écologie des virus influenza aviaires en Camargue - IRD

Émergence du virus H5N1 hautement pathogèneProduction of viral particles in aerosols is probably the most efficient transmission strategyin confined environments with high densities of birds, such as under intensive farmingconditions [58], leading to selection for systemic infection in these circumstances.While AIV persistence in water appears to be the natural mechanism to maintain andtransmit influenza viruses in wild bird populations, Brown et al. [55] recently found that HPH5N1 does not persist as long as LP AIV in water, at least under experimental conditions.HP AIV are thus potentially less adapted to survive in aquatic ecosystems, suggesting thatalternative forms of transmission, such as aerosol dispersal and inhalation, may have beenselected for these subtypes.AIV in a man­made worldConnectivity in modern human populations, through transportation, has undoubtedlyincreased during the last century. On theoretical grounds, Boots and Sasaki [59] providedevidence that these increasing connections may boost emergence risks of virulent diseases.The past two decades have seen a huge increase in poultry production and associated nationaland international trade in south­east Asia [60]. After adapting to intensive farming processes,AIV hitch­hike human transportation (both deliberate and accidental) to spreadintercontinentally among poultry populations. This appears to be the most likely scenario forthe spread of HP H5N1 from Asia to Europe and Africa, in which the poultry trade (legal,unregulated and illegal) seems to have been the predominant mechanism [61].Human activities thus artificially shape AIV evolutionary ecology and select for traits(e.g. virulence, oropharyngeal excretion, host specialisation, etc.) that confer optimal fitness131