Black billed gull
Image: Andrew Walmsley | ©

Avian influenza

Introduction

Avian influenza (also called bird flu) is a contagious viral disease that affects both domestic and wild birds and is caused by avian influenza viruses.

Monitoring of bird populations is part of DOC’s core work. We encourage anyone who sees three or more dead or dying birds, marine mammals or other wildlife to report it to Biosecurity New Zealand: 0800 80 99 66. 

Do not touch or attempt to move any dead or dying wildlife.

On this page:

What is avian influenza?

Avian influenza is a contagious viral disease that affect both domestic and wild birds and is caused by avian influenza (AI) viruses.

Strains of this virus are classed as either low pathogenic (LPAI) - causing no or minimal illness, or highly pathogenic (HPAI) - causing severe illness.

Most wild birds infected with the virus are asymptomatic.

Where avian influenza has been detected

Strains of HPAI have been circulating globally for many years, with many countries having seasonal outbreaks every year. In 2021, a new H5N1 virus emerged in domesticated and wild birds across the northern hemisphere and began to spread. Early detections were seen in United Kingdom, Europe, and the United States, before the disease began spreading further:

  • In 2023, this strain was detected in the southern hemisphere, including in South America.
  • In late 2023, it was detected in the sub-Antarctic island of South Georgia in the South Atlantic Ocean.
  • In February 2024, it was detected in the Antarctic peninsula near South America. 

New Zealand, Australia and the Pacific are currently free of the H5N1 strain of HPAI. New Zealand has never had a case of HPAI and the likelihood of it arriving on pathways that we manage is low.

HPAI is currently spreading internationally in wild birds, which is the most plausible path by which it would reach New Zealand. As information emerges about the distribution of the disease in Antarctica, there will be a better understanding about the likelihood of HPAI reaching New Zealand through wild bird movements.

Once in New Zealand, it could spread by direct contact between infected and healthy birds, or through contaminated equipment and materials, including water and feed.

DOC is working with others to monitor disease spread

We are actively monitoring disease spread, particularly towards the Ross Sea region in Antarctica and globally. We’re talking regularly with colleagues around the world so we can learn as much as we can about how the disease is behaving as it spreads, and what other countries are doing to manage the disease.

International experience has shown that a One Health approach to the current strain of HPAI is essential. If HPAI is detected in New Zealand or its territories, Biosecurity New Zealand will be the lead agency and will coordinate any response in partnership with DOC and the Ministry of Health.

How is avian influenza spread?

Avian influenza can spread by close contact between infected birds and healthy birds or contact with environments, equipment or materials (including water and feed) that have been contaminated with faeces or respiratory secretions from infected birds. It can also spread via ingestion of sick infected birds. 

This highly contagious viral infection can affect all species of birds both wild and domestic. Cases have also been seen in marine mammals including seals and sea lions, predatory land mammals and domestic livestock.

The transmission of avian influenza from birds to humans is rare but the World Health Organisation states HPAI in humans has a 50% mortality rate. People who are in close and repeated contact with infected birds or heavily contaminated environments are at risk of being infected with avian influenza.

What to look out for and how to report it

While there are many other possible causes of illness and death in wild birds, be aware of HPAI so you can minimise risks to yourselves and other animals if you encounter sick or dead birds.

The most obvious sign of HPAI is sudden death in several birds. Other signs can include weakness, tremors, paralysis, difficulty breathing, lack of co-ordination, blindness, trembling and diarrhoea.

HPAI is a notifiable disease and must be reported to MPI.

If you see three or more sick or dead wild birds in a group, report it immediately to Biosecurity New Zealand’s Exotic Pest and Disease Hotline on 0800 80 99 66. Provide as much detail to Biosecurity New Zealand as you can, including:

  • a GPS reading or other precise location information
  • photographs and/or videos of sick and dead birds
  • species identity and estimate of numbers affected
  • note how many are sick or freshly dead, and the total number present.

Biosecurity New Zealand will take details and an incursion investigator will be in contact with you. Follow any instructions from Biosecurity New Zealand for handling of sick or dead birds.

Do not handle sick or dead birds if you suspect HPAI.

What is the risk of avian influenza arriving in New Zealand?

New Zealand has never had a case of HPAI, but low-pathogenicity avian influenza viruses have been detected via surveillance in wild mallard ducks in the past.

A variety of migratory shorebirds do return here and could bring avian influenza. The most numerous shorebirds are the bar-tailed godwit, red knot, ruddy turnstone and Pacific golden plover. The bar-tailed godwit flies directly from Alaska to New Zealand without stopovers. 

Other species may visit estuaries along the Asian coastline, the Philippines and Australia on their annual migrations south from arctic Russia.

Seabirds such as Arctic and pomarine skuas arrive every spring and summer from the Arctic region. Arctic tern, little terns and common terns are also regular annual visitors to New Zealand, and many species of pelagic seabirds breed here after spending winter feeding in the Pacific and Southern Oceans.

Vulnerable New Zealand wildlife species 

We don’t know exactly what impact HPAI would have on native species but, based on overseas evidence, it is likely to affect colony nesting birds such as red and black-billed gulls, gannets, terns and other seabirds.

This virus spreads rapidly through close contact. HPAI is transmitted between colony birds through secretions and faeces, and to predator/scavenger species such as raptors and marine mammals through exposure and consumption.

How can we protect our wildlife?

Management options are limited, bird flu in wild birds is not an eradicable disease. The best way to protect our native birds is to ensure there are strong, healthy populations at multiple locations. This means continuing, and where possible increasing, the great work done by breeding and predator control programmes. We also need to have strong biosecurity and quarantine practices.

Protecting our native birds and other native species is a key focus of our preparedness work for the possibility of high pathogenicity avian influenza (HPAI) coming to New Zealand.

HPAI viruses can cause high numbers of deaths in wild birds, including shorebirds and seabirds. They can also spill over to mammals, including marine mammals.

Vaccine trial

DOC is developing plans to mitigate risks to threatened species should HPAI (highly pathogenic avian influenza, H5N1) arrive in New Zealand including actions to enhance detection, reduce spread and protect threatened species. 

For a few species, using vaccination might be an effective tool during outbreaks to protect a core breeding population to prevent species extinction. It is not possible to vaccinate all our endangered birds, but we can focus on those species in captivity where the full two doses of vaccine can be given.

The Ministry for Primary Industries manages use of HPAI vaccines, which are not commercially available in New Zealand. MPI has granted approval for DOC to use the Poulvac Flufend RG vaccine in a controlled trial to test its safety and efficacy in a select number of endangered native birds. The vaccine contains inactivated (dead) virus that cannot cause a bird flu infection. It has been shown to be safe and effective in zoos in Europe.

The trial is limited to a small number of threatened native species in specified captive facilities. It is being carried out under strictly controlled conditions by DOC.

Five native species have been selected for the vaccination trial, due to their critical conservation status and reliance on captive breeding for species survival: kakī/black stilt, takahē, kākāpō, tūturuatu/shore plover and red-crowned parakeet/kākāriki (as a surrogate species for kākāriki karaka/orange-fronted parakeet).   

The first phase of the vaccine trial on five native bird species is now complete. This involved giving all the birds involved in the trial two doses of the vaccine at least one month apart.

The second phase of the trial is still underway and will be completed by July 2025. This involves regular health assessments and blood tests of the trial birds to monitor their reactions and presence of antibodies.

None of the birds have shown any adverse reaction to the vaccine and initial tests show antibodies have been detected in all five species. However, we need to wait until the trial is complete for a fuller picture and more conclusive results on the potential protection provided by the vaccine against HPAI.

If shown to be effective, the vaccine could be used if HPAI arrived in New Zealand. It would need to be used once HPAI was here to ensure the protection was recent and strong.

Further resources

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