流行病学模型及建模步骤

流行病学模型可作为动物疫病风险评估及防控策略制定的有力工具。论文介绍了流行病学模型的定义及其在动物疫病管理决策中的应用,讨论了模型的分类及建模的方法,重点阐述了动物疫病流行病学模型的构建步骤,包括建模系统和研究目标的确定、动物群体和疫病流行病学数据信息的收集、概念模型的构建、概念模型的确认、概念模型的公式化或编程、模型的验证、运行有效性的评估、敏感性分析、执行研究、输出结果的解释和交流。提出了一些建模的基本准则和应该着重考虑的问题,以期为动物疫病流行病学模型和风险评估预警研究提供参考。     

地理信息系统与动物流行病学

地理信息系统作为一种能对空间数据进行处理的计算机程序系统已被广泛应用在众多与空间信息操作有关的领域。在动物流行病学研究中 ,研究人员通过建立一些用于分析疫病分布时空模式的方法和模型 ,应用地理信息系统进行了许多疾病的空间分布模式、流行趋势、环境危险因素分布、辅助控制计划制定及控制效果评估等方面的研究 ,取得了很好的效果。地理信息系统已经成为当前进行流行病学研究的重要工具     

The parasites, predators, places and people I have known: a great adventure

I am extremely proud to receive the WAAVP/Pfizer Animal Health award, and particularly so in Africa, the continent where I have spent a large part of my professional life. In the nearly 40 years in research I have had the privilege and excitement of being involved with many great parasites, predators, places and people. In my early days in Kenya I saw all the great wild animal predators, but soon came to appreciate that the greatest predator of all was disease, particularly parasitic disease, with the devastating effects of tsetse and ticks and the infections they transmitted, and of the all-prevailing roundworms. I learned several key lessons while working with research teams to develop better diagnostics, to improve epidemiological understanding as a basis for rational treatment and control, and to extend the understanding of disease processes with the view to developing novel methods of treatment or prevention. The Power of Pathology in diagnosing diseases, identifying new diseases and as a major tool for pathogenic diseases. The Power of Pathogenesis in identifying key mechanisms that led to new diagnostic techniques, improved methods of treatment, and possibly to future vaccines. The Power of Application of what we already know; while recognising that molecular biology will make a massive contribution to improving animal and human health, it is important to appreciate that we already have a very powerful armamentaria to diagnose, treat, control or prevent disease, and when used properly they have been successful and cost-effective. The Power of Genetic Resistance: the recognition that certain species, certain breeds, and certain individuals within breeds possess remarkable resistance to certain parasitic diseases such as trypanosomosis and helminthosis, and that this trait is genetically correlated with production, opens up a very powerful additional approach to improving animal health. The Importance of Measurement: I completely endorse the sentiments of Lord Kelvin, Professor of Natural Philosophy at Glasgow University who stated in 1846: "When you can measure what you are speaking about, and express it in numbers, you know something about it: but when you cannot measure it, your knowledge is of a meagre and unsatisfactory kind." This applies very much to Parasitology. The future is bright. The combination and integration of the new technologies of Biotechnology, Mathematical Methods and Bioinformatics coupled with advances in Computer Power will produce new standards in animal and human health in the 21st century. New methods of predicting, diagnosis, treating, controlling, prognosing and preventing disease will become available. WAAVP has a major role to play by ensuring that veterinary parasitologists are provided with the proper training, infrastructure and forum to advance new technologies and that the veterinary profession plays a leading role in the future direction they take.     

动物饲养管理与疾病防控的关系

在养殖业生产过程中,动物疾病防控是非常重要的工作,防控工作做得成功与否,事关养殖业成效,直接影响养殖户经济收入,做好动物疾病防控就显得尤为重要了,本人认为要做好动物疾病防控工作,就从平时日常管理做起,建立一整套完善的饲养管理制度,为畜禽提供优异的圈舍环境和优质的饲草料,做好防寒防暑措施,落实动物疫病防控措施,增强动物个体抗病能力,就会有效地降低动物疾病的发生,尤其是传染病发生都可以避免;即使发生传染病,也能及时得到有效控制。在大规模养殖过程中,我们要把重点放在做好饲养管理,确保各项生理指标健康,增加个体抗病能力,从而增强群体抗病能力,而不是忙于治疗个别病畜,否则会因小失大,会使动物疾病防控工作完全陷入被动局面。为此不难看出,动物饲养管理和疾病防控工作有着密切关系,本人通过调查研究、查阅资料,对动物饲养管理与疾病防控的关系进行探讨。     

病毒性动物疫病诊断技术研究进展

动物疫病的大暴发不仅严重影响畜牧业的生产与发展，造成巨大经济损失，而且会严重危害人类健康。病毒性疫病的增加使得动物疫病更加复杂，流行趋势更加严峻。灵敏、特异、快速地诊断动物疫病是实施疫病防控措施的关键环节。基于PCR技术及等温扩增技术的分子生物学诊断解决了传统病原学诊断费时费力、免疫血清学存在的窗口期等问题并摆脱了对高精度温控设备的依赖，成为目前常用的病原体筛查方法。但大多数检测方法一次只能检测到一个或几个病原体，且复杂的试验流程及对设施的高要求降低了立即干预突发疫情的能力，同时无法满足某些检测分析需求。近年来，学科间相互渗透融合的高通量诊断技术发展迅速，具有同时监测、检测和表征成百上千个靶点的能力，能满足在多种环境下的病原体快速检测的需求，是生命科学发展过程中一种重要的生物学检测手段。笔者从病原学、免疫血清学、分子生物学及高通量诊断等方面对主要的病毒性动物疫病检测技术进行了综述，展望未来动物疫病诊断检测技术的发展，以期为动物疫病快速诊断提供更多的方案思路，提升动物疫病的防控能力。     

Emerging diseases: a global and biological perspective

The 'Livestock Revolution' and globalization with enormous increases in free trade of animals and food products are not a choice but a reality (Thiermann, J. Vet. Med. Educ., 28, 2001, 56). Conditions of modern life, some of them related to or being the result of globalization, ensure that factors responsible for disease emergence are more prevalent than ever. Categorization of the factors is somewhat arbitrary but are representative of the underlying processes that cause emergence. Major responsible factors include ecological changes, such as changes due to agriculture or economic development or to anomalies in climates, human demographical changes and behaviour, travel and commerce, technology and industry, microbial adaptation and change, and the breakdown of public health measures (Morse, Emerg. Infect. Dis., 1, 1995, 7). Furtheron, concerning pathogens, their most striking feature emerging and re-emerging is their diversity, ranging from viruses and prions, over bacteria and rickettsia, fungi, protozoa to helminths. As presently the epidemiological perspective does not permit reliable prediction and prevention of most damaging new pathogens, and as the evolutionary perspective only provides rough theoretical estimates for selective processes in pathogen populations, surveillance and monitoring remain the most important methods to recognize early that 'something has happened'. In light of the complexity and diversity of likely new emerging diseases, such surveillance may be more broadly targeted and aimed more realistically at early recognition of disease syndromes rather than at identifying microbial diseases. The complex and rapid-paced development of international trade, coupled with increasing societal demands for not only abundant and inexpensive food as well as for protection from diseases originating from animals, demands immediate attention from the veterinary community. The inter-relationship at the minimum between animal production, animal diseases and human diseases demands that we consider our concepts, methods and structures. There exists a huge growth area for the veterinary profession; substantial need exists for trained individuals who understand the science of foreign diseases, who can facilitate emergency management operations against diseases (Brown, J. Vet. Med. Educ., 30, 2003, 112) and who can contribute to adjust and strategically develop animal production systems further.     

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.     

高寒阴湿地区蕨麻猪多种病调查与防控试验报告

针对蕨麻猪多种病给当地养殖业造成的损失,进行了甘南高寒阴湿地区蕨麻猪多种病防控模式的研究,通过流行病学调查,临床症状、病原检测、实验室诊断,查出了弓形虫病,仔猪腹泻,气喘病,疥螨四种病。通过药敏试验表明,弓形虫病治愈率达91%;仔腹泻病治愈率高达90%;气喘病治愈率达100%;疥螨病驱治率高达92%,同时,采取强心、止痛、利尿、健胃、止泻、消炎、驱虫等防和治并举措施,防治效果显著。     

Animal transboundary diseases: European union and asian network of veterinary research cooperation for quality livestock production

Transboundary animal diseases (TADs) constitute a global threat that afflict livestock. They are characterized by the suddenness, acuteness, the rapidity with which they can spread in susceptible livestock populations and the widespread nature of the losses that they can produce. The havoc they play renders individual farmers and private veterinary services relatively powerless to take effective action. As TADs do not recognize national borders, there is a great demand for regional cooperation which must be put into a global term. From the epidemiological point of view, the prospects for eradication of a disease with minimal production losses and other costs are best, if the disease can be recognized early where it is localized and then a disease control programme be quickly implemented.     

Epidemiological simulation modeling and spatial analysis for foot-and-mouth disease control strategies: a comprehensive review

Foot-and-mouth disease (FMD) is one of the most serious transboundary, contagious viral diseases of cloven-hoofed livestock, because it can spread rapidly with high morbidity rates when introduced into disease-free herds or areas. Epidemiological simulation modeling can be developed to study the hypothetical spread of FMD and to evaluate potential disease control strategies that can be implemented to decrease the impact of an outbreak or to eradicate the virus from an area. Spatial analysis, a study of the distributions of events in space, can be applied to an area to investigate the spread of animal disease. Hypothetical FMD outbreaks can be spatially analyzed to evaluate the effect of the event under different control strategies. The main objective of this paper is to review FMD-related articles on FMD epidemiology, epidemiological simulation modeling and spatial analysis with the focus on disease control. This review will contribute to the development of models used to simulate FMD outbreaks under various control strategies, and to the application of spatial analysis to assess the outcome of FMD spread and its control.     

Inherited diseases of cattle — A perspective

Extract

Genetic variation, whether due to the fortuitous recombination of genes at meiosis and fertilization, or to mutation, is the means of evolution and the tool of the animal breeder. Along with favourable variations of the genome, there may be unfavourable variations, some so unfavourable as to result in clinically apparent disease. Therefore, it is biologically normal for genetically induced diseases to occur in all species, races or breeds. Such disease may be caused by structural or functional defects of many kinds and it is important to differentiate these from similar diseases induced by environmental agents. Although the cost of inherited diseases to the national economy may be lower than that caused by diseases of infectious or nutritional origin, inherited diseases may be economically important, particularly to individual breeders. Certain genetically caused diseases may spread insidiously through a breed until they are difficult to control economically. It is therefore highly desirable that diseases with a genetic basis be recognized at an early stage and control measures instigated. Apart from the economic aspects of inherited diseases, they may be important as experimental models for the study of similar diseases in man.     

Control of trichinellosis by inspection and farm management practices

The prevention of human trichinellosis by proper meat inspection is a classic example of successful veterinary public health measures. The microscopic methods which have been used for more than a century to test pigs for trichinae were intended to prevent human disease. However, the value of these relatively insensitive direct detection methods, including trichinoscopy and pooled sample digestion, was debated as soon as more sensitive indirect (serological) methods became available. Two issues related to testing were discussed. First, should public health authorities endeavour to prevent all infections of humans rather than simply prevent the occurrence of disease, and second, would epidemiological surveillance and monitoring of the pig population on farms not provide a better control system to prevent human infection. This latter issue is of particular importance for those countries in the world where human trichinellosis acquired from farmed animals is absent and examination of pigs at the abattoir only results in negative findings. In countries where domestic pig infections are virtually non-existent, monitoring of Trichinella infection in wildlife could also contribute to understanding the infection pressure from nature to livestock. Trichinella-free pig farming is a feasible option for controlling this zoonosis, even in endemic areas. This approach provides an opportunity to combine good veterinary practice, in order to prevent animal diseases, with the prevention of Trichinella infection. All animals with access to the environment, or animals which are fed with potentially Trichinella-infected feed (swill, carcasses) will always constitute a public health threat, and must be inspected individually at slaughter (swine, horses, wild boars). Finally, it is important to recognize that trichinellosis is a world-wide problem that needs continuous public health attention. If no control system exists, for whatever reason, the public should be educated not to consume improperly cooked meat.     

Specific immunoprophylaxis of some viral diseases in cattle

Specific immunoprophylaxis has played a key role in prevention and control of animal infectious diseases for many years. Vaccines are commonly used to diminish economic losses in animal production caused by infectious agents. Currently, respiratory diseases are the main health problem in cattle. BHV1, BRSV and BVD-MD viruses are among the most important pathogens worldwide. They can cause a disease themselves or they can be one of many agents causing a respiratory syndrome. The following article describes the specific immunoprophylaxis of cattle viral diseases caused by such viruses.     

Zoonoses control--new challenges in health protection of consumers]

The eradication of bovine tuberculosis and brucellosis of domestic stock in Germany through the combined efforts of veterinary medicine, the agricultural section and the state was an historic achievement. Since the two diseases are zoonoses, their successful control can also be seen as a valuable contribution to public health. Both these zoonoses are classic animal diseases presenting themselves as clinical entities complete with gross pathological lesions. In contrast, today we are confronted with pathogens causing zoonoses characterised by latent, i.e. clinically inapparent herd infections that do not result in visible tissue changes. Nevertheless, through contaminated foodstuffs, these pathogens contribute to food-borne infections leading to the outbreak of genuine zoonoses in humans. It has been estimated that there could be as many as two million cases of food-borne infections annually in Germany. Among them are salmonellosis, campylobacteriosis, yersiniosis, infections with verotoxin producing E. coli, listeriosis and toxoplasmosis. While the national animal disease legislation only foresees the control of notifiable diseases, the basis for zoonoses control is laid down in the EU Zoonosis-Directive, which is presently awaiting its transposition into national law and into practice. In order, for instance, to combat the most important Salmonella infections of humans, Integrated Quality Systems (IQS) have been formulated as a means of implementing the proven HACCP concept in animal production units and ensuring animal health from the point of view of consumer protection. The aim of all measures must be to free infected herds of pathogens, to investigate and eliminate all sources with a potential for further pathogen introductions, to maintain pathogen-free herds--with a reduced pathogen challenge in mid-term time periods--, as well as to develop diagnostics capable of identifying pathogen carriers before slaughter. For the disinfection of stock, it is important to have epidemiological data collecting systems and information systems that allow complete diagnostic tracing from herd to slaughterhouse and vice versa. All sides, including research and surveillance, as well as producers are called upon to actively share in protecting the health of consumers as far as it is threatened by latent infections in domestic stock.     

Detection of Trichinella infection in food animals

The first part of this review article deals with classical methods used for the detection of Trichinella larvae in muscle samples of those animal species which are recognized as traditional sources of trichinellosis for human beings, as well as those species which are important for epidemiological reasons. Special consideration is given to the main applications of these methods (routine slaughter inspection, and epidemiological studies in reservoir animals), and to the major factors that may influence detection methods (sampling site, sample size). Historical, current and future aspects concerning national and EU legislation for Trichinella inspection are also presented. The latter part of this review is directed at serodiagnostic methods for the detection of Trichinella-specific antibodies in different animal species. Classical methods of serodiagnosis such as the complement fixation test and immunofluorescence antibody test are reviewed and the characteristics and performance of the ELISA are discussed. Factors dependent upon the animal species being tested or on components of the ELISA test system are considered. This paper also reviews systematic development of the ELISA in relation to improvements in test specificity and sensitivity. Additionally, remarks are made on implementing this test for surveillance and control programs in domestic pigs and wildlife.     

A Qualitative Study of State‐Level Zoonotic Disease Surveillance in New England

Zoonotic diseases are infectious diseases transmittable between animals and humans and outbreaks of these diseases in animals can signify that humans are also infected (or vice versa). Thus, communication between animal and human health agencies is critical for surveillance. Understanding how these agencies conduct surveillance and share information is important for the development of successful automated zoonotic monitoring systems. Individual interviews were conducted with 13 professionals who perform animal or human zoonotic disease surveillance in one of the New England states. Questions centred on existing surveillance methods, collaborations between animal and human health agencies, and technological and data needs. The results showed that agencies routinely communicate over suspected zoonotic disease cases, yet there are barriers preventing automated electronic linking of health data of animals and humans. These include technological barriers and barriers due to sensitivity and confidentiality of information. Addressing these will facilitate the development of electronic systems for integrating animal and human zoonotic disease surveillance data.     

PrP genetics in ruminant transmissible spongiform encephalopathies

Scrapie, bovine spongiform encephalopathy (BSE), and chronic wasting disease (CWD) are prion diseases in ruminants with considerable impact on animal health and welfare. They can also pose a risk to human health and control is therefore an important issue. Prion protein (PrP) genetics may be used to control and eventually eradicate animal prion diseases. The PrP gene in sheep and other representatives of the order Artiodactyles has many polymorphisms of which several are crucial determinants of susceptibility to prion diseases, also known as transmissible spongiform encephalopathies (TSE). This review will present the current understanding of PrP genetics in ruminants highlighting similarity and difference between the species in the context of TSE.     

Livestock manure as a vector for infectious agents

The causative agents of nearly all bacterial and viral infectious diseases are either directly excreted by the infected animals or they reach the floor via other ways and thus end-up also in the fecal and urinary excretions of the animals. Occasionally pathogens also can be found in slurries of clinically unsuspected livestock for a short period of time while they pass through the gut of individual animals without colonization or invasion of the tissues (e.g. salmonellas). Consequently the manures are a potential for spreading infectious diseases. But their real significance as a vector for infectious agents is to a large extent still unsolved, because in the literature only very few and sometimes doubtful cases are described. During storage of manures the numbers of pathogens are reduced. This effect can be intensified by prolongation of the storage time. To assess the real epidemiological significance of the animal manures as vectors for infectious diseases further research work is urgently needed. After disinfection of animal manures in accordance with the regulations during eradication of notifiable diseases no cases of spread of disease became known in the Federal Republic of Germany. The problems of agricultural utilization of manures in water protection areas are discussed from a microbiological point of view.     

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.     

Developments in international standardization

Trade in animals and animal products has reached global proportions and so too has the threat of infectious diseases of veterinary importance. The Manual of Standards for Diagnostic Tests and Vaccines, published by the Office International des Epizooties (OIE), contains chapters on infectious diseases that may cause various degrees of socio-economic, public health, and/or zoo-sanitary consequence. These chapters cover the major diseases of cattle, sheep, goats, horses, pigs, poultry, lagomorphs and bees. A number of factors are considered when qualifying animals and animal products for international trade including epidemiological, clinical and testing parameters. Of particular note and relevance is a strong international movement to standardize the test methods and reference reagents in order to promote harmonization of testing and facilitation of trade. There is message here that is directed to those of us involved in the development and application of test methods for infectious disease diagnosis. Serological test methods have been and still remain the mainstay of diagnostic methods prescribed for trade. More than ever, there is a need to observe and apply international guidelines for the development and validation of serological test methods. There is also a need to develop international standard reagents for use in the calibration of test methods and the production of national and working standards. In the future, veterinary diagnostic testing laboratories involved in trade may also require a form of international accreditation unique to their specialty. This presentation describes the current developments in international standardization of test methods and reference reagents.