Avian influenza

Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (HA) and neuraminidase (NA). There are 18 known hemagglutinin subtypes and 11 known neuraminidase subtypes. In birds, 16 hemagglutinin and nine neuraminidase subtypes have been identified.

Avian influenza A viruses are classified into two categories:

• low pathogenicity avian influenza (LPAI) A viruses
• highly pathogenic avian influenza (HPAI) A viruses.

The pathogenicity refers to the severity of disease in birds, rather than humans (e.g. LPAI H7N9 has caused serious infections in humans but causes no, or minimal disease in birds). LPAI also have the potential to spontaneously mutate and become HPAI virus variants, causing high mortality in poultry.

HPAI A (H5N1) clade 2.3.4.4b emerged in 2020 and is of particular concern, since it has spread around the world via migratory birds and has been detected in places and in species where it has not previously been reported. This includes mammals such as dairy cows, farmed minks and seals. This strain has now spread to continental Antarctica—any further spread to the Ross Dependency or Aotearoa New Zealand’s sub-Antarctic islands would create an additional plausible pathway for spread to mainland Aotearoa.

Human infections, while uncommon, have occurred sporadically in many countries, usually after unprotected exposures to infected poultry or virus-contaminated environments. A small number of human infections have been attributed to exposure to infected wild birds or dairy cattle, and for some human infections, the source of the virus infection was not determined. Transmission of avian influenza between humans is also rare, with the last reported cases in 2007 (H5) and 2013 (H7) [1]. However, the emergence of HPAI outbreaks in domestic poultry and cattle, high fatality rates in infected poultry, and reported high case-fatality rates (dependant on the subtype) in infected humans, are significant causes for concern.

Both HPAI and LPAI viruses have caused mild to severe illness and death in humans and other mammals, and public health precautions are therefore warranted for any strain that has the potential to transmit to humans and cause disease, regardless of its pathogenicity in birds. Severe human illness has predominantly been associated with HPAI A(H5N1) and A(H5N6), and with avian influenza A (H7N9), but other avian influenza viruses have uncommonly been detected in humans [1]. Infection with the H5N1 strain of HPAI has been reported to have a case fatality rate of approximately 50%. However, due to international variations in the ability to detect cases, many mild cases of H5N1 could be undetected, likely inflating the reported fatality rate.

• For further information on Avian influenza type viruses, visit: Avian Influenza Viruses
• For information on subtypes of avian influenza associated with infections in humans, visit: Reported Human Infections with Avian Influenza A Viruses | Bird Flu | CDC
• For international mapping of recent outbreaks, visit: United Nations Food and Agriculture Organization
• For international risk assessments and summaries of influenza at the human-animal interface, visit: World Health Organization Global Influenza Programme

At the time of publishing this chapter, no animal or human cases of HPAI have been detected in Aotearoa New Zealand.

The H5N1 strain of HPAI has been reported to have a higher death rate among infants and young children [3]. Other avian influenza viruses range in severity in humans, for further information visit: Reported Human Infections with Avian Influenza A Viruses | Bird Flu | CDC

Due to lack of evidence to date, it is unclear which groups may be at higher risk of severe disease for avian influenza infection. In the absence of this information, it is noted that the risk of severe disease with seasonal influenza (including influenza A) is increased in:

• Māori and Pacific peoples aged 55 and over
• people aged 65 years or over
• infants and young children
• people with medical risk factors (see medical risk factors section).

The risk of severe disease with seasonal influenza (including influenza A) is increased among:

• pregnant people and those who have just given birth
• people with chronic health conditions
• people who are immunocompromised
• people with obesity
• people with serious mental health or addiction issues.

The risk of infection has so far almost entirely been confined to people who have prolonged, unprotected exposure to sick or dead birds, other animals with avian influenza, and their environments or materials (e.g. faeces, animal droppings, secretions or potentially raw milk).

Health and safety guidance is being developed for occupational and recreational groups at risk of exposure to avian influenza, which will include advice on personal protective equipment requirements. This guidance will be published in November 2024.

Illness in humans from all avian influenza virus infections ranges in severity, from no symptoms or mild illness to severe disease resulting in death. The spectrum of illness caused by human infection with current H5N1 viruses is unknown. Signs, symptoms and complications are listed in the clinical criteria section. 

Due to the non-specific nature and spectrum of clinical presentations, it is the responsibility of public health staff to apply a high index of suspicion for any symptomatic people with relevant travel/exposure history (i.e. those who meet the epidemiological criteria).

Various avian species (primarily waterfowl, wild gulls, terns and shorebirds) act as reservoirs for avian influenza. However, avian influenza has a wide species range and readily mutates, so what is considered a reservoir for different strains may vary. Poultry and mammalian species, although not considered to be reservoirs, play a significant role in the spread of avian influenza to other animals and humans.

The incubation period in humans will vary according to the specific strain of avian influenza and may range from 1-10 days.

While infection has been predominantly reported in avian species, virus spill over (cross species avian-to-mammal transmission) of H5N1 into mammalian species has been reported, including in dairy cattle, swine and sea lions. The spread of HPAI from animals to humans is rare but can occur if people have close contact or are exposed to an infected animal (e.g. through handling, culling, slaughtering or processing sick or dead animals), or with animal materials (e.g. faeces, droppings, mucus, raw milk from cows), or from an environment contaminated with these materials.

People are exposed when infectious droplets or contaminated dust in the air is inhaled or comes into contact with a person’s eyes, nose, or mouth. Exposure can also occur when people touch contaminated surfaces, objects, or materials and then touch their mouth, nose, or eyes.

There have been no instances of sustained human-to-human transmission detected, however, the occurrence of avian influenza in mammals likely increases the risk of the virus developing the ability to be transmitted from mammal–to–mammal.

Properly cooked meat or poultry products are not sources of infection. But potential transmissibility through uncooked or partially cooked animal food products (e.g. eggs and unpasteurised milk) should be considered. For up-to-date information on food safety and avian influenza, visit: Avian influenza, food safety, and human health | NZ Government (mpi.govt.nz)

There is no evidence of sustained human-to-human transmission documented to date, so the exact infectious period of avian influenza in humans is not clearly defined.

Based on the available evidence from other influenza viral infections in humans, the infectious period is likely to be from one day before symptom onset until seven days after symptoms begin, or until major symptoms have resolved (whichever is the longest). However, long term shedding has been reported (e.g. from children, elderly people or immunocompromised individuals) with the infectious period varying considerably depending on a number of factors, including the person’s overall health, age and immune response. Therefore, the infectious period in these groups should be considered and reviewed by the Medical Officer of Health on a case-by-case basis.

In healthcare settings, standard, airborne and contact infection prevention and control (IPC) precautions are required.

• For more information on each precaution and healthcare IPC information, visit: Avian influenza, food safety, and human health | NZ Government (tewhatuora.govt.nz)
• For more information on each precaution and public health IPC information, visit: Appendix 6: Infection prevention and control guidance.

Health and safety guidance is being developed for occupational and recreational groups at risk of exposure to avian influenza, which will include advice on personal protective equipment requirements. This guidance will be published in November 2024.

Prevention in Aotearoa New Zealand requires a one health approach across multiple agencies. One health is an integrated, unifying approach that aims to sustainably balance and optimise the health of people, animals and ecosystems [4].

Ministry for Primary Industries

• Biosecurity New Zealand (BNZ) and New Zealand Food Safety (NZFS) sit within the Ministry for Primary Industries (MPI) and lead preparedness and response to avian influenza in animals or animal products in Aotearoa. Avian influenza A is notifiable under the Biosecurity Act 1993.
• MPI strictly regulates the importation of animals and animal products (such as live poultry and poultry products).
• BNZ has a number of programmes in place to support early detection of and response to HPAI. For more information, visit: Avian influenza, food safety and human health and Surveillance and planning for avian influenza in New Zealand.

Department of Conservation

• The Department of Conservation monitor bird populations. For more information, visit: Avian influenza.

Health New Zealand | Te Whatu Ora and the Ministry of Health | Manatū Hauora

Both the National Public Health Service (NPHS) within Health New Zealand and the Public Health Agency (PHA) within the Ministry of Health have responsibilities for human public health issues relating to avian influenza.

Public health preventative measures (including border health) include:

• Promotion of health and safety practices, including appropriate use of personal protective equipment (PPE) and hygiene measures for anyone working with potentially infected birds (carried out by NPHS Protection and Health New Zealand Infection, Prevention and Control).
• Weekly horizon scanning for emerging threats and reporting and escalating when indicated (carried out by ESR – the Institute of Environmental Science and Research).
• Standard health messaging at major Aotearoa airports to provide information and promote personal hygiene and appropriate health-seeking behaviour (carried out by NPHS Protection).
• Advice to travellers to practice good hand hygiene and avoid close contact with birds in wet markets or on farms, in countries where avian influenza is endemic in domestic poultry (carried out by NPHS Protection, PHA/Ministry of Health).
• Aircraft and ships coming into Aotearoa from overseas are liable to quarantine (Section 96(2) of the Health Act 1956) until pratique (quarantine clearance) is granted by authorities (Section 98(1) of the Health Act 1956) (carried out by NPHS Protection).
• Border health advisories and alerts to border agencies and frontline border staff (carried out by Ministry of Foreign Affairs and Trade, NPHS Protection).

Surveillance

The Institute of Environmental Science and Research (ESR) coordinates acute respiratory illness surveillance programmes which may incidentally detect cases of avian influenza or identify signals of unusual acute respiratory illness activity, including:

• During the winter illness season, laboratories are asked to send an additional five samples (beyond those already required/requested) per week to ESR for subtyping for H1 and H3, with any non H1/H3 results triggering further subtyping (for H5, H7 and H9).
• Sentinel General Practice Respiratory Surveillance Programme (year-round) - a network of 50-100 general practice clinics around the country who take a respiratory swab from a subset of patients presenting with influenza-like illness (ILI) each week. These swabs are routinely subtyped by ESR as described above.
• Sentinel hospital surveillance – this system monitors patients admitted with severe acute respiratory infection (SARI) to respiratory wards and Intensive Care Units (ICUs) in the Auckland region. Samples are referred to ESR in the same scheme as requested of all laboratories for subtyping.
• Syndromic surveillance within community, hospital and institutional settings aids the detection of unusual acute respiratory illness outbreak activity, which supports the initiation of epidemiological and laboratory investigations. This includes ILI surveillance using Healthline consultations, SARI surveillance in the Auckland region, and EpiSurv-based acute respiratory illness outbreak surveillance.

Vaccination

• Vaccination against any strain of avian influenza is not on the routine immunisation schedule in Aotearoa (or any country globally). The National Reserve Supply has stocks of vaccines that are expected to have efficacy against the current strain of H5N1. However, this is based on laboratory experiments, with no human trials having taken place.
• Seasonal influenza vaccination is recommended for workers at risk of exposure to avian influenza (See page 148 of the Immunisation Handbook 2024). While the seasonal human influenza vaccine does not provide protection from avian influenza, it protects against seasonal influenza, and therefore reduces the risk of co-infection, reducing the risk of viral reassortment to produce a new and highly infectious virus (as was likely the trigger in the 2008/09 H1N1 swine flu pandemic).

Confirmed: A person that has laboratory definitive evidence.

Probable: A clinically compatible illness in a person who meets the epidemiological criteria and has laboratory suggestive evidence.

Under investigation: A clinically compatible illness in a person who has been notified and meets the epidemiological criteria (i.e. a suspected case), but information is not yet available to classify further. This includes positive influenza A results where subtyping is outstanding.

Not a case: A person that has been investigated and subsequently found not to meet the case definition.

Symptoms of avian influenza in humans may range from no symptoms or mild illness to severe illness or death.

Signs and symptoms include, but are not limited to:

• fever
• upper respiratory tract symptoms (cough, sore throat, runny nose)
• lower respiratory tract symptoms (shortness of breath, pneumonia)
• gastrointestinal symptoms
• conjunctivitis
• muscle or joint pain
• headache
• fatigue
• other severe or life-threatening illness suggestive of infective process (e.g. altered mental status, seizures, hypoxaemia (low blood oxygen), acute respiratory failure, multi-organ failure, sepsis, meningo-encephalitis).

The below epidemiological criteria have been developed for the current situation of no human-to-human transmission. However, it will be reviewed and updated should the epidemiological situation or risk level increase.

Close contact or exposure (shared indoor airspace, or if outside, within 2 metres) with any of the following within 10 days prior to symptom onset. 

 1) Animals, animal fluids or faeces, or their environments suspected to be infected with avian influenza, including:

• Live, sick or dead domestic poultry or wild birds, including live bird markets, in an area affected by avian influenza.* 
• Any infected animal with confirmed avian influenza, or a high index of suspicion of avian influenza.
• Environments contaminated with faeces or droppings, bodily fluids, unpasteurised (raw) milk or other unpasteurised dairy products, or animal parts (e.g. carcasses, internal organs) in an avian influenza affected area and species.*
• Consuming raw or undercooked poultry, eggs or unpasteurised (raw) milk products from an area affected by avian influenza.*

2) Humans with suspected or confirmed avian influenza infection, or their clinical samples, including:

• A confirmed, probable or suspected human case of avian influenza
• A human case(s) with severe unexplained respiratory illness, or severe illness of unknown aetiology resulting in death, who has been in an avian influenza affected area.*
• Close contact with a human case in a healthcare setting, including directly providing care, touching a case, or being in close vicinity to an aerosol generating procedure during their infectious period.

Co-travellers on public transport (e.g. flights, buses etc.) used by a case during their infectious period should be assessed on a situation-by-situation basis by a medical officer of health, supported by the NPHS Protection Clinical team and/or Clinical and Technical Advisory Group). 

*A map showing recent outbreaks is available from the United Nations Food and Agriculture Organization. Affected areas will be designated by Ministry of Primary Industries (generally within 10 kilometres of domestic poultry outbreak and 50 kilometres of infected wildlife outbreak). Discuss with NPHS Protection Clinical on call if uncertain.

Laboratory definitive evidence: Laboratory confirmation requires identification of an avian influenza virus by at least one of the following.

• Detection of an avian influenza A specific subtype (H5, H7 or H9 antigen) by real time polymerase chain reaction (PCR) testing. 
• Four-fold rise in avian influenza virus-specific neutralising antibodies.
• Whole genome sequencing identification of an avian influenza virus.

Laboratory suggestive evidence: Confirmation of an influenza A infection by polymerase chain reaction (PCR) testing but further subtyping for confirmation of avian influenza has not been possible.

Laboratory confirmation should be urgently sought to confirm all cases under investigation.

Testing of asymptomatic people for avian influenza virus infection is not routinely recommended.

Ensure the attending health provider consults with microbiology (or virology, where available) and infectious disease specialists prior to testing and for guidance regarding packaging and transportation of samples. Advise the requester of the test to record ‘suspected avian influenza’ on the laboratory form.

Polymerase chain reaction (PCR) testing is the primary diagnostic tool. Laboratory confirmation requires a PCR positive result for non-seasonal influenza (i.e. H5,7,9). Interpretation of test results should be in consultation with microbiology.

Cases will be managed in a hospital setting initially; therefore, it is expected that samples will initially be taken in a hospital setting.

At present, diagnostic laboratories around the country generally employ influenza PCR testing that detects the presence of influenza A with a high degree of sensitivity and specificity. However, these tests do not distinguish between seasonal influenza and avian influenza subtyping. An avian influenza-specific PCR is required for H5, H7 or H9 detection, and whole genome sequencing is required for other emerging subtypes (e.g. H10).

Where there is reasonable suspicion that the person has avian influenza (e.g. in a person meeting the epidemiological criteria), influenza A positive samples should be subtyped. Some, but not all local laboratories routinely subtype a proportion of influenza A samples for H1 and H3, with any non H1/H3 results triggering further subtyping (for H5, H7 and H9).

However, generally subtyping will not automatically occur—the healthcare worker carrying out testing should write ‘suspected avian influenza’ on the lab form, and the local clinical microbiologist should be consulted prior to sending any samples. Local laboratories should send samples that test positive for influenza A to ESR for further subtyping.

Specific H5, H7 and H9 PCR subtyping is currently available at the WHO National Influenza Centre national reference laboratory operated by ESR, and a limited number of other laboratories (See Appendix 4: Direct laboratory notification of communicable diseases flowcharts). Avian influenza-specific PCR testing is the primary diagnostic tool. On detection, further investigation is likely to include whole genome sequencing. In rare circumstances, serological testing may be considered if indicated by clinical microbiology and ESR. Neutralising antibody testing may be performed in Australia.

HPAI and LPAI (as non-seasonal influenza types capable of transmission between humans) are notifiable diseases. The notification pathway (including a direct lab notification, or notification from a healthcare provider) is the primary mechanism by which public health services will become aware of a human case.

On receiving the notification, the PHS should ensure that the:

• attending health provider notes avian influenza risk factors (such as recent travel history to avian influenza affected countries and occupation) and ‘suspected avian influenza’ on the laboratory form, so that if influenza A positive, further subtyping will be undertaken
• local clinical microbiologist and infectious disease specialists have been notified. Suspected cases reported by community health practitioners will require urgent liaison with local microbiology teams to arrange laboratory testing for influenza, since this is not available in the community. See Laboratory Testing for more details on testing.
• suspected case has been advised to isolate until their results are known.

Ensure complete case information is entered into the appropriate surveillance database for notifiable diseases (i.e. EpiSurv or Notifiable Disease Management System (NDMS)).

A single case of avian influenza in humans, or an animal case of any strain that has the potential to cause disease in humans, would require immediate escalation via the Escalation pathways. Following escalation:

• the NPHS Public Health Emergency Management (PHEM) team would coordinate any public health response required, which may include standing up an Incident Management Team. The response could be led regionally or nationally, depending on what is most appropriate.
• a Clinical and Technical Advisory Group (CTAG) would be stood up to provide expert guidance and support to the public health response.
• the NPHS Protection Clinical team will notify the Office of the Director of Public Health and activate the Escalation pathways (including notifying, when necessary, New Zealand’s International Health Regulations National Focal Point team at the Ministry of Health who would then notify the World Health Organization).

Internal NPHS notification pathways are detailed in the Escalation pathways summary.

For notification pathways between agencies, see Appendix 2 of the HPAI incursion health sector framework.

The Ministry of Health’s International Health Regulations National Focal Point must notify the World Health Organization (WHO) of events involving human influenza caused by a new subtype. The National Focal Point must also use the International Health Regulations Decision Instrument (see Annex 2 of the International Health Regulations) for any unusual or potentially serious public health event, and then notify WHO if required.

The National Focal Point will notify the WHO as soon as possible and no later than 72 hours after receiving notification of the case.

People under investigation, probable and confirmed cases where there is a moderate or high index of suspicion of avian influenza are considered urgent and should be managed as the highest priority, and therefore actioned within 2 hours during 0800-2100 hours 7 days a week. If notification is received outside of these hours, it should be actioned immediately the following day. Escalation via escalation pathways should take place within 2 hours of notification.

Since Aotearoa New Zealand has never had a case of avian influenza, and infection poses pandemic potential, any cases should be rigorously and urgently investigated for potential human-to-human transmission (through case investigation and active case finding, contact tracing, and laboratory investigation). If recent overseas travel has been reported, liaison with the National Focal Point will be necessary (see Escalation pathways for an overview of this process).

Where animal infections or transmission between animals and humans has been identified, public health services should urgently begin case finding and active surveillance of people who were exposed to the infectious source (e.g. poultry or wild avian birds) and continue active surveillance of these people for the duration of their infectious period.

This approach will be reviewed and updated to support any situational changes required.

When following up with cases, it is important to engage with manaakitanga (kindness and respect), to build a relationship with the case to understand what matters to them and what can be done to support them through their isolation period.

For more information on this approach see the Equity and Te Tiriti o Waitangi and Māori Health chapters.

For more information on accessing manaaki (support) and welfare assistance, see the Manaaki and Welfare Appendix.

Wherever possible, all relevant clinical and demographic information on a case under investigation should be collected by public health staff on the same day as notification.

Case investigation and interview should include gathering information on symptom history (including onset date), travel history, occupation, and timing and duration of exposure to epidemiological criteria.

Use the Case Investigation Questionnaire (see Attachment 1).

Location

Cases will initially be managed in a hospital setting. Suspected, probable and confirmed cases should immediately be isolated in a single room (ideally a negative pressure/respiratory isolation room).

If cases have been discharged from hospital and are isolating at home for the remainder of their infectious period, guidance for managing isolation at home should be followed (see Appendix 6: Infection, prevention and control guidance).

A broader summary of guidance for the case will also be provided in the Case Information Letter.

Isolation period

All cases and persons under investigation should isolate for the duration of their infectious period (from 1 day before, until 7 days after symptom onset, or until major symptoms have resolved—whichever is the longest), or until laboratory testing confirms they are not a case. A post viral cough may persist beyond 7 days, and by itself does not require continued isolation. Cases who have been discharged from hospital must continue to isolate until the end of their infectious period.

Release from isolation for cases who remain hospitalised, or who are immunocompromised, will require consideration on a case-by-case basis (by infection prevention and control, infectious diseases, microbiology, and public health staff).

For cases who work in a healthcare setting, their return to work should be discussed with their local occupational health team. Generally, if major symptoms have resolved, cases can return to work in healthcare settings after completing the recommended 7-day isolation period, but should wear a correctly fitted seal checked FFP2 or N95 particulate respirator until 10 days after their symptoms first started.

Precautionary measures

In a healthcare setting, in addition to standard precautions, airborne and contact precautions should be used for all suspected, probable and confirmed cases during their infectious period. The minimum personal protective equipment (PPE) to be worn by healthcare staff and visitors is a correctly fitted seal checked FFP2/N95 particulate respirator (preferably fit tested), gown, gloves and eye protection. For healthcare IPC information, visit: Infection prevention and control – Health New Zealand | Te Whatu Ora

Staff and other patients should have minimal contact or exposure with cases while they are infectious and cases should wear a surgical mask (if possible) whenever someone enters the room, or if they are transferred to another area. A case’s requirement to wear a surgical mask must never compromise their care.

During the case’s infectious period:

• visitors should be restricted to only essential visitors (who should wear the minimum PPE items defined above)
• a list of all contacts should be kept by healthcare staff
• linen should be treated as infectious
• waste should be treated as clinical waste and disposed of responsibly.

Treatment of the case is the responsibility of the attending clinician, in consultation with infectious disease and microbiology specialists.

Any person who meets the confirmed, probable or under investigation case definition for avian influenza should start antiviral treatment immediately (oseltamivir as first line), ideally within 48 hours of symptom onset and not wait for laboratory confirmation.

Beginning treatment later than 5 days after symptom onset is unlikely to provide any benefit to those with mild illness (i.e. cases who are well enough to be managed in the community), but it is recommended for people who are hospitalised or immunocompromised. Treatment can be stopped if tests return negative.

Provide the case with the case information letter and avian influenza information sheet which provides guidance about avian influenza, isolation requirements and precautions that can prevent transmission to others. Aim to provide information in an accessible format.

For cases that have been discharged from hospital, active daily follow up should be undertaken by the public health service until the end of the isolation period. The daily follow-up should include checking:

• on symptoms
• they can successfully isolate at home for the duration of their isolation period
• overall wellbeing (e.g. directing the case to services that can provide them with welfare support if needed).

If the case interview conducted by public health staff identifies that local transmission of avian influenza is possible, a thorough review of potential contributing environmental factors should be undertaken. Where relevant, strong collaboration between animal and human health agencies, and the employer (or WorkSafe) is paramount for an effective environmental evaluation and response. Mana whenua, the indigenous people (Māori) who have historic and territorial rights over the land, also have a special cultural and spiritual relationship with the environment and have a leading role in managing their environments. Formal mechanisms should be established for mana whenua to participate in any environmental response and evaluation. 

See ‘Roles and responsibilities’ for practical guidance on roles and responsibilities in environmental investigation and the HPAI Incursion Health Sector Framework for roles and responsibilities within the health sector.

If transmission is thought to be avian/other animal-related, environmental assessment including review of opportunities for exposure to infected animals should be led by MPI (and appropriate control measures introduced). See ‘Referrals’ section for details on how information is shared between agencies.

If health care-associated infection is suspected, infection prevention and control staff in conjunction with public health staff should lead an environmental investigation for any healthcare setting exposures. If transmission is thought to be food related, New Zealand Food Safety should lead the investigation and control measures.

All staff conducting the environmental evaluation (e.g. MPI staff carrying out sampling or inspection of animals) must have a thorough understanding of infection prevention and control practices and be competent in using personal protective equipment. Health and safety guidance is being developed for occupational and recreational groups at risk of exposure to avian influenza, which will include advice on personal protective equipment requirements. This guidance will be published in November 2024.

If there is a chance anyone conducting the environmental evaluation will be at risk of exposure to avian influenza, seasonal influenza vaccination is recommended (See page 148 of the Immunisation Handbook 2024).

If anyone conducting the environmental evaluation experiences avian influenza symptoms, they should isolate and seek immediate medical assessment.

See contact management for guidance on management of exposed workers.

Where transmission has been identified from animals-to-humans, public health services (PHS) should undertake active case finding to search for other people who were exposed to the infected animal(s) and initiate active surveillance of these people for the duration of the infectious period.

The local PHS has responsibility for risk-assessing and managing all contacts and exposed people when a case or outbreak of avian influenza has been reported. The PHS will be supported by national teams and can liaise with local providers and support services (including Hauora Māori providers and Iwi) as needed. The case interview should investigate information regarding exposure events and exposed persons or contacts to assist with contact tracing.

For wild birds or other wild animals with avian influenza: Where there is a risk of avian influenza exposure, such as collection of birds for surveillance or vaccination and carcass disposal, the Ministry for Primary Industries (MPI) is responsible for sharing details of the people involved in response activities, with the relevant local PHS for follow up.

For birds or other animals in industry settings with avian influenza (ie poultry or dairy farms): The employer is responsible for sharing details of exposed persons with the relevant PHS for follow up.

For birds or other animals in domestic settings with avian influenza (ie backyard poultry): The local PHS should work with MPI and the owner to identify exposed persons for follow up.

Identification of people exposed to animal cases or outbreaks should include all people who have been exposed to the infected animals during the high-risk window (defined by MPI and animal health experts in the Clinical Technical Advisory Group for each case or outbreak). Risk assessment and management of all exposed persons should be undertaken (see contact management).

For human case exposure events of avian influenza: The local PHS has responsibility for identifying, risk assessing and managing all contacts.

Avian influenza Health and Safety Guidance (Health and safety guidance is being developed for occupational and recreational groups at risk of exposure to avian influenza, which will include advice on personal protective equipment requirements. This guidance will be published in November 2024) describes health and safety measures for staff responding to an exposure event, including what personal protective equipment (PPE) must be worn. These measures should be followed by any public health teams visiting infected premises. All staff responding to the exposure event must have a thorough understanding of infection prevention and control practices and be competent in using PPE. If staff responding to an exposure event experience avian influenza symptoms, they should isolate and seek immediate medical assessment.

See contact management for guidance on management of exposed workers.

Contact: Any person with contact (shared internal space, or within 2 metres outdoors) with a human case of avian influenza (suspected, probable, or confirmed), their secretions or their laboratory samples during their infectious period.

Exposed person: Any person with close contact with any animal, animal materials (faeces, droppings, bodily fluids, unpasteurised milk, or animal parts) or contaminated environment that is confirmed or highly suspected to be infected with avian influenza during the high-risk window.* 

*High risk window defined by Ministry for Primary Industries (MPI) and animal health experts in Clinical Technical Advisory Group (CTAG) for each case or outbreak.

A risk assessment (using Attachment 2) should be undertaken on all people identified through contact tracing to meet the contact definition. Following this assessment of duration, degree and type of exposure, contacts can then be categorised by high, medium and low exposure risk (see Table 1) and managed accordingly (see Table 3).

A risk assessment (using Attachment 3) should be undertaken on all people identified to meet the exposed person definition. Following this assessment of duration, degree and type of exposure, exposed persons can then be categorised by high, medium and low exposure risk (see Table 2) and managed accordingly (see Table 4).

Avian influenza can be severe or life-threatening and close contacts and exposed persons may be distressed. A manaaki first approach where the needs and priorities of whānau and friends of the case are understood first will help with finding the most effective approach to follow up.

For more information on this approach see the Equity and Te Tiriti o Waitangi and Māori health chapters. For more information on accessing manaaki (support) and welfare assistance, see the Manaaki and Welfare Appendix.

Identification and risk assessment of contacts and exposed persons is a high priority (i.e. this should be initiated on the same day).

High risk contacts and exposed persons should be managed (assessed, offered post-exposure prophylaxis if appropriate and active monitoring commenced) within one day. 

On notification of a probable, confirmed or under investigation case of avian influenza, all persons meeting the contact or exposed person definition should be identified through the Case Investigation Questionnaire. Contact tracing should begin with the support of Occupational Health and Infection Prevention and Control teams for human contacts, and Ministry for Primary Industries (MPI), workplaces and domestic animal owners for people exposed to animal cases. Risk assessment (using attachment 2 and attachment 3) for identified contacts and exposed persons should be undertaken to assess and categorise exposure risk. If an individual is both a contact and an exposed person (i.e. they work at a poultry farm and there are chicken and human cases, and they are exposed to both) then both attachment 2 and attachment 3 should be used. 

In some regions, hospital occupational health services may be able to assist public health services with contact tracing and contact monitoring for staff. Public health services should check with their local occupational health colleagues to see if they have capacity to assist.

Contacts and exposed persons are not required to quarantine.

Contacts and exposed persons who are assessed as being at high risk of exposure should avoid high risk settings (farms/animal shows, healthcare settings, large gatherings) and interactions with individuals at higher risk of severe illness (e.g. immunosuppressed, pregnant people, the very young and old) for 10 days after exposure (see ‘Table 3: Management of contacts of human cases’ and ‘Table 4: Management of persons exposed to animal cases’).

Management of contacts and exposed persons

Management of asymptomatic contacts and exposed persons includes:

• assessment for chemoprophylaxis or treatment (see Table 3 and Table 4)
• provision of appropriate education and advice (see advice to contact)
• recommending people assessed as high exposure avoid high-risk settings and individuals at higher risk of severe illness (see Table 3 and Table 4)
• arranging active or passive monitoring

Testing of asymptomatic contacts and exposed persons is not routinely recommended.

Management of symptomatic contacts or exposed persons includes:

• urgent assessment as a case under investigation if a contact or exposed person develops symptoms.
• advise to self-isolate while arrangements are rapidly made for clinical assessment and investigation
• commencement of treatment for avian influenza (with an appropriate antiviral agent as advised by the attending clinician in consultation with infectious disease specialists) ahead of laboratory confirmation
• contact tracing and informing contacts about monitoring of symptoms.

Interim guidance for accessing antiviral post-exposure prophylaxis

Currently oseltamivir (the recommended antiviral for treatment and post-exposure prophylaxis unless contraindications exist) is restricted by Pharmac for use on hospitalised patients only. 

Health NZ and the Ministry of Health are working with Pharmac to extend access of oseltamivir to include post-exposure prophylaxis for contacts of avian influenza, and treatment of non-hospitalised avian influenza cases.

An outcome is expected by November 2024; following this the avian influenza chapter of the CDC Manual will be updated and communicated to Public Health Services. Should antivirals be needed prior to this, please contact the national protection clinical team for guidance.

Antiviral post-exposure prophylaxis with oseltamivir is recommended for contacts or exposed persons assessed as high exposure risk (see Table 3 and Table 4). Antiviral prophylaxis should be started as soon as possible (ideally within 48 hours of exposure) but can be started up to 7 days after the last exposure. Post exposure prophylaxis should be provided for 10 days for time-limited exposures. If the exposure is ongoing, a longer duration may be recommended—discuss with national Protection Clinical team and local Infectious Disease team. Any contacts taking prophylaxis will still need to avoid high risk settings and individuals at higher risk of severe illness for 10 days following exposure.

Pre-exposure prophylaxis (e.g. for workers prior to commencing decontamination or culling) is not routinely recommended.

Forms for prescribing antivirals, checking for contraindications or special dosage, and obtaining consent will be available in the near future (as of October 2024).

The recommended oseltamivir regimen for adults, or children >40kg is 75mg orally once daily for 10 days. Prescribers should ensure they have read up to date medsafe guidance prior to prescribing oseltamivir. If oseltamivir is contraindicated, or a special dosage is required due to renal impairment or paediatric use, discuss with the local Infectious Disease team.

The recommended oseltamivir regimen for chemoprophylaxis for close contacts of cases of A(H7N9) is different to other avian influenza strains. This is based on virological evidence of oseltamivir resistance in cases of A(H7N9) and is in line with CDC and UKHSA guidance. The recommended oseltamivir regimen for H7N9 for adults or children >40kg is 75mg orally twice daily for 5 days.

Ensure that the contact or exposed person is aware of any restriction requirements and the infection prevention and control practices and precautions that can prevent the transmission of avian influenza. Provide them with the appropriate contact management letter and information sheet, aiming to ensure information provided is accessible.

The letter includes information about:

• avian influenza - what is it, transmission, symptoms
• what to do if symptoms occur
• post-exposure prophylaxis (if prescribed)
• any restriction advice (if applicable)
• information about active or passive monitoring (if applicable)
• advice on minimising further exposure
• contact details for public health services.

The detection of a single human case of avian influenza should prompt an urgent investigation, including the prioritised investigation of illness arising within a defined time, place and population based on the case epidemiology.

An outbreak of avian influenza is defined as two or more human cases associated in time, place or person. As with cases, any suspected outbreaks of avian influenza must be immediately reported to the local medical officer of health and entered into the appropriate surveillance database for notifiable diseases (i.e. EpiSurv or NDMS). Escalation to a national level and the World Health Organization will occur as described in the following section ‘Notification and reporting’.

An outbreak may be declared over 20 days (two maximum incubation periods) after the last day of the infectious period of the most recent case, or from the date of isolation of that case if standard, airborne and contact precautions (see Appendix 6 Infection prevention and control guidance) have been implemented and with no breaches occurring. However, this should be considered in the context of outbreak epidemiology and features of the response. Various factors, including evidence suggesting undetected transmission, may extend this.

Any avian influenza outbreak in animals that has the potential to cause disease in humans should activate a public health response.

The highest priority areas of focus should be primary prevention (including infection prevention and control, and antiviral post-exposure prophylaxis), case finding, risk assessment, management of cases and exposed persons and public education.

Successful containment of a case or outbreak requires a one health response between Health New Zealand, the National Public Health Service (NPHS), Ministry of Health, Ministry for Primary Industries (MPI), Department of Conservation (DOC) and affected animal industries. In the event of an avian influenza outbreak in animals, with sporadic human cases but no sustained human-to-human transmission, MPI have responsibility for leadership of the outbreak response, with NPHS managing human cases, and DOC supporting wildlife. Depending on the strain of avian influenza involved, animal health response activities will differ from outbreak to outbreak.

The HPAI Incursion Health Sector Framework is a joint Ministry of Health and Health New Zealand framework to prepare for and respond to a case or outbreak of avian influenza, and provides an overview of key health sector activities at different public health risk levels.

In the event of sustained human-to-human transmission, Ministry of Health would provide leadership of an All of Government response, with Health New Zealand leading the operational health response. The New Zealand Influenza Pandemic Plan sets out the All-of-Government measures to be taken to respond to an influenza pandemic.

For a step-by-step guide to the basics of disease outbreak management and a reference guide to specific aspects of outbreak management see the ESR Guidelines for the investigation and control of disease outbreaks.

Legislation and use of statutory powers

Health Act 1956

The Health Act 1956 provides the main legislative basis for the surveillance and management of infectious diseases in humans. For an incursion scenario, this will largely be the legislation under which risk to humans is managed. The Health Act enables Medical Officers of Health and other statutory officers or delegates to undertake functions such as case investigation, contact tracing, isolation/quarantine and preventing certain activities.

Epidemic Preparedness Act 2006

The Health Act 1956 specifies a list of quarantinable diseases, an outbreak of which may trigger the declaration of an Epidemic Notice and other actions under the Epidemic Preparedness Act 2006. HPAI is a quarantinable disease as it is encompassed by the definition of “Avian influenza (capable of being transmitted between human beings)”—this means that an Epidemic Notice may be declared in response to an outbreak of HPAI. The declaration of an Epidemic Notice is one of the triggers for Section 70 and 71 of the Health Act to be activated, which expands the usual suite of powers available to medical officers of health.

See HPAI incursion health sector framework Appendix 2 for notification pathways between agencies.

The avian influenza health sector Incident Management Team will include Ministry for Primary Industries, Department of Conservation and WorkSafe representation (where relevant).

[1] Reported Human Infections with Avian Influenza A Viruses | Bird Flu | CDC

[2] Natural History of Influenza Infection in the Severely Immunocompromised vs Nonimmunocompromised Hosts | Clinical Infectious Diseases | Oxford Academic (oup.com)

[3] cumulative-number-of-confirmed-human-cases-for-avian-influenza-a(h5n1)-reported-to-who--2003-2024.pdf

[4] One health (who.int)

• Ministry of Health. 2017. New Zealand Influenza Pandemic Plan Wellington: Ministry of Health.
• Ministry of Health and Health New Zealand 2024. Highly Pathogenic Avian Influenza (HPAI) Incursion Health Sector Framework
• Avian influenza Health and Safety Guidance (Health and safety guidance is being developed for occupational and recreational groups at risk of exposure to avian influenza, which will include advice on personal protective equipment requirements. This guidance will be published in November 2024)

Updated information on circulating subtypes and affected species is available from:

• 2020-2024 Highlights in the History of Avian Influenza (Bird Flu) Timeline | Bird Flu | CDC
• Avian Influenza - WOAH - World Organisation for Animal Health
• High pathogenicity avian influenza information - H5N1 global outbreak (wildlifehealthaustralia.com.au)

This chapter is guided by avian influenza guidance from the following countries:

• The UK Health Security Agency, Managing the human health risk of avian influenza in poultry and wild birds, Guidance for health protection teams, Jan 2023 and,
• The Centers for Disease Control and Prevention, Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations, March 2024 and,
• British Columbia Centre for Disease Control, Communicable Disease Control Chapter I – Management of Specific Diseases Interim H5N1 Avian Influenza Outbreak June 2023 and,
• European Centre for Disease Prevention and Control. Investigation protocol for human exposures and cases of avian influenza in the EU/EEA; 2023
• Communicable Disease Network Australia, Avian influenza in humans – CDNA National Guidelines for Public Health Units, 2015

• Case Investigation Questionnaire (Attachment 1)
• Initial Risk Assessment Form for Contacts (Attachment 2)
• Initial Risk Assessment Form for Exposed Persons (Attachment 3)
• Infection prevention and control guidance (CD Manual Appendix 6 – to be updated soon)
• Case and Contact Management Material (to be developed soon and likely stored on Pikau)
• Highly Pathogenic Avian Influenza (HPAI) Incursion Health Sector Framework
• Escalation pathways (CD Manual Appendix 5)
• Forms for prescribing antivirals (to be developed soon and likely stored on Pikau)
• Forms for checking for contraindications or special dosage for antivirals (to be developed soon and likely stored on Pikau)
• Form for obtaining consent for antiviral prophylaxis (to be developed soon and likely stored on Pikau)
• Process for obtaining antivirals (to be developed soon and likely stored on Pikau)
• Template Avian Influenza Case Investigation Checklist