Avian influenza viruses may cause mild or severe disease
in birds. There have been five recorded outbreaks of
highly pathogenic avian influenza in birds in Australia,
all of which were caused by the H7 subtype. These were
quickly controlled and similar coordinated responses are
expected for possible future outbreaks of avian influenza.
Migratory birds are not regarded as the source of these
outbreaks, and the prevalence of avian influenza viruses in
wild birds in Australia is very low. Avian influenza H5N1,
which emerged in birds in China in 1996, has spread to
bird flocks in Asia, Europe and Africa. The main carriers
of avian influenza, ducks, do not migrate to Australia, and
currently the risk of H5N1 occurring in Australian birds
appears to be low. Nevertheless, surveillance and response
plans for outbreaks of highly pathogenic avian influenza
have recently been upgraded across Australia.