Flu The Role of Environmental Transmission in Recurrent Avian In

Discussion in 'Survival Medicine' started by eeyore, Apr 17, 2009.

  1. eeyore

    eeyore Monkey+++

    The Role of Environmental Transmission in Recurrent Avian Influenza Epidemics
    Avian influenza virus (AIV) persists in North American wild
    waterfowl, exhibiting major outbreaks every 2-4 years. Attempts to
    explain the patterns of periodicity and persistence using simple
    direct transmission models are unsuccessful. Motivated by empirical
    evidence, we examine the contribution of an overlooked AIV
    transmission mode: environmental transmission. It is known that
    infectious birds shed large concentrations of virions in the
    environment, where virions may persist for a long time. We thus
    propose that, in addition to direct fecal/oral transmission, birds
    may become infected by ingesting virions that have long persisted in
    the environment. We design a new host-pathogen model that combines
    within-season transmission dynamics, between-season migration and
    reproduction, and environmental variation. Analysis of the model
    yields 3 major results. 1st, environmental transmission provides a
    persistence mechanism within small communities where epidemics cannot
    be sustained by direct transmission only (i.e., communities smaller
    than the critical community size). 2nd, environmental transmission
    offers a parsimonious explanation of the 2-4 year periodicity of
    avian influenza epidemics. 3rd, very low levels of environmental
    transmission (i.e., few cases per year) are sufficient for avian
    influenza to persist in populations where it would otherwise vanish.

    Citation: Breban R, Drake JM, Stallknecht DE, Rohani P (2009) The
    Role of Environmental Transmission in Recurrent Avian Influenza
    Epidemics. PLoS Comput Biol 5(4): e1000346.

    Communicated by:
    ProMEDmail Rapporteur Mary Marshall

    [It is nice to see a past LSU graduate student, David Stallknecht,
    returning to the topic of his dissertation (1989) which was on the
    shedding of LPAI wild viruses by migrating ducks. After presenting an
    analysis of the very large number of isolates he had obtained by
    cloacal swabbing of ducks shot by hunters, he was asked how long did
    the virus survive in the fresh and brackish waters where these birds
    fed and slept. To cut a long story short, at the right water salinity
    and temperature they were immortal. The moral of this story is beware
    of simple questions posed by your professors. The above paper is
    worth reading in its entirety. - Mod.MHJ]


  2. dragonfly

    dragonfly Monkey+++

    Re: The Role of Environmental Transmission in Recurrent Avia

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