree modelling 164.2.2 Spatial and temporal analysis 164.3 Test validation 175 Spread, establishment and impact of pathogens 185.1 Identifying routes of spread 185.1.1 Ex-ante studies of disease spread 195.1.2 Ex-post observational studies 215.2 Identifying risk factors for disease establishment 235.3 Assessing impact at the population level 245.3.1 Recording mortality 245.3.2 Farm health and production records 265.3.3 Assessing the impact of disease in wild populations 276 Conclusions 317 Competing interests 328 Authors' contributions 329 Acknowledgements 3310 References 33.     

The application of risk analysis in aquatic animal health management

Risk analysis has only been regularly used in the management of aquatic animal health in recent years. The Agreement on the Application of Sanitary and Phytosanitary measures (SPS) stimulated the application of risk analysis to investigate disease risks associated with international trade (import risk analysis-IRA). A majority (9 of 17) of the risk analyses reviewed were IRA. The other major focus has been the parasite of Atlantic salmon--Gyrodactylus salaris. Six studies investigated the spread of this parasite, between countries, rivers and from farmed to wild stocks, and clearly demonstrated that risk analysis can support aquatic animal health policy development, from international trade and biosecurity to disease interaction between wild and farmed stocks. Other applications of risk analysis included the spread of vertically transmitted pathogens and disease emergence in aquaculture. The Covello-Merkhofer, risk analysis model was most commonly used and appears to be a flexible tool not only for IRA but also the investigation of disease spread in other contexts. The limitations of the identified risk assessments were discussed. A majority were qualitative, partly due to the lack of data for quantitative analysis, and this, it can be argued, constrained their usefulness for trade purposes (i.e. setting appropriate sanitary measures); in other instances, a qualitative result was found to be adequate for decision making. A lack of information about the disease hazards of the large number of fish species traded is likely to constrain quantitative analysis for a number of years. The consequence assessment element of a risk analysis was most likely to be omitted, or limited in scope and depth, rarely extending beyond examining the evidence of susceptibility of farmed and wild species to the identified hazard. The reasons for this are discussed and recommendations made to develop guidelines for a consistent, systematic and multi-disciplinary approach to consequence assessment. Risk analysis has improved decision making in aquatic animal health management by providing a transparent method for using the available scientific information. The lack of data is the main constraint to the application of risk analysis in aquatic animal health. The identification of critical parameters is an important output from risk analysis models which should be used to prioritise research.     

The future of training for aquatic animal health veterinarians

This article describes educational approaches for training veterinary students, veterinary graduates, and practicing veterinarians in the area of aquatic animal health and lists a range of general research, training, internship/residency, and continuing-education resources.     

健康养殖,水产疫病防治的主要措施

我国既是一个水产养殖大国，又是一个疫病多发的国家。多年来水产疫病紧随水产业的发展而发展。上世纪70～80年代，全国以养殖“四大家鱼”为主的时期，主要流行草鱼出血病，死亡率高达30％以上；90年代以对虾为主的海水养殖，白斑病使对虾损失过半；同期甲鱼白斑病死亡率逾20％～30％。至2002年全国水产     

水产动物营养研究与应用的反思

与历经100多年的人类营养学研究相比,水产动物营养学在全球范围都是一门年轻的学科.在20世纪50年代,美国华盛顿州立大学John Halver博士首先创建了系统的鱼类营养学研究方法,并在鲑鳟鱼类的营养需求方面首先进行了研究.     

水产动物微颗粒饲料加工工艺研究进展

水产动物幼体微颗粒饲料是近些年来国内外研究开发的热点,文中综述了国际上较为流行的几种微颗粒饲料造粒工艺,包括微黏合工艺、微包膜工艺、聚合反应工艺、相分离技术造粒工艺、物理机械法造粒以及混合法造粒工艺。微颗粒饲料制粒工艺是微颗粒饲料产业乃至水产育苗行业的关键技术,其进一步发展有赖于制粒工艺技术研究和水产动物幼苗营养及消化生理研究的综合进展。     

水产动物饲料中非营养性添加剂的研究与应用前景

本文综述了近年来水产动物配合饲料中的促生长剂、诱食剂、粘合剂、着色剂等非营养性添加剂的研究动态和发展趋势，为配合饲料的研制提供了基础资料。     

功能性水产配合饲料的研发与应用

在水产健康养殖业的发展过程中,功能性水产配合饲料的研发与应用意味着拥有更多的机会和更广阔的市场前景。功能性水产配合饲料能够提高养殖水产动物生长性能,改善其健康状况,促进其免疫系统发育,增强机体免疫力,提高饲料的消化吸收率,减轻养殖自身污染,提升水产品品质,比传统的水产配合饲料带来更佳的生理效应,产生良好的经济效益、社会效益和环境效益。本文简要介绍功能性水产配合饲料的概念与类型、研发的理论基础、关键技术以及其研发与推广应用若干思考,以期为其进一步开发与应用提供参考。     

菜粕、棉粕在水产饲料中的合理应用

鱼粉是水产饲料中重要的蛋白原料,但是近年来,鱼粉资源短缺,价格不断上涨,目前鱼粉的价格已达13 000～14 000元/t,较一年前上涨了近一倍;与此同时,豆粕作为优质的植物蛋白源,其价格也一直在较高范围内波动,其最高价格曾达4 000元/t以上.     

Epidemiological approach to aquatic animal health management: opportunities and challenges for developing countries to increase aquatic production through aquaculture

Aquaculture appears to have strongest potential to meet the increasing demands for aquatic products in most regions of the world. The world population is on the increase, as is the demand for aquatic food products. Production from capture fisheries at a global level is levelling off. Potential contributions from aquaculture to local food security, livelihoods and nutrition can be highly significant, especially in many remote and resource-poor rural areas. One of the major constraints to aquaculture production is the losses due to diseases. Over the decades, the sector has faced significant problems with disease outbreaks and epidemics which caused significant economic losses. The use of sound epidemiological principles and logical and science-based approach to identify and manage risks comprise two of the most important components of an effective biosecurity program. The maintenance of effective biosecurity in aquaculture is becoming more and more essential. There will be more demand for aquatic animal epidemiologists as well as epidemiological tools/resources in the region. The use of epidemiology will significantly improve health management, risk analysis and disease control. Although there are clear limitations and complications in the use of epidemiology for controlling aquatic animal pathogens, some positive results have recently emerged from a series of studies and trials to control diseases affecting the small-scale shrimp farming sector in southern India. This paper summarises the results of one such study which emphasizes the significant benefit of close collaboration with farmers, both individually and as groups, and capacity and awareness building among them and the importance of understanding the risk factors and implementing better management practices.     

瘦素对水生动物代谢、生长发育和繁殖的影响及机理

瘦素(leptin)是一种蛋白质类激素。痩素参与机体调节摄食、代谢、生长、发育、生殖、激素分泌和免疫等。文章主要综述瘦素对水生动物代谢、生长发育和繁殖的影响及其机理研究进展。旨在深入理解和研究之,以便更好地利用瘦素,调控水生动物代谢、生长发育和繁殖,促进养殖渔业的健康快速发展,提高经济效益和社会效益。     

乳酸菌在水产养殖中的应用及其应用于海参养殖的可行性

本文综述了近年来乳酸菌对不同水产动物生长促进和免疫力诱导的作用机制的研究,并探讨了乳酸菌应用于海参养殖的可行性。     

VC对水产动物的免疫增强作用研究与应用展望

VC（L－抗坏血酸）是一种具有广泛生理和免疫作用的免疫调节因子，它作为免疫增强剂应用于水产动物时，可以增强水产动物对多种传染性病原的非特异性免疫反应，提高其机体抗病力，缓解水产动物的应激症状，并提高水产动物的存活率。本文主要从VC对水产动物的体液免疫和细胞免疫两个方面阐述VC对水产动物的免疫增强作用，还就水产动物VC最适免疫剂量的影响因素作了浅议。     

博落回的药理作用及其在动物保健中的应用

综述了博落回的药理作用及其在动物保健中的应用。大量研究表明:博落回具有抗菌,杀虫,杀蛆,改善肝功能、增强免疫力,抗肿瘤等作用,并在动物保健中具有广阔的发展前景。     

黄芪多糖的药理作用及其在畜禽保健中的应用

黄芪多糖是黄芪的主要活性成分之一。综述了黄芪多糖的药理作用：增强机体免疫功能；抗病毒；抗肿瘤等以及它们在畜禽保健中的应用。     

水产养殖动物摄食节律与投喂模式的研究进展

投喂模式是集约化养殖管理的核心之一,是由投饲量(或投饲率)、投饲频率、投饲方式等环节构成的有机整体,使其最优化是获取最佳生长速度、减少饲料浪费、降低养殖自污染的有效途径。动物内在摄食节律则是建立科学投喂模式的生物学基础。投饲量和投饲频率与养殖动物的生长和饲料利用密切相关。文章针对国内外关于水产养殖动物摄食节律、投饲量、投饲频率和投饲方式等的最新进展进行综述,期望能对投喂模式的科学研究和生产实践有所帮助。     

The quality assurance of proficiency testing programs for animal disease diagnostic laboratories.

Laboratory data credibility has 3 major components: 1) valid methods, 2) proficiency testing (PT) to verify that the analyst can conduct the method and to compare results of other laboratories using the same method, and 3) third-party accreditation to verify that the laboratory is competent to conduct testing and that the method validation has been done within the environment and requirements of an effective quality-management system. Participation in external PT programs by a laboratory is strongly recommended in International Organization for Standardization/International Electrotechnical Commission International Standard 17025. Most laboratory accreditation bodies using this standard require that laboratories participate in such programs to be accredited. Internal PT is also recommended for each analyst. Benchmarking, or comparison between laboratories using PT or reference materials, is also recommended as part of the validation and evaluation of test methods. These requirements emphasize the need for proficiency test providers to demonstrate their competence. Requirements for competence are documented in national and international standards and guidelines, and accreditation is available for providers. This article discusses the activities and the components that are necessary and recommended for PT projects and programs for animal disease diagnostic testing. These are based on the requirements of the national and international standards, which address this subject, and on the experience of the author. The accreditation of external PT programs is also discussed. Organizations that accredit PT providers or that provide PT programs are listed. Existing references, guidelines, and standards that are relevant to PT in veterinary diagnostic laboratories are discussed.