NZ bird flu 'could mutate into more serious form'

An Australian researcher says it is theoretically possible that the low-grade bird flu virus detected in wild mallard ducks in New Zealand could mutate into a more serious form of the virus.

Professor Gregor Tannock told the Australian Broadcasting Corporation that the virus could pose a threat to New Zealand poultry "if it mutates from low pathogenic to high pathogenic".

Prof Tannock, who is studying bird flu at the MacFarlane Burnet Institute for Medical Research and Public Health in Melbourne, told the Australian Broadcasting Corporation the virus was probably present in many more estuaries than those where it was found.

Both the infected ducks were found near Invercargill, one at an estuary 2km west of the city and one at Roslyn Bush, following a surveillance programme in February that tested six other sites throughout the country. Invercargill was the only site with infected ducks when the findings were confirmed this week.

Now Australian poultry owners are being warned to step up their own biosecurity checks in the wake of the discovery.

Australian poultry owners should ensure wild waterbirds cannot access poultry feed or water and should limit contact between wild waterbirds and poultry, Biosecurity Queensland's chief veterinary officer Ron Glanville told AAP.

"This is just a commonsense, precautionary measure," Dr Glanville said.

Biosecurity New Zealand team manager Andre van Halderen said the Southland ducks were the first time that low-pathogenicity avian influenza H5N1 strain had been recorded in New Zealand.

He stressed it should not be mistaken for the highly pathenogenic (HPAI) H5N1 virus that spread throughout parts of Asia, Europe and Africa, killing more than 200 people and forcing the destruction of millions of birds.

Dr van Halderen said the nature of the virus meant it was impossible it could cross-species jump into humans and mutation was "highly unlikely".

"There's a negligible risk of it firstly getting into birds and because it's `low-path': it causes very mild or no clinical disease in domestic poultry.

"It's only through mutation into highly pathogenic strains that you will get strains arising which cause problems.

"The low pathenogenic avian influenza viruses are adapted to waterfowl and shorebirds, which are their natural hosts."

- NZPA