title: Demographic and Spatiotemporal Patterns of Avian Influenza Infection at the Continental Scale, and in Relation to Annual Life Cycle of a Migratory Host.
abstract: Since the spread of highly pathogenic avian influenza (HPAI) H5N1 in the eastern hemisphere, numerous surveillance programs and studies have been undertaken to detect the occurrence, distribution, or spread of avian influenza viruses (AIV) in wild bird populations worldwide. To identify demographic determinants and spatiotemporal patterns of AIV infection in long distance migratory waterfowl in North America, we fitted generalized linear models with binominal distribution to analyze results from 13,574 blue-winged teal (Anas discors, BWTE) sampled in 2007 to 2010 year round during AIV surveillance programs in Canada and the United States. Our analyses revealed that during late summer staging (July-August) and fall migration (September-October), hatch year (HY) birds were more likely to be infected than after hatch year (AHY) birds, however there was no difference between age categories for the remainder of the year (winter, spring migration, and breeding period), likely due to maturing immune systems and newly acquired immunity of HY birds. Probability of infection increased non-linearly with latitude, and was highest in late summer prior to fall migration when densities of birds and the proportion of susceptible HY birds in the population are highest. Birds in the Central and Mississippi flyways were more likely to be infected compared to those in the Atlantic flyway. Seasonal cycles and spatial variation of AIV infection were largely driven by the dynamics of AIV infection in HY birds, which had more prominent cycles and spatial variation in infection compared to AHY birds. Our results demonstrate demographic as well as seasonal, latitudinal and flyway trends across Canada and the US, while illustrating the importance of migratory host life cycle and age in driving cyclical patterns of prevalence.
authors.affiliation: Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Wildlife Conservation Society, Greater Madidi-Tambopata Landscape Conservation Program, La Paz, Bolivia.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Nallar
authors.affiliation: Environment Canada, Science & Technology Branch, Saskatoon, Saskatchewan, Canada.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Papp
authors.affiliation: Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Tasha
authors.initials: T
authors.lastname: Epp
authors.affiliation: Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Canadian Wildlife Health Cooperative, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Leighton
authors.affiliation: United States Department of Interior, US Fish and Wildlife Service, Yazoo City, Mississippi, United States of America.
authors.forename: Seth R
authors.initials: SR
authors.lastname: Swafford
authors.affiliation: United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Disease Program, Fort Collins, Colorado, United States of America.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: DeLiberto
authors.affiliation: United States Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin, United States of America.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Dusek
authors.affiliation: United States Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin, United States of America.
authors.forename: Hon S
authors.initials: HS
authors.lastname: Ip
authors.affiliation: United States Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin, United States of America.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Hall
authors.affiliation: National Centre for Foreign Animal Disease, Canadian Food Inspection Agency, Winnipeg, Manitoba, Canada.
authors.forename: Yohannes
authors.initials: Y
authors.lastname: Berhane
authors.affiliation: United States Fish and Wildlife Service, Division of Migratory Bird Management, Laurel, Maryland, United States of America.
authors.forename: Samantha E J
authors.initials: SE
authors.lastname: Gibbs
authors.affiliation: Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Environment Canada, Science & Technology Branch, Saskatoon, Saskatchewan, Canada.
authors.forename: Catherine
authors.initials: C
authors.lastname: Soos
mesh_terms: D025041:Animal Migration; D000818:Animals; D000835:Animals, Wild / Q000821:virology*; D001717:Birds / Q000821:virology*; D053124:Influenza A Virus, H5N1 Subtype / Q000302:isolation & purification*; D005585:Influenza in Birds / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D008018:Life Cycle Stages; D015995:Prevalence