In past months China has repeatedly reported isolation of H5N1 avian influenza from migratory species, including cranes and shelducks. These birds, among others have been implicated in long-distance dissemination of avian influenza.

It is considered ironic that China reports outbreaks of avian influenza in free-living species but apparently does not encounter cases in commercial poultry.  It is question whether this is due to failure to report outbreaks of H5 and H7 avian influenza, irrespective of pathogenicity, as required by the World Organization for Animal Health or is due to an extraordinarily comprehensive and effective vaccination program to protect both commercial and subsistence flocks.