Bird flu has spread to another shed on an Otago farm, the Ministry for Primary Industries has confirmed
MPI's chief veterinary office, Mary van Andel, said 80,000 chickens would now need to be culled at Mainland Poultry's Hillgrove Egg Farm, doubling from 40,000.
She says there's no indication the H7N6 virus has spread beyond the farm.
But van Andel told Morning Report it was not unexpected for the disease to spread between sheds on the same property.
The farm has four sheds in total with 160,000 birds across them.
"We're preparing to take measures across all of those sheds if it is required," van Andel said.
It was not a region with very dense poutry production and six other farms were to be tested.
Van Andel said the virus can spread with human movements.
"It's moving with the movements of people, equipment and machinery, those types of things," she said
Van Andel was confident the the country could continue free range farming.
Otago Federated Farmers' Luke Kane told Morning Report he wasn't surprised by the spread as it appeared the sheds were in close proximity to each other.
The detection of the virus on the farm would be difficult for those involved, he said.
"It's taking a toll on all the people that are involved here, the staff, the owners, everybody."
Kane said the industry needed to be aware of the risk of farm birds interacting with native or wild birds.
Distinguished professor of infectious disease epidemiology and public health Dr Nigel French told Morning Report there is always a possibility of the virus spreading to humans.
"It doesn't spread from person to person but the reason that we need to be careful is there's an indication that is can cause very severe disease and even death in people."
The advice is to avoid coming into contact with a bird with the disease, he said.
Minister for Biosecurity and Food Safety Andrew Hoggard on Monday said there's been no evidence of any cases of people contracting the disease and MPI is "fairly confident" there is minimal risk to Kiwis.
French said the incubation period of bird flu can be up to about three weeks.
Surveillance is key "the earlier you can detect it the earlier you can prevent it's spread".
Unlike the spread of bird flu internationally, this particular situation has happened because the virus has converted from a low pathogenic strain to a high pathogenic strain, French said.
High pathogenic viruses cause very serious disease and can lead to sudden death and respiratory symptoms whereas a low pathogenic virus can cause some disease but causes flu-like symptoms, he said.
'No food safety concerns'
The outbreak should not result in an egg shortage, the Finance Minister says.
Nicola Willis told First Up there was also no risk to humans.
"They've done the right thing and reported early so we're in a good position here and there are no further reports of any avian flu symptoms at any other poultry farms so at this point it appears contained.
"The other thing I really want people to know is there are no food safety concerns, there's no evidence that people can be affected with this strain."
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