Avian influenza (HPAI) and dairy cows

Important information about HPAI H5N1 for dairy and other farmers

New Zealand has never had high pathogenicity avian influenza (HPAI). The likelihood of the introduction of the current H5N1 strain on pathways that we manage is low. As information emerges about the distribution of the disease in Antarctica, we will have a better understanding about the likelihood of HPAI H5N1 reaching New Zealand through wild bird movements.

An incursion of HPAI into New Zealand is likely to come from migratory birds. It could spread to native birds and wildlife through contact with infected birds or contaminated material.

HPAI is not a cattle disease. The situation in the US, where HPAI H5N1 has been detected in a number of dairy herds, is the only known transmission (referred to as ‘spillover’) to cows worldwide. Many other countries that have this virus have not detected spillover to cows. HPAI has not been detected or reported in beef cattle to date. Information from the American Veterinary Medical Association is that most cattle recover in 2 to 3 weeks with supportive care.

Genomics of the virus in dairy cattle in the USA suggests that the infection was from a locally contained spillover event where birds infected cattle on a handful of farms in northern Texas. That has then spread across the country through movement of infected cattle. Spread on farm is probably through human-associated milking practices.

The United States Department of Agriculture (USDA) has identified spread between cows within the same herd, spread from cows to poultry, and cattle movement spread between farms/states. Some cows without clinical signs of disease have tested positive for HPAI. 

The virus has been detected in a small number of dairy farm workers in the United States who had been in close contact with infected cattle. To reduce the risk of infection, the Centers for Disease Control and Prevention (CDC) recommends that livestock farmers and workers should avoid unprotected direct physical contact or close exposure with the following animals and materials potentially infected or confirmed to be infected with HPAI A(H5N1) virus:

sick birds, livestock, or other animals
carcasses of birds, livestock, or other animals
faeces or litter
raw milk
surfaces and water (ponds, waterers, buckets, pans, troughs) that might be contaminated with animal excretions.

It recommends that farmers and farm workers wear appropriate PPE when in direct or close physical contact with sick birds, livestock, or other animals, carcasses, faeces, litter, raw milk, or surfaces and water that might be contaminated.

In April 2024, the USDA issued a federal order requiring cattle to be tested for HPAI and return a negative result before they can be moved between states and mandatory reporting of positive HPAI results.

High pathogenicity avian influenza – information for farmers [PDF, 1.6 MB]

Pasteurisation kills the virus

There is no risk to human health from consuming pasteurised milk and milk products. Repeated testing of milk in the US has confirmed that, although viral fragments may be present in pasteurised milk, pasteurisation kills the virus and these fragments are not infectious.

US authorities have issued caution against consuming raw milk. New Zealand does not import unpasteurised dairy products from the US.

Ongoing monitoring

We are continuing to work with international colleagues to learn everything we can from their experiences and keeping our industry partners, and the dairy community, informed.

We are closely monitoring updates from the World Organisation for Animal Health, the World Health Organization, United States Department of Agriculture (USDA), United States Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC), as well as keeping in regular contact with the US Chief Veterinary Officer. Our industry and scientific communities have close linkages with colleagues in the US.

We encourage all farmers to practice good on-farm biosecurity and be aware of the potential risk should HPAI arrive here.

What we're doing to prepare for HPAI

MPI will be the lead agency if HPAI is detected in New Zealand. We're working with the Department of Conservation, the Ministry of Health and our industry partners to prepare for any detection of HPAI in New Zealand.

Practice good biosecurity

Should HPAI arrive in New Zealand, early detection will help us manage an incursion.

Farmers are advised to be prepared by using good biosecurity practices, monitoring the health of their herds, and seeking veterinary advice if animals become unwell.

By following our biosecurity guidelines including good hygiene practices, you can reduce the risk of pests and diseases on your farm or lifestyle block.

Biosecurity on your farm or lifestyle block

Complete the Dairy NZ Biosecurity Planner to help manage risks on your farm and visit the Dairy NZ website for more dairy-specific information and resources.

Biosecurity Planner ‐ Dairy NZ

Clinical signs of HPAI H5N1 in cattle

Cattle with mild illness show non-specific clinical signs such as decreased milk production, thicker colostrum-like milk, reduced appetite, lethargy, fever and dehydration.

Ways to prevent farm-to-farm bovine spread

keep NAIT (National Animal Identification and Tracing) updated. NAIT is a legal requirement and key to good biosecurity, as it makes it easier and faster to trace animals.
run cattle in management units that don't mix. Minimise introductions and keep any introductions low risk (for example, keep mobs separate for their duration on grazing blocks).
secure boundaries through fencing and due diligence. Make sure nose-to-nose contact is not possible between cattle held on neighbouring properties.
ensure any biological products and equipment you bring on-farm (such as borrowed milk feeding equipment) is clean and disinfected prior to use on your property.

HPAI in birds

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

Poultry show more severe signs than wild birds. These include lethargy, reduced appetite, droopy head, darkened and/or swollen comb/wattle, panting and nasal secretions, unusual drop in egg production and bleeding disorders.

If you notice poultry or domestic birds exhibiting signs of HPAI, contact your veterinarian first to rule out more common avian diseases. Wait for your veterinarian's instructions before handling any sick or dead birds.

If you see 3 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. Do not handle the birds.

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.