International trade, animal health and veterinary epidemiology: challenges and opportunities

Asfarviruses and Closely Related Giant Viruses

Acanthamoeba polyphaga mimivirus, so called because of its "mimicking microbe", was discovered in 2003 and was the founding member of the first family of giant viruses isolated from amoeba. These giant viruses, present in various environments, have opened up a previously unexplored field of virology. Since 2003, many other giant viruses have been isolated, founding new families and taxonomical groups. These include a new giant virus which was isolated in 2015, the result of the first co-culture on Vermamoeba vermiformis. This new giant virus was named "Faustovirus". Its closest known relative at that time was African Swine Fever Virus. Pacmanvirus and Kaumoebavirus were subsequently discovered, exhibiting phylogenetic clustering with the two previous viruses and forming a new group with a putative common ancestor. In this study, we aimed to summarise the main features of the members of this group of giant viruses, including Abalone Asfarvirus, African Swine Fever Virus, Faustovirus, Pacmanvirus, and Kaumoebavirus.

Livestock Network Analysis for Rhodesiense Human African Trypanosomiasis Control in Uganda

Background: Infected cattle sourced from districts with established foci for Trypanosoma brucei rhodesiense human African trypanosomiasis (rHAT) migrating to previously unaffected districts, have resulted in a significant expansion of the disease in Uganda. This study explores livestock movement data to describe cattle trade network topology and assess the effects of disease control interventions on the transmission of rHAT infectiousness. Methods: Network analysis was used to generate a cattle trade network with livestock data which was collected from cattle traders (n = 197) and validated using random graph methods. Additionally, the cattle trade network was combined with a susceptible, infected, recovered (SIR) compartmental model to simulate spread of rHAT (R o 1.287), hence regarded as "slow" pathogen, and evaluate the effects of disease interventions. Results: The cattle trade network exhibited a low clustering coefficient (0.5) with most cattle markets being weakly connected and a few being highly connected. Also, analysis of the cattle movement data revealed a core group comprising of cattle markets from both eastern (rHAT endemic) and northwest regions (rHAT unaffected area). Presence of a core group may result in rHAT spread to unaffected districts and occurrence of super spreader cattle market or markets in case of an outbreak. The key cattle markets that may be targeted for routine rHAT surveillance and control included Namutumba, Soroti, and Molo, all of which were in southeast Uganda. Using effective trypanosomiasis such as integrated cattle injection with trypanocides and spraying can sufficiently slow the spread of rHAT in the network. Conclusion: Cattle trade network analysis indicated a pathway along which T. b. rhodesiense could spread northward from eastern Uganda. Targeted T. b. rhodesiense surveillance and control in eastern Uganda, through enhanced public-private partnerships, would serve to limit its spread.

Timeliness of vesicular disease notification system in Brazilian foot-and-mouth disease surveillance programme

Animal health surveillance programmes should be reliable and informative to ensure their effective implementation. As such, the regular assessment of those aiming to demonstrate the absence of disease, as well as the ability to detect outbreaks on time, is of vital importance. Several criteria make it possible to assess the performance of surveillance systems, including timeliness, which represents the speed between steps in a surveillance system. Therefore, the objective of this study was to evaluate the variability in the timeliness, within and between states, of the surveillance programme of the Brazilian Veterinary Services (BVS) for foot-and-mouth disease (FMD), for the notification of vesicular disease. A total of 14 years (2004-2017) of data relating to vesicular syndromes from the Brazilian Continental Information and Surveillance System (SivCont) were included. A categorical variable was created with four classes to group the notified vesicular processes in the SivCont, according to two criteria, the similarity of the symptoms of the diseases reported with FMD and aetiology (viral, bacterial, fungal and non-infectious). The three timeliness values (TL-1, TL-2 and TL-3) related to different portions of the FMD surveillance system were analysed as a response in a generalized linear model in which the states of Brazil were the explanatory variables. The analyses were performed separately for each notification class (FMD, vesicular stomatitis, similar symptoms and similar non-infectious symptoms) and included comparisons within and between states. The study results provide an understanding and evaluation of the timeliness of the Brazilian FMD surveillance system, thereby providing a base of knowledge from which involved agents and decision-makers can evaluate BVS and reinforce surveillance measures in the states with poorer timeliness than permitted.

Transboundary spread of pig diseases: the role of international trade and travel

As globalization increases the interconnectedness between nations, economies, and industries, the introduction of diseases will continue to remain a prominent threat to the livestock sector and the trade of animals and animal products, as well as the livelihoods of farmers, food security and public health. The global pig sector, with its size and dichotomy between production type and biosecurity level, is particularly vulnerable to the transmission of transboundary animal diseases such as African and classical swine fever, foot and mouth disease, or porcine reproductive and respiratory syndrome. All of the above pose a constant threat to swine health, mainly as a result of both formal and informal international trade.Inspired in the risk assessment methodology, this paper classifies and provides an overview of the different pig disease introduction and exposure pathways, illustrated with abundant examples. Introduction pathways are classified as formal international trade (by product), informal international trade (by product), and spread through fomites. Formal trade of pigs and pork products is regulated by legislation and measures protecting animal populations from exotic diseases. Much more difficult to control is the transboundary swine disease transmission originating through informal trade, which entails illegal smuggling, but also the informal cross-border transfer of animals and products for personal use or within informal market chains. Meat products are most commonly mentioned, although fomites have also played a role in some cases, with live pigs, being more difficult to smuggle playing a role less frequently. The main exposure pathways are also described with the oral route playing a prominent role.Risk assessments can aid in the identification of pathways of pathogen introduction and exposure. However, quantitative information on informal disease introduction pathways remains very scarce and often incomplete, making it difficult to estimate the actual magnitudes of risks. Nevertheless, this knowledge is deemed essential to set up risk based awareness, prevention and surveillance programs that correspond to reality.

Challenges and Opportunities Developing Mathematical Models of Shared Pathogens of Domestic and Wild Animals

Diseases that affect both wild and domestic animals can be particularly difficult to prevent, predict, mitigate, and control. Such multi-host diseases can have devastating economic impacts on domestic animal producers and can present significant challenges to wildlife populations, particularly for populations of conservation concern. Few mathematical models exist that capture the complexities of these multi-host pathogens, yet the development of such models would allow us to estimate and compare the potential effectiveness of management actions for mitigating or suppressing disease in wildlife and/or livestock host populations. We conducted a workshop in March 2014 to identify the challenges associated with developing models of pathogen transmission across the wildlife-livestock interface. The development of mathematical models of pathogen transmission at this interface is hampered by the difficulties associated with describing the host-pathogen systems, including: (1) the identity of wildlife hosts, their distributions, and movement patterns; (2) the pathogen transmission pathways between wildlife and domestic animals; (3) the effects of the disease and concomitant mitigation efforts on wild and domestic animal populations; and (4) barriers to communication between sectors. To promote the development of mathematical models of transmission at this interface, we recommend further integration of modern quantitative techniques and improvement of communication among wildlife biologists, mathematical modelers, veterinary medicine professionals, producers, and other stakeholders concerned with the consequences of pathogen transmission at this important, yet poorly understood, interface.

Private animal health and welfare standards in quality assurance programmes: a review and proposed framework for critical evaluation

In recent years, 'private standards' in animal health and welfare have become increasingly common, and are often incorporated into quality assurance (QA) programmes. Here, we present an overview of the use of private animal health and welfare standards in QA programmes, and propose a generic framework to facilitate critical programme review. Private standards are being developed in direct response to consumer demand for QA, and offer an opportunity for product differentiation and a means to drive consumer choice. Nonetheless, a range of concerns have been raised, relating to the credibility of these standards, their potential as a discriminatory barrier to trade, the multiplicity of private standards that have been developed, the lack of consumer input and compliance costs. There is a need for greater scrutiny of private standards and of associated QA programmes. We propose a framework to clarify the primary programme goal(s) and measureable outputs relevant to animal health and welfare, the primary programme beneficiaries and to determine whether the programme is effective, efficient and transparent. This paper provides a theoretical overview, noting that this framework could be used as a tool directly for programme evaluation, or as a tool to assist with programme development and review.

Detection of Batrachochytrium dendrobatidis in Amphibians Imported into the UK for the Pet Trade

There is increasing evidence that the global spread of the fungal pathogen Batrachochytrium dendrobatidis (Bd) has been facilitated by the international trade in amphibians. Bd was first detected in the UK in 2004, and has since been detected in multiple wild amphibian populations. Most amphibians imported into the UK for the pet trade from outside the European Union enter the country via Heathrow Animal Reception Centre (HARC), where Bd-positive animals have been previously detected. Data on the volume, diversity and origin of imported amphibians were collected for 59 consignments arriving at HARC between November 2009 and June 2012, along with a surveillance study to investigate the prevalence of Bd in these animals. Forty-three amphibian genera were recorded, originating from 12 countries. It was estimated that 5000-7000 amphibians are imported through HARC into the UK annually for the pet trade. Bd was detected in consignments from the USA and Tanzania, in six genera, resulting in an overall prevalence of 3.6%. This suggests that imported amphibians are a source of Bd within the international pet trade.

A análise de risco como ferramenta estratégica para o serviço veterinário oficial brasileiro: dificuldades e desafios

O serviço veterinário oficial é responsável por proteger a saúde pública e animal, assegurando a oferta de produtos de origem animal inócuos aos consumidores. Uma ferramenta que auxilia na busca desses objetivos é a análise de risco, que iniciou a ser utilizada na segunda metade da década de 90 pelos serviços veterinários oficiais dos países. Para a realização de uma análise de risco, qualitativa ou quantitativa, inicialmente deve-se identificar o perigo, a qual na área da saúde animal geralmente é o agente patogênico causador de uma doença. A etapa subsequente é a avaliação do risco, na qual devem ser analisados, com suporte de trabalhos científicos ou especialistas na área, as formas possíveis de introdução, exposição e manutenção do agente patogênico na população susceptível, bem como as consequências, biológicas, econômicas, políticas e sociais trazidas pela enfermidade. A terceira etapa da análise de risco refere-se ao manejo dos riscos, que visa propor medidas que mitiguem o risco verificado até o nível desejado, bem como avaliar o custo/benefício de cada medida. A última fase de uma análise de risco é a comunicação dos riscos. Essa etapa é fundamental para o sucesso do estudo e deve ser iniciada juntamente com a análise de risco em si, sempre deixando aberto um canal permanente de comunicação com todos os atores sociais interessados na análise de risco. A análise de risco tornou-se um importante instrumento utilizado pelos gestores dos serviços veterinários oficiais na tomada de decisões, contribuindo para a escolha de alternativas que confiram, cientificamente, o menor risco sanitário. Este trabalho realizou uma revisão da literatura sobre análise de risco objetivando expor sua definição e processo de elaboração, assim como verificar como ela está sendo utilizada, quais limitações e desafios do uso dessa ferramenta pelo serviço veterinário oficial brasileiro.

A Review of Hypothesized Determinants Associated with Bighorn Sheep (Ovis canadensis) Die-Offs

Multiple determinants have been hypothesized to cause or favor disease outbreaks among free-ranging bighorn sheep (Ovis canadensis) populations. This paper considered direct and indirect causes of mortality, as well as potential interactions among proposed environmental, host, and agent determinants of disease. A clear, invariant relationship between a single agent and field outbreaks has not yet been documented, in part due to methodological limitations and practical challenges associated with developing rigorous study designs. Therefore, although there is a need to develop predictive models for outbreaks and validated mitigation strategies, uncertainty remains as to whether outbreaks are due to endemic or recently introduced agents. Consequently, absence of established and universal explanations for outbreaks contributes to conflict among wildlife and livestock stakeholders over land use and management practices. This example illustrates the challenge of developing comprehensive models for understanding and managing wildlife diseases in complex biological and sociological environments.

Shared Bacterial and Viral Respiratory Agents in Bighorn Sheep (Ovis canadensis), Domestic Sheep (Ovis aries), and Goats (Capra hircus) in Montana

Transmission of infectious agents from livestock reservoirs has been hypothesized to cause respiratory disease outbreaks in bighorn sheep (Ovis canadensis), and land management policies intended to limit this transmission have proven controversial. This cross-sectional study compares the infectious agents present in multiple populations of bighorn sheep near to and distant from their interface with domestic sheep (O. aries) and domestic goat (Capra hircus) and provides critical baseline information needed for interpretations of cross-species transmission risks. Bighorn sheep and livestock shared exposure to Pasteurellaceae, viral, and endoparasite agents. In contrast, although the impact is uncertain, Mycoplasma sp. was isolated from livestock but not bighorn sheep. These results may be the result of historic cross-species transmission of agents that has resulted in a mosaic of endemic and exotic agents. Future work using longitudinal and multiple population comparisons is needed to rigorously establish the risk of outbreaks from cross-species transmission of infectious agents.

Global health and foreign policy

Health has long been intertwined with the foreign policies of states. In recent years, however, global health issues have risen to the highest levels of international politics and have become accepted as legitimate issues in foreign policy. This elevated political priority is in many ways a welcome development for proponents of global health, and it has resulted in increased funding for and attention to select global health issues. However, there has been less examination of the tensions that characterize the relationship between global health and foreign policy and of the potential effects of linking global health efforts with the foreign-policy interests of states. In this paper, the authors review the relationship between global health and foreign policy by examining the roles of health across 4 major components of foreign policy: aid, trade, diplomacy, and national security. For each of these aspects of foreign policy, the authors review current and historical issues and discuss how foreign-policy interests have aided or impeded global health efforts. The increasing relevance of global health to foreign policy holds both opportunities and dangers for global efforts to improve health.

Veterinary epidemiology in Latin America

Veterinary epidemiology began in different Latin American countries during the 1960s and the 1970s in different universities and state-run institutes of animal health. The discipline evolved as a continuation of the activities veterinarians carried out in the areas of public health, infectious diseases, biostatistics, and the planning and administration of animal health programs. From the outset, the concepts were oriented towards covering the whole spectrum of factors involved in animal health, including political and social factors. Subsequently, the aforementioned factors were complemented with scientific and methodological support, backed by post graduate qualifications offered by the North America and European universities, together with financial support from intergovernmental organizations. One important contribution for the Latin American veterinary epidemiology and economics community was the ISVEE 10 which took place in Chile in 2003, which served to link many professionals and scientists with the world of people working in those themes. Whilst the study programs of veterinarians of the Latin American universities have different forms and depths when delivering competencies in epidemiology, most have similar conceptual and methodological elements. Ideally, the profile of an epidemiology teacher should include the qualities of dreamer and explorer of new theme worlds, combined with simplicity and openness to the world. A teacher's knowledge should transcend worlds and be enriched by what takes place outside the bounds of their geographic or university frontiers.

African swine fever: how can global spread be prevented?

African swine fever (ASF) is a devastating haemorrhagic fever of pigs with mortality rates approaching 100 per cent. It causes major economic losses, threatens food security and limits pig production in affected countries. ASF is caused by a large DNA virus, African swine fever virus (ASFV). There is no vaccine against ASFV and this limits the options for disease control. ASF has been confined mainly to sub-Saharan Africa, where it is maintained in a sylvatic cycle and/or among domestic pigs. Wildlife hosts include wild suids and arthropod vectors. The relatively small numbers of incursions to other continents have proven to be very difficult to eradicate. Thus, ASF remained endemic in the Iberian peninsula until the mid-1990s following its introductions in 1957 and 1960 and the disease has remained endemic in Sardinia since its introduction in 1982. ASF has continued to spread within Africa to previously uninfected countries, including recently the Indian Ocean islands of Madagascar and Mauritius. Given the continued occurrence of ASF in sub-Saharan Africa and increasing global movements of people and products, it is not surprising that further transcontinental transmission has occurred. The introduction of ASF to Georgia in the Caucasus in 2007 and dissemination to neighbouring countries emphasizes the global threat posed by ASF and further increases the risks to other countries. We review the mechanisms by which ASFV is maintained within wildlife and domestic pig populations and how it can be transmitted. We then consider the risks for global spread of ASFV and discuss possibilities of how disease can be prevented.

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 impact of food regulation on the food supply chain

Food regulation in the main is aimed at protecting the consumer's health, increasing economic viability, harmonizing well-being and engendering fair trade on foods within and between nations. Consumers nowadays are faced with food or food ingredients that may derive from distant countries or continents, and with a less transparent food supply. Safety concerns must cover the range of different food chains relevant to a certain food product or product group, including all relevant producers, manufacturing sites and food service establishments within a country as well as those importing into the country. Hazard analysis at critical control points (HACCP), good manufacturing practice (GMP) and good hygiene practice (GHP) are major components of the safety management systems in the food supply chain. Principally, "a hazard" is a biological, chemical or physical agent in, or condition of, food that has the potential to cause an adverse health effect. The likelihood of occurrence and severity of the same is important for the assessment of the risk presented by the hazard to the food supply chain. The Government's regulatory mechanisms in accordance with the WTO agreements (HACCPs, sanitary and phytosanitary measures, etc.) oversee the analyses of public health problems and their association to the food supply. Under the WTO SPS Agreements and the codes of practices issued by the Codex Alimentarius Commission, there now exists a benchmark for international harmonization that guarantee the trade of safe food. Inevitably, food safety is still mainly the responsibility of the consumer.

Monte Carlo simulation of animal-product violations incurred by air passengers at an international airport in Taiwan

Our aim was to evaluate the inspection of arriving passengers for the illegal transport of animal products through the international airport into Taiwan. Passenger-violation data were retrieved from the Bureau of Animal and Plant Health Inspection and Quarantine (BAPHIQ) in Taiwan. Monte Carlo simulations with 5000 iterations were applied to estimate the predicted violation numbers considering factors such as passenger's nationality/ethnicity, sex, and monthly statistics of violations. The results showed that Chinese-related passengers and passengers from South East Asian countries have a relatively higher potential risk for incurring violations during the period from Christmas to Chinese Lunar New Year. Most monthly estimated violation risks are significantly higher than observed violation risks in 2001 and 2002, except April, July, and August. Due to the low sensitivity of the current detection system (reflected by the higher estimated violation risks and a two-fold detection increase after the implementation of an inspection service using detector dogs), we recommend additional preventive measures be taken.

The role of veterinary epidemiology and veterinary services in complying with the World Trade Organization SPS agreement

The agreement on the application of sanitary and phytosanitary measures (SPS agreement) was one of the major products of the GATT's Uruguay round of multilateral trade negotiations, signed in Marrakesh on 15 April 1994. This agreement and others are part of the treaty that established the World Trade Organization (WTO). The WTO superseded the GATT as the umbrella organization for international trade (WTO, 1998a). The SPS agreement's main intent is to provide guidelines and provisions to member countries to facilitate trade while taking measures to protect human, animal or plant life or health. The agreement dictates that all sanitary measures must be scientifically based and not more restrictive than required to avoid the risk identified. The agreement recommends the use of international standards from the World Organization for Animal Health (OIE), Codex Alimentarius (CAC) and the International Plant Protection Convention (IPPC) as the basis for import requirements. If a country chooses to apply more restrictive measures than those in the international standards, it has to justify its position through a risk analysis, thus avoiding the use of sanitary and phytosanitary measures as unjustified barriers to trade. More than ever, veterinary services worldwide are faced with having to fulfill a crucial role in protecting their country's animal health status, provide sound surveillance information on the occurrence of diseases within their territories, and conduct scientifically valid risk analyses to establish justified import requirements. During the past two decades, most countries have experienced resource reduction in their veterinary services. The effect of these policies has been severe, in many cases leading to an inability of veterinary services to conduct their disease prevention and control duties. There is a clear inconsistency between the demands placed on veterinary services and the current level of funding and support they are receiving, particularly in the developing world. This paper analyzes the implications in complying with the SPS agreement and explores the role of veterinary epidemiology in developing viable alternatives that can enhance the veterinary services' ability to perform under the current economic reality. The key provisions of the SPS agreement are regionalization, risk analysis, harmonization, equivalence and transparency. The paper focuses on the contribution of epidemiology in each of these areas in the effective implementation of the SPS agreement.

Implications of agricultural and wildlife policy on management and eradication of bovine tuberculosis and brucellosis in free-ranging wood bison of northern Canada

Although disease is often an important factor in the population dynamics of wild ungulates, it is largely the threat-both real and perceived-that sylvatic disease reservoirs pose to the health status of commercial livestock or game farm industry that has led governments to establish policy and legislation for disease management, trade, and movement. With respect to bovine tuberculosis and brucellosis in wildlife, policies are largely borrowed from the existing regulatory framework for domestic livestock. In this paper, we review how general policy goals for managing these reportable diseases in domestic livestock have also affected conservation and management of bison in Canada. We argue that there is a need to better integrate conservation biology with agricultural livestock policy to develop management options and better address the unique conservation challenges that diseased free-ranging bison populations present.

A method of probability diagnostic assignment that applies bayes theorem for use in serologic diagnostics, using an example of Neospora caninum infection in cattle

OBJECTIVE

To develop a method of probability diagnostic assignment (PDA) that uses continuous serologic measures and infection prevalence to estimate the probability of an animal being infected, using Neospora caninum as an example.

ANIMALS

196 N caninum-infected beef and dairy cattle and 553 cattle not infected with N caninum; 50 dairy cows that aborted and 50 herdmates that did not abort.

PROCEDURE

Probability density functions corresponding to distributions of N caninum kinetic ELISA results from infected and uninfected cattle were estimated by maximum likelihood methods. Maximum likelihood methods also were used to estimate N caninum infection prevalence in a herd that had an excessive number of abortions. Density functions and the prevalence estimate were incorporated into Bayes formula to calculate the conditional probability that a cow with a particular ELISA value was infected with N caninum.

RESULTS

Probability functions identified for infected and uninfected cattle were Weibull and inverse gamma functions, respectively. Herd prevalence was estimated, and probabilities of N caninum infection were determined for cows with various ELISA values.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of PDA offers an advantage to clinicians and diagnosticians over traditional seronegative or seropositive classifications used as a proxy for infection status by providing an assessment of the actual probability of infection. The PDA permits use of all diagnostic information inherent in an assay, thereby eliminating a need for estimates of sensitivity and specificity. The PDA also would have general utility in interpreting results of any diagnostic assay measured on a continuous or discrete scale.