title: Surveillance of influenza A virus in migratory waterfowl in northern Europe.
abstract: We conducted large-scale, systematic sampling of influenza type A virus in migratory waterfowl (mostly mallards [Anas platyrhynchos]) at Ottenby Bird Observatory, southeast Sweden. As with previous studies, we found a higher prevalence in fall than spring, and among juveniles compared with adults. However, in contrast to other studies, we found that prevalence in spring was sometimes high (mean 4.0%, highest 9.5%). This finding raises the possibility that ducks are capable of perpetuating influenza A virus of different subtypes and subtype combinations throughout the year and from 1 year to the next. Isolation of the H5 and H7 subtypes was common, which suggests risk for transmission to sensitive domestic animals such as poultry. We argue that wild bird screening can function as a sentinel system, and we give an example of how it could have been used to forecast a remote and deadly outbreak of influenza A in poultry.
authors.affiliation: Smedby Health Center, Kalmar, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Wallensten
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Munster
authors.forename: Neus
authors.initials: N
authors.lastname: Latorre-Margalef
authors.forename: Mia
authors.initials: M
authors.lastname: Brytting
authors.forename: Johan
authors.initials: J
authors.lastname: Elmberg
authors.forename: Ron A M
authors.initials: RA
authors.lastname: Fouchier
authors.forename: Thord
authors.initials: T
authors.lastname: Fransson
authors.forename: Paul D
authors.initials: PD
authors.lastname: Haemig
authors.forename: Malin
authors.initials: M
authors.lastname: Karlsson
authors.forename: Ake
authors.initials: A
authors.lastname: Lundkvist
authors.forename: Albert D M E
authors.initials: AD
authors.lastname: Osterhaus
authors.forename: Martin
authors.initials: M
authors.lastname: Stervander
authors.forename: Jonas
authors.initials: J
authors.lastname: Waldenström
authors.forename: Olsen
authors.initials: O
authors.lastname: Björn
mesh_terms: D025041:Animal Migration; D000818:Animals; D000835:Animals, Wild / Q000145:classification / Q000821:virology*; D004196:Disease Outbreaks / Q000517:prevention & control / Q000662:veterinary*; D004372:Ducks / Q000145:classification / Q000821:virology*; D005260:Female; D005544:Forecasting; D009980:Influenza A virus / Q000145:classification / Q000302:isolation & purification*; D005585:Influenza in Birds / Q000517:prevention & control*; D008297:Male; D011201:Poultry Diseases / Q000517:prevention & control; D012621:Seasons; D018571:Sentinel Surveillance; D013045:Species Specificity; D013548:Sweden / Q000453:epidemiology