A strain of bird flu (H7N6) in Otago

Situation update – 28 April 2025

The strict movement controls placed on a commercial egg farm in rural Otago have been lifted. The disease was successfully contained to just one property and stamped out.

Actions taken when HPAI was detected

On 2 December 2024, the Ministry for Primary Industries (MPI) placed movement controls on Mainland Poultry’s farm at Hillgrove after testing confirmed the H7N6 strain of high pathogenicity avian influenza (HPAI).

All chickens on the farm were humanely culled.

More than 5,600 tests were carried out on samples from poultry and wild birds, including from 36 flocks across 5 farms linked to Mainland’s Hillgrove property. HPAI was not found anywhere, other than Hillgrove, giving confidence that the disease had been contained and stamped out.

While there is still work to be done, the lifting of movement controls is a significant milestone in the response and means that Mainland Poultry can begin the process of returning to business.

MPI will continue to support Mainland as the farm is repopulated.

What is HPAI H7N6?

Avian influenza is a viral disease of birds found globally. Virus strains are described as low pathogenicity (LPAI) or high pathogenicity (HPAI).

The H7N6 strain is closely related to LPAI strains present in wild birds in New Zealand.

LPAI has been present in wild bird populations in New Zealand for decades and many species of wild birds may have strains of the virus. Internationally, over 5,000 species of wild birds have this type of avian influenza.

LPAI causes few or no signs of illness in wild birds. However, when a low pathogenicity strain of avian influenza is introduced to chickens, it can mutate into a high pathogenicity strain.

Testing indicates that the infection at the Hillgrove farm happened after free-range laying hens foraging outside were exposed to the low pathogenicity virus from wild birds, which then mutated in the hens to become HPAI. It was the first detection of HPAI in New Zealand.