We need to be ready for bird flu
Avian influenza, also known as bird flu, is a highly contagious viral disease that mainly affects birds. However, it can also spread to mammals – including people.
There are 2 main types of avian influenza:
- high pathogenicity avian influenza (HPAI), which can cause severe signs and high death rates in birds. There are a number of strains including H5, H7, and H9
- low pathogenicity avian influenza (LPAI), which typically causes few or no signs in birds but can possibly mutate to HPAI.
LPAI is present in wild birds in New Zealand. We have an active surveillance programme for LPAI and test around 2,000 samples from wild birds each year. 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.
Strains of HPAI have circulated globally for years. Many countries have seasonal outbreaks in poultry every year.
New Zealand has been monitoring the spread of HPAI globally for the past 20 years. Biosecurity New Zealand and our partners have surveillance programmes in place to detect the arrival of HPAI and other exotic diseases.
A strain of avian influenza, H7N6, was detected at an Otago egg farm in December 2024. We have strong evidence that the strain may have developed after free-range laying hens foraging outside were exposed to the low pathogenicity virus from wild waterfowl, which then mutated in the hens to become HPAI. While it is not the H5N1 type circulating among wildlife around the world that has caused concern, we have worked with the farm owner and industry to stamp out this strain of bird flu.
A strain of bird flu (H7N6) in Otago
Global spread of HPAI H5N1
In 2020, a new H5N1 strain – known as H5N1 2.3.4.4b – emerged in the northern hemisphere. It established in wild birds and spread to the United Kingdom, Europe, the United States, and other regions.
In 2023, it was detected in the southern hemisphere. Since then, it has spread through South America to the sub-Antarctic islands and the Antarctic peninsula.
The new H5N1 strain can infect a much broader range of wild birds and spread across a larger geographical range than previous strains have.
It can cause high numbers of deaths in poultry (chickens and turkeys), waterfowl (ducks, geese and swans), shorebirds (godwits, stilts and plovers) and seabirds (gulls and terns).
It has also spilled over to more than 60 species of mammal, including marine mammals, companion animals and livestock.
If this strain of HPAI arrived in New Zealand, it could spread by direct contact between infected and healthy birds, or through contamination of equipment and materials, including water and feed.
New Zealand and our neighbours remain free from HPAI H5N1
Our neighbours, including Australia and the Pacific Islands, remain free from H5N1 and the likelihood of it coming into New Zealand on pathways that we manage is low.
Unlike many biosecurity threats, H5N1 is not expected to be brought to New Zealand by human activity, but by migratory wild birds. For this reason, it is not likely that it could be kept out of New Zealand over the long-term or eradicated once it establishes in the wild bird population.
As more information emerges about how the disease affects wild bird species in the Southern Ocean, we’ll have a better understanding of the likelihood of it reaching New Zealand through migrating birds.
Risks to humans and animals
Human infection with HPAI of any strain is rare. It is usually only found in people who have had a lot of contact with infected birds or other infected animals.
So far, no human-to-human transmission has been reported.
Overseas, some mammals, including dairy cattle in the United States, have been infected after contact with infected birds. With supportive care, infected cattle generally recover in 2 to 3 weeks.
Avian influenza, food safety, and human health
Dairy and other livestock that may be affected by avian influenza
Signs of HPAI
The most obvious sign of HPAI is sudden death in several birds. Other signs in birds can include:
- weakness and trembling
- paralysis
- breathing difficulties
- lack of coordination
- blindness
- diarrhoea.
Poultry may show more severe signs than wild birds, including lethargy, loss of appetite, droopy head, darkened or swollen comb/wattle, panting, nasal discharge, unusual drop in egg production, and bleeding disorders.
Commercial poultry flocks and avian influenza
Domestic poultry and birds and avian influenza
Reporting avian influenza
If you see 3 or more sick or dead wild birds in a group, report it immediately to the exotic pest and disease hotline on 0800 809 966. Do not handle or move the birds.
Provide as much detail as you can, including:
- a GPS reading or other precise location information
- photographs and videos of sick and dead birds
- species name and estimate of the numbers affected
- how many are sick or freshly dead, and the total number of birds present.
We will note the details and an incursion investigator will contact you.
How to report suspected bird flu – fact sheet [PDF, 700 KB]
