Quantification of the risk for introduction of virulent Newcastle disease virus into Spain through legal trade of live poultry from European Union countries

Dynamic paramyxovirus type 1 seroprevalence maps in broilers in the Valencian Community (eastern Spain) during a five-year period (2008-2012)

Newcastle disease is a devasting disease in poultry production worldwide, thus it is important to implement control measures to avoid entrance of the disease and its spread in the field. In this context, the aim of this study was to design and implement a seroprevalence map based on business intelligence for avian paramyxovirus type 1 (APMV-1) in broilers in the Valencia Community (eastern Spain). This tool consists in software mapping based on data collection, data analysis and data representation. In order to obtain the serological data, 12 495 sera from 131 broiler farms over 5 years were analysed (2008-2012). The data were represented on a map of the Valencian Community including geographical information of flock locations to facilitate disease monitoring. No clinical signs of APMV-1 were reported in the studied flocks. The data from this study showed no evidence contact with APMV-1 in broiler flocks and the novel software mapping tool as a valuable method for easily monitoring the serological response to avian paramyxovirus type 1 (APMV-1) including geographical information.

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.

Assessment of the control measures of the category A diseases of Animal Health Law: Newcastle disease

EFSA received a mandate from the European Commission to assess the effectiveness of some of the control measures against diseases included in the Category A list according to Regulation (EU) 2016/429 on transmissible animal diseases ('Animal Health Law'). This opinion belongs to a series of opinions where these control measures will be assessed, with this opinion covering the assessment of control measures for Newcastle disease (ND). In this opinion, EFSA and the AHAW Panel of experts review the effectiveness of: (i) clinical and laboratory sampling procedures, (ii) monitoring period and (iii) the minimum radius of the protection and surveillance zone, and the minimum length of time the measures should be applied in these zones. The general methodology used for this series of opinions has been published elsewhere. Several scenarios for which these control measures had to be assessed were designed and agreed prior to the start of the assessment. The monitoring period (21 days) was assessed as effective in non-vaccinated chicken and turkey flocks, although large uncertainty remains surrounding the effectiveness of this period in vaccinated galliform flocks and flocks of other bird species. It was also concluded that the protection (3 km radius) and the surveillance (10 km radius) zones contain 99% of the infections from an infectious establishment. Recommendations provided for each of the scenarios assessed aim to support the European Commission in the drafting of further pieces of legislation, as well as for plausible ad hoc requests in relation to ND.

Quantitative risk assessment of the introduction of low pathogenic avian influenza H5 and H7 strains into Poland via legal import of live poultry

Low pathogenic avian influenza (LPAI) caused by H5 and H7 viruses is considered a threatening disease for poultry production due to the possibility of prolonged undetected virus circulation in a poultry flock and its potential to mutate to highly pathogenic avian influenza (HPAI). The occurrence of HPAI may have devastating impact on the poultry industry and has serious economic consequences. The possibility of LPAI virus (LPAIV) being introduced into Poland via import of live poultry from EU countries was considered. The main aim of the study was to quantitatively assess the probability of LPAIV H5 and H7 introduction into Poland (P_LPAI) via this pathway, to evaluate the relative contribution of exporting countries and species of poultry to this probability and to present the spatial distribution of the introduction probability in Poland. To this end, a stochastic multilevel binomial risk model, taking into account uncertainty and variability of input parameter values, was developed. The results of this model indicate that the mean annual probability of LPAIV H5 or H7 introduction into Poland is 0.088 [95 % uncertainty interval: 0.0575, 0.128], which corresponds to, on average, one outbreak every 11 years. The countries contributing most to this probability are Germany, Czech Republic and Denmark. Importations of ducks, chickens and turkeys contribute most to P_LPAI, whereas importations of geese and guinea fowl represent a minor risk. The probability of LPAIV introduction is not equally distributed across Poland with the majority of counties having a high probability of LPAIV introduction being located in the Western part of the country. The results of this study can be used to support decision makers on targeted prevention or risk-based surveillance strategies for LPAI.

Description and analysis of the poultry trading network in the Lake Alaotra region, Madagascar: implications for the surveillance and control of Newcastle disease

Madagascar's 36.5-million-head poultry industry holds a foremost place in its economy and the livelihood of its people. Unfortunately, regular Newcastle disease outbreaks associated with high mortality causes high losses for smallholders and threatens their livelihood. Therefore, Madagascar is seeking concrete, achievable and sustainable methods for the surveillance and the control of Newcastle disease. In this paper, we present and analyze the results of a field study conducted in Madagascar between December 2009 and December 2010. The study area was the Lac Alaotra region, a landlocked area in the north-eastern part of the country's center. Poultry trading is suspected of playing a major role in the spread of avian diseases, especially in developing countries characterized by many live-bird markets and middlemen. Therefore, the goals of our study were to: (i) describe and analyze smallholders' poultry trading network in the Lake Alaotra region using social network analysis; (ii) assess the role of the network in the spread of Newcastle disease; and (iii) propose the implementation of a targeted disease surveillance based on the characteristics of the poultry trading network. We focused our field study on the harvesting of two data sets. The first is a complete description of the poultry trading network in the landlocked area of Lac Alaotra, including a description of the poultry movements between groups of villages. The second set of data measures the occurrence of outbreaks in the same area by combining a participatory approach with an event-based surveillance method. These data were used to determine the attributes of the network, and to statistically assess the association between the position of nodes and the occurrence of outbreaks. By using social network analysis techniques combined with a classification method and a logistic model, we finally identified 3 nodes (set of villages), of the 387 in the initial network, to focus on for surveillance and control in the Lac Alaotra area. This result is of primary importance in the ongoing efforts to effectively improve the wellbeing of people in the region.

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.

Use of reverse transcriptase polymerase chain reaction (RT-PCR) in molecular screening of Newcastle disease virus in poultry and free-living bird populations

The aim of this study was to evaluate a simple molecular method of reverse transcriptase polymerase chain reaction (RT-PCR) to differentiate Newcastle disease virus strains according to their pathogenicity, in order to use it in molecular screening of Newcastle disease virus in poultry and free-living bird populations. Specific primers were developed to differentiate LaSota--LS--(vaccine strain) and Sao Joao do Meriti--SJM--strain (highly pathogenic strain). Chickens and pigeons were experimentally vaccinated/infected for an in vivo study to determine virus shedding in feces. Validation of sensitivity and specificity of the primers (SJM and LS) by experimental models used in the present study and results obtained in the molecular analysis of the primers by BLAST made it possible to generalize results. The development of primers that differentiate the level of pathogenicity of NDV stains is very important, mainly in countries where real-time RT-PCR is still not used as a routine test. These primers were able to determine the presence of the agent and to differentiate it according to its pathogenicity.

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.