Avian influenza information for veterinarians

Agriculture Victoria is responding to an outbreak of three strains of avian influenza (AI). There is an outbreak of highly pathogenic H7N7 (HPAI) on two properties near Lethbridge in the Golden Plains Shire. Additionally, low pathogenicity H5N2 (LPAI) has been detected on two linked properties – one in the Golden Plains Shire and a second property near Bairnsdale in East Gippsland Shire.

Avian influenza has been confirmed at an additional poultry farm in the Golden Plains Shire and also an emu farm near Kerang.

The Golden Plains farm, with approximately 37,000 birds onsite, is within the existing Restricted and Control Areas, has been confirmed as being high pathogenic H7N7 avian influenza and has consequently been placed under quarantine.

The emu farm near Kerang reported sick birds to Agriculture Victoria and subsequent testing has confirmed H7N6 Low Pathogenic avian influenza. A Restricted Area of 2km and a Control Area of 5km will be put in place around the farm.

AI is a serious disease of poultry, and highly pathogenic strains can cause high mortality. Australia has previously had a small number of outbreaks of avian influenza. These were all quickly and successfully eradicated.

Wild birds can carry AI without showing any signs of infection and are the most likely source of infection in poultry. It is not unusual for “spill over events” to occur when AI from wild birds infects domestic poultry flocks.

Veterinarians who suspect AI MUST report it IMMEDIATELY to Agriculture Victoria by calling the all-hours Emergency Animal Disease Watch Hotline on 1800 675 888.

How is Agriculture Victoria responding to this incident?

Agriculture Victoria is responding in accordance with the avian influenza AUSVETPLAN and the Emergency Animal Disease Response Plan, under the approval of the national Consultative Committee on Emergency Animal Disease and the National Emergency Animal Disease Management Group.

Victoria’s Chief Veterinary Officer issued a Housing of Livestock clause for 30 days from 7 August 2020, legally requiring all poultry keepers within the Golden Plains Restricted and Control Areas – even those with just two or three chickens or birds – to keep their birds housed.

The affected properties have been quarantined and movement controls are in place to stop any birds, eggs and equipment from leaving the premises, except under permit issued by Agriculture Victoria. Humane depopulation has occurred and is in progress for the affected properties. Depopulation will also occur on the LPAI affected properties.

Restricted Areas are in place around infected properties. Agriculture Victoria is contacting property owners in the vicinity of the infected properties and is conducting enhanced surveillance testing of domestic birds in this area.

A Control Area across a wider area has also been created. More information about the movement controls that have been implemented in the Golden Plains and East Gippsland Shires, including maps, is available from the Agriculture Victoria website or by contacting the Customer Contact Centre on (03) 4334 2715.

Human health

The Victorian Department of Health and Human Services has advised that the detected strains of AI are not a risk to the public as they rarely affect humans unless there is direct and close contact with sick birds. There are no food safety issues identified; properly cooked chicken meat and eggs are safe to eat.

This infection is not the highly pathogenic influenza H5N1 or H1N1 strains that have gained worldwide attention due to serious public health impacts. 

Avian influenza is in no way related to the current coronavirus (COVID-19) pandemic.

If you have had contact with birds on an affected property and you are experiencing cold or flu symptoms, call your doctor or the Department of Health and Human Services on 1300 651 160 for medical advice.

Investigating suspected cases

Veterinarians investigating suspected cases of AI MUST IMMEDIATELY notify Agriculture Victoria by calling the all-hours Emergency Animal Disease Watch Hotline on 1800 675 888.

Agriculture Victoria will advise on samples required, sample transport requirements and any additional activities required.

About avian influenza (AI)

Avian Influenza (AI) (also known as bird flu or fowl plague) is a highly infectious viral disease of birds which occurs worldwide.

There are many combinations of subtypes (strains) of avian influenza virus that cause infections of different severity. These range from low pathogenic or mild strains (causing ‘low pathogenicity avian influenza’ or LPAI), to highly pathogenic strains that are associated with severe disease and high mortality in poultry (highly pathogenic avian influenza or HPAI).

Chickens, ducks, geese, turkeys, guinea fowl, quail, pheasants and ostriches are included in the more than 140 species that are susceptible to AI. Many species of wild birds, including waterfowl and seabirds, can also carry the virus without showing any signs of infection.

The virus is mostly spread by wild birds, particularly ducks, contaminating food or water supplies.

Migratory birds, predominantly shore birds and waders from nearby countries in South East Asia, can pose a risk if they harbour AI infection and then mingle with, and transmit this infection to waterfowl that are nomadic within Australia. These nomadic birds can then mingle with and spread the infection to domestic birds such as poultry.

It is not unusual for AI virus to be detected in wild birds in Australia. Wild birds can carry the virus without showing any signs of infection.

AI can also spread by the movement of eggs, birds, people, vehicles and equipment between farms, and by clothing, footwear, aerosols, water, feed, litter, biting insects and vermin.

There is currently no effective treatment available for birds once clinical signs of AI appear.

Vaccines are available for certain subtypes of the AI virus, which may protect poultry from clinical signs of disease if they subsequently become infected. However, routine vaccination for AI is not permitted in Australia.

Clinical signs

The clinical signs of AI infection are variable and influenced greatly by:

  • the virulence of the viruses involved
  • the species affected
  • age
  • concurrent bacterial disease
  • the environment.

Signs of low pathogenicity avian influenza (LPAI)

Clinical signs range from inapparent to mild or severe and can include:

  • respiratory distress (can be confused with infectious laryngotracheitis)
  • coughing, sneezing or rasping respiration
  • rapid drop in feed intake, water intake and egg production
  • typical 'sick bird' signs — for example, ruffled feathers, dopiness and closed eyes
  • death of small proportions of the chicken flocks of 3% to 15%.

Signs of highly pathogenic avian influenza (HPAI)

HPAI should be considered as a possible cause if a high proportion of a flock or group of birds become ill very quickly, progressing from normal to gravely ill or dead within 24 to 48 hours.

Clinical signs may include:

  • sudden death
  • respiratory distress
  • swelling and purple discolouration of the head, comb, wattles and neck
  • coughing, sneezing or rasping respiration
  • rapid drop in feed intake, water intake and egg production
  • typical 'sick bird' signs — for example, ruffled feathers, dopiness and closed eyes
  • diarrhoea
  • occasionally, nervous symptoms.

Differential diagnoses of AI include Newcastle disease, acute fowl cholera and other septicaemic diseases, infectious laryngotracheitis, duck plague, acute poisonings and bacterial cellulitis of the comb and wattles.

Gross pathology

Birds that die of peracute AI may show minimal gross lesions, consisting of dehydration and congestion of viscera and muscles.

In birds that die after a prolonged clinical course, petechial and ecchymotic haemorrhages occur throughout the body, particularly in the larynx, trachea and proventriculus and epicardial fat, and on serosal surfaces adjacent to the sternum. There is extensive subcutaneous oedema, particularly around the head and hocks. The carcase may be dehydrated. The pancreas, liver, spleen, kidney and lungs can display yellowish necrotic foci. The air sacs may contain an exudate. The spleen may be enlarged and haemorrhagic.

Good biosecurity is important

Regardless of whether your clients are commercial producers or just keep a few chickens in their backyard, there are several biosecurity practices they should be putting in place to protect their birds from disease:

  • Restrict contact between kept birds and wild birds. Contact with wild birds can be minimised by making the free-range environment less attractive to them, for example, place feeders and water sources inside sheds, rather than in the open where wild birds will have easier access. Using fencing or netting for free-ranging birds, are other options.
  • Keep poultry sheds, yards and aviaries clean, including equipment. Clean thoroughly with a detergent before applying a disinfectant.
  • Quarantine new birds before introducing them to the resident flock.
  • Limit visitors to your birds. Check if essential visitors have recently visited other premises where poultry is kept.
  • If attending bird shows, always practice good hygiene.
  • Always wash hands before and after handling birds and eggs.
  • Poultry farmers should change into clean footwear before entering poultry houses or hen facilities, to stop the potential transfer of disease from outside.

Best practice farm hygiene and biosecurity practices are adopted in the Australian poultry industry and are standard practice. National biosecurity manuals outline these measures.

Further information

  • Visit the dedicated avian influenza page on the Agriculture Victoria website
  • See the AUSVETPLAN disease strategy for AI
  • Contact your local Agriculture Victoria District Veterinary Officer or Animal Health Officer
  • Contact the Agriculture Victoria Customer Contact Centre on (03) 4334 2715 if you require information about movement controls during the AI response.
  • If you have had contact with birds on an affected property and you are experiencing cold or flu symptoms, call your doctor or the Department of Health and Human Services on 1300 651 160 for medical advice.
  • Visit the national pest and disease outbreak website.
Page last updated: 28 Aug 2020