Detection of influenza A viruses and influenza epidemics in wild pelagic birds by sentinels and population studies.

Field experiments with domestic ducks as sentinels and virological and serological population observations on wild pelagic birds on a seabird-breeding island in the Baltic sea and on rivers and lakes near Berlin were conducted to detect the influenza A virus circulation and epidemics in wild pelagic bird populations. Influenza A virus isolates were detected in tracheal and cloacal swabs from sentinel ducks and from healthy pelagic birds. Influenza A virus epidemics with different subtypes in an influenza season beginning in July/August occurred approximately monthly. According to serological population studies in wild pelagic birds there were some epidemics with influenza A viruses, also related to Fowl Plaque Virus (Hav1) and Swine influenza virus (Hsw1). It is possible to recognize epidemics among wild birds by sentinels and by periodic serological observations of wild pelagic bird populations. One isolate from sentinel ducks - A/duck/Potsdam/81 (Hav8 Nav5) - had an hitherto undescribed combination of the surface antigens.