Seroprevalence and incidence of Puumala orthohantavirus in its bank vole (Myodes glareolus) host population in northeastern France: Between-site and seasonal variability.

Given the difficulty of measuring pathogen transmission in wildlife, epidemiological studies frequently rely on cross-sectional seroprevalence. However, seropositivity indicates only exposure to a pathogen at an unknown time. By allowing to obtain repeated test results from individuals sampled multiple times over an extended period, longitudinal data help reduce this uncertainty. We used capture-mark-recapture data on bank vole (Myodes glareolus) individuals collected at four sites over ten years in northeastern France to investigate the impact of environmental variables on seroprevalence and incidence of Puumala orthohantavirus (PUUV). PUUV causes a chronic infection without apparent symptoms, that may however impair survival of its rodent host in the wild. Viral transmission between rodents may occur through direct contact or via the environment. Principal component analysis was used to deal with multicollinearity among environmental variables. Incidence and seroprevalence were investigated with either generalized estimating equations or Poisson regression models depending on the number of observations for each season. In spring, only the factor site was found to be significant for seroprevalence, while a principal component including meteorological conditions of the previous winter and the normalized difference vegetation index (NDVI) of both the previous winter and spring had a significant effect on incidence. In autumn, only the factor site was significant for incidence, while two principal components, including either the meteorological conditions of the autumn and previous spring or NDVI of the autumn significantly affected seroprevalence. We discuss these results in light of the particular demography of small mammals. We encourage other researchers to investigate the relationships between demographic parameters of wild host populations and the environment, by using both incidence and seroprevalence.

First insights into Puumala orthohantavirus circulation in a rodent population in Alsace, France.

In-depth knowledge on the mechanisms that maintain infection by a zoonotic pathogen in an animal reservoir is the key to predicting and preventing transmission to humans. The Puumala orthohantavirus (PUUV), the most prevalent orthohantavirus in Western Europe, causes a mild form of haemorrhagic fever with renal syndrome (HFRS) in humans. In France, this endemic illness affects the north-eastern part of the country. We conducted a 4-year capture-mark-recapture study in a bank vole population, combined with molecular analyses, to explore the epidemiological situation of PUUV in Alsace, a French region where human cases have occurred, but for which no studies have been conducted on this reservoir host. PUUV-infected bank voles were detected in the 2 years that showed high bank vole density with a prevalence of 4%. The individual PUUV sequences identified in this study were similar from year to year and similar to other French sequences. On a very small spatial scale, the distribution of seropositive bank voles was very heterogeneous in time and space. The short distances travelled on average by bank voles resulted in spatial clusters of seropositive rodents, which spread only very gradually throughout the year.

Review of bovine brucellosis surveillance in Europe in 2015.

Bovine brucellosis is a major zoonosis and is responsible for significant reproductive disorders and production losses in cattle. Surveillance and control are regulated at the European level with specific conditions to obtain and maintain the officially free status, which facilitates access to export markets. These European standards allow for harmonisation in brucellosis surveillance and diagnosis while leaving some flexibility to countries in the choice of measures to meet the desired objectives. This study reviews the bovine brucellosis surveillancesystems currently in place across the European continent, according to countries' brucellosis status, based on a survey addressed to brucellosis diagnosis expertsin the National Reference Laboratory of each country. Experts were asked toprovide synthesised surveillance data and to describe technical conditions andscreening tests carried out for the surveillance of abortions, serological testing inherds, movement controls and any other surveillance components in 2015. Results were obtained for 34 out of 37 countries (92%). Surveillance systems included abortion surveillance (34 countries), routine herd screening (28 countries), movement testing (14 countries), routine testing at bull stations (9 countries),and screening tests at slaughterhouses (4 countries). The review highlighted variability in technical conditions and screening tests among countries. These results are discussed with regard to the European Union regulations, disease risks and epidemiological situations, with the aim of improving surveillance efficacy and efficiency.

La brucellose bovine est une zoonose majeure qui entraîne chez les bovins de graves troubles de la reproduction ainsi qu'une baisse importante de la production. La surveillance et le contrôle de cette maladie font l'objet d'une réglementation spécifique au niveau européen, à travers des dispositions conditionnant l'obtention et le maintien du statut officiel indemne, lequel facilite l'accès aux marchés d'exportation. Les normes européennes permettent d'harmoniser la surveillance et le diagnostic de la brucellose tout en laissant aux pays une certaine marge de manoeuvre quant au choix des mesures appliquées pour atteindre les objectifs souhaités. En se basant sur les résultats d'une enquête conduite auprès des experts des Laboratoires de référence nationaux pour le diagnostic de la brucellose dans chaque pays, les auteurs font le point sur les systèmes de surveillance de la brucellose bovine appliqués actuellement en Europe en fonction du statut des pays au regard de la brucellose. Il a été demandé aux experts de présenter une synthèse des données de surveillance et de décrire le dispositif technique de suivi et les tests de dépistage effectués en cas d'avortement, ainsi que la surveillance sérologique conduite à l'échelle des troupeaux, les contrôles exercés sur les mouvements d'animaux et toute autre composante de la surveillance en 2015. Au total, 34 des 37 pays interrogés (92 %)ont répondu à l'enquête. Les systèmes de surveillance en place portaient sur les points suivants : surveillance des avortements (34 pays), dépistage systématique à l'échelle des troupeaux (28 pays), tests sur les animaux déplacés (14 pays), dépistage systématique dans les stations de monte et les taurelleries (neuf pays) et dépistage à l'abattoir (quatre pays). Les résultats de l'enquête mettent en relief la diversité du contexte technique et des tests de dépistage d'un pays à l'autre. Les auteurs analysent ces résultats au regard de la réglementation de l'Union européenne, des risques sanitaires spécifiques et des diverses situations épidémiologiques, dans le but d'améliorer l'efficacité et l'efficience de la surveillance.

La brucelosis bovina es una importante zoonosis, causante de graves trastornos reproductivos y de cuantiosas pérdidas en el sector de la producción pecuaria. En los reglamentos europeos, que rigen las actividades de vigilancia y control, se establecen también requisitos específicos para obtener y mantener el estatutode «oficialmente libre de la enfermedad¼, que facilita el acceso a los mercados de exportación. Estas normas europeas permiten armonizar las actividades devigilancia y diagnóstico de la brucelosis y ofrecer a la vez cierta flexibilidad alos países en la elección de las medidas necesarias para cumplir los objetivos fijados. Los autores pasan revista a los sistemas de vigilancia de la brucellosis bovina actualmente implantados en todo el continente europeo, en funcióndel estatuto del país con respecto a la enfermedad, utilizando para ello los datosde un cuestionario dirigido a los especialistas en diagnóstico de la brucelosis decada laboratorio nacional de referencia. A cada uno se le pedía una síntesis delos datos de vigilancia y una descripción (incluidas las condiciones técnicas) delas pruebas de detección realizadas con fines de vigilancia de abortos, análisis serológico de rebaños, controles en caso de movimiento de animales y demás componentes de la vigilancia que se hubieran aplicado en 2015. Se obtuvieron así datos de 34 países sobre un total de 37 (un 92%). Los sistemas de vigilancia descritos incluían la vigilancia de abortos (34 países), la realización sistemática de pruebas de detección en rebaños (28 países), en corrales de toros (nueve países) y en mataderos (cuatro países) y la realización de pruebas antes y/o después del movimiento de animales (14 países). El estudio puso de manifiesto la heterogeneidad reinante entre los países en cuanto a las pruebas de detección practicadas y a sus condiciones técnicas. Los autores examinan esos resultados en relación con las normas de la Unión Europea, los riesgos de enfermedad y las situaciones epidemiológicas, con el objetivo de conferir más eficacia y eficiencia a las labores de vigilancia.

Spatial and Temporal Epidemiology of Nephropathia Epidemica Incidence and Hantavirus Seroprevalence in Rodent Hosts: Identification of the Main Environmental Factors in Europe.

In Europe, the increasing number of nephropathia epidemica (NE) infections in humans, caused by Puumala virus carried by bank voles (Myodes glareolus), has triggered studies of environmental factors driving these infections. NE infections have been shown to occur in specific geographical areas characterized by environmental factors that influence the distribution and dynamics of host populations and virus persistence in the soil. Here, we review the influence of environmental conditions (including climate factors, food availability and habitat conditions) with respect to incidence in humans and seroprevalence in rodents, considering both direct and indirect transmission pathways. For each type of environmental factor, results and discrepancies between studies are presented and examined in the light of biological hypotheses. Overall, food availability and temperature appear to be the main drivers of host seroprevalence and NE incidence, but data quality and statistical approaches varied greatly among studies. We highlight the issues that now need to be addressed and suggest improvements for study design in regard to the current knowledge on hantavirus epidemiology.

Identifying Areas Suitable for the Occurrence of Rift Valley Fever in North Africa: Implications for Surveillance.

Rift Valley fever (RVF) is a vector-borne zoonotic disease that has caused widespread outbreaks throughout Africa and the Arabian Peninsula, with serious consequences for livestock-based economies and public health. Although there have never been any reports of RVF in Morocco, Algeria, Tunisia and Libya, it is a priority disease in the Maghreb, due to the threat of introduction of the virus through transboundary livestock movements or infected mosquito vectors. However, the implementation of surveillance activities and early warning contingency plans requires better knowledge of the epidemiological situation. We conducted a multicriteria decision analysis, integrating host distribution with a combination of important ecological factors that drive mosquito abundance, to identify hotspots and suitable time periods for RVF enzootic circulation (i.e. stable transmission at a low to moderate level for an extended period of time) and an RVF epizootic event (i.e. a sudden occurrence of a large number of infected animals over a large geographic area) in the Maghreb. We also modelled vector species distribution using available information on vector presence and habitat preference. We found that the northern regions of the Maghreb were moderately suitable for RVF enzootics, but highly suitable for RVF epizootics. The vector species distribution model identified these regions as the most favourable mosquito habitats. Due to the low density of animal hosts and arid conditions, the desert region showed low RVF suitability, except in oases. However, the presence of competent vectors in putative unsuitable areas underlines the need for further assessments of mosquito habitat preference. This study produced monthly RVF suitability maps useful for animal health managers and veterinary services involved in designing risk-based surveillance programmes. The suitability maps can be further enhanced using existing country-specific sources of information and by incorporating knowledge - as it becomes available - on the epidemiology of the disease and distribution of vectors in the Maghreb.