Le virus West Nile: diagnostic, surveillance et évolution épidémiologique en Europe

Abstract

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.

Clinical Sentinel Surveillance of Equine West Nile Fever, Spain

“…Horses as non-human vertebrate hosts are particularly sensitive to WNV, and among clinically affected horses, approximately 10% present neurological disorders compared with 1% of humans (Petersen and Roehrig, 2001;Leblond et al, 2007), rendering its detection in equids highly pertinent in a public health perspective. The incubation period for WNV in horses appears to be between 3 and 15 days (Lecollinet et al, 2012).…”