Ecological Surveillance for West Nile in Catalonia (Spain), Learning from a Five‐Year Period of Follow‐up

Abstract

To enhance early detection of West Nile virus (WNV) transmission, an integrated ecological surveillance system was implemented in Catalonia (north-eastern Spain) from 2007 to 2011. This system incorporated passive and active equine surveillance, periodical testing of chicken sentinels in wetland areas, serosurveillance wild birds and testing of adult mosquitoes. Samples from 298 equines, 100 sentinel chickens, 1086 wild birds and 39 599 mosquitoes were analysed. During these 5 years, no acute WNV infection was detected in humans or domestic animal populations in Catalonia. WNV was not detected in mosquitoes either. Nevertheless, several seroconversions in resident and migrant wild birds indicate that local WNV or other closely related flaviviruses transmission was occurring among bird populations. These data indicate that bird and mosquito surveillance can detect otherwise silent transmission of flaviviruses and give some insights regarding possible avian hosts and vectors in a European setting.

Detection of West Nile virus lineage 2 in North‐Eastern Spain (Catalonia)

“…The fact that WNV was detected in Catalonia was probably due to the implementation of a comprehensive surveillance program (including active and passive surveillance in wild birds and horses) for more than 12 years. In fact, since 2010, WNV positivity by SNT has been detected in wild birds (mainly raptors) in this same area, which was not included among the high‐risk areas for WNV in Catalonia (Alba et al., ). However, local WNV circulation could never be demonstrated as positive animals were always potentially migratory.…”

Clinical Sentinel Surveillance of Equine West Nile Fever, Spain

“…Usutu virus was commonly found in different European countries in birds (Vázquez et al., ) and horses (Barbic et al., ), in mosquitoes (Busquets et al.,; Vazquez et al., ), and was also documented in neurologically affected horses in Italy (Macini et al., ). In Spain, seropositive birds were found based on positive results of WNV ELISA, but unconfirmed with specific SNT, and therefore, these animals may have been infected with other flaviviruses of the Japanese encephalitis complex (García‐Bocanegra et al., ; Alba et al., ), especially because both Usutu virus and Bagaza virus have been recently detected in Andalusia (García‐Bocanegra et al., ; Llorente et al., ), while Meaban virus has been recently detected in Medes Islands (Catalonia; Arnal et al., ). These flaviviruses species have been detected in birds, ticks and mosquitoes, but not in equines.…”

Low Seroprevalence of West Nile Virus in Blood Donors from Catalonia, Spain

“…An ecological surveillance for WNV in Catalonia has been recently described (Alba et al 2014). Horses, sentinel chickens, wild birds and mosquitoes were analyzed from 2007 to 2011.…”