lol.... I know it does my ed in ....the only thing I can think of is , swine (AH1N1) flu is a mix of swine flu (north American and European ) , Avian Flu ( Asian ) and human flu (European) . That would then make it possible for it to pass to an avian member , chicken, duck, or turkey !!! Which if in turn had another more virulent form of avian flu , could cause serious problems.
However, The new strain (AH1N1) was initially described as an apparent re assortment of at least four strains of influenza A virus subtype H1N1, including one strain endemic in humans, one endemic in birds, and two endemic in swine.[43] Subsequent analysis suggested it was a re assortment of just two strains, both found in swine.[47] Although initial reports identified the new strain as swine influenza (i.e., a zoonos-is originating in swine), its origin is unknown.
As you say though, it must mutate at least a bit, to pass to another form of animal (avian) if ?, IF ? it is (as the subsequent analysis suggested ), a re assortment of two strains both found in swine !!!
Like I said ...it does my ed in .....
cheers
Russ