The French Epidemic Intelligence System: comparing disease surveillance at the national and international level using data from the Program for Monitoring Emerging Diseases.

In a context of globalisation and climate change, the risk of emerging infectious diseases spreading around the world has significantly increased in the past decades. In response to this growing threat, an epidemic intelligence team has been set up within the framework of the French animal health epidemiological surveillance platform (ESA platform). The French Epidemic Intelligence System (FEIS) monitors animal health risks in Europe and beyond that threaten animal populations in France (emerging and exotic diseases not yet present). The FEIS expert network covers all 53 category 1 health hazards identified as priority diseases by the French authorities. From January 2016 to December 2017, the FEIS published 126 reports on animal health events related to infectious diseases, of which 76.2% were related to events in Europe. When comparing FEIS reports to posts from the Program for Monitoring Emerging Diseases (ProMED), an FEIS report was produced for 52.6% of ProMED themes (combinations of disease and country) posted in 2016-2017 on events in Europe. The remaining European ProMED themes did not meet the criterion for the production of an FEIS report because either the disease was already present in France, the risk of introduction into France was considered low or negligible, or the introduction of the pathogen would have low or negligible economic and societal impacts. The FEIS efficiently detected and reported on all health hazards identified by ProMED to alert health authorities and stakeholders when needed (according to the criterion). Compared with international epidemic intelligence systems such as ProMED, which provide general information, the FEIS adds another layer of filtering and interpretation to available information on animal health threats tailored to France's specific needs, in order to communicate only essential information to health authorities.

Dans un contexte caractérisé par la mondialisation et le changement climatique, le risque de propagation mondiale des maladies infectieuses émergentes s'est significativement accru en quelques décennies. Pour répondre à cette menace croissante, une équipe de veille épidémique a été mise en place dans le cadre de la Plateforme française d'épidémiosurveillance en santé animale (Plateforme ESA). Le système de Veille sanitaire internationale (VSI) surveille les risques sanitaires en santé animale présents en Europe, voire au-delà, dès lors qu'ils représentent une menace pour les populations animales sur le territoire français (maladies émergentes et maladies exotiques jamais introduites en France). Le réseau d'experts de la VSI couvre les 53 risques sanitaires de catégorie 1 définis par les autorités françaises comme maladies prioritaires. De janvier 2016 à décembre 2017, 126 rapports de la VSI ont été publiés sur des événements de santé animale liés à des maladies infectieuses, dont 76,2 % concernaient des événements survenus en Europe. La comparaison entre les rapports émanant de la VSI et ceux du Programme de suivi des maladies émergentes (ProMED) fait apparaître que 52,6 % des thématiques publiées en 2016-2017 par ProMED (associant une maladie et un pays) relatives à des événements survenus en Europe avaient également fait l'objet d'un rapport par la VSI. Les thématiques restantes sur ProMED correspondant à des événements européens ne répondaient pas aux critères de la VSI, soit parce qu'il s'agissait d'une maladie déjà présente en France, soit parce que le risque d'introduction de l'agent pathogène en France était considéré comme faible ou négligeable, soit enfin parce que l'impact économique et sociétal d'une telle introduction, si elle survenait, aurait été faible ou négligeable. La VSI a détecté (en fonction de ses critères) l'ensemble des risques sanitaires identifiés par ProMED et les a notifiés avec efficacité aux autorités et acteurs en charge de la santé, chaque fois que nécessaire. Par rapport aux systèmes de veille sanitaire internationaux tels que ProMED qui fournissent des informations générales, la VSI, qui est spécifiquement adaptée aux besoins français, ajoute une strate supplémentaire de filtrage et d'interprétation des données disponibles sur les menaces de santé animale, afin de ne transmettre aux autorités sanitaires que les informations qui leur sont essentielles.

De unos decenios a esta parte, en un contexto marcado por la mundialización y el cambio climático, ha aumentado sustancialmente el riesgo de propagación por todo el mundo de enfermedades infecciosas emergentes. Para responder a esta creciente amenaza se ha establecido, dentro del dispositivo francés de vigilancia epidemiológica zoosanitaria (plataforma ESA), un equipo de inteligencia epidemiológica. El Sistema Francés de Información Epidemiológica (épidémiologique) está dedicado a seguir de cerca los riesgos zoosanitarios que, desde Europa u otras partes del mundo, amenacen a las poblaciones animales de Francia (enfermedades emergentes y exóticas que aún no estén presentes en el país). La red de especialistas de la VSI cubre la totalidad de los 53 peligros sanitarios de categoría 1 que las autoridades francesas tienen definidos como enfermedades prioritarias. Entre enero de 2016 y diciembre de 2017, la VSI publicó 126 informes sobre episodios zoosanitarios relacionados con enfermedades infecciosas, de los que un 76,2% tenían que ver con episodios ocurridos en Europa. Al comparar los informes de la VSI con las notas publicadas por el Programa de Vigilancia de Enfermedades Emergentes (ProMED) se constató que ela VSI había elaborado un informe en relación con el 52,6% de los temas (combinación de enfermedades y países) tratados por el ProMED en sus notas de 2016 y 2017 sobre episodios ocurridos en suelo europeo. Los restantes temas europeos tratados por el ProMED no cumplían el criterio de que hubiera un informe de la VSI al respecto, ya fuera porque la enfermedad ya estaba presente en Francia, porque se consideró bajo o insignificante el riesgo de penetración en Francia o porque la llegada del patógeno tendría una repercusión escasa o insignificante en la economía o la sociedad. La VSI detectó y comunicó con eficacia todos los peligros sanitarios identificados por el ProMED para alertar a las autoridades sanitarias y demás interlocutores cada vez que fue necesario (con arreglo al criterio). En comparación con los sistemas internacionales de información epidemiológica, como el ProMED, que proporcionan información general, la VSI agrega un filtro y un nivel de interpretación suplementarios a la información disponible sobre amenazas zoosanitarias, adaptándola así a las necesidades específicas de Francia, con el fin de comunicar únicamente información esencial a las autoridades sanitarias.

Estimation of French cattle herd immunity against bluetongue serotype 8 at the time of its re-emergence in 2015.

BACKGROUND: From 2006 to 2010, France experienced two bluetongue epidemics caused by serotype 1 (BTV-1) and 8 (BTV-8) which were controlled by mass vaccination campaigns. After five years without any detected cases, a sick ram was confirmed in August 2015 to be infected by a BTV-8 strain almost identical to that circulating during the previous outbreak. By then, part of the French cattle population was expected to be still protected, since bluetongue antibodies are known to last for many years after natural infection or vaccination. The objective of this study was to estimate the proportion of cattle in France still immune to BTV-8 at the time of its re-emergence in 2015. RESULTS: We used BTV group-specific cELISA results from 8525 cattle born before the vaccination ban in 2013 and 15,799 cattle born after the ban. Samples were collected from January to April 2016 to estimate seroprevalence per birth cohort. The overall seroprevalence in cattle at national and local levels was extrapolated from seroprevalence results per birth cohort and their respective proportion at each level. To indirectly assess pre-immune status of birth cohorts, we computed prevalence per birth cohort on infected farms in autumn 2015 using 1377 RT-PCR results. These revealed limited BTV circulation in 2015. Seroprevalence per birth cohort was likely to be connected to past exposure to natural infection and/or vaccination with higher seroprevalence levels in older animals. A seroprevalence of 95% was observed for animals born before 2008, of which > 90% were exposed to two compulsory vaccination campaigns in 2008-2010. None of the animals born before 2008 were found to be infected, unlike 19% of the young cattle which had never been vaccinated. This suggests that most ELISA-positive animals were pre-immune to BTV-8. We estimated that 18% (from 12% to 32% per département) of the French cattle population was probably pre-immune in 2015. CONCLUSIONS: These results strongly suggest a persistence of antibodies for at least 5-6 years after natural infection or vaccination. The herd immunity of the French cattle population probably limited BTV circulation up to 2015, by which time more than 80% of cattle were naive.

Study on seroprevalence and serotyping of foot and mouth disease in Chad.

Foot and mouth disease (FMD) is a highly contagious viral disease that affects all Artiodactyla. Seven immunologically distinct serotypes of FMD virus (FMDV) exist. In Chad, although FMD is included in the list of diseases monitored by the Chadian Animal Disease Surveillance Network (REPIMAT), the epidemiological situation remains unclear. A serological survey was conducted in the cattle population in eight of the nine administrative regions of the country (those regions with the highest cattle densities), to evaluate the prevalence and serotypes of circulating FMDV.A total of 796 sera from randomly selected cattle were analysed at the World Organisation for Animal Health/Food and Agriculture Organization of the United Nations FMD Reference Laboratory at the Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna(IZSLER), in Brescia (Italy). An enzyme-linked immunosorbent assay (ELISA), called 3ABC ELISA, was used to detect antibodies against non-structural proteins (NSPs), as well as a series of six competitive ELISAs to detect and serotype antibodies against the structural proteins of FMDV serotypes O, A, SAT 1, SAT 2, Asia 1 and C. Based on the detection of anti-NSP antibodies, the animal-level seroprevalence was 35.6%(95% confidence interval [CI]: 32.2-38.9) and the herd-level seroprevalence was 62.3% (95%CI: 53.0-71.5). FMD was present in all livestock administrative divisions surveyed, with a higher prevalence in southern regions, which are characterised by higher rainfall and humidity and more important transboundary animal movements. Cattle aged more than four years had a higher seroprevalence, which may be due to repeated exposure. Semi-sedentary farming and transhumance were also risk factors. Antibodies against serotypes A, O, SAT 1 and SAT 2 were detected.

La fièvre aphteuse est une maladie virale extrêmement contagieuse qui affecte l'ensemble des artiodactyles. Sept sérotypes du virus de la fièvre aphteuse ont été répertoriés, qui sont distincts au plan immunologique. Au Tchad, bien que la fièvre aphteuse figure sur la liste des maladies visées par le Réseau d'épidémiosurveillance des maladies animales du Tchad (REPIMAT), la situation épidémiologique demeure mal connue. Une enquête sérologique a été réalisée dans la population bovine de huit régions administratives sur les neuf que compte le pays (afin de couvrir les régions où la densité de la population bovine est la plus élevée), dans le but d'évaluer la prévalence du virus de la fièvre aphteuse et de caractériser les sérotypes présents. Au total, 796 sérums prélevés sur des bovins sélectionnés de manière aléatoire ont été analysés au Laboratoire de référence pour la fièvre aphteuse de l'Organisation mondiale de la santé animale/Organisation des Nations Unies pour l'alimentation et l'agriculture à l'Istituto Zooprofilattico Sperimentale dellaLombardia e dell'Emilia Romagna (IZSLER) de Brescia (Italie). Les anticorps dirigés contre les protéines non structurales ont été détectés au moyen d'une épreuve immuno-enzymatique 3ABC (ELISA 3ABC) tandis qu'une série de six ELISA de compétition a permis de détecter et de caractériser les anticorps spécifiques des protéines structurales des sérotypes O, A, SAT 1, SAT 2, Asia 1 et C du virus de la fièvre aphteuse. D'après les résultats de la détection d'anticorps dirigés contre les protéines non structurales, la prévalence sérologique à l'échelle individuelle était de35,6 % (avec un intervalle de confiance [IC] à 95 % de 32,2 à 38,9) tandis que la prévalence à l'échelle des troupeaux s'élevait à 62,3 % (IC à 95 % de 53,0 à 71,5).La fièvre aphteuse était présente dans chacune des divisions administratives étudiées, avec une prévalence plus élevée dans les régions méridionales, qui se caractérisent par des précipitations et une hygrométrie plus fortes et par l'importance des mouvements transfrontaliers d'animaux. La prévalence sérologique était plus élevée chez les bovins âgés de plus de quatre ans, ce qui s'explique probablement par un nombre répété d'expositions. Le rôle de l'élevage semi-sédentaire et de la transhumance en tant que facteurs de risque a été misen lumière. Les anticorps détectés étaient dirigés contre les sérotypes A, O, SAT 1et SAT 2.

La fiebre aftosa es una patología vírica muy contagiosa que afecta a todos los artiodáctilos. Existen siete serotipos inmunológicamente diferenciados del virus que la causa. En el Chad, aunque la fiebre aftosa figura en la lista de enfermedades sometidas a vigilancia por la Red Chadiana de Vigilancia Zoosanitaria (REPIMAT), la situación epidemiológica de la enfermedad sigue rodeada de incertidumbre. Los autores describen un estudio serológico realizado en la población vacuna de ocho de las nueve regiones administrativas del país (las que presentan la mayor densidad de ganado vacuno) con objeto de determinar la prevalencia y los serotipos del virus de la fiebre aftosa circulante. Tras seleccionar aleatoriamente un total de 796 cabezas de ganado y obtener de ellas muestras de suero, estas fueron analizadas en el Istituto Zooprofilattico Sperimentale della Lombardia e dell'EmiliaRomagna (IZSLER) de Brescia (Italia), que es el Laboratorio de Referencia de la Organización Mundial de Sanidad Animal y la Organización de las Naciones Unidas para la Alimentación y la Agricultura para la fiebre aftosa. Para detectar anticuerpos dirigidos específicamente contra proteínas no estructurales se empleó un ensayo inmunoenzimático (ELISA) denominado ELISA 3ABC, a lo que se agregó una serie de seis técnicas ELISA de competición concebidas para detectar y tipificar anticuerpos dirigidos contra las proteínas estructurales de los serotipos O, A,SAT 1, SAT 2, Asia 1 y C del virus de la fiebre aftosa. A tenor de los niveles detectados de anticuerpos contra proteínas no estructurales, la seroprevalencia individual era de un 35,6% (intervalo de confianza [IC] al 95%:32,2­38,9) y la seroprevalencia de rebaño era de un 62,3% (IC 95%: 53,0­71,5).La fiebre aftosa, presente en todas las divisiones administrativas ganaderas estudiadas, alcanzaba sus máximos niveles de prevalencia en las regiones meridionales, caracterizadas por tasas de pluviosidad y humedad más altas y por un mayor volumen de movimientos transfronterizos de animales. La seroprevalencia era más elevada en los ejemplares de más de cuatro años de edad, hecho que puede deberse a exposiciones reiteradas. La producción ganadera en régimen semisedentario y la trashumancia eran también factores de riesgo. Se detectaron anticuerpos contra los serotipos A, O, SAT 1 y SAT 2.

Comparative evaluation of three surveillance systems for infectious equine diseases in France and implications for future synergies.

It is necessary to assess surveillance systems for infectious animal diseases to ensure they meet their objectives and provide high-quality health information. Each system is generally dedicated to one disease and often comprises various components. In many animal industries, several surveillance systems are implemented separately even if they are based on similar components. This lack of synergy may prevent optimal surveillance. The purpose of this study was to assess several surveillance systems within the same industry using the semi-quantitative OASIS method and to compare the results of the assessments in order to propose improvements, including future synergies. We have focused on the surveillance of three major equine diseases in France. We have identified the mutual and specific strengths and weaknesses of each surveillance system. Furthermore, the comparative assessment has highlighted many possible synergies that could improve the effectiveness and efficiency of surveillance as a whole, including the implementation of new joint tools or the pooling of existing teams, tools or skills. Our approach is an original application of the OASIS method, which requires minimal financial resources and is not very time-consuming. Such a comparative evaluation could conceivably be applied to other surveillance systems, other industries and other countries. This approach would be especially relevant to enhance the efficiency of surveillance activities when resources are limited.

A spatiotemporal model to assess the introduction risk of African horse sickness by import of animals and vectors in France.

BACKGROUND: African horse sickness (AHS) is a major, Culicoides-borne viral disease in equines whose introduction into Europe could have dramatic consequences. The disease is considered to be endemic in sub-Saharan Africa. Recent introductions of other Culicoides-borne viruses (bluetongue and Schmallenberg) into northern Europe have highlighted the risk that AHS may arrive in Europe as well. The aim of our study was to provide a spatiotemporal quantitative risk model of AHS introduction into France. The study focused on two pathways of introduction: the arrival of an infectious host (PW-host) and the arrival of an infectious Culicoides midge via the livestock trade (PW-vector). The risk of introduction was calculated by determining the probability of an infectious animal or vector entering the country and the probability of the virus then becoming established: i.e., the virus's arrival in France resulting in at least one local equine host being infected by one local vector. This risk was assessed using data from three consecutive years (2010 to 2012) for 22 regions in France. RESULTS: The results of the model indicate that the annual risk of AHS being introduced to France is very low but that major spatiotemporal differences exist. For both introduction pathways, risk is higher from July to October and peaks in July. In general, regions with warmer climates are more at risk, as are colder regions with larger equine populations; however, regional variation in animal importation patterns (number and species) also play a major role in determining risk. Despite the low probability that AHSV is present in the EU, intra-EU trade of equines contributes most to the risk of AHSV introduction to France because it involves a large number of horse movements. CONCLUSION: It is important to address spatiotemporal differences when assessing the risk of ASH introduction and thus also when implementing efficient surveillance efforts. The methods and results of this study may help develop surveillance techniques and other risk reduction measures that will prevent the introduction of AHS or minimize AHS' potential impact once introduced, both in France and the rest of Europe.

Veterinarians as practitioners and as key players in epidemiological surveillance: two tasks, two paradigms to be reconciled.

Veterinary practitioners are often involved in epidemiological surveillance systems, where their task is to detect animals suspected of suffering from diseases subject to surveillance and to include them in surveillance. However, these two tasks--practising veterinary medicine and taking part in surveillance--are based on different paradigms. Faced with a sick animal, a practitioner tries to maximise the probability of a correct diagnosis, whereas, when implementing surveillance, a veterinarian is required to maximise the inclusion of suspected cases in surveillance systems. Based on an analysis of the difficulties and problems posed by these coexisting tasks, the authors propose potential solutions through veterinary education and training. The implementers and coordinators of epidemiological surveillance systems must take these factors into account.

[Cost estimation of an epidemiological surveillance network for animal diseases in Central Africa: a case study of the Chad network]. / Estimation du coûét d'un réseau d'épidèmiosurveillance des maladies animales en Afrique centrale: le cas du réseau tchadien.

In sub-Saharan Africa, most epidemiological surveillance networks for animal diseases were temporarily funded by foreign aid. It should be possible for national public funds to ensure the sustainability of such decision support tools. Taking the epidemiological surveillance network for animal diseases in Chad (REPIMAT) as an example, this study aims to estimate the network's cost by identifying the various costs and expenditures for each level of intervention. The network cost was estimated on the basis of an analysis of the operational organisation of REPIMAT, additional data collected in surveys and interviews with network field workers and a market price listing for Chad. These costs were then compared with those of other epidemiological surveillance networks in West Africa. The study results indicate that REPIMAT costs account for 3% of the State budget allocated to the Ministry of Livestock. In Chad in general, as in other West African countries, fixed costs outweigh variable costs at every level of intervention. The cost of surveillance principally depends on what is needed for surveillance at the local level (monitoring stations) and at the intermediate level (official livestock sectors and regional livestock delegations) and on the cost of the necessary equipment. In African countries, the cost of surveillance per square kilometre depends on livestock density.

OASIS: an assessment tool of epidemiological surveillance systems in animal health and food safety.

The purpose of this study was to develop a standardized tool for the assessment of surveillance systems on zoonoses and animal diseases. We reviewed three existing methods and combined them to develop a semi-quantitative assessment tool associating their strengths and providing a standardized way to display multilevel results. We developed a set of 78 assessment criteria divided into ten sections, representing the functional parts of a surveillance system. Each criterion was given a score according to the prescription of a scoring guide. Three graphical assessment outputs were generated using a specific combination of the scores. Output 1 is a general overview through a series of pie charts synthesizing the scores of each section. Output 2 is a histogram representing the quality of eight critical control points. Output 3 is a radar chart representing the level reached by ten system attributes. This tool was applied on five surveillance networks.

A simplified method of performance indicators development for epidemiological surveillance networks--application to the RESAPATH surveillance network.

BACKGROUND: Develop and calculate performance indicators allows to continuously follow the operation of an epidemiological surveillance network. This is an internal evaluation method, implemented by the coordinators in collaboration with all the actors of the network. Its purpose is to detect weak points in order to optimize management. A method for the development of performance indicators of epidemiological surveillance networks was developed in 2004 and was applied to several networks. Its implementation requires a thorough description of the network environment and all its activities to define priority indicators. Since this method is considered to be complex, our objective consisted in developing a simplified approach and applying it to an epidemiological surveillance network. METHODS: We applied the initial method to a theoretical network model to obtain a list of generic indicators that can be adapted to any surveillance network. RESULTS: We obtained a list of 25 generic performance indicators, intended to be reformulated and described according to the specificities of each network. It was used to develop performance indicators for RESAPATH, an epidemiological surveillance network of antimicrobial resistance in pathogenic bacteria of animal origin in France. CONCLUSION: This application allowed us to validate the simplified method, its value in terms of practical implementation, and its level of user acceptance. Its ease of use and speed of application compared to the initial method argue in favor of its use on broader scale.

Surveillance of avian influenza in the Caribbean through the Caribbean Animal Health Network: surveillance tools and epidemiologic studies.

The Caribbean region is considered to be at risk for avian influenza (AI) due to a large backyard poultry system, an important commercial poultry production system, the presence of migratory birds, and disparities in the surveillance systems. The Caribbean Animal Health Network (CaribVET) has developed tools to implement AI surveillance in the region with the goals to have 1) a regionally harmonized surveillance protocol and specific web pages for AI surveillance on www.caribvet.net, and 2) an active and passive surveillance for AI in domestic and wild birds. A diagnostic network for the Caribbean, including technology transfer and AI virus molecular diagnostic capability in Guadeloupe (real-time reverse transcription-polymerase chain reaction for the AI virus matrix gene), was developed. Between 2006 and 2009, 627 samples from four Caribbean countries were tested for three circumstances: importation purposes, following a clinical suspicion of AI, or through an active survey of wild birds (mainly waders) during the southward and northward migration periods in Guadeloupe. None of the samples tested were positive, suggesting a limited role of these species in the AI virus ecology in the Caribbean. Following low pathogenic H5N2 outbreaks in the Dominican Republic in 2007, a questionnaire was developed to collect data for a risk analysis of AI spread in the region through fighting cocks. The infection pathway of the Martinique commercial poultry sector by AI, through introduction of infected cocks, was designed, and recommendations were provided to the Caribbean Veterinary Services to improve cock movement control and biosecurity measures. The CaribVET and its organization allowed interaction between diagnostic and surveillance tools on the one hand and epidemiologic studies on the other, both of them developed in congruence with regional strategies. Together, these CaribVET activities contribute to strengthening surveillance of avian influenza virus (AIV) in the Caribbean region and may allow the development of research studies on both AI risk analysis and on AIV ecology.

[Epidemiological surveillance networks for animal diseases in French-speaking West and Central Africa]. / Les réseaux d'epidémiosurveillance des maladies animales en Afrique francophone de l'Ouest et du Centre.

One of the objectives of the Pan African Programme for the Control of Epizootics (PACE) was to set up epidemiological surveillance networks in African countries. A survey based on a written questionnaire was conducted to review the technical and institutional organisation of epidemiological surveillance networks in nine French-speaking countries, including five in West Africa (Senegal, Burkina Faso, Côte d'lvoire, Togo and Guinea) and four in Central Africa (Cameroon, Central African Republic, Democratic Republic of Congo and Chad). The survey results showed that there are more similarities than differences among epidemiological surveillance networks. In general, they were found to be technically and institutionally well established. However, the two weaknesses of the majority of networks are the inadequate diagnostic capacity of laboratories and the insufficient operationality of steering committees. Epidemiological surveillance should exclusively be the domain of Veterinary Services and it is crucial for ensuring that any change in the health status of an animal population is detected rapidly. However, the networks' continuing survival after external financing ceases is generally not guaranteed because, in many cases, governments fail to fund them adequately.

EGFP fluorescence as an indicator of cancer cells response to methotrexate.

Methotrexate action in viable cells was monitored by registering changes in EGFP (Enhanced Green Fluorescent Protein) fluorescence intensity. Treatment with 1 microM methotrexate for 48 h of human colorectal adenocarcinoma C85 cells, stably transfected to express EGFP, caused 5-fold increase in EGFP fluorescence assayed by flow cytometry with no distinct increase in EGFP protein level. This was correlated with morphological changes, including an increase of cell granularity and cell shape flattening, as well as cell cycle G1 phase arrest revealed by DNA content analysis. Methotrexate removal allowed the morphology of the cells in culture to revert in 10 days to normal. The cells that survived methotrexate exposure were propagated as C85r cell subline and displayed kinetics of methotrexate sensitivity parallel to that of the parental C85 line. As the increase in EGFP fluorescence could also be visualized by fluorescence microscopy, this reporter system may be employed to image methotrexate action in cancer cells in living models.

West Nile virus outbreak detection using syndromic monitoring in horses.

Recent outbreaks of West Nile virus-associated (WNV) diseases, both in the old World and Americas, underline the importance for early warning systems that rapidly identify emerging and re-emerging diseases and thus help in their control. Traditional approaches of disease monitoring become less reliable and increasingly costly when used for rare health-related events, such as WNV outbreaks in southern France. The objective of this work was to discuss methodological issues related to syndromic monitoring of WNV-associated disease in Camargue horses by veterinary practitioners. Tracking cases of equine encephalitis by veterinarians is an example of such syndromic monitoring of an emerging disease. Signs of illness, observed prior diagnostic confirmation, can be of interest because they may provide an early warning for WNV circulation in a given area and allow authorities to take appropriate preventive measures for public health.

Fallen stock data: An essential source of information for quantitative knowledge of equine mortality in France.

BACKGROUND: Quantitative information about equine mortality is relatively scarce, yet it could be of great value for epidemiological purposes. In France, data from rendering plants are centralised in the Fallen Stock Data Interchange database (FSDI), managed by the French Ministry of Agriculture, while individual equine data are centralised in the French equine census database, SIRE, managed by the French horse and riding institute (IFCE). OBJECTIVES: To evaluate whether the combined use of the FSDI and SIRE databases can provide representative and accurate quantitative information on mortality for the French equine population and to propose enhancements of these databases to improve the quality of the resulting demographic information. STUDY DESIGN: Descriptive study. METHODS: Mortality ratios for the French equine population were calculated per year between 2011 and 2014 and temporal variations in equine mortality modelled during the same period. Survival analyses were performed on a sample of equines traceable in both the FSDI and SIRE databases. RESULTS: Estimates of the annual mortality ratios varied from 3.02 to 3.40% depending on the years. Survival rates of equines 2-years-old and over differed according to breed categories with the highest median age at death for the ponies. The weekly description of mortality highlighted marked seasonality of deaths whatever the category of equines. Modelling temporal variations in equine mortality also brought to light excess mortality. MAIN LIMITATIONS: Insufficient traceability of equines between the two databases. CONCLUSION: The FSDI database provided an initial approach to equine death ratios on a national scale and an original description of temporal variations in mortality. Improvement in the traceability of equines between the FSDI and SIRE databases is needed to enable their combined use, providing a representative description of equine longevity and a more detailed description of temporal variations in mortality.

[The design and establishment of epidemiological surveillance systems for high-risk diseases in developed countries]. / Elaboration et mise en place de systèmes de surveillance epidémiologique des maladies a haut risque dans les pays développés.

In animal pathology, epidemiological surveillance has, over the last two decades, gradually become a top priority in developed countries, due to progress made in fighting major animal diseases. The management of effective epidemiological surveillance networks for high-risk animal diseases in developed countries is based on general rules governing epidemiological surveillance networks, but involves certain specificities. This article first of all sets out the requirements for the optimal functioning of epidemiological surveillance networks. It then describes and analyses the qualities expected of high-risk animal disease surveillance networks: detection sensitivity and specificity, simplicity and adaptability, and good cost efficiency. Finally, it illustrates these general concepts via four examples of animal disease epidemiological surveillance in developed countries: foot and mouth disease in Europe, West Nile virus in the United States of America and France, and bluetongue in France.

Estimating the incidence of equine viral arteritis and the sensitivity of its surveillance in the French breeding stock.

Equine viral arteritis (EVA) may have serious economic impact on the equine industry. For this reason, it is monitored in many countries, especially in breeding stock, to avoid its spread during breeding activities. In France, surveillance is mainly based on serological tests, since mares are not vaccinated, but difficulties in interpreting certain series of results may impair the estimation of the number of outbreaks. In this study, we propose specific rules for identifying seroconversion in order to estimate the number of outbreaks that were detected by the breeding stock surveillance component (BSSC) in France between 2006 and 2013. A consensus among multidisciplinary experts was reached to consider seroconversion as a change in antibody titer from negative to at least 32, or as an eight-fold or greater increase in antibody level. Using these rules, 239 cases and 177 outbreaks were identified. Subsequently, we calculated the BSSC's sensitivity as the ratio of the number of detected outbreaks to the total number of outbreaks that occurred in breeding stock (including unreported outbreaks) estimated using a capture-recapture model. The total number of outbreaks was estimated at 215 (95% credible interval 195-249) and the surveillance sensitivity at 82% (CrI95% 71-91). Our results confirm EVA circulation in French breeding stock, show that neutralizing antibodies can persist up to eight years in naturally infected mares and suggest that certain mares have been reinfected. This study shows that the sensitivity of the BSSC is relatively high and supports its relevance to prevent the disease spreading through mating.

Monitoring of leukemia growth in a rat model using a highly sensitive assay for the detection of LacZ marked leukemic cells.

A very sensitive assay for the detection of LacZ marked cells of an in vitro growing subline of the brown Norway rat myelocytic leukemia (BNML) model was developed. By combining cytochemical X-gal staining with D-galactose mediated suppression of endogenous background beta-galactose activity, a detection sensitivity of one leukemic cell per 10(8) normal bone marrow cells could be achieved. A detailed analysis of the in vivo growth pattern and kinetics of this cell line is presented. Also, it is shown that after cyclophosphamide treatment of leukemic rats no leukemic colonies are formed in an agar-colony assay, whereas the leukemic cells remain detectable in the bone marrow for a considerable time period. Eventually, however, all leukemic cells disappear from the marrow. These findings are discussed in the light of prolonged detection of rare leukemic cells in patients in continuing remission.

Retrovirus-mediated transfer and expression of marker genes in the BN rat acute myelocytic leukemia model for the study of minimal residual disease (MRD).

To study minimal residual disease (MRD) in leukemia, we transferred the Escherichia coli genes encoding beta-galactosidase (lacZ) and neomycin resistance (neo(r)) into the subline LT12 of the Brown Norway rat acute myelocytic leukemia (BNML), employing the retroviral BAG vector. In this way leukemic cells were genetically marked. Ten independent cell lines were characterized during in vitro growth as well as during two subsequent in vivo passages for expression of neo(r) for which the neomycin analogue G418 was used, and for lacZ expression for which the substrate 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal) was used. Out of 10 lines, four revealed permanent high expression of lacZ in all cells. In four other lines greatly varying lacZ expression between the individual cells from these lines was observed. In the remaining two lines lacZ expression was gradually lost. In contrast, neo(r) expression was gradually lost in eight out of the 10 lines, particularly rapidly during in vivo passaging. In the remaining two lines neo(r) expression was retained. The genetic modification did not alter the in vitro leukemogenicity of the cells. Long term in vivo expression of neo(r) and lacZ was followed in two selected lines up to 12 subsequent passages, i.e. one from the group of homogeneous high lacZ expression and one from the group of heterogeneous lacZ expression. In both lines lacZ expression was retained whereas neo(r) expression was rapidly lost after the third passage. The feasibility of using genetically marked leukemic cells for studies of minimal residual disease (MRD) was explored by injecting rats with leukemic cells, treating them with chemotherapy at full blown leukemia development to reduce the tumor load, mimicking the induction of a state of MRD and studying lacZ expression at relapse. LacZ expression was evident in 100% of the cells whereas neo(r) expression was lost in a considerable fraction. These results indicate that the viral vector BAG can be used to mark leukemia cells genetically although a selection of clones with the desired stability of long-term expression is required.

Homing of fluorescently labeled murine hematopoietic stem cells.

PKH-26 was used as a viable fluorescent membrane stain for murine hematopoietic stem cells. The presence of the dye on the cells was shown not to interfere with their ability to form day-8 and -12 spleen colonies in lethally irradiated mice. To study their in vivo homing behavior in detail, 10(4) labeled cells from a population enriched for CFU-S were injected intravenously into nonirradiated mice and into mice irradiated 3 hours previously. At 17, 41, and 65 hours after injection, the numbers of labeled cells per organ were quantified using the specialty developed flow cytometric fluorescence hypercompensation procedure for the detection of rare events, which allows a detection sensitivity of 1 per 10(6). Spleen homing in irradiated and nonirradiated mice was virtually identical, whereas homing to nonirradiated bone marrow was 2.5 times higher than to irradiated bone marrow. This indicates a different homing mechanism for spleen and bone marrow. The results of this direct homing assay were placed in perspective with results of indirect homing studies from the literature, introducing a new "h-factor." From the CFU-S data, putative specific enrichment factors for spleen-specific and bone marrow-specific homing were derived. Examination of the fluorescence intensity distribution among the labeled cell population indicated that virtually all cells started to proliferate rapidly after injection into both irradiated and nonirradiated animals. This indicates that specific signals from stromal elements in the stem cell niches are needed to keep the cells quiescent and that the majority of the transplanted stem cells do not home to such niches. The potential use of PKH-26 for in vivo characterization of stem cell niches is discussed.

Construction and expression of an adenosine deaminase::lacZ fusion gene.

A eukaryotic expression vector was constructed in which the coding nucleotide sequences (ADA) of human adenosine deaminase (ADA) were fused in frame with the coding sequences of the bacterial gene lacZ encoding beta-galactosidase (beta Gal). This ADA::lacZ fusion gene was anticipated to encode a hybrid protein that has retained the biological functions of both proteins. Transfection of mammalian cells with the fusion gene resulted in the synthesis of both ADA and beta Gal. Cells expressing the gene could therefore be detected with the histochemical staining procedure that relies on the conversion of the indicator, XGal, by beta Gal. In addition, the transfected cells could be sorted on a fluorescence-activated cell sorter with the use of a vital staining procedure described for the selection of beta Gal-producing cells. Cell lines that harbored the fusion gene were tested for ADA overexpression by exposing them to the cytotoxic adenosine analog 9-beta-D-xylofuranosyl adenine (Xyl-A), in the presence of the ADA inhibitor deoxycoformycin (dCF). Resistance to Xyl-A/dCF was observed in the lines carrying ADA::lacZ and moreover, the fraction of cells that survived a stringent selection for ADA overexpression also exhibited significantly increased levels of beta Gal, which confirmed the direct linkage between ADA and lacZ expression. The use of this and other fusion genes might be useful in the development of gene-therapy protocols where they could help to meet the demand for versatile methods to detect and select cells with newly introduced genes.