écologie des virus influenza aviaires en Camargue - IRD

Influenza aviaires en CamargueThese results depend both on the bird community dynamics and AIV prevalencerecorded in our study site. AIV prevalence is known to vary not only by region, but also byspecies, in which case differences are likely to be a result of feeding behavior (Garamszegiand Moller 2007). Our mathematical model follows the assumptions that all species have thesame duration of virus excretion, immunity, number of viral particles produced and watercontact rate. More ecological data concerning these aspects are required in order to refinesuch mathematical model. Along the same idea, identifying habitat heterogeneity (e.g.salinity, pH, temperature) is particularly important in order to identify potential hot­spots ofaquatic transmission risks. We are also aware that our model simplify the impacts of birdmigrations in term of introduction and dispersion of influenza viruses. It seems plausible thatmigrations may explain alone the observed disease dynamics. However, investigations ofsuch aspects would require precise dataset concerning birds movements, according to thespecies and periods of the year. Our results highlight that disease dynamics may however notbe driven only by immigration and emigration rates of infected birds.The recent spread of the HP H5N1 AIV is a matter of concern for public healthauthorities. Despite the fact that the relative contribution of wild water birds in the spread ofthe disease remains controversial (Gauthier­Clerc et al. 2007), the dynamics and pathways ofvirus dispersion has started to become clearer (Kilpatrick et al. 2006). Recent studiesreporting the effects of wild bird infections with HP H5N1 AIV highlighted that the virusreplicates (and for a longer time) in the host bird trachea rather than in the digestive tract(Sturm­Ramirez et al. 2005; Brown et al. 2006; Keawcharoen et al. 2008) suggesting thatairborne transmission may be more significant for HP than for LP AIV. In artificialconditions (i.e. intensive farming), HP AIV are likely to be transmitted by density­ or71