Highly pathogenic avian influenza

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[Shore birds - Image – Guy Weerasinghe]

Background

Avian influenza is a global viral disease of birds and there are many strains of the virus that cause infections of differing severity, and all bird species are considered vulnerable to avian influenza. High pathogenicity avian influenza (HPAI) viruses are associated with severe disease and high mortality in poultry. HPAI H5N1 clade 2.3.4.4b is the predominant strain causing recent outbreaks globally.

Avian influenza viruses (both low pathogenicity and high pathogenicity strains) have also been known to infect other animal species overseas. Spill over infections of the H5N1 strain of HPAI virus in non-avian animal species such as pigs, tigers, leopards and domestic cats have been reported in some countries.

Australia’s largest outbreak of HPAI viruses (H7 subtypes) occurred in Victoria in 2020, and after successful eradication Australia has been free of HPAIs since February 2021. However, ongoing outbreaks of H5N1 globally have increased Australia’s level of risk for incursions of HPAI viruses of global concern. Migratory birds returning to Australian shores annually between September and November may introduce HPAI viruses.

Avian influenza is a national notifiable emergency animal disease (EAD) and any unusual bird deaths must be reported to the Emergency Animal Disease Hotline on 1800 675 888. This number will connect you with your state or territory’s department of primary industries or agriculture.

Latest updates:

For the latest updates and further information about HPAI visit:

The Wildlife Health Australia website: https://wildlifehealthaustralia.com.au/Incidents/Incident-Information/high-pathogenicity-avian-influenza-information

The Department of Agriculture, Fisheries and Forestry (DAFF) website: https://www.agriculture.gov.au/biosecurity-trade/pests-diseases-weeds/animal/avian-influenza

The World Organisation for Animal Health (WOAH) situation reports website: https://www.woah.org/en/disease/avian-influenza/#ui-id-2

For information on current emergency animal disease (EAD) outbreaks in Australia along with an overview of emerging risks, visit the Outbreak website: https://www.outbreak.gov.au/

Zoonotic disease:

Avian influenza is a zoonotic disease and is potentially fatal to humans. The disease can be passed from birds to humans who are in close contact with poultry or other birds. In Australia, there is minimal risk of people being affected by avian influenza viruses through normal contact with birds, however it is important to always practice good personal hygiene when handling birds.

For more information about avian influenza in humans, visit the Department of Health and Aged Care website:  https://www.health.gov.au/diseases/avian-influenza-in-humans-bird-flu

Good biosecurity practices are the key to preventing the spread of avian influenza in poultry species and are critical in combating any incursion. The following information about bird biosecurity is a valuable resource to make clients aware of: https://www.agriculture.gov.au/biosecurity-trade/pests-diseases-weeds/protect-animal-plant/bird-owners

Key information about the clinical signs:

The clinical signs of avian influenza in birds are variable and depend on a range of factors including the virulence of the virus, the species and age of the birds infected, the presence of concurrent diseases, and the environment. In severe forms, such as H5N1 infection, the disease appears suddenly and birds die quickly.

HPAI should be considered as a differential diagnosis in the following scenarios for wild birds:

  • Small groups or clusters (5 or more) of sick or dead wild birds of any species.
  • Individual or <5 sick or dead wild birds:
    • seabirds, waterbirds, shorebirds or birds of prey
    • any other bird species with signs of avian influenza infection as outlined below.

Infected live birds may show a wide range of clinical signs, including:

  • Neurological signs (ataxia, paralysis, seizures, tremors, abnormal posture)
  • Respiratory signs (conjunctivitis, increased nasal secretions, oedema of the head, dyspnoea)
  • Gastrointestinal signs (diarrhoea)
  • Sudden death

Some species may be asymptomatic or show only very mild clinical signs. In some cases, birds may die suddenly without displaying any clinical signs.

High Pathogenicity Avian Influenza and Wild Birds - Advice for veterinarians and animal health professionals: https://wildlifehealthaustralia.com.au/Portals/0/Incidents/HPAI_Advice_for_veterinarians_and_animal_health_professionals.pdf

Emergency animal diseases: A field guide for Australian veterinarians https://www.outbreak.gov.au/prepare-respond/identify-pests-diseases/emergency-animal-diseases-field-guide

[Eastern Curlews - Image - Guy Weerasinghe]

Useful resources:

Wildlife Health Australia https://wildlifehealthaustralia.com.au/Incidents/Incident-Information/high-pathogenicity-avian-influenza-information

Antarctic HPAI monitoring project: https://scar.org/resources/hpai-monitoring-project/

World Organisation for Animal Health (WOAH) https://www.woah.org/en/disease/avian-influenza/

CSIRO https://www.csiro.au/en/research/animals/veterinary/tracking-avian-influenza

Queensland Government https://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/biosecurity/animals/diseases/guide/avian-influenza#

New South Wales Government https://www.dpi.nsw.gov.au/animals-and-livestock/poultry-and-birds/health-disease/avian-influenza

Victorian Government https://agriculture.vic.gov.au/biosecurity/animal-diseases/poultry-diseases/avian-influenza-bird-flu

South Australian Government https://pir.sa.gov.au/biosecurity/animal_health/animal_species/poultry/avian_influenza#

Western Australian Government https://www.agric.wa.gov.au/livestock-biosecurity/avian-influenza

Tasmanian Government https://nre.tas.gov.au/biosecurity-tasmania/animal-biosecurity/animal-health/poultry-and-pigeons/avian-influenza

Northern Territory Government https://health.nt.gov.au/public-health-notifiable-diseases/avian-influenza

Further learning and networking:

Join the Commercial Poultry Veterinarians group: https://www.ava.com.au/about-us/ava-groups/poultry/

Join the Australian Veterinary Conservation Biology group: https://www.ava.com.au/about-us/ava-groups/conservation-biology/

Join the Unusual Pet and Avian Veterinarians group: https://www.ava.com.au/about-us/ava-groups/unusual-pet-avian/

Join the Australian Veterinarians in Public Health group: https://www.ava.com.au/about-us/ava-groups/public-health/

PDF resources side bar:

High Pathogenicity Avian Influenza and Wild Birds - Advice for veterinarians and animal health professionals: https://wildlifehealthaustralia.com.au/Portals/0/Incidents/HPAI_Advice_for_veterinarians_and_animal_health_professionals.pdf

National Wildlife Biosecurity Guidelines – Wildlife Health Australia: https://wildlifehealthaustralia.com.au/Portals/0/ResourceCentre/BiosecurityMgmt/National_Wildlife_Biosecurity_Guidelines.pdf

Avian influenza in wild birds in Australia fact-sheet – Wildlife Health Australia: https://wildlifehealthaustralia.com.au/Portals/0/ResourceCentre/FactSheets/Avian/Avian_Influenza_in_Wild_Birds_in_Australia.pdf

Highly pathogenic avian influenza - PDF Resources