Serologic evidence of West Nile virus infections in wild birds captured in Germany

To assess the risk of acquiring a West Nile virus (WNV) infection in Germany, we investigated samples from migrating and from resident birds. Because of their stay in or migration through WNV-endemic regions, these birds are at risk to become infected with WNV. Blood samples from 3,399 birds, representing 87 bird species, were collected in Germany in 2000 and in 2002-2005. Overall, 53 birds belonging to 5 species had WNV-neutralizing antibodies. Fifty-nine birds belonging to 9 species were reactive by WNV immunofluorescence assay, and 8 birds had neutralizing antibodies against Usutu virus. Because of maternal antibody transfer via egg yolk, WNV-antibody titers in white stork nestlings were generally lower than those in adults. Despite a relatively high percentage of stork nestlings with antibodies, no viral genomes were detectable by polymerase chain reaction. In Germany, the prevalence of antibodies to WNV in migrating birds wintering in Africa or southern Europe is comparatively low.