Serosurvey of West Nile Virus and Other Flaviviruses of the Japanese Encephalitis Antigenic Complex in Birds from Andalusia, Southern Spain

Abstract

Flaviviruses of the Japanese encephalitis virus (JEV) antigenic complex, including West Nile virus (WNV), are recognized as emerging and reemerging pathogens. Circulation of flaviviruses has been recently detected in different mosquito and vertebrate species in several European countries. A serosurvey study was carried out to evaluate the circulation of WNV and other flaviviruses of the JEV antigenic complex in different wild bird species in Spain between 2006 and 2009. Seropositiviy against JEV using a competitive enzyme-linked immunosorbent assay was found in common coot, Montagu's Harrier, black kite, black vulture, Bonelli's eagle, Spanish imperial eagle, Egyptian vulture, and Eurasian spoonbill. Seropositivity to JEV antigenic complex viruses was significantly higher in samples collected during autumn compared with animals sampled during summer. Significantly higher seroprevalence was also observed in 2007 compared with 2009, whereas there were no significant differences in seropositivity among taxonomic levels, migratory versus resident behavior, body size (large vs. medium), or habitats (free-ranging vs. captivity). Neutralizing antibodies against WNV were detected in common coot and Spanish imperial eagle using a virus-neutralization test. Oral shedding of WNV was not detected in any of the Spanish imperial eagles, Egyptian vultures, Eurasian Spoonbills, Lammergeiers, and the Black vultures analyzed by means of real-time reverse transcription-polymerase chain reaction. The results indicate that WNV and others flaviviruses of the JEV antigenic group circulated in migratory and resident wild bird species in Spain between 2007 and 2008. Further studies are necessary to determine the precise role that each of these wild bird species, some of them cataloged as "near threatened," "vulnerable," or "endangered," play in the epidemiology of those viruses.

Spatio-temporal trends and risk factors affecting West Nile virus and related flavivirus exposure in Spanish wild ruminants

“…Most of the WNV outbreaks in horses in Spain have been reported in late summer and autumn [40], confirming the higher risk of flavivirus infection during these seasons. In addition, the higher seropositivity observed in autumn in farmed deer is also in agreement with what has been reported in wild birds in Spain [5, 6]. …”

“…Five of them have circulated in Spain in the last decade. WNV exposure has been documented in mosquitoes [4], wild birds [5, 6] and different mammalian species, including humans [7], horses [8], dromedary camels ( Camelus dromedarios ) [9], wild boar ( Sus scrofa ) and Iberian pigs and red foxes ( Vulpes vulpes ) [10]. Clinical disease and mortality associated with WNV infection has also been detected in wild birds, horses and humans in this country [11, 12].…”

West Nile Fever Outbreak in Horses and Humans, Spain, 2010

“…Previous serologic surveys in migratory and resident wild birds from the affected area indicated WNV circulation during 2007 and 2008 ( 3 ). Although high numbers of dead birds were reported in resident wild birds concurrently with the equine WNF outbreak, it appeared to be caused by another flavivirus, Bagaza virus, not previously found in Europe ( 8 ).…”

“…In Spain, WNV seropositivity has been reported for humans (2001), horses (2005–2008), and wild birds (2007–2008) ( 1 – 3 ). Clinical disease has been described for humans (2004) and raptors (2001–2005) ( 4 , 5 ) but not for horses.…”

Lack of identification of Flaviviruses in oral and cloacal swabs from long- and short-distance migratory birds in Trentino-Alto Adige (North-eastern Italy)

“…Since the first appearance of WNV in North America in 1999 [30], much research has been carried out to understand the epidemiological role of bird species, demonstrating that migratory birds are implicated in the spread of diseases over long distances, such as from Africa into Europe, while the successive spread at a local level is mainly induced by resident and short-distance migrants, both for WNV and USUV e.g. : [23,26,29,31] and references therein. At the stopover sites along their migratory route and once they reach their destination grounds, migratory birds share common habitats with resident species from which they are otherwise separated during the rest of the year, and this exposes them to a great range of vectors and pathogens.…”