African horse sickness

African horse sickness (AHS) is a devastating disease of equids caused by an arthropod-borne virus belonging to the Reoviridae family, genus Orbivirus. It is considered a major health threat for horses in endemic areas in sub-Saharan Africa. African horse sickness virus (AHSV) repeatedly caused large epizootics in the Mediterranean region (North Africa and southern Europe in particular) as a result of trade in infected equids. The unexpected emergence of a closely related virus, the bluetongue virus, in northern Europe in 2006 has raised fears about AHSV introduction into Europe, and more specifically into AHSV-free regions that have reported the presence of AHSV vectors, e.g. Culicoides midges. North African and European countries should be prepared to face AHSV incursions in the future, especially since two AHSV serotypes (serotypes 2 and 7) have recently spread northwards to western (e.g. Senegal, Nigeria, Gambia) and eastern Africa (Ethiopia), where historically only serotype 9 had been isolated. The authors review key elements of AHS epidemiology, surveillance and prophylaxis.La peste équine est une maladie extrêmement grave des équidés causée par un Orbivirus appartenant à la famille des Reoviridae. Le virus est transmis par des arthropodes. La maladie constitue une menace sanitaire majeure pour les équidés des régions endémiques de l’Afrique subsaharienne. Le virus de la peste équine est à l’origine de vastes épizooties récurrentes dans la région méditerranéenne (particulièrement au nord de l’Afrique et au sud de l’Europe), associées aux échanges internationaux d’équidés infectés. L’émergence inattendue du virus de la fièvre catarrhale ovine dans le nord de l’Europe en 2006, virus étroitement apparenté à celui de la peste équine, a suscité de grandes inquiétudes quant au risque d’introduction du virus de la peste équine en Europe et plus particulièrement dans les régions indemnes de cette maladie mais ayant rapporté la présence des vecteurs compétents pour le virus, notamment les moucherons du genre Culicoides. Les pays d’Afrique du Nord et d’Europe devraient se préparer à faire face à des incursions du virus de la peste équine à l’avenir, en particulier depuis la récente propagation de deux sérotypes du virus (les sérotypes 2 et 7) en direction du nord, aussi bien en Afrique occidentale (Sénégal, Nigeria, Gambie...) qu’en Afrique orientale (Éthiopie), régions où par le passé seul le sérotype 9 avait été isolé. Les auteurs font le point sur les principaux éléments de l’épidémiologie, la surveillance et la prophylaxie de la peste équine.La peste equina es una devastadora enfermedad de los équidos cuyo agente etiológico es un virus transmitido por artrópodos del género Orbivirus, familia Reoviridae. Esá considerada una importante amenaza sanitaria para los caballos de las zonas del África subsahariana en las que es endémica. En repetidas ocasiones, las operaciones comerciales con équidos infectados por el virus han causado grandes epizootias en la región del Mediterráneo (norte de África y sur de Europa en particular). Desde 2006, cuando en el norte de Europa apareció inesperadamente el virus de la lengua azul, estrechamente emparentado con el de la peste equina, existe el temor de que este último penetre en Europa, y más concretamente en regiones hasta ahora exentas de él donde está descrita la presencia de vectores como los jejenes Culicoides. Los países norteafricanos y europeos deben estar preparados para responder en el futuro a incursiones del virus de la peste equina, máxime cuando dos de sus serotipos (el 2 y el 7) se han propagado en fechas recientes hacia el norte hasta alcanzar el África Occidental (Senegal, Nigeria, Gambia...) y Oriental (Etiopía), zonas donde hasta entonces solo se había aislado el serotipo 9. Los autores pasan revista a los principales aspectos de la epidemiología, vigilancia y profilaxis de la enfermedad.http://www.oie.int/en/publications-and-documentation/scientific-and-technical-review-free-accessam201

Are tree squirrels involved in the circulation of flaviviruses in Italy?

West Nile virus (WNV), Usutu virus (USUV) and tick-borne encephalitis virus (TBEV) are emerging zoonotic flaviviruses (family Flaviviridae), which have circulated in Europe in the past decade. A cross-sectional study was conducted to assess exposure to these antigenically related flaviviruses in eastern grey squirrels (Sciurus carolinensis) in Italy. Seventeen out of 158 (10.8%; CI95%: 5.9-15.6) squirrels' sera tested through bELISA had antibodies against flaviviruses. Specific neutralizing antibodies to WNV, USUV and TBEV were detected by virus neutralization tests. Our results indicate that tree squirrels are exposed to Culex and tick-borne zoonotic flaviviruses in Italy. Moreover, this study shows for the first time USUV and TBEV exposure in grey squirrels, broadening the host range reported for these viruses. Even though further studies are needed to define the real role of tree squirrels in the epidemiology of flaviviruses in Europe, this study highlights that serology could be an effective approach for future investigations aimed at broadening our knowledge about the species exposed to these zoonotic infections

Dendritic Cell-Mediated-Immunization with Xenogenic PrP and Adenoviral Vectors Breaks Tolerance and Prolongs Mice Survival against Experimental Scrapie

In prion diseases, PrPc, a widely expressed protein, is transformed into a pathogenic form called PrPSc, which is in itself infectious. Antibodies directed against PrPc have been shown to inhibit PrPc to PrPSc conversion in vitro and protect in vivo from disease. Other effectors with potential to eliminate PrPSc-producing cells are cytotoxic T cells directed against PrP-derived peptides but their ability to protect or to induce deleterious autoimmune reactions is not known. The natural tolerance to PrPc makes difficult to raise efficient adaptive responses. To break tolerance, adenovirus (Ad) encoding human PrP (hPrP) or control Ad were administered to wild-type mice by direct injection or by transfer of Ad-transduced dendritic cells (DCs). Control Ad-transduced DCs from Tg650 mice overexpressing hPrP were also used for immunization. DC-mediated but not direct administration of AdhPrP elicited antibodies that bound to murine native PrPc. Frequencies of PrP-specific IFNγ-secreting T cells were low and in vivo lytic activity only targeted cells strongly expressing hPrP. Immunohistochemical analysis revealed that CD3+ T cell infiltration was similar in the brain of vaccinated and unvaccinated 139A-infected mice suggesting the absence of autoimmune reactions. Early splenic PrPSc replication was strongly inhibited ten weeks post infection and mean survival time prolonged from 209 days in untreated 139A-infected mice to 246 days in mice vaccinated with DCs expressing the hPrP. The efficacy appeared to be associated with antibody but not with cytotoxic cell-mediated PrP-specific responses

Nile virus epidemiology and factors triggering change in its distribution

Summary West Nile virus (WNV) has historically been considered among the least virulent members of the Japanese serogroup complex (family Flaviviridae, genus Flavivirus). The WNV natural cycle involves birds as the main amplifying hosts and several species of mosquito as vectors. Many outbreaks occurred during the past decade, causing severe human encephalitis in the Old World, and the virus has become established in many European countries. Emergence of WNV is difficult to predict and even more difficult to prevent. In this review, the latest information on the epidemiology, transmission dynamics and clinical aspects of WNV is presented, with particular focus on specific factors likely to trigger changes in the distribution of the disease in Europe, such as climate changes and their consequences on the potential vectors of WNV or bird migration routes. The control of some anthropogenic and environmental factors could help prevent extension and re-emergence of WNV epidemics

Clinical screening of horses and early warning for West Nile virus

Clinical screening of horses and early warning for West Nile viru

Arboviroses émergentes : fièvre West Nile, fièvre catarrhale ovine et virus Schmallenberg

International audienceThe increase in international trade over the last thirty years, climate change owing to the industrial revolution, disruption of ecosystems, etc. are some of the factors that may explain the dynamics of disease emergence in regions of the world where they were not present. Thus in 1999, West Nile virus was introduced on the American continent where it spread at high speed. More than 2300 deaths and more than 25,000 neuroinvasive forms were recorded in humans from 1999 to 2019 in the United States of America. In the field of animal diseases, two viruses have made headlines in Europe: bluetongue virus (BTV) and Schmallenberg virus (SBV). The bluetongue virus, previously absent from Europe, was introduced in 1999. Numerous serotypes (1, 2, 4, 6, 8, 9, 25, 27) have since been identified in the European Union. Schmallenberg virus was identified in 2011 in Northern Germany and rapidly spread to other European countries. This virus had never been identified in the world before. These three viruses (WNV, BTV and SBV) are transmitted by arthropod vectors (mosquitoes and Culicoldes). These emergences are a good illustration of the challenges that our countries will face in the coming years, in public, human and veterinary health. (C) 2020 l'Acadernie nationale de medecine. Published by Elsevier Masson SAS. All rights reserved