title: Wild bird migration across the Qinghai-Tibetan plateau: a transmission route for highly pathogenic H5N1.
abstract: BACKGROUND
  Qinghai Lake in central China has been at the center of debate on whether wild birds play a role in circulation of highly pathogenic avian influenza virus H5N1. In 2005, an unprecedented epizootic at Qinghai Lake killed more than 6000 migratory birds including over 3000 bar-headed geese (Anser indicus). H5N1 subsequently spread to Europe and Africa, and in following years has re-emerged in wild birds along the Central Asia flyway several times.
  
  
  RESULTS
  To better understand the potential involvement of wild birds in the spread of H5N1, we studied the movements of bar-headed geese marked with GPS satellite transmitters at Qinghai Lake in relation to virus outbreaks and disease risk factors. We discovered a previously undocumented migratory pathway between Qinghai Lake and the Lhasa Valley of Tibet where 93% of the 29 marked geese overwintered. From 2003-2009, sixteen outbreaks in poultry or wild birds were confirmed on the Qinghai-Tibet Plateau, and the majority were located within the migratory pathway of the geese. Spatial and temporal concordance between goose movements and three potential H5N1 virus sources (poultry farms, a captive bar-headed goose facility, and H5N1 outbreak locations) indicated ample opportunities existed for virus spillover and infection of migratory geese on the wintering grounds. Their potential as a vector of H5N1 was supported by rapid migration movements of some geese and genetic relatedness of H5N1 virus isolated from geese in Tibet and Qinghai Lake.
  
  
  CONCLUSIONS
  This is the first study to compare phylogenetics of the virus with spatial ecology of its host, and the combined results suggest that wild birds play a role in the spread of H5N1 in this region. However, the strength of the evidence would be improved with additional sequences from both poultry and wild birds on the Qinghai-Tibet Plateau where H5N1 has a clear stronghold.
authors.affiliation: Patuxent Wildlife Research Center, United States Geological Survey, Beltsville, Maryland, United States of America. dprosser@usgs.gov
authors.forename: Diann J
authors.initials: DJ
authors.lastname: Prosser
authors.forename: Peng
authors.initials: P
authors.lastname: Cui
authors.forename: John Y
authors.initials: JY
authors.lastname: Takekawa
authors.forename: Mingjie
authors.initials: M
authors.lastname: Tang
authors.forename: Yuansheng
authors.initials: Y
authors.lastname: Hou
authors.forename: Bridget M
authors.initials: BM
authors.lastname: Collins
authors.forename: Baoping
authors.initials: B
authors.lastname: Yan
authors.forename: Nichola J
authors.initials: NJ
authors.lastname: Hill
authors.forename: Tianxian
authors.initials: T
authors.lastname: Li
authors.forename: Yongdong
authors.initials: Y
authors.lastname: Li
authors.forename: Fumin
authors.initials: F
authors.lastname: Lei
authors.forename: Shan
authors.initials: S
authors.lastname: Guo
authors.forename: Zhi
authors.initials: Z
authors.lastname: Xing
authors.forename: Yubang
authors.initials: Y
authors.lastname: He
authors.forename: Yuanchun
authors.initials: Y
authors.lastname: Zhou
authors.forename: David C
authors.initials: DC
authors.lastname: Douglas
authors.forename: William M
authors.initials: WM
authors.lastname: Perry
authors.forename: Scott H
authors.initials: SH
authors.lastname: Newman
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D000835:Animals, Wild / Q000821:virology*; D001717:Birds / Q000821:virology*; D001947:Breeding; D004196:Disease Outbreaks / Q000662:veterinary; D017753:Ecosystem; D005618:Fresh Water; D005777:Geese / Q000821:virology; D005843:Geography; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000453:epidemiology / Q000635:transmission* / Q000821:virology*; D010802:Phylogeny; D011200:Poultry / Q000821:virology; D012044:Regression Analysis; D012621:Seasons; D018609:Tibet / Q000453:epidemiology; D053833:Wetlands