Low West Nile virus circulation in wild birds in an area of recurring outbreaks in Southern France

• Published in: Vector borne and zoonotic diseases (Larchmont, N.Y.) Vol. 9; no. 6; p. 737
• Main Authors: Balança, Gilles, Gaidet, Nicolas, Savini, Giovanni, Vollot, Benjamin, Foucart, Antoine, Reiter, Paul, Boutonnier, Alain, Lelli, Rossella, Monicat, François
• Format: Journal Article
• Language: English
• Published: United States 01.12.2009
• Subjects: Animals; Antibodies, Viral - blood; Bird Diseases - epidemiology; Bird Diseases - immunology; Birds - blood; Birds - immunology; Birds - virology; France - epidemiology; Neutralization Tests - veterinary; Seroepidemiologic Studies; West Nile Fever - epidemiology; West Nile Fever - veterinary; West Nile virus - immunology; France
• ISSN: 1557-7759
• DOI: 10.1089/vbz.2008.0147

West Nile virus (WNV) has a history of irregular but recurrent epizootics in countries of Mediterranean and of Central and Eastern Europe. We have investigated the temporal enzootic activity of WNV in free-ranging birds over a 3-year period in an area with sporadic occurrences of WNV outbreaks in Southern France. We conducted an intensive serologic survey on several wild bird populations (>4000 serum samples collected from 3300 birds) selected as potential indicators of the WNV circulation. WNV antibodies were detected by seroneutralization and/or plaque reduction neutralization in house sparrows, black-billed magpies, and scops owls, but these species appeared to be insufficient indicators of WNV circulation. Overall seroprevalence was low (<1%), including in birds that had been potentially exposed to the virus during recent outbreaks. However, the detection of a seroconversion in one bird, as well as the detection of seropositive birds in all years of our monitoring, including juveniles, indicate a constant annual circulation of WNV at a low level, including in years without any detectable emergence of WN fever in horses or humans.