@X31Andy I am not confident that those are relevant as from the information available it seems that the major factor in that is animal welfare as stress and keeping the animals close together lowers their immune system and makes that basically perfect environment for the virus to appear, spread and mutate.
@kreyren I also blame the people who breed millions of pheasants then release them into the countryside every year.
May be coincidence but the avian flu outbreaks seem to shortly follow these releases.