Quantitative assessment of the likelihood of the introduction of classical swine fever virus into the Danish swine population

Risk Factors and Spatiotemporal Analysis of Classical Swine Fever in Ecuador

Classical swine fever (CSF) is one of the most important re-emergent swine diseases worldwide. Despite concerted control efforts in the Andean countries, the disease remains endemic in several areas, limiting production and trade opportunities. In this study, we aimed to determine the risk factors and spatiotemporal implications associated with CSF in Ecuador. We analysed passive surveillance and vaccination campaign datasets from 2014 to 2020; Then, we structured a herd-level case-control study using a logistic and spatiotemporal Bayesian model. The results showed that the risk factors that increased the odds of CSF occurrence were the following: swill feeding (OR 8.53), time until notification (OR 2.44), introduction of new pigs during last month (OR 2.01) and lack of vaccination against CSF (OR 1.82). The spatiotemporal model showed that vaccination reduces the risk by 33%. According to the priority index, the intervention should focus on Morona Santiago and Los Rios provinces. In conclusion, the results highlight the complexity of the CSF control programs, the importance to improve the overall surveillance system and the need to inform decision-makers and stakeholders.

SWOT analysis of risk factors associated with introduction of African Swine Fever through vehicles returning after export of pigs

Denmark is a major pig exporter and applies a high level of biosecurity, with washing and disinfecting stations for returning livestock vehicles. The introduction of African Swine Fever (ASF) would have significant economic consequences related to loss of export of live pigs and products thereof. In this study, we focused on the role of empty livestock vehicles returning after exports of pigs for the introduction of ASF. Initially, the current components and measures related to export of livestock were described. Next, analyses of strengths, weaknesses, opportunities, and threats (SWOT) were conducted, covering the components and measures identified. Then, export of pigs was described either through assembly centers or directly from farms. Washing and disinfection, as required and undertaken at the designated stations, constitutes the most important among all risk-reducing measures identified. Recommendations are to: (1) ensure the quality of washing and disinfection through staff training; (2) find new, safe, and more efficient disinfectants; (3) ensure the required temperature, and therefore effect, of the disinfectant and water. It was impossible to assess, the influence of export through assembly centers compared to direct transport. However, through SWOT analyses we identified the strengths and weaknesses of the two pathways. Moreover, components/measures with risks of unknown sizes are also discussed, such as vehicles undertaking cabotage and the current vehicle quarantine periods.

Transmission of antimicrobial resistance (AMR) during animal transport

The transmission of antimicrobial resistance (AMR) between food-producing animals (poultry, cattle and pigs) during short journeys (< 8 h) and long journeys (> 8 h) directed to other farms or to the slaughterhouse lairage (directly or with intermediate stops at assembly centres or control posts, mainly transported by road) was assessed. Among the identified risk factors contributing to the probability of transmission of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs), the ones considered more important are the resistance status (presence of ARB/ARGs) of the animals pre-transport, increased faecal shedding, hygiene of the areas and vehicles, exposure to other animals carrying and/or shedding ARB/ARGs (especially between animals of different AMR loads and/or ARB/ARG types), exposure to contaminated lairage areas and duration of transport. There are nevertheless no data whereby differences between journeys shorter or longer than 8 h can be assessed. Strategies that would reduce the probability of AMR transmission, for all animal categories include minimising the duration of transport, proper cleaning and disinfection, appropriate transport planning, organising the transport in relation to AMR criteria (transport logistics), improving animal health and welfare and/or biosecurity immediately prior to and during transport, ensuring the thermal comfort of the animals and animal segregation. Most of the aforementioned measures have similar validity if applied at lairage, assembly centres and control posts. Data gaps relating to the risk factors and the effectiveness of mitigation measures have been identified, with consequent research needs in both the short and longer term listed. Quantification of the impact of animal transportation compared to the contribution of other stages of the food-production chain, and the interplay of duration with all risk factors on the transmission of ARB/ARGs during transport and journey breaks, were identified as urgent research needs.

Models to assess the risk of introduction of selected animal viral diseases through the importation of live animals as a key part of risk analysis

Introduction of an animal viral disease, especially a notifiable disease, into an importing country or region free from the disease may lead to serious epidemiological consequences and economic losses. Trade in live animals is historically considered one of the most important risk pathways. To estimate the magnitude of such risk, the likelihood of a virus’ entry into a country and the consequences of this event should be jointly evaluated. Depending on data availability, the urgency of the problem and the detail level of the objectives, a risk assessment may be conducted in a qualitative, semi-quantitative or quantitative way. The purpose of this review was firstly to provide a brief description of each step of the risk analysis process, with particular emphasis on the risk assessment component, and subsequently to supply examples of different approaches to the assessment of the risk of the introduction of selected animal viral diseases. Based on the reviewed models, the overall likelihood of introduction of particular diseases was generally estimated as low. The output risk value was strongly dependent on the duration of the silent phase of the epidemic in the country of origin. Other parameters with some bearing upon the risk derived from the epidemiological situation in the country of origin and the biosecurity or mitigation measures implemented in the country of destination. The investigated models are universal tools for conducting assessment of the risk of introduction of various animal diseases to any country. Their application may lead to timely implementation of appropriate measures for the prevention of the spread of a disease to another country or region.

Risk of Introduction of Classical Swine Fever Into the State of Mato Grosso, Brazil

Classical swine fever (CSF) is considered one of the most important diseases of swine because of the far-reaching economic impact the disease causes to affected countries and regions. The state of Mato Grosso (MT) is part of Brazil's CSF-free zone. CSF status is uncertain in some of MT's neighboring States and countries, which has resulted in the perception that MT is at high risk for the disease. However, the risk for CSF introduction into MT has not been previously assessed. Here, we estimated that the risk for CSF introduction into the MT is highly heterogeneous. The risk associated with shipment of commercial pigs was concentrated in specific municipalities with intense commercial pig production, whereas the risk associated with movement of wild boars was clustered in certain municipalities located close to the state's borders, mostly in northern and southwestern MT. Considering the two pathways of possible introduction assessed here, these results demonstrate the importance of using alternative strategies for surveillance that target different routes and account for different likelihoods of introduction. These results will help to design, implement, and monitor surveillance activities for sustaining the CSF-free status of MT at times when Brazil plans to expand the recognition of disease-free status for other regions in the country.

Biosecurity in pig farms: a review

The perception of the importance of animal health and its relationship with biosecurity has increased in recent years with the emergence and re-emergence of several diseases difficult to control. This is particularly evident in the case of pig farming as shown by the recent episodes of African swine fever or porcine epidemic diarrhoea. Moreover, a better biosecurity may help to improve productivity and may contribute to reducing the use of antibiotics. Biosecurity can be defined as the application of measures aimed to reduce the probability of the introduction (external biosecurity) and further spread of pathogens within the farm (internal biosecurity). Thus, the key idea is to avoid transmission, either between farms or within the farm. This implies knowledge of the epidemiology of the diseases to be avoided that is not always available, but since ways of transmission of pathogens are limited to a few, it is possible to implement effective actions even with some gaps in our knowledge on a given disease. For the effective design of a biosecurity program, veterinarians must know how diseases are transmitted, the risks and their importance, which mitigation measures are thought to be more effective and how to evaluate the biosecurity and its improvements. This review provides a source of information on external and internal biosecurity measures that reduce risks in swine production and the relationship between these measures and the epidemiology of the main diseases, as well as a description of some systems available for risk analysis and the assessment of biosecurity. Also, it reviews the factors affecting the successful application of a biosecurity plan in a pig farm.

Risks of introduction and economic consequences associated with African swine fever, classical swine fever and foot-and-mouth disease: A review of the literature

African swine fever (ASF), classical swine fever (CSF) and foot-and-mouth disease (FMD) are considered to be three of the most detrimental animal diseases and are currently foreign to the U.S. Emerging and re-emerging pathogens can have tremendous impacts in terms of livestock morbidity and mortality events, production losses, forced trade restrictions, and costs associated with treatment and control. The United States is the world's top producer of beef for domestic and export use and the world's third-largest producer and consumer of pork and pork products; it has also recently been either the world's largest or second largest exporter of pork and pork products. Understanding the routes of introduction into the United States and the potential economic impact of each pathogen are crucial to (a) allocate resources to prevent routes of introduction that are believed to be more probable, (b) evaluate cost and efficacy of control methods and (c) ensure that protections are enacted to minimize impact to the most vulnerable industries. With two scoping literature reviews, pulled from global data, this study assesses the risk posed by each disease in the event of a viral introduction into the United States and illustrates what is known about the economic costs and losses associated with an outbreak.

Development of a quantitative risk assessment of bovine viral diarrhea virus and bovine herpesvirus-1 introduction in dairy cattle herds to improve biosecurity

A quantitative risk assessment model was developed to estimate the annual probability of introducing bovine viral diarrhea virus (BVDV) and bovine herpesvirus 1 (BoHV-1) at the farm level through animal movements. Data from 2017 official animal movements, biosecurity questionnaires, scientific literature, and expert opinion from field veterinarians were taken into consideration for model input parameters. Purchasing or introducing cattle, rearing replacement heifers offsite, showing cattle at competitions, sharing transport vehicles with other herds, and transporting cattle in vehicles that have not been cleaned and disinfected were considered in the model. The annual probability of introducing BVDV or BoHV-1 through infected animals was very heterogeneous between farms. The median likelihoods of BVDV and BoHV-1introduction were 12 and 9%, respectively. Farms that purchased cattle from within their region (i.e., local movements) and shared transport with other farms had a higher probability for BVDV and BoHV-1 introduction. This model can be a useful tool to support decision-making on biosecurity measures that should be prioritized to reduce the probability of introduction of these 2 diseases in dairy herds.

A questionnaire survey of the illegal importation of pork products by air travelers into Japan from China and exploration of causal factors

With the aim of obtaining information to establish an import risk assessment on African swine fever (ASF) and other transboundary animal diseases (TADs) into Japan, a questionnaire survey was conducted between 1 August and 20 September 2019 on air travellers arriving into Japan from China. There were 248 responses with 2.8 % of respondents illegally importing pork products. The quantity imported per traveller varied between 250 g and 2 kg. Concerning the travellers' perception in regard to the difficulty of importing a pork product in their luggage, 32 respondents (12.9 %) considered it very easy or rather easy and 216 (87.1 %) very difficult or rather difficult. In regard to the recognition of respondents of the illegality of importing pork products into Japan, seven respondents (2.8 %) did not consider this practice to be illegal whilst 241 (97.2 %) had some idea of the illegal nature of this behaviour. The regression analysis revealed that the practice of illegal importation of pork products was significantly affected by the level of difficulty perception held by the traveller (P < 0.001) and that the difficulty perception is significantly affected by the level of recognition of illegality by the traveller (P < 0.001). The result of this study will not only provide useful data in developing a model to assess the probability of introduction of ASF and other TADs into Japan and other countries, but also in monitoring the effect of measures taken by the government to reduce the illegal importation of meat and meat products.

Multilayer network analysis unravels haulage vehicles as a hidden threat to the British swine industry

When assessing the role of live animal trade networks in the spread of infectious diseases in livestock, attention has focused mainly on direct movements of animals between premises, whereas the role of haulage vehicles used during transport, an indirect route for disease transmission, has largely been ignored. Here, we have assessed the impact of sharing haulage vehicles from livestock transport service providers on the connectivity between farms as well as on the spread of swine infectious diseases in Great Britain (GB). Using all pig movement records between April 2012 and March 2014 in GB, we built a series of directed and weighted static multiplex networks consisting of two layers of identical nodes, where nodes (farms) are linked either by (a) the direct movement of pigs and (b) the shared use of haulage vehicles. The haulage contact definition integrates the date of the move and the duration Δ s that lorries are left contaminated by pathogens, hence accounting for the temporal aspect of contact events. For increasing Δ s , descriptive network analyses were performed to assess the role of haulage on network connectivity. We then explored how viruses may spread throughout the GB pig sector by computing the reproduction number R . Our results showed that sharing haulage vehicles increases the number of contacts between farms by >50% and represents an important driver of disease transmission. In particular, sharing haulage vehicles, even if Δ s  < 1 day, will limit the benefit of the standstill regulation, increase the number of premises that could be infected in an outbreak, and more easily raise R above 1. This work confirms that sharing haulage vehicles has significant potential for spreading infectious diseases within the pig sector. The cleansing and disinfection process of haulage vehicles is therefore a critical control point for disease transmission risk mitigation.

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.

ILLEGAL ANIMAL-ORIGIN PRODUCTS SEIZED IN BAGGAGE FROM INTERNATIONAL FLIGHTS AT SAO PAULO GUARULHOS AIRPORT (GRU / SBGR), BRAZIL

Abstract Air transportation is one of the most important means to introduce illegally imported animal-origin products into a country. Studies have demonstrated that these items pose a risk of disseminating diseases. São Paulo Guarulhos International Airport (GRU / SBGR) is the main international airport in Brazil in terms of people movement and it has the largest number of seizures of animal-origin products. The aim of the present work was to describe the dynamics of the seizure of illegally imported animal-origin products in baggage from international flight passengers at GRU / SBGR Airport in Brazil. Five hundred and eighty-nine different flights from 43 airlines, arriving from 117 countries were analyzed between 2006 and 2009. The total number of seized items increased from 2006 to 2009 and a single flight from France had the highest number of seizures, followed by flights from South Africa and Germany. Countries were grouped into regions or continents to facilitate the analysis. This grouping was based on historical and cultural ties rather than geographical aspects. Seafood was the most frequently seized product, followed by dairy products, as well as processed and raw meat.

Process Review for Development of Quantitative Risk Analyses for Transboundary Animal Disease to Pathogen-Free Territories

Outbreaks of transboundary animal diseases (TADs) have the potential to cause significant detriment to animal, human, and environmental health; severe economic implications; and national security. Challenges concerning data sharing, model development, decision support, and disease emergence science have recently been promoted. These challenges and recommendations have been recognized and advocated in the disciplines intersecting with outbreak prediction and forecast modeling regarding infectious diseases. To advance the effective application of computation and risk communication, analytical products ought to follow a collaboratively agreed common plan for implementation. Research articles should seek to inform and assist prioritization of national and international strategies in developing established criteria to identify and follow best practice standards to assess risk model attributes and performance. A well-defined framework to help eliminate gaps in policy, process, and planning knowledge areas would help alleviate the intense need for the formation of a comprehensive strategy for countering TAD outbreak risks. A quantitative assessment that accurately captures the risk of introduction of a TAD through various pathways can be a powerful tool in guiding where government, academic, and industry resources ought to be allocated, whether implementation of additional risk management solutions is merited, and where research efforts should be directed to minimize risk. This review outlines a part of a process for the development of quantitative risk analysis to collect, analyze, and communicate this knowledge. A more comprehensive and unabridged manual was also developed. The framework used in supporting the application of aligning computational tools for readiness continues our approach to apply a preparedness mindset to challenges concerning threats to global biosecurity, secure food systems, and risk-mitigated agricultural economies.

Simulating the epidemiological and economic effects of an African swine fever epidemic in industrialized swine populations

African swine fever (ASF) is a notifiable infectious disease with a considerable impact on animal health and is currently one of the most important emerging diseases of domestic pigs. ASF was introduced into Georgia in 2007 and subsequently spread to the Russian Federation and several Eastern European countries. Consequently, there is a non-negligible risk of ASF spread towards Western Europe. Therefore it is important to develop tools to improve our understanding of the spread and control of ASF for contingency planning. A stochastic and dynamic spatial spread model (DTU-DADS) was adjusted to simulate the spread of ASF virus between domestic swine herds exemplified by the Danish swine population. ASF was simulated to spread via animal movement, low- or medium-risk contacts and local spread. Each epidemic was initiated in a randomly selected herd - either in a nucleus herd, a sow herd, a randomly selected herd or in multiple herds simultaneously. A sensitivity analysis was conducted on input parameters. Given the inputs and assumptions of the model, epidemics of ASF in Denmark are predicted to be small, affecting about 14 herds in the worst-case scenario. The duration of an epidemic is predicted to vary from 1 to 76days. Substantial economic damages are predicted, with median direct costs and export losses of €12 and €349 million, respectively, when epidemics were initiated in multiple herds. Each infectious herd resulted in 0 to 2 new infected herds varying from 0 to 5 new infected herds, depending on the index herd type.

The costs of preventive activities for exotic contagious diseases-A Danish case study of foot and mouth disease and swine fever

The present paper provides an overview of the costs of preventive activities, currently undertaken in Denmark, related to foot and mouth disease (FMD) and classical and African swine fever (SF). Only costs held between outbreaks were included. Costs were divided into public costs and costs paid by the pig and cattle industries, respectively. Data were retrieved from multiple sources such as databases, legal documents, official statistics, yearly reports and expert opinions. As no previous studies have assessed such costs, data collection and estimation procedures were discussed and decided upon in a group of experts from universities, industry, and public authorities. The costs of each preventive activity were related to the type of activity, the number of times the activity was carried out and the share of costs that could be associated with FMD or SF. Uncertainty about parameters was incorporated in the analysis by assuming that the FMD/SF shares of costs as well as total costs for each activity could take on a most likely as well as a minimum and maximum value. A high degree of transparency was prioritized in the cost analysis, which enables reproducibility and easy access to conducting sensitivity analyses. A total of 27 FMD/SF preventive activities were identified. The estimated median (minimum-maximum) of total costs amounted to €32 (18-50) million in 2013. The single most costly FMD/SF related activity, amounting to €8 (5-13) million or 26% of total costs, was a national legal requirement to clean lorries immediately after transportation of live animals. The distribution of costs between stakeholders was estimated to be as follows: pig industry 63%, cattle industry 27%, and the public authorities 10%. Most of the activities focused on reducing the probability of spreading FMD/SF, while only a few activities were directed mainly towards reducing the probability of introduction. Legally required FMD/SF activities (mainly based on EU legislation) accounted for 60% of the activities, while FMD/SF related measures agreed on at sector level and measures implemented due to individual initiatives, such as farmer's investment in specially built delivery facilities, each accounted for 20%.

Modular framework to assess the risk of African swine fever virus entry into the European Union

Background

The recent occurrence and spread of African swine fever (ASF) in Eastern Europe is perceived as a serious risk for the pig industry in the European Union (EU). In order to estimate the potential risk of ASF virus (ASFV) entering the EU, several pathways of introduction were previously assessed separately. The present work aimed to integrate five of these assessments (legal imports of pigs, legal imports of products, illegal imports of products, fomites associated with transport and wild boar movements) into a modular tool that facilitates the visualization and comprehension of the relative risk of ASFV introduction into the EU by each analyzed pathway.

Results

The framework’s results indicate that 48% of EU countries are at relatively high risk (risk score 4 or 5 out of 5) for ASFV entry for at least one analyzed pathway. Four of these countries obtained the maximum risk score for one pathway: Bulgaria for legally imported products during the high risk period (HRP); Finland for wild boar; Slovenia and Sweden for legally imported pigs during the HRP. Distribution of risk considerably differed from one pathway to another; for some pathways, the risk was concentrated in a few countries (e.g., transport fomites), whereas other pathways incurred a high risk for 4 or 5 countries (legal pigs, illegal imports and wild boar).

Conclusions

The modular framework, developed to estimate the risk of ASFV entry into the EU, is available in a public domain, and is a transparent, easy-to-interpret tool that can be updated and adapted if required. The model’s results determine the EU countries at higher risk for each ASFV introduction route, and provide a useful basis to develop a global coordinated program to improve ASFV prevention in the EU.

How commercial and non-commercial swine producers move pigs in Scotland: a detailed descriptive analysis

BACKGROUND

The impact of non-commercial producers on disease spread via livestock movement is related to their level of interaction with other commercial actors within the industry. Although understanding these relationships is crucial in order to identify likely routes of disease incursion and transmission prior to disease detection, there has been little research in this area due to the difficulties of capturing movements of small producers with sufficient resolution. Here, we used the Scottish Livestock Electronic Identification and Traceability (ScotEID) database to describe the movement patterns of different pig production systems which may affect the risk of disease spread within the swine industry. In particular, we focused on the role of small pig producers.

RESULTS

Between January 2012 and May 2013, 23,169 batches of pigs were recorded moving animals between 2382 known unique premises. Although the majority of movements (61%) were to a slaughterhouse, the non-commercial and the commercial sectors of the Scottish swine industry coexist, with on- and off-movement of animals occurring relatively frequently. For instance, 13% and 4% of non-slaughter movements from professional producers were sent to a non-assured commercial producer or to a small producer, respectively; whereas 43% and 22% of movements from non-assured commercial farms were sent to a professional or a small producer, respectively. We further identified differences between producer types in several animal movement characteristics which are known to increase the risk of disease spread. Particularly, the distance travelled and the use of haulage were found to be significantly different between producers.

CONCLUSIONS

These results showed that commercial producers are not isolated from the non-commercial sector of the Scottish swine industry and may frequently interact, either directly or indirectly. The observed patterns in the frequency of movements, the type of producers involved, the distance travelled and the use of haulage companies provide insights into the structure of the Scottish swine industry, but also highlight different features that may increase the risk of infectious diseases spread in both Scotland and the UK. Such knowledge is critical for developing more robust biosecurity and surveillance plans and better preparing Scotland against incursions of emerging swine diseases.

A systems approach to the policy-level risk assessment of exotic animal diseases: network model and application to classical swine fever

Exotic animal diseases (EADs) are characterized by their capacity to spread global distances, causing impacts on animal health and welfare with significant economic consequences. We offer a critique of current import risk analysis approaches employed in the EAD field, focusing on their capacity to assess complex systems at a policy level. To address the shortcomings identified, we propose a novel method providing a systematic analysis of the likelihood of a disease incursion, developed by reference to the multibarrier system employed for the United Kingdom. We apply the network model to a policy-level risk assessment of classical swine fever (CSF), a notifiable animal disease caused by the CSF virus. In doing so, we document and discuss a sequence of analyses that describe system vulnerabilities and reveal the critical control points (CCPs) for intervention, reducing the likelihood of U.K. pig herds being exposed to the CSF virus.

Introduction of African swine fever into the European Union through illegal importation of pork and pork products

Transboundary animal diseases can have very severe socio-economic impacts when introduced into new regions. The history of disease incursions into the European Union suggests that initial outbreaks were often initiated by illegal importation of meat and derived products. The European Union would benefit from decision-support tools to evaluate the risk of disease introduction caused by illegal imports in order to inform its surveillance strategy. However, due to the difficulty in quantifying illegal movements of animal products, very few studies of this type have been conducted. Using African swine fever as an example, this work presents a novel risk assessment framework for disease introduction into the European Union through illegal importation of meat and products. It uses a semi-quantitative approach based on factors that likely influence the likelihood of release of contaminated smuggled meat and products, and subsequent exposure of the susceptible population. The results suggest that the European Union is at non-negligible risk of African swine fever introduction through illegal importation of pork and products. On a relative risk scale with six categories from negligible to very high, five European Union countries were estimated at high (France, Germany, Italy and United Kingdom) or moderate (Spain) risk of African swine fever release, five countries were at high risk of exposure if African swine fever were released (France, Italy, Poland, Romania and Spain) and ten countries had a moderate exposure risk (Austria, Bulgaria, Germany, Greece, Hungary, Latvia, Lithuania, Portugal, Sweden and United Kingdom). The approach presented here and results obtained for African swine fever provide a basis for the enhancement of risk-based surveillance systems and disease prevention programmes in the European Union.

Risk of African swine fever introduction into the European Union through transport-associated routes: returning trucks and waste from international ships and planes

Background

The uncontrolled presence of African swine fever (ASF) in Russian Federation (RF) poses a serious risk to the whole European Union (EU) pig industry. Although trade of pigs and their products is banned since the official notification in June 2007, the potential introduction of ASF virus (ASFV) may occur by other routes, which are very frequent in ASF, and more difficult to control, such as contaminated waste or infected vehicles. This study was intended to estimate the risk of ASFV introduction into the EU through three types of transport routes: returning trucks, waste from international ships and waste from international planes, which will be referred here as transport-associated routes (TAR). Since no detailed and official information was available for these routes, a semi-quantitative model based on the weighted combination of risk factors was developed to estimate the risk of ASFV introduction by TAR. Relative weights for combination of different risk factors as well as validation of the model results were obtained by an expert opinion elicitation.

Results

Model results indicate that the relative risk for ASFV introduction through TAR in most of the EU countries (16) is low, although some countries, specifically Poland and Lithuania, concentrate high levels of risk, the returning trucks route being the analyzed TAR that currently poses the highest risk for ASFV introduction into the EU. The spatial distribution of the risk of ASFV introduction varies importantly between the analyzed introduction routes. Results also highlight the need to increase the awareness and precautions for ASF prevention, particularly ensuring truck disinfection, to minimize the potential risk of entrance into the EU.

Conclusions

This study presents the first assessment of ASF introduction into the EU through TAR. The innovative model developed here could be used in data scarce situations for estimating the relative risk associated to each EU country. This simple methodology provides a rapid and easy to interpret results on risk that may be used for a target and cost-effective allocation of resources to prevent disease introduction.

Comparative assessment of analytical approaches to quantify the risk for introduction of rare animal diseases: the example of avian influenza in Spain

Trade of animals and animal products imposes an uncertain and variable risk for exotic animal diseases introduction into importing countries. Risk analysis provides importing countries with an objective, transparent, and internationally accepted method for assessing that risk. Over the last decades, European Union countries have conducted probabilistic risk assessments quite frequently to quantify the risk for rare animal diseases introduction into their territories. Most probabilistic animal health risk assessments have been typically classified into one-level and multilevel binomial models. One-level models are more simple than multilevel models because they assume that animals or products originate from one single population. However, it is unknown whether such simplification may result in substantially different results compared to those obtained through the use of multilevel models. Here, data used on a probabilistic multilevel binomial model formulated to assess the risk for highly pathogenic avian influenza introduction into Spain were reanalyzed using a one-level binomial model and their outcomes were compared. An alternative ordinal model is also proposed here, which makes use of simpler assumptions and less information compared to those required by traditional one-level and multilevel approaches. Results suggest that, at least under certain circumstances, results of the one-level and ordinal approaches are similar to those obtained using multilevel models. Consequently, we argue that, when data are insufficient to run traditional probabilistic models, the ordinal approach presented here may be a suitable alternative to rank exporting countries in terms of the risk that they impose for the spread of rare animal diseases into disease-free countries.

Epidemic threats to the European Union: expert views on six virus groups

In recent years, several animal disease epidemics have occurred within the European Union (EU). At the 4th Annual Meeting of the EPIZONE network (7-10 June 2010, St. Malo, France), an interactive session was run to elicit the opinions of delegates on a pre-defined list of epidemic threats to the EU. Responses from over 190 delegates, to questions relating to impact and likelihood, were used to rank six virus groups with respect to their perceived threat now (2010) and in 2020. The combined opinions of all delegates suggested that, from the pre-selected list of virus groups, foot-and-mouth disease and influenza are currently of most concern. Delegates thought that influenza would be less of a threat and zoonotic arboviruses would be more of a threat in 2020. Although the virus group rankings should not be taken as definitive, the results could be used in conjunction with experimental and field data, by scientists, policy-makers and stakeholders when assessing and managing risks associated with these virus groups.

Clostridium difficile PCR ribotype 027: assessing the risks of further worldwide spread

Highly virulent strains of Clostridium difficile have emerged since 2003, causing large outbreaks of severe, often fatal, colitis in North America and Europe. In 2008–10, virulent strains spread between continents, with the first reported cases of fluoroquinolone-resistant C difficile PCR ribotype 027 in three Asia-Pacific countries and Central America. We present a risk assessment framework for assessing risks of further worldwide spread of this pathogen. This framework first requires identification of potential vehicles of introduction, including international transfers of hospital patients, international tourism and migration, and trade in livestock, associated commodities, and foodstuffs. It then calls for assessment of the risks of pathogen release, of exposure of individuals if release happens, and of resulting outbreaks. Health departments in countries unaffected by outbreaks should assess the risk of introduction or reintroduction of C difficile PCR ribotype 027 using a structured risk-assessment approach.

A stochastic model to quantify the risk of introduction of classical swine fever virus through import of domestic and wild boars

Classical swine fever (CSF) is a disease of pigs that imposes major hardship on the industry of infected regions. The recent history of CSF epidemics suggests that animal movements remain the main source of CSF virus (CSFV) infection for susceptible populations in Europe. This study presents an assessment of the risk of introducing CSFV into Spain through the importation of live susceptible animals. Results suggest that, if prevailing conditions persist, introduction of CSFV into Spain is likely to occur on average every 9 years and that introduction is almost three times more likely to occur via domestic pigs than through wild boars. The highest risk was concentrated in March and in the Northeastern provinces of Spain. Results were consistent with the time and location of previous CSFV introductions into the country. The methodology and the results presented here will contribute to improve the CSF prevention programme in Spain.