Evaluation of post-farm-gate passive surveillance in swine for the detection of foot and mouth disease in Australia

Pigs are considered high risk for the introduction and spread of foot and mouth disease (FMD) in Australia. One of the most likely pathways of introduction of FMD into Australia would be through the illegal importation of FMD-contaminated meat, which is then fed to feral or domestic pigs. Locations where animals from different origins are commingled, such as livestock markets and abattoirs, pose a risk for disease spread. Early detection of exotic diseases at these locations is crucial in limiting the spread of an outbreak. The aims of this study were to evaluate the likelihood of exotic disease detection with current passive disease surveillance activities for pigs at saleyards and abattoirs in eastern Australia, and make recommendations for improving surveillance. Sensitivity (Se) of the current post-farm-gate passive surveillance for detection of exotic diseases was estimated using the scenario tree modelling methodology (Martin et al., 2007a). Four surveillance system components were identified: (i) domestic saleyard, (ii) export saleyard, (iii) domestic abattoir, and (iv) export abattoir. Pig farms were classified according to herd size (Small vs. Large) and subsequently into two risk categories depending on the probability of swill feeding (Swill feeding vs. Not swill feeding). A scenario tree representing the pathways by which infected animals could be detected was developed and the Se of detection in each surveillance system component was estimated. Industry statistics, information on previous exotic disease outbreaks, and interviews with pig producers were used to estimate herd category proportions and the relative risk of swill feeding. Quantitative estimates for probabilities of detection were sourced from State legislation and policies, stakeholder consultation and observational studies at saleyards and abattoirs. Results of a FMD case study showed a Se of detection at a representative location for each surveillance system component during a 2-week period of 0.19 at domestic saleyards, 0.40 at export saleyards, 0.32 at domestic abattoirs and, 0.53 at export abattoirs. This output assumed the country was infected with herd and unit design prevalences of 1% and 30%, respectively. Improving disease awareness of saleyard and abattoir stockmen, increasing the presence of inspectors at these venues and identifying those herds posing a higher risk for FMD introduction, could improve the capacity of the country for early detection of emerging animal diseases.     

Advances in biosecurity to 2010 and beyond: towards integrated detection, analysis and response to exotic pest invasions

In order to limit the number and impact of exotic pest invasions, leading-edge technologies must be embraced and embedded within integrated national and international biosecurity systems. Outlined here are recent advances in the detection of exotic pests, and prospects for the early recognition of disease. Applications of new tools are described, using our understanding of the genomes of pathogens and vectors. In addition, the role of mathematical and simulation models to aid both biosecurity planning, and decision making in the face of an epidemic, are discussed, and recent attempts to unify epidemiology and evolutionary dynamics are outlined. Given the importance of emerging diseases and zoonoses, the need to align human and veterinary surveillance within fully integrated systems is underlined.     

Advances in biosecurity to 2010 and beyond: Towards integrated detection,analysis and response to exotic pest invasions

In order to limit the number and impact of exotic pest invasions, leading-edge technologies must be embraced and embedded within integrated national and international biosecurity systems. Outlined here are recent advances in the detection of exotic pests, and prospects for the early recognition of disease. Applications of new tools are described, using our understanding of the genomes of pathogens and vectors. In addition, the role of mathematical and simulation models to aid both biosecurity planning, and decision making in the face of an epidemic, are discussed, and recent attempts to unify epidemiology and evolutionary dynamics are outlined. Given the importance of emerging diseases and zoonoses, the need to align human and veterinary surveillance within fully integrated systems is underlined.     

The transmissible spongiform encephalopathies: disease risks for North America.

Transmissible spongiform encephalopathies exotic to North America (BSE and associated diseases) are unlikely to be introduced or to persist should they be introduced into the United States [2]. Domestic TSEs (scrapie, CWD, and TME) seem to be relatively restricted in their host range, and none of these diseases is known to naturally cause disease in cattle. It is important that surveillance for TSEs continues, however, particularly in cattle because of the extreme consequences to the livestock industries, and potentially, public health, if BSE becomes established. Because the TSEs have implications beyond effects on their natural host species, adequate surveillance, control, and even eradication of these diseases should be goals for the livestock industries, wildlife managers, and animal health agencies in the United States.     

Concentrating, purifying and detecting waterborne parasites

There has been recent emphasis on developing better methods for detecting diseases of zoonotic and veterinary importance. This has been prompted by an increase in human disease agents detectable in environmental samples, the potential for bioterrorism, and the lowering of international trade barriers and expansion of personal travel, which are bringing previously considered exotic diseases to new geographical localities. To appreciate the complexities of developing detection methods and working with environmental samples, it is appropriate to review technologies currently in use, as well as those in development and presently limited to research laboratories. Discussion of parasite detection would not be possible without including methods for parasite sampling, concentration, and purification because it is often necessary to process large sample volumes prior to analysis, and no reliable methods are available for significantly amplifying parasites in vitro. Reviewing proven methods currently in use will provide a baseline for generating, accepting and implementing the more sensitive and specific methods under development today.     

Exotic ticks introduced into the United States on imported reptiles from 1962 to 2001 and their potential roles in international dissemination of diseases

Since 1962, a total of 29 species of exotic ticks have been introduced into the United States on imported reptiles, with 17 species from the genus Amblyomma, 11 from the genus Aponomma and one from the genus Hyalomma. In the absence of measures to control introduction of these importations, some exotic tick species will develop breeding colonies and become established as indigenous species and some tickborne diseases may be introduced to wreak havoc among susceptible native populations. However, formulation of risk assessments and rational control measures have been hampered by a lack of knowledge of these exotic ticks, with much of the available data published in older and relatively obscure publications. This report is an attempt to collate information for all 29 exotic tick species, including previously unpublished data from our laboratory, with particular reference to their geographical distribution, hosts, life cycles and vector potential, and to review methods to minimize their global dissemination.     

Concurrent 2009 Pandemic Influenza A (H1N1) Virus Infection in Ferrets and in a Community in Pennsylvania

We report a fall 2010 cluster of pandemic influenza A/H1N1 (pH1N1) infections in pet ferrets in Lehigh Valley region of Pennsylvania. The ferrets were associated with one pet shop. The influenza cluster occurred during a period when the existing human surveillance systems had identified little to no pH1N1 in humans in the Lehigh Valley, and there were no routine influenza surveillance systems for exotic pets. The index case was a 2.5‐month‐old neutered male ferret that was presented to a veterinary clinic with severe influenza‐like illness (ILI). In response to laboratory notification of a positive influenza test result, and upon request from the Pennsylvania Department of Health (PADOH), the Pennsylvania Department of Agriculture (PDA) conducted an investigation to identify other ill ferrets and to identify the source and extent of infection. PDA notified the PADOH of the pH1N1 infection in the ferrets, leading to enhanced human surveillance and the detection of pH1N1 human infections in the surrounding community. Five additional ferrets with ILI linked to the pet shop were identified. This simultaneous outbreak of ferret and human pH1N1 demonstrates the important link between animal health and public health and highlights the potential use of veterinary clinics for sentinel surveillance of diseases shared between animals and humans.     

The role of the public sector in the development and implementation of animal health policies.

Although it is widely accepted that both the public and private sectors have a role to play in improving animal health, the debate centers on the balance between the two. The comparative advantages of each sector depend on: (i) whether the targeted disease can affect humans; (ii) its degree of contagiousness; (iii) whether it is endemic or exotic; and (iv) the economic costs associated with the disease. The rationale for public intervention is weaker for non-contagious than for contagious diseases; governments, though, can play a support role in several areas: e.g. generation and dissemination of information on health management, fostering participation of producers' organization in the eradication of endemic diseases, or helping private research institutions and funders to overcome the hurdles posed by widespread uncertainty and high costs associated with basic research. Control and eradication of contagious diseases in characterized by strong externalities; bio-security measures implemented by any producer affect his/her neighbors. A major factor affecting the design of appropriate health policies for contagious diseases is whether the disease is endemic or exotic in a particular population. The externality exists for endemic diseases--but for exotic diseases there is only the possibility of an externality (which materializes solely in the case of an outbreak). For exotic diseases, therefore, the perception of the risk of an outbreak is a major determinant of producers' behavior and of public prevention policies. The perception by producers and policy makers of the probability of occurrence of an outbreak of an exotic disease depends on the time elapsed since the last outbreak in the country or in neighboring countries. In general, perception of the risk of an outbreak will be lower than the true risk for most exotic diseases that have been absent for many years--but might be higher than the true risk if an outbreak was recently reported in the region. Taxes and private insurance have been proposed to internalize the externality; however, these policies cannot solve the health externality. Alternative programs (such as joint public-private eradication campaigns) are proposed as a means to minimize the externality.     

The future of veterinary parasitology: a time for change?

The future of veterinary parasitology is discussed at a time when R&D funding from the pharmaceutical industry is declining, yet the opportunities for veterinary parasitologists to diversify their activities has never been greater. Emerging and re-emerging areas requiring input from veterinary parasitologists include: veterinary public health; conservation and wildlife diseases; emerging and exotic infectious diseases; surveillance strategies; economic effects of parasitic diseases; aquaculture; molecular epidemiology; dietary and biological control of parasitic diseases; animal welfare; organic agricultural systems; novel vaccination strategies; drug target characterisation and rational drug design. Without change, the survival of veterinary parasitology as a viable, distinct discipline is under threat. In this environment, veterinary parasitologists must be adaptable, imaginative and pro-active in terms of setting the agendas for establishing strategic alliances, promoting research needs and developing research programs.     

Surveillance of Human Rabies by National Authorities – A Global Survey

Effective prevention of deaths due to human rabies is currently hampered by a lack of understanding of the scale of the problem, and the distribution of both animal and human cases across countries, regions and continents. Unfortunately, despite the severity of the disease, accurate data on which to assess these questions and to prioritize and direct public health interventions are not available for many parts of the world. This survey sought to understand the current global situation regarding the surveillance of human rabies. Data were collected from 91 countries across all continents and all categories of human rabies risk, generating the most complete and representative global data set currently available. Respondents were asked key questions about whether human rabies was a notifiable disease, how the surveillance system for human rabies operated and whether the respondent considered that the surveillance system was working effectively. Across the 91 countries from which data were collated, human rabies was a notifiable disease in all but eight. Despite international guidance, surveillance systems were very varied. Even where rabies is a notifiable disease, many countries had surveillance system judged to be ineffective, almost all of these being high and moderate rabies risk countries in Africa and Asia. Overall, 41% of the population covered by this survey (around 2.5 billion people) live in countries where there is no or ineffective rabies surveillance. The lack of robust surveillance is hindering rabies control efforts. However, whilst worldwide rabies surveillance would be improved if rabies were notifiable in all countries, many other challenges to the implementation of effective global human rabies surveillance systems remain.     

Assessment of the management practices facilitating the establishment and spread of exotic diseases of pigs in the Sydney region

OBJECTIVE: To assess management factors that would influence the establishment and spread of exotic diseases in pigs in the Sydney region. DESIGN: Saleyard and pig producer practices that could assist the initiation and subsequent spread of exotic diseases in pigs were surveyed and assessed over a 12 month period. PROCEDURE: Two saleyards in the Sydney region selling pigs were attended weekly for 12 months (2002-2003) to collect details on vendors and purchasers of pigs. Pig producer locations were mapped. All pig farmers on the Department of Primary Industries temporary brand register were surveyed to record management practices and knowledge of exotic diseases. Swine brands were inspected to determine their quality as a tracing mechanism. RESULTS: There were 101 pig sale days during the survey period with 13,869 pigs sold. There were 305 vendors, of whom 95% were identifiable through saleyard records. However, only 40% of the 377 purchasers were identifiable. More than one third of the 1749 transactions were for cash without the identity of the purchaser being recorded at the saleyards. Some 3% of pigs failed to sell and were returned to the property of origin. A total of 64 of 132 pig producers in the Sydney region were surveyed and 52 responded with survey information. The production systems of pig producers were predominately intensive or semi-intensive (88%) with 69% of these operators being small hobby producers. Pigs were mostly fed household and commercial scraps that were free of meat scraps, however, 2 producers were found to be feeding meat scraps (swill) illegally. Some 56% of producers surveyed did not have a tattoo swine brand and of the 23 producers with registered brands, 3 were not available for inspection or were not functional and 2 used the brand irregularly. CONCLUSION: This survey has identified factors that would assist the establishment and spread of vesicular and other exotic diseases in pigs. The factors included feeding meat scraps (swill), poor farmer knowledge of exotic diseases, ineffective pig owner identification at saleyards, the practice of cash sales that precluded the collection of purchaser details, and inadequate identification of pigs. Tracing the movements of pigs under these circumstances would be difficult.     

A Bayesian hierarchical analysis to compare classical and atypical scrapie surveillance data; Wales 2002-2006

We describe the application of Bayesian hierarchical models (BHM) to the analysis of risk of sheep scrapie using data from multiple surveillance sources. More specifically, we analysed data from the test results of three surveillance sources on classical and atypical scrapie in Wales for the period 2002-2006. For each form of scrapie, a BHM was fitted to assess the occurrence of spatial patterns of risk shared by the multiple surveillance sources and the association between covariates and disease. We defined a shared-component model whereby the two types of data sources: exhaustive lists (e.g. reports of clinical cases) and sample-based data sources (e.g. abattoir survey) shared a common spatial pattern of risks at parish level. This shared component was adjusted by a risk-gradient parameter that moderated the individual contribution of the datasets. For both forms of scrapie, the risk-gradient was not significantly different indicating that the sensitivity of the two types of dataset was similar for the two diseases. The spatial patterns of the combinations of data sources appeared similar within disease. However, our results suggest that classical and atypical scrapie differ in their spatial patterns and disease determinants. The joint approach permitted inference from all the available evidence and resulted in robust and less biased estimates of risk, particularly for atypical scrapie where the number of observations was very limited.     

Optimizing early detection of avian influenza H5N1 in backyard and free-range poultry production systems in Thailand

For infectious diseases such as highly pathogenic avian influenza caused by the H5N1 virus (A/H5N1 HP), early warning system is essential. Evaluating the sensitivity of surveillance is a necessary step in ensuring an efficient and sustainable system. Stochastic scenario tree modeling was used here to assess the sensitivity of the A/H5N1 HP surveillance system in backyard and free-grazing duck farms in Thailand. The whole surveillance system for disease detection was modeled with all components and the sensitivity of each component and of the overall system was estimated. Scenarios were tested according to selection of high-risk areas, inclusion of components and sampling procedure, were tested. Nationwide passive surveillance (SSC1) and risk-based clinical X-ray (SSC2) showed a similar sensitivity level, with a median sensitivity ratio of 0.96 (95% CI 0.40-15.00). They both provide higher sensitivity than the X-ray laboratory component (SSC3). With the current surveillance design, the sensitivity of detection of the overall surveillance system when the three components are implemented, was equal to 100% for a farm level prevalence of 0.05% and 82% (95% CI 71-89%) for a level of infection of 3 farms. Findings from this study illustrate the usefulness of scenario-tree modeling to document freedom from diseases in developing countries.     

Establishing a cost-effective national surveillance system for Bluetongue using scenario tree modelling

Vector-borne diseases pose a special challenge to veterinary authorities due to complex and time-consuming surveillance programs taking into account vector habitat. Using stochastic scenario tree modelling, each possible surveillance activity of a future surveillance system can be evaluated with regard to its sensitivity and the expected cost. The overall sensitivity of various potential surveillance systems, composed of different combinations of surveillance activities, is calculated and the proposed surveillance system is optimized with respect to the considered surveillance activities, the sensitivity and the cost. The objective of this project was to use stochastic scenario tree modelling in combination with a simple cost analysis in order to develop the national surveillance system for Bluetongue in Switzerland. This surveillance system was established due to the emerging outbreak of Bluetongue virus serotype 8 (BTV-8) in Northern Europe in 2006. Based on the modelling results, it was decided to implement an improved passive clinical surveillance in cattle and sheep through campaigns in order to increase disease awareness alongside a targeted bulk milk testing strategy in 200 dairy cattle herds located in high-risk areas. The estimated median probability of detection of cases (i.e. sensitivity) of the surveillance system in this combined approach was 96.4%. The evaluation of the prospective national surveillance system predicted that passive clinical surveillance in cattle would provide the highest probability to detect BTV-8 infected animals, followed by passive clinical surveillance in sheep and bulk milk testing of 200 dairy cattle farms in high-risk areas. This approach is also applicable in other countries and to other epidemic diseases.     

狂犬病实验室诊断研究进展

狂犬病是世界上最可怕的人兽共患传染病,所有温血动物对狂犬病均易感,狂犬病已成为世界严重的公共卫生问题。暴露后疫苗接种可以达到有效的预防,狂犬病的预防和暴露后处理措施的有效实施均有赖于实验室的安全、准确、快速诊断。另外,免疫后及时对血清中和抗体效价进行监测,也是防控狂犬病的关键措施。文章从狂犬病实验室诊断的安全问题、实验室检测样本的选择、组织学检查、病毒抗原检测、生物学鉴定、核酸检测及血清抗体检测等方面对狂犬病实验室诊断方法及研究进展等进行综述和评价。     

The impact of national policies on animal disease reporting within selected Pacific Island Countries and Territories (PICTs)

A semi-systematic literature review of national policies was carried out in relation to surveillance and disease reporting in Pacific Island Countries and Territories (PICTs). It also analysed the animal disease reporting structures in Fiji, Papua New Guinea (PNG), Vanuatu and the Solomon Islands. The strengths, weaknesses, opportunities and threats (SWOT) of those reporting structures were examined in relation to how they impacted the detection and management of animal diseases in PICTs. Field missions collected information on animal disease reporting structures and these were discussed in detail with country officials and documented. The findings from the literature review indicated that there is very little policy to support work in surveillance and disease reporting within national government structures of the countries studied. This increases the potential for disease transmission and the introduction of exotic diseases as the efficiency of disease reporting is low. The findings from the SWOT analysis of the reporting structures indicated that there were commonalities across the countries studied, i.e. reporting structures were long with multiple legs that were not functioning properly and this was worsened when positions were vacant in the reporting structure. The hierarchical nature of the reporting structure also reduced reporting efficiency as reports took a longer time to reach decision makers at the top of the structure. High officer turnover and the shortage of veterinarians in the countries studied also affected the efficiency of disease reporting as most in-county officials were inexperienced and could not recognise disease signs and there were no veterinarians to supervise them. Existing reporting structures need to be reviewed to remove duplication and shorten the chain. However, this could override existing command structures and would need to be documented and awareness created with the officers involved. There also needs to be more collaboration with FAO, OIE, academic institutions and national governments to create an environment conducive for the development of policies that support work on surveillance to improve disease reporting in PICTs. The shortage of veterinarians could be addressed by influencing national governments to create better policies to retain veterinarians in the animal health services; this should be supported by creating reasonable work conditions and remuneration packages. This should also be supported with policies to send young graduates to study veterinary science overseas and have a career path for them when they return. Engagement of retired veterinarians from developed countries and re-evaluating the criteria for veterinarian registration could be short-term solutions to address the shortage of veterinarians in PICTs.     

猪细菌性传染病病原检测新方法研究进展

细菌性传染病是生猪养殖业的严重威胁之一，近年来其发病情况呈现出新变化，对动物产品质量和公共卫生安全造成严重危害。对病原进行快速、准确的检测，是预防和控制猪病的有效手段，对养猪业发展和人畜健康具有重要意义。伴随生命科学技术的发展和学科间的交叉融合，传统的病原菌分离培养、普通PCR方法和早期免疫学等检测技术均朝着精确高效的方向不断发展革新，并以传统方法为基础建立了多种新型检测技术。文章重点介绍了猪细菌性传染病病原检测的几种新技术：以核酸分子生物学为基础的实时荧光定量PCR法（qPCR）、环介导等温扩增法（LAMP）、夹心DNA杂交（DNAH）等；以免疫学为基础的免疫胶体金标记技术、时间分辨荧光免疫分析法（TRFIA）、免疫磁珠分离法（IMS）等；以蛋白质分子生物学为基础的细菌质谱鉴定技术；以及适用于现场快速诊断的即时检测（POCT）技术，并分析了这几种新技术的优缺点，为不同条件的检测机构和研究部门在开展猪细菌性传染病检测和研究时选择相应的方法提供一定的参考，以期在猪病预防控制中发挥更加积极的作用。     

Exotic diseases of dogs and cats at risk of importation to Ireland

: Changes in legislation that facilitate movement of companion animals within the European Union will expose those animals to microbial and parasitic organisms currently exotic to Ireland. This paper reviewed information on the exotic diseases most likely to be introduced to Ireland by travelling dogs and cats: rabies, leishmaniosis, babesiosis, ehrlichiosis, anaplasmosis and dirofilariosis.     

Gastrointestinal Disease in Exotic Small Mammals

Exotic small mammal medicine is a relatively new specialty area within veterinary medicine. Ferrets, rabbits, and rodents have long been used as animal models in human medical research investigations, resulting in a body of basic anatomic and physiologic information that can be used by veterinarians treating these species. Unfortunately, there is a paucity of veterinary articles that describe clinical presentation, diagnosis, and treatment options of gastrointestinal (GI) disease as it affects exotic small mammals. Although there is little reference material relating to exotic small mammal GI disease, patients are commonly presented to veterinary hospitals with digestive tract disorders. This article provides the latest information available for GI disease in ferrets (Helicobacter mustelae gastritis, inflammatory bowel disease [IBD], GI lymphoma, systemic coronavirus, coccidiosis, and liver disease), rabbits (GI motility disorders, liver lobe torsion, astrovirus, and coccidiosis), guinea pigs (gastric dilatation volvulus [GDV]), rats (Taenia taeniaeformis), and hamsters (Clostridium difficile). Both noninfectious diseases and emerging infectious diseases are reviewed as well as the most up-to-date diagnostics and treatment options.     

四川养猪场常见病毒性病原流行病学调查及疾病有效防控能力分析

为了解四川地区养猪场常见病毒性疾病感染情况,分析不同养猪场对疾病有效防控能力,进一步推测各猪场对新发和外来动物疫病的感染风险。研究采用高通量检测方法,对不同类型养猪场采集的426份临床样品进行病毒性病原流行病学调查,结果显示四川地区养猪场病毒性病原阳性检出率较高,普遍存在多病原混合感染情况,且较为严重,病原感染种类增多,且具有流行普遍性。其中以PCV2、PRRSV、PRV、PEDV的感染最为常见,特别是PCV2和PRRSV的混合感染,已经成为目前猪病中最为多发的病毒性疾病。猪场应进一步完善生物安全措施,做好猪群的饲养管理,结合现有疫苗控制和降低猪场疾病感染的可能。