And in the presence of viral mutations, it has infected mammals including sea lions, ferrets, minks, and cats.
This year, cows are on the list.
This is a surprising development, given that they are not thought to be susceptible to this type of influenza.
And now a dairy worker in Texas has been infected with the virus -- the first known transmission between mammals and humans.
Although bird flu has yet to be detected in Australia, experts warn its arrival is inevitable and we must prepare.
