Avian influenza information for veterinarians

This advice has been developed for veterinarians who may be required to investigate suspect avian influenza outbreaks in sick or dead poultry, wild birds or wild animals.

Information regarding avian influenza disease can be found at the  Agriculture Victoria avian influenza webpage

Avian influenza (AI) is a notifiable disease, and veterinarians who know of or suspect the presence of avian influenza MUST IMMEDIATELY report it to Agriculture Victoria.

You can do this by calling:

• an Animal Health Officer or District Veterinary Officer at Agriculture Victoria on 136 186 (Monday – Friday 8.30 am – 5 pm)
• The  Emergency Animal Disease hotline on 1800 675 888
• the VicEmergency Hotline on 1800 226 226.

Good biosecurity practices, including the use of protective personal equipment (PPE) remain essential to reduce the risk of disease.

Species affected

Domestic poultry, ducks, geese, turkeys, guinea fowl, quail, pheasants, emus and ostriches are most susceptible to being affected by avian influenza. Many species of wild birds, including waterfowl and seabirds can carry the low pathogenic avian influenza (LPAI) virus but usually show no signs of disease.

All bird species are thought to be susceptible to HPAI H5N1 clade 2.3.4.4.b, and it has been detected in over 50 species of mammals. Marine mammals and carnivores are at higher risk of infection, presumably following close contact or ingestion of infected birds. Mammal to mammal transmission is likely to have occurred in some marine mammals that live in colonies.  HPAI H5N1 clade 2.3.4.4.b has been confirmed in some dairy cattle and goats in the USA.

Clinical signs of AI in birds

Most strains of avian influenza virus are usually asymptomatic in wild birds but can cause severe illness in domestic bird species. Infected birds will experience fever and respiratory problems leading to death in a matter of hours or days.

Low Pathogenic Avian Influenza (LPAI)

The clinical signs of AI infection are variable and influenced greatly by the virulence of the viruses involved, the species affected, age, concurrent disease and the environment.

Clinical signs range from no apparent symptoms to mild or severe symptoms and may 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 – ruffled feathers, depression, closed eyes
• death of small proportions of the chicken flocks ranging from 3-15%.

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 severe illness or death within 24 to 48 hours.

Clinical signs may include:

• sudden death
• respiratory signs (dyspnoea, tachypnoea, coughing, sneezing, increased nasal secretions)
• swelling and purple discoloration of the head, comb, wattles and neck
• rapid drop in feed intake, water intake and egg production

• typical “sick bird” signs – ruffled feathers, depression, closed eyes
• diarrhoea
• neurological signs (twisted neck, inability to stay upright, inability to fly, uncoordinated movement, walking or swimming in circles, partial or full paralysis).

HPAI H5N1 clade 2.3.4.4.b

Highly Pathogenic H5N1 has caused mass mortalities in many wild bird populations overseas, endangering some species. It has also devastated the poultry industries in affected countries. If a flock of birds has a sudden increase in illness and deaths, then H5N1 must be considered.

Wild birds

HPAI H5 clade 2.3.4.4b should be considered as a differential diagnosis in the following situations:

i. Where there are 5 or more sick or dead wild birds of any species with any clinical or pathological presentation.

ii. Where there are less than 5 sick or dead wild birds of the following orders with any clinical or pathological presentation: seabirds, waterbirds, shorebirds, birds of prey or scavenging birds.

iii. Where there are less than 5 sick or dead wild birds of any species presenting with sudden unexplained death, gastrointestinal, respiratory, neurological signs and/or other clinical or pathology signs indicative of a viral infection. Note: Some species may show only very mild clinical signs of disease.

Wild mammals

HPAI H5 clade 2.3.4.4b should be considered as a differential diagnosis in sick or dead wild marine mammals, predators or scavenger species presenting with neurological, respiratory signs or sudden death, including mass mortality events and/or other clinical or pathology signs indicative of a viral infection.

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.

Zoonotic potential

The spread of avian influenza from birds to people is rare but may occur with some strains of the virus if there is close contact with infected birds or their droppings, or with heavily contaminated environments.

What are the human symptoms of avian influenza?

The reported symptoms of avian influenza in humans range from very mild typical influenza-like symptoms (e.g. cough, fever, sore throat and muscle aches) to eye infections, pneumonia, acute respiratory distress and in rare cases death. The most common sign is conjunctivitis. Overall, there have been few human mortalities as a result of AI.

Medical advice should be sought immediately if you or anyone you have been in close contact with, or experience symptoms noted above after coming into contact with infected or suspect birds. This also applies if you think you have been exposed to other infected materials.

Use of personal protective equipment (PPE)

Appropriate use of personal protective equipment (PPE) has proven to be highly effective against contracting illness.

Practise good hygiene principles when wearing PPE:

• Avoid touching your mouth, eyes, and nose.
• Cover any cuts or grazes with a water-resistant dressing under PPE (i.e. band-aid).
• Do not eat or drink while wearing PPE.
• Ensure PPE is removed safely and in the correct sequence (seek guidance from Agriculture Victoria staff).
• Thoroughly wash hands and face after removing PPE & shower at the end of the shift before handling other animals.

PPE requirements will vary depending upon the level of risk associated with the work you are undertaking.

When working on properties and in contact with potentially infected animals or materials:

• Waterproof footwear, i.e. gumboots
• Disposable overalls and gloves
• P2 facemask (minimum)
• Protective eyewear

When working on properties without contact with potentially infected animals or materials:

• Waterproof footwear, i.e. gumboots
• Disposable overalls and gloves

People working with poultry and/or responding to avian influenza outbreaks should have a current seasonal influenza vaccine at least 2 weeks prior to coming in contact with infected birds. This will not prevent infection with avian influenza but will reduce the risk of co-infection with human influenza (‘flu’) and genetic reassortment to produce new influenza viruses that may pose a threat to the wider community.

People who are ill should be discouraged from entering a poultry house, a response location or processing facility.

Any additional recommendations or requirements will be provided by Agriculture Victoria, in conjunction with the Department of Health, based on a case-by-case assessment of the risk.

Sample collection and diagnosis

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

Samples requested may include:

• oropharyngeal and cloacal swabs -plain, sterile swabs transported in viral transport media (VTM)
• a range of post-mortem tissues.

All samples and carcasses must be stored at 4° C prior to submission.

Biosecurity

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.
• If attending an AI-suspected flock, always practise good hygiene and biosecurity, wearing a face mask and gloves.

Further information

• Agriculture Victoria avian influenza
• Avian influenza factsheet
• Avian influenza FAQs for backyard poultry owners
• AUSVETPLAN disease strategy 
• Wildlife Health Australia
• National pest and disease outbreak
• Contact your local Agriculture Victoria District Veterinary Officer or Animal Health Officer on 136 186 (Monday–Friday 8.30 am – 5 pm)
• 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.