Serologic Survey of Birds for West Nile Flavivirus in Southern Moravia (Czech Republic)

A serosurvey for West Nile virus (WNV) was carried out in 54 domestic birds (geese and ducks bred on fishponds) and 391 wild birds representing 28 migratory and resident species, using a plaque-reduction neutralization microtest with Vero cells and Egyptian topotype Eg-101 strain as test virus. The birds were sampled in the South-Moravian fishpond ecosystem between 2004 and 2006. Antibodies to WNV were not detected in domestic waterfowl, but 23 (5.9%) free-living birds of 10 species showed a positive response. These were the common coot ( Fulica atra , 5 positive 18 examined), common kingfisher ( Alcedo atthis , 1 1), reed warbler ( Acrocephalus scirpaceus , 2 80), sedge warbler ( A. schoenobaenus , 3 80), marsh warbler ( A. palustris , 2 28), Savi's warbler ( Locustella luscinioides , 3 12), reed bunting ( Emberiza schoeniclus , 1 28), blackcap ( Sylvia atricapilla , 2 11), penduline tit ( Remiz pendulinus , 1 14), blue tit ( Parus caeruleus , 1 1), and starling ( Sturnus vulgaris , 2 4). The antibody titers were comparatively low (1:20-1:40), and the only high titer (1:160) was found in an adult marsh warbler. When 14 of the sera reacting with WNV were titrated in parallel with Usutu Flavivirus , 12 were interpreted as having specific antibodies to WNV, one coot had a higher titer against Usutu virus, and another one could not be attributed to either of the two viruses. In conclusion, 13 (3.3%) of 391 wild birds had specific antibodies to WNV. The results indicate that WNV activity in southern Moravia was limited during 2004-2006.