Examples of recent emergences of arthropod-borne diseases in europe: Bluetongue and Schmallenberg. Case of african horse sickness for the equine industry

Up to 1998, Bluetongue (BT) was regarded as an exotic disease in Europe. In 2006 and 2007, its unexpected spread in Northern Europe has underlined the emergence potential of vector-borne diseases. Impressively, since 2008, nine BT virus serotypes (out of 26 currently described) have been reported in Europe. African Horse Sickness (AHS) is an arthropod-borne disease which only affects the Equidae but which shares many similarities with BT: similar endemic zones in Africa, structure, transmission routes, preventive and control methods, identical or comparable insect vectors (Culicoides). Moreover, at the end of 2011, a novel orthobunyavirus (the Schmallenberg virus – or SBV –), also transmitted by Culicoides midges, was identified in Germany and subsequently spread to all Europe. This paper will describe the analogies between BT, SBV disease and AHS and considering the experience gained through BT and SBV epizootics in Europe, will underline the prevention methods, the strengths and weaknesses of the European systems in facing the probable reemergence of AHS in Europe or France.Jusqu’en 1998, en Europe, la fièvre catarrhale ovine (FCO, Bluetongue ou BT) était considérée comme une maladie exotique. En 2006 et 2007, son explosion inattendue dans le nord de l’Europe a fourni un éclairage nouveau sur les capacités d’émergence et d’extension des maladies vectorielles. Depuis la fin de 2008, neuf sérotypes (sur les 26 décrits) circulent ou auront circulé en Europe. La peste équine (PE) est une arbovirose qui affecte les seuls équidés mais qui présente de nombreuses analogies avec la FCO ; berceau de la maladie, structure, méthodes de lutte et de prévention similaires à ceux de la FCO, mode de transmission identique, insecte vecteur (Culicoides) identique ou proche. Par ailleurs, fin 2011, un nouvel orthobunyavirus (le virus Schmallenberg – SBV –), également transmis par des Culicoides, a été identifié en Allemagne. Ce virus s’est ensuite répandu dans toute l’Europe. Cet article présente les analogies entre FCO, SBV et PE et décrit, à la lumière de l’expérience acquise sur la FCO et sur SBV, les menaces, les méthodes de prévention, les forces et les faiblesses des systèmes européens et nationaux face à une réémergence probable de la peste équine en Europe ou en France

West Nile virus: diagnosis, surveillance and epidemiology in Europe

West Nile virus is an arbovirus affecting horses and humans, highly susceptible incidental and deadend hosts. Its presence in Europe is not new, as West Nile virus infections were first reported in the 1960’s: at the time, human and equine cases had already been described in France in the Camargue region. After 30 years without any reported outbreak, West Nile virus re-emerged in Europe at the end of the 90’s with limited (Czech Republic 1997, Italy 1998, France 2000) or large-scale sporadic outbreaks (Romania 1996, Russia 1999). More recently, a resurgence of WNV has been observed since 2008, probably related to changes in the multiple viral strains present in Europe, and in ecological and climatic conditions favourable to the multiplication of vector mosquitoes. This resurgence peaked in 2010, with unprecedented numbers of equine outbreaks and human cases in numerous countries in Europe, particularly in the Mediterranean basin: 8 countries (Bulgaria, Spain, Greece, Hungary, Italy, Portugal, Romania and Russia) were affected, with large-scale foci in Greece and Russia. Even though an equine vaccine is available in Europe since 2009, the control of West Nile Virus infection still relies heavily on reinforced surveillance of neurological conditions in humans and horses.Le virus West Nile est un arbovirus pouvant infecter le cheval et l'Homme, hôtes accidentels sensibles et culs-de-sac épidémiologiques. Sa présence en Europe est ancienne, puisque les premiers rapports d'infection par le virus West Nile datent des années 1960: à cette époque, des cas équins et humains avaient déjà été décrits en France dans la région de la Camargue. Après un long silence de plus de 30 ans, le virus West Nile a réémergé en Europe à la fin des années 1990, causant des foyers sporadiques d'ampleur limitée (République Tchèque 1997, Italie 1998, France 2000) à importante (Roumanie 1996, Russie 1999). Plus récemment, un regain d'activité du virus West Nile a été observé à partir de 2008, probablement dû à une évolution des multiples souches virales présentes en Europe, ainsi qu'à des conditions écologiques et climatiques favorables à la multiplication des moustiques vecteurs. Il a culminé, en 2010, avec une flambée d'épizooties équines et de cas humains sans précédent dans plusieurs pays européens, notamment du pourtour méditerranéen: huit pays (Bulgarie, Espagne, Grèce, Hongrie, Italie, Portugal, Roumanie et Russie) ont été touchés, avec des foyers d'ampleur considérable en Grèce et en Russie. Dans ce contexte européen en pleine évolution, et même si un vaccin est disponible pour l'espèce équine en Europe depuis 2009, la lutte contre l'infection par le virus West Nile continue de reposer sur une surveillance renforcée des affections neurologiques chez l'homme et le cheval

Influence of water on the circulation of the West Nile Virus in horses in Southern France

International audienc

Le moustique, ennemi public n° 1 ?

The invasive presence of mosquitoes and their pathogens is changing our daily lives and challenging our lifestyles. Mosquitoes contribute to thousands of deaths worldwide each year by transmitting various parasites and viruses, responsible for diseases with well-known names: malaria, dengue, zika, chikungunya, etc. What is less well known, however, is that mosquitoes also contribute to the balance of ecosystems as a source of food for many species and help pollinate plants. Their great morphological, biological, ecological and genetic diversity must be well understood before solutions can be considered to better control their spread and outbreak, and thus control the transmission of pathogens. Faced with this rapidly evolving threat, innovative and concerted strategies to control these insects are being deployed in many countries. Aimed at a wide audience, but also at students and their teachers, this book, illustrated with numerous examples, is a synthesis of knowledge on mosquitoes and current control methods

Identification of hotspots in the European Union for the introduction of four zoonotic arboviroses by live animal trade

Live animal trade is considered a major mode of introduction of viruses from enzootic foci into disease-free areas. Due to societal and behavioural changes, some wild animal species may nowadays be considered as pet species. The species diversity of animals involved in international trade is thus increasing. This could benefit pathogens that have a broad host range such as arboviruses. The objective of this study was to analyze the risk posed by live animal imports for the introduction, in the European Union (EU), of four arboviruses that affect human and horses: Eastern and Western equine encephalomyelitis, Venezuelan equine encephalitis and Japanese encephalitis. Importation data for a five-years period (2005-2009, extracted from the EU TRACES database), environmental data (used as a proxy for the presence of vectors) and horses and human population density data (impacting the occurrence of clinical cases) were combined to derive spatially explicit risk indicators for virus introduction and for the potential consequences of such introductions. Results showed the existence of hotspots where the introduction risk was the highest in Belgium, in the Netherlands and in the north of Italy. This risk was higher for Eastern equine encephalomyelitis (EEE) than for the three other diseases. It was mainly attributed to exotic pet species such as rodents, reptiles or cage birds, imported in small-sized containments from a wide variety of geographic origins. The increasing species and origin diversity of these animals may have in the future a strong impact on the risk of introduction of arboviruses in the EU. (Résumé d'auteur

Protective efficacy of multivalent replication-abortive vaccine strains in horses against African horse sickness virus challenge.

African horse sickness virus (AHSV) is an orbivirus, a member of the Reoviridae family. Nine different serotypes have been described so far. AHSV is vectored by Culicoides spp. to equids, causing high mortality, particularly in horses, with considerable economic impacts. For development of a safe attenuated vaccine, we previously established an efficient reverse genetics (RG) system to generate Entry Competent Replication-Abortive (ECRA) virus strains, for all nine serotypes and demonstrated the vaccine potential of these strains in type I interferon receptor (IFNAR)-knockout mice. Here, we evaluated the protective efficacies of these ECRA viruses in AHSV natural hosts. One monoserotype (ECRA.A4) vaccine and one multivalent cocktail (ECRA.A1/4/6/8) vaccine were tested in ponies and subsequently challenged with a virulent AHSV4. In contrast to control animals, all vaccinated ponies were protected and did not develop severe clinical symptoms of AHS. Furthermore, the multivalent cocktail vaccinated ponies produced neutralizing antibodies against all serotypes present in the cocktail, and a foal born during the trial was healthy and had no viremia. These results validate the suitability of these ECRA strains as a new generation of vaccines for AHSV

Unexpected progression of two arboviral diseases : West Nile fever and bluetongue

This paper describes the spread of two arboviral diseases in Europe, and the control measures implemented by health authorities. Bluetongue, which affects only animals, occurred for the first time in Europe in 1998, and West Nile Fever, which affects horses and humans, re-emerged in 1996. Up until 1998, bluetongue was considered as an exotic disease. In 2006 and 2007, its unexpected explosion in Northern Europe highlighted the emergence and expansion capacities of vector-borne diseases. Surprisingly, the disease became perennial in Europe, rapidly spreading to eight European countries and crossing the English Channel and contaminating several herds in England. Its expansion resulted from vector movements carried over long distances by the wind (100 km), and followed a centrifugal pattern in 2006/2007. By 2008, the bluetongue virus (BTV) was occupying a wider European territory. The only control measure available is vaccination, which has been largely implemented in 2008. West Nile fever is a viral disease transmitted by mosquitoes, whose amplifying hosts are birds, whereas horses and humans are incidental but particularly sensitive hosts. West Nile fever appeared in Europe in the 60’s and 70’s, especially in the Camargue region of France, with sporadic foci. At the end of the 90’s, besides the introduction and expansion of the virus on the American continent, major epidemics affected several hundreds of people in Europe (Romania in 1996 and Russia in 1999). Since then, four distinct episodes of West Nile virus (WNV) circulation, associated with clinical cases in horses, were reported in France: in the Camargue region in 2000 and 2004, in the Var department in 2003 and in the Eastern Pyrenees in 2006. An increase in WNV activity was observed in Europe in 2008, with cases of infection reported in Italy, Romania, Hungary and Austria. An inactivated vaccine (Fort Dodge) has recently received a marketing agreement from the European commission. However, until now, control measures rely exclusively on a reinforced surveillance of neurological conditions in humans and animals (horses and birds generally), and on information of exposed people.Cet article décrit l'extension de deux arboviroses en Europe ainsi que les mesures de lutte mises en oeuvre par les autorités sanitaires. La fièvre catarrhale ovine (FCO), strictement animale, est apparue pour la première fois en Europe en 1998, tandis que la fièvre du Nil occidental, transmissible à l'homme, a ré-émergé en 1996. Jusqu'en 1998, la FCO était considérée comme une maladie exotique. En 2006 et 2007, son explosion inattendue dans le nord de l'Europe a fourni un éclairage nouveau sur les capacités d'émergence et d'extension des maladies vectorielles. De façon surprenante, la maladie s'est installée de façon pérenne en Europe gagnant rapidement huit pays européens et traversant la Manche pour contaminer plusieurs élevages en Angleterre. Son extension résulte du déplacement du vecteur porté par le vent sur de grandes distances (100 km), et a donc été centrifuge en 2006/7. L'année 2008 confirme cette extension et l'installation du virus sur un territoire européen élargi. La seule méthode de lutte est la vaccination mise en oeuvre de façon massive en 2008. La fièvre du Nil occidental, ou West Nile Fever, est une virose transmise par les moustiques dont les hôtes amplificateurs sont les oiseaux, tandis que le cheval et l'homme sont des hôtes accidentels particulièrement sensibles. Elle était apparue en Europe dans les années 1960-1970 et, en particulier, en France métropolitaine dans la région de la Camargue, en des foyers sporadiques. À la fin des années 1990, outre l'introduction et la progression du virus sur le continent américain, des épidémies importantes ont touché plusieurs centaines de personnes en Europe (Roumanie en 1996, Russie en 1999). Puis, quatre épisodes distincts de circulation du virus West Nile (VWN), associés à des cas cliniques chez le cheval, ont été décrits en France: en Camargue, en 2000 et 2004, dans le Var en 2003 et dans les Pyrénées-Orientales en 2006. Un regain de l'activité du virus a été observé en 2008 en Europe, l'Italie, la Roumanie, la Hongrie et l'Autriche ayant rapporté des cas d'infection par le VWN. Un vaccin inactivé (Fort Dodge) a récemment obtenu une AMM européenne. Cependant, jusqu'ici, les méthodes de lutte s'appuient jusqu'ci sur la surveillance renforcée des affections nerveuses chez l'homme et l'animal (chevaux et oiseaux généralement) et sur l'information des personnes exposées