Biosecurity New Zealand continues to work closely with Mainland Poultry following the detection of a high pathogenic strain of avian influenza, H7N6, at one of its commercial egg farms in rural Otago.

"Testing has confirmed further cases of an H7N6 subtype of avian influenza in chickens in a second shed at the farm," Biosecurity New Zealand deputy director-general Stuart Anderson says.

"The remote farm remains under strict biosecurity controls to restrict the movement of birds, poultry products, feed, and equipment on or off the property. The detection of further positive cases on the farm is not unexpected given the nature of the virus."

Mr Anderson says the birds in both sheds, which total about 80,000 layer hens, would be humanely culled with the farmer’s cooperation and this is planned to start tomorrow (Wednesday).

"This is expected to take 2 to 3 days, using existing industry standard practice of CO2 containerised gas, which farms regularly use to euthanise chickens. At present, there will be no major impact on egg supplies as New Zealand has about 3.9 million layer hens a year.

"Once the sheds have been depopulated, they will be thoroughly cleaned. It will be sometime before those sheds can be safely repopulated. We have Biosecurity New Zealand response staff on-site in Otago, and they are providing advice and guidance, including logistics and planning with depopulation and disposal of the birds."

Testing of other sheds on the property continues.

"If required, we will put more restrictions in place, however, at this stage, there have been no further reports of any avian influenza type symptoms showing in chickens in any other poultry farm.

Mr Anderson says the risk to human health remains low, and there are no concerns for food safety or wildlife.

The property, managed by Mainland Poultry, was placed under a restricted place notice on Sunday after results from testing confirmed H7N6 strain in chickens from one shed on the property. The virus has likely developed from interactions with local waterfowl and wild birds.

Mr Anderson is on site at the Otago farm today to observe operations.

"We acknowledge this is an extremely difficult time for the farm’s operator, but we commend their actions," Mr Anderson says.

"Mainland Poultry took the right steps by notifying us of sick and dying birds. The farm has strong biosecurity standards. 3 specialist veterinarians from the Ministry for Primary Industries (MPI) are on site.

"They have been carrying out further investigations and taking samples from birds in other sheds on the farm and conducting tracing work to 6 other poultry farms in the area that are linked to the affected property.

"We are also tracing all movements to and from the farm over the past week. We will place biosecurity controls on any property if we need to manage any biosecurity risk."

Mr Anderson says next steps include continuing to collect samples for testing. The incubation period for the virus is usually 3 to 14 days, with a possibility up to 21 days, so testing will continue over the next 2 to 3 weeks.

"Biosecurity New Zealand has a comprehensive surveillance programme of all poultry properties in the area, where we are testing birds on those properties for any signs of avian influenza."