Avian influenza virus wild bird surveillance in the Azov and Black Sea regions of Ukraine (2010-2011).

The Azov and Black Sea basins are part of the transcontinental wild bird migration routes from Northern Asia and Europe to the Mediterranean, Africa, and Southwest Asia. These regions constitute an area of transit, stops during migration, and nesting for many different bird species. From September 2010 to September 2011, a wild bird surveillance study was conducted in these regions to identify avian influenza viruses. Biological samples consisting of cloacal and tracheal swabs and fecal samples were collected from wild birds of different ecological groups, including waterfowl and sea- and land-based birds, in places of mass bird accumulations in Sivash Bay and the Utlyuksky and Molochniy estuaries. The sampling covered the following wild bird biological cycles: autumn migration, wintering, spring migration, nesting, and postnesting seasons. A total of 3634 samples were collected from 66 different species of birds. During the autumn migration, 19 hemagglutinating viruses were isolated, 14 of which were identified as low pathogenicity avian influenza (LPAI) virus subtypes H1N?, H3N8, H5N2, H7N?, H8N4, H10N7, and H11N8. From the wintering samples, 45 hemagglutinating viruses were isolated, 36 of which were identified as LPAI virus subtypes H1N1, H1N? H1N2, H4N?, H6N1, H7N3, H7N6, H7N7, H8N2, H9N2, H10N7, H10N4, H11N2, H12N2, and H15N7. Only three viruses were isolated during the spring migration, nesting, and postnesting seasons (serotypes H6, H13, and H16). The HA and NA genes were sequenced from the isolated H5 and N1 viruses, and the phylogenetic analysis revealed possible ecological connections between the Azov and Black Sea regions and Europe. The LPAI viruses were isolated mostly from mallard ducks, but also from shellducks, shovelers, teals, and white-fronted geese. The rest of the 14 hemagglutinating viruses isolated were identified as different serotypes of avian paramyxoviruses (APMV-1, APMV-4, APMV-6, and APMV-7). This information furthers our understanding of the ecology of avian influenza viruses in wild bird species.