| surveillance of avian influenza viruses in northern pintails (anas acuta) in tohoku district, japan. | among winter migratory waterfowl, northern pintails (anas acuta), in one of the largest flocks in tohoku district, northeast japan, were surveyed for influenza a viruses at five wintering sites in three prefectures, viz., aomori, akita, and miyagi. a total of 38 influenza a viruses were isolated from 2066 fecal samples collected during november 2006 through march 2007. the overall isolation rate was 1.84%. eleven different subtypes were isolated, including nine h5n2, seven h6n8, seven h10n1, fou ... | 2008 | 18459295 |