Title : Insights into West Nile Virus Seroprevalence in wild birds and equines: A focus on Madrid Province, Spain
Abstract:
West Nile virus (WNV), classified under the Orthoflavivirus genus and Flaviviridae family, is a reemerging flavivirus perpetuated in an enzootic cycle between avian hosts and mosquito vectors. Periodic outbreaks of WNV in humans and horses can result in neuroinvasive disease and fatalities. Spain, particularly Andalusia, Extremadura, and Catalonia, has experienced numerous WNV outbreaks. In 2020, an outbreak in Andalusia and Extremadura reported seventy-seven human cases, including eight fatalities. WNV seropositivity has been identified in horses in the Community of Madrid, but, to the best of our knowledge, wild bird transmission remains unreported in this region. To assess WNV seroprevalence, wild birds from a wildlife rescue center and privately owned equines were sampled. Results showed thirteen birds (8.2%) and one equine (4.0%) positive using a WNV competitive Enzyme-Linked Immunosorbent Assay (cELISA). Four avian samples (2.5%) and one equine (4.0%) were confirmed positive for specific WNV antibodies through microneutralization testing (VNT). Positive birds comprised both migratory and resident species, including juveniles and adults. The presence of seropositive resident and juvenile birds, particularly a nestling and a fledgling, suggests local flavivirus transmission within Madrid. The potential circulation of flaviviruses, including WNV, within Madrid Community raises concerns, necessitating further surveillance in mosquitos, wild birds, and horses.
