A major number of West Nile virus (WNV) infections in humans occurred in 2010 in northern Greece, with 262 laboratory confirmed
cases. In 2011, fewer cases were reported, but the pattern was more dispersed throughout the Greek mainland. Isolated strains
were similar to lineage 2 strains detected in previous years in Austria and Hungary from birds of prey. We conducted a serological
surveillance study on hunter-harvested wild birds, to determine possible exposure of avian species during the current outbreak.
Serum samples from a total of 113 Eurasian magpies and 85 turtle doves (abundant resident and migratory avian species, respectively,
with potential roles in WNV epidemiology) were tested. These birds were hunter-harvested during 2011 from various prefectures
both affected and not affected by the WNV outbreak in Greece. Sera were tested for the presence of WNV IgG antibodies by indirect
immunofluorescence assay (IFA). Verification of positive results by a micro-virus neutralization test (VNT) was also performed.
A total of 23 out of 113 (20.4%) Eurasian magpies and 6/85 (7.1%) turtle doves were found positive. Results showed association
of human cases with wild birds’ exposure to the virus; no avian sera were found positive in prefectures not affected by the
WNV outbreak. In contrast, positive avian sera were found in every prefecture that human WNV cases occurred in 2011. High
seroprevalence in Eurasian magpies suggests high activity of WNV in the areas. Findings of past exposure of migratory birds
like turtle doves to WNV upon their arrival in resting areas in Greece suggest various avian species with similar migration
traits as target species for viral isolation studies, as they can be considered candidates for the introduction of WNV lineage
2 in Greece from Central Europe.
Keywords Eurasian magpies – Greece –
Pica pica
–
Streptopelia turtur
– Turtle doves – West Nile virus
Communicated by C. Gortázar