First Serological Evidence of West Nile Virus in Horses and Dogs from Corsica Island, France.

West Nile virus (WNV) is widely distributed over the world, including Europe, Africa, and Asia and spread over the past two decades to North and South America. In the south of France, sporadic cases are frequently described and the virus is endemic in Italy with frequent cases and outbreaks. The aim of this study was to identify a possible WNV circulation in Corsica (French island in the Mediterranean Sea) in sheep, horses, and dogs as sentinel animals for the virus surveillance. In 2014, 386 blood samples were collected from 219 sheep, 96 horses, and 71 dogs, in 12 localities in Corsica, in the oriental coast of Corsica. Each sample was systematically tested for WNV immunoglobulin G using an in-house enzyme-linked immunosorbent assay (ELISA) with inactivated WNV as antigen. The result of the ELISA for the WNV antibody test on the sheep sera was all negative, whereas 9 of 96 horses (9.4%) and 6 of 71 dogs (8.4%) presented WNV antibodies. All the positive samples from horses and dogs were confirmed by serum neutralization test. Although no clinical case in humans and horses was reported to date, this report highlights the necessity to improve WNV surveillance in animals and humans, as well as in blood donors in Corsica.