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Revue scientifique et technique (International Office of Epizootics)2016; 35(3); 811-824; doi: 10.20506/rst.35.3.2571

West Nile virus epizootics in the Camargue (France) in 2015 and reinforcement of surveillance and control networks.

Abstract: West Nile virus (WNV) infection is a non-contagious disease mainly transmitted by the bites of infected mosquitoes from the genus Culex. The virus is maintained in a mosquito-bird-mosquito cycle, and can accidentally be transmitted to mammalian hosts. Among mammalian hosts, equines and humans are the most sensitive to WNV infection and can develop severe meningoencephalitis. As WNV infections are zoonotic and can be severe in humans and equines, West Nile fever is considered to be a public and animal health concern. After a silent period of almost ten years, WNV re-emerged in France at the periphery of the Camargue area during the summer of 2015, underlining the fact that the Camargue area creates favourable conditions for WNV emergence and amplification in France. The French Network for Epidemiological Surveillance of Equine Diseases (Réseau d'Épidémio-Surveillance en Pathologie Équine [RESPE]) facilitated the early detection of WNV cases in horses. In total, 49 horses were found to be infected; among them, 44 presented clinical signs, 41 with meningoencephalitis and three with hyperthermia only. Six horses among the 41 with nervous symptoms died from the disease or were euthanised (a case fatality rate of 14.6%). The authors describe the characteristics of the 2015 WNV epizootics, the early detection of the first WNV equine cases via the RESPE network and the coordination of WNV surveillance in France. L’infection par le virus de West Nile est une maladie non contagieuse essentiellement transmise lors de piqûres de moustiques infectés appartenant au genre Culex ; le virus se maintient dans la nature au moyen d’un cycle moustique– oiseau–moustique ; la transmission à des hôtes mammifères a lieu de manière accidentelle. Parmi les mammifères hôtes, les plus sensibles à l’infection par le virus de West Nile sont les équidés et l’homme, chez qui l’infection peut se manifester sous forme d’une méningo-encéphalite sévère. Les infections par le virus de West Nile étant des zoonoses potentiellement graves chez l’homme et chez les équidés, la fièvre de West Nile doit être considérée comme une priorité de santé publique et animale. Resté silencieux pendant plus d’une décennie, le virus de West Nile est réapparu en France à l’été 2015 en bordure de la Camargue, confirmant que les conditions de cette région sont favorables à l’émergence et à l’amplification du virus. Le réseau français d’épidémiosurveillance en pathologie équine (RESPE) a contribué à la détection précoce du virus de West Nile chez les chevaux. Au total, 49 chevaux étaient infectés, parmi lesquels 44 présentaient des signes cliniques, correspondant à une méningo-encéphalite pour 41 d’entre eux et à une hyperthermie seule pour les trois autres. Six chevaux parmi les 41 qui présentaient des signes neurologiques ont succombé à la maladie ou ont été euthanasiés (taux de létalité de 14,6 %). Les auteurs de cet article décrivent les principales caractéristiques de l’épizootie de 2015 due au virus de West Nile ainsi que la détection précoce des premiers cas équins grâce au réseau RESPE et la coordination des activités de surveillance du virus en France. La infección por el virus West Nile es una enfermedad no contagiosa que se transmite básicamente por la picadura de mosquitos infectados del género Culex. El virus, que se instala en un ciclo mosquito–ave–mosquito, también puede transmitirse accidentalmente a mamíferos, de entre los cuales los más sensibles a la infección son los equinos y el ser humano, que pueden contraer graves meningoencefalitis. Puesto que las infecciones por este virus son zoonóticas y pueden revestir gravedad en personas y equinos, se considera que la fiebre West Nile es una enfermedad de importancia sanitaria y zoosanitaria. En Francia, tras un periodo silente de más de diez años, el virus reapareció en verano de 2015 en la periferia de la zona de la Camarga, poniendo así de manifiesto que esta zona genera condiciones propicias al surgimiento y la amplificación del virus en el país. La red francesa de vigilancia epidemiológica de patologías equinas (Réseau d’Épidémio-Surveillance en Pathologie Équine: RESPE]) facilitó la rápida detección de caballos infectados por el virus West Nile. Se detectaron en total 49 animales infectados, entre ellos 44 con signos clínicos, de los que 41 sufrían meningoencefalitis y tres solo presentaban hipertermia. Seis de los 41 caballos que mostraban signos neurológicos murieron a causa de la enfermedad o fueron sacrificados con métodos de eutanasia (lo que supone una tasa de letalidad del 14,6%). Los autores describen las principales características de la epizootia causada por el virus West Nile en 2015, la pronta detección de los primeros casos de caballos infectados gracias a la red RESPE y la coordinación de las labores de vigilancia del virus en Francia.
© OIE (World Organisation for Animal Health), 2016.
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Publication Date: 2016-01-01 PubMed ID: 28332648DOI: 10.20506/rst.35.3.2571Google Scholar: Lookup
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Summary

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The research deals with the re-emergence of the West Nile virus (WNV), a mosquito-borne disease, in the Camargue area of France in 2015. This event triggered surveillance and control efforts, leading to the detection of 49 cases in horses, some of which developed severe nervous system diseases. The study offers insights into the disease’s characteristics, spread mechanism, and the surveillance activities in France.

Understanding West Nile Virus

  • The West Nile virus (WNV) is a non-contagious disease predominantly transferred through the bites of Culex mosquitoes infected with the virus. The WNV maintains its existence through a cycle that involves mosquitoes and birds.
  • The virus can inadvertently be transmitted to mammalian hosts, including humans and equines (horses, donkeys etc). Among these mammals, equines and humans are the most vulnerable to the infection.
  • WNV infections can lead to severe meningoencephalitis, a condition characterized by inflammation of the brain and its surrounding membranes, in both humans and equine species.
  • Considering the severity and zoonotic nature of this disease (a zoonotic disease is one that can be passed from animals to humans), West Nile fever poses a significant public and animal health concern.

West Nile Virus in France

  • After an unnoticed duration of roughly ten years, WNV resurfaced in France around the Camargue region during the summer of 2015. This area provides favourable conditions for WNV to emerge and proliferate.
  • The RESPE (Réseau d’Épidémio-Surveillance en Pathologie Équine), the French Network for Epidemiological Surveillance of Equine Diseases, played a crucial role in early detection of WNV cases in horses.
  • A total of 49 horses were found to be infected, with 44 exhibiting clinical signs. Forty-one had developed meningoencephalitis while only three showed hyperthermia (high body temperature).
  • Out of the 41 horses with nervous symptoms, six died or were euthanized resulting in a case fatality rate of 14.6%.

Surveillance and Control of West Nile Virus

  • The research thoroughly discusses the 2015 WNV epizootics (disease outbreaks in animal populations), the methodology through which the first cases were detected among equines via the RESPE network, and the overall coordination of WNV surveillance in France.
  • These findings underscore the importance of robust surveillance systems in identifying and managing the spread of zoonotic diseases like WNV, which pose significant threats to both human and animal health.

Cite This Article

APA
Bahuon C, Marcillaud-Pitel C, Bournez L, Leblond A, Beck C, Hars J, Leparc-Goffart I, L'Ambert G, Paty MC, Cavalerie L, Daix C, Tritz P, Durand B, Zientara S, Lecollinet S. (2016). West Nile virus epizootics in the Camargue (France) in 2015 and reinforcement of surveillance and control networks. Rev Sci Tech, 35(3), 811-824. https://doi.org/10.20506/rst.35.3.2571

Publication

Revue scientifique et technique (International Office of Epizootics)
ISSN: 0253-1933
NlmUniqueID: 8712301
Country: France
Language: English
Volume: 35
Issue: 3
Pages: 811-824

Researcher Affiliations

Bahuon, C
    Marcillaud-Pitel, C
      Bournez, L
        Leblond, A
          Beck, C
            Hars, J
              Leparc-Goffart, I
                L'Ambert, G
                  Paty, M-C
                    Cavalerie, L
                      Daix, C
                        Tritz, P
                          Durand, B
                            Zientara, S
                              Lecollinet, S

                                MeSH Terms

                                • Animals
                                • Animals, Wild
                                • Antibodies, Viral / blood
                                • Birds
                                • Communicable Diseases, Emerging / epidemiology
                                • Communicable Diseases, Emerging / prevention & control
                                • Communicable Diseases, Emerging / transmission
                                • Culex / virology
                                • Epidemics / prevention & control
                                • Epidemics / veterinary
                                • Epidemiological Monitoring / veterinary
                                • France / epidemiology
                                • Horse Diseases / epidemiology
                                • Horse Diseases / prevention & control
                                • Horse Diseases / virology
                                • Horses
                                • Humans
                                • Mosquito Vectors / virology
                                • Sentinel Surveillance / veterinary
                                • West Nile Fever / epidemiology
                                • West Nile Fever / prevention & control
                                • West Nile Fever / transmission
                                • West Nile virus / genetics
                                • West Nile virus / immunology

                                Citations

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