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Demographic and spatiotemporal patterns of avian influenza at the continental scale, and in relation to annual life cycle of a migratory host / Rodolfo Nallar, Zsuzsanna Papp, Tasha Epp, Frederick A Leighton, Seth R. Swafford, Thomas J. DeLiberto, Robert J. Dusek, Hon S. Ip, Jeffrey Hall, Yohannes Berhane, Samantha E.J. Gibbs, and Catherine Soos.

By: Contributor(s): Material type: TextTextSeries: PLoS ONE. 10(6) e0130662 Publication details: 2015Description: colour illustrations, colour map ; 28 cmLOC classification:
  • NAL
Online resources: Summary: 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.

Includes bibliographical references.

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.

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