Australian poultry farms have started going into a lockdown after a second case of the H5N1 strain was confirmed on Monday in migratory sea birds in Western Australia (WA).
Poultry giant Inghams Group told ASX it was preventing non-essential access to its WA farms and processing sites and seeking to keep free range poultry indoors as a precaution.
Authorities are working on responses in both countries to prepare for the threat of a wildlife emergency threatening native birds and a wider outbreak into commercial flocks.
Overseas, the highly pathogenic virus has killed millions of birds, spreading into wild and domestic mammals.
University of Otago evolutionary virologist Prof Jemma Geoghegan said NZ had managed to avoid H5N1 since its spread from Asia in 2021, but it was getting closer after being detected on the Australian mainland.
While NZ was quite isolated from many migratory bird pathways, an East Australasian fly way connected it to the northern hemisphere and Sub Antarctic Islands, she said.
‘‘So it’s only really a matter of time when this virus occurs in NZ’s wildlife too.’’
Prof Geoghegan said H5N1 had caused major mortalities in wild birds and marine mammals, as well as the poultry industry and spread between dairy cattle in the United States.
‘‘It’s a multi-vectorial problem where it’s infecting both wildlife with huge conservation consequences of that as well as the economic consequence for livestock.’’
Bird flu could be expected to spread rapidly once established as wild birds could not be controlled or isolated, she said.
The strain is different from the H7N6 bird flu found on an Otago chicken farm in December, 2024.
Mainland Poultry’s large chicken flock was culled at the farm at Hillgrove to contain the outbreak.
In Australia a H7 HPAI outbreak in Victoria resulted in authorities killing 2 million birds, and egg shortages.
Prof Geoghegan said the Otago event was a ‘‘dress rehearsal’’ for H5N1.
The locally-adapted strain was not highly pathogenic in wild birds, but when it jumped to chickens had caused severe disease and many deaths.
This lineage of H5N1 was different as it had genetically adapted to expand its host range and geographical spread and had a high mortality rate particularly in wildlife, she said.
‘‘We have seen the impact on poultry and it affects the farmers, the people and the customers and it affects the birds. We have seen in the US alone over 200 million chickens be culled because of this virus.’’
She said its spread into US dairy cattle was a concern for NZ and a ‘‘huge’’ flow-on effect could be expected when it entered poultry stocks.
Poultry Industry Association of NZ (Pianz) executive director Fiona MacMillan said it was a concern to see the disease getting closer to NZ.
‘‘But we have been expecting that the H5N1 variant would get to this part of the world eventually, so we are not surprised.’’
Pianz was in talks with Australia’s industry body and authorities from both countries were working hard to prepare, she said.
She said little could be done to prevent it entering because the most likely vector was migratory wild birds.
However, international travellers could make sure they follow biosecurity protocols at the border to avoid being a vector for the disease themselves.
Poultry farmers were putting in place on-farm biosecurity and had prepared for bird flu for some time, she said.
‘‘An event like this one in Australia gives an added boost and greater sense of urgency to that work.’’
Ms MacMillan said the H5N1 variant was expected to have a significant impact on all birds including commercial poultry, backyard flocks, domestic pets and wild birds.
‘‘The industry, working closely with MPI, managed to contain and eradicate the H7 strain. It is thought that the H5 strain will be harder if not impossible to eliminate when it arrives in NZ as it will be likely then be established in wild birds.’’
She said NZ’s isolation had given poultry producers time to learn from international experience about managing the disease and outbreak waves.
The industry was investigating overseas technology such as using heat over a week to decontaminate emptied sheds as an alternative to intensive washing and decontamination.
‘‘Much of this work is still in the early stages, but the point is that we have had time to start testing these things before the disease gets here.’’
Prof Geoghegan said the first sign of the virus would likely be from the public stumbling across several sea bird deaths and they should immediately call the MPI hotline.
Touching the birds should be avoided as humans had been infected by the virus through direct contact with infected animals.
She said vaccination trials carried out on critically endangered NZ birds in captivity had been found to be successful and some countries were vaccinating poultry against H5N1.
