Avian Influenza in Backyard Chickens | Bird Flu

Bird Flu or Avian influenza virus H7N3 has been found in a flock of chickens in Victoria near Geelong, resulting in the birds having to be culled. The Avian Influenza outbreak has been contained.

There is an ever-present threat of Avian Influenza or bird flu in our poultry and backyard birds. Chicken Avian Influenza circulates in the wild bird population. Each year new Avian -Influenza strains enter Australia due to migrating birds. This disease, caused by a type A influenza virus, has left a trail of destruction due to the massive culling of infected birds. (Once Virulent Avian Influenza H5N1 is detected, AS in Europe  there is no effective treatment to combat it.)

A veterinary alert from Victoria's Chief Veterinary Officer is shared below for your attention:

High Pathogenicity Avian Influenza (HPAI) - Biosecurity Alert

Confirmed HPAI H7 in two Victorian poultry farms

High pathogenicity avian influenza (HPAI) H7N3 virus is confirmed as the cause of death of hens on a property located near Meredith. A second related property near Terang was confirmed as being positive to HPAI H7 virus on 23 May 2024, with further results to follow. These two properties have management and business connections. The HPAI virus detected is not a HPAI H5N1 virus that has caused recent outbreaks in birds and mammals overseas. The affected properties have been quarantined and movement controls are in place to minimise the risk of disease spread. Poultry, other domestic birds and wild birds in the area will be closely monitored for any additional cases.

This incident highlights the importance of early reporting and the need to consider HPAI as a differential diagnosis whenever sudden onset and progression of illness with respiratory signs, or sudden death, occurs in a flock or group of birds.

Avian Influenza is a notifiable disease, and any suspect or confirmed cases must be reported to Agriculture Victoria on the all-hours Emergency Animal Disease hotline 1800 675 888.

Background

Avian Influenza (AI) is a highly contagious viral infection of birds. The disease is caused by either high pathogenicity or low pathogenicity strains. Some HPAI can cause severe clinical signs and high mortality (up to 100%) in domestic poultry (chickens) and turkeys. AI in pet birds such as budgies, canaries and other caged birds has not been a feature of previous outbreaks in Australia.

Wild birds are considered the natural host for AI. Certain water birds act as reservoirs of influenza viruses by carrying the virus and spreading it to susceptible birds through contact with contaminated nasal, respiratory, and faecal material. It is not unusual for “spill over events” to occur when AI from wild birds infects domestic poultry flocks.

Although the spread of AI from birds to people is rare, it may occur with some strains of the virus if there has been close contact with infected birds or heavily contaminated environments. This potential zoonotic risk one of the main reasons we control AI virus infections in poultry.

HPAI H5N1: The virus detected in Meredith is NOT a HPAI H5N1 virus.

Since 2021, the subtype H5N1 has spread rapidly across most continents, causing mass mortalities in wild birds and poultry. It has also caused death in some mammal populations, especially those which scavenge on birds infected with AI, such as sea lions and seals. The severity of illness, and high death rates affecting such a wide range of species is unusual in these international incidents, compared to previous outbreaks of AI.

Clinical signs of HPAI in poultry

HPAI should be considered 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 (coughing, sneezing, breathing difficulties), swelling and purple discoloration of the comb or head, decreased food or water intake, decreased egg production, diarrhoea, nervous signs (occasionally seen).

Avian Infuenza in people

Reported symptoms in people range from very mild to typical flu-like symptoms (eg conjunctivitis, cough, fever, sore throat, muscle aches) to pneumonia and very rarely, death. Anyone who has been in close contact with infected animals or materials, or has "influenza-like" symptoms should seek medical advice immediately and contact the Communicable Disease Prevention Unit at the Department of Health on 1300 651 160 (24 hours).

There are no food safety issues identified. Properly cooked chicken meat and eggs are safe to eat.

Prevention of AI in birds

AI viruses can be easily transmitted from property to property by the movement of infected birds, as well as contaminated boots, vehicles and equipment. Using good biosecurity practices between and within properties, and preventing contact between local water birds and poultry, will lower the risk of disease spread.

People working with poultry and/or responding to avian influenza outbreaks should have a current seasonal influenza vaccine at least two 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 of viruses to produce new influenza viruses that may pose a threat to the wider community.

Prevention of AI in people

Appropriate use of Personal Protective Equipment (PPE) has been very effective in preventing illness. When coming into contact with potentially infected animals or materials, appropriate PPE to wear includes protective overalls, gloves and rubber boots, P2 facemask (a basic surgical mask is NOT suitable) and protective eyewear.

How does Avian Infuenza affect our beloved backyard birds, that are often well loved pets?

1. Is an Avian Influenza vaccination available for chickens?

At this stage, AI vaccination for backyard yard birds or commercial poultry is not available in Australia.

2. What is the risk ot Avain-Infuenza to my pet chickens?

The poultry-vet believes the risk to the pet chickens we see coming into Bird Vet Melbourne is very low. The strain of virus that has been found in chickens in Meredith Victoria in 2024 is not that virulent meaning it does not cause disease healthy pet chickens.

3. What are the symptoms of pathogenic avian influenza?

The Pathogenic Avian-influenza symptoms expected at Melbourne-Chicken-vet are close to 100% death in 3 days. Respiratory signs predominate.

4. What should I be doing to prevent AI in my backyard poultry?

The chicken vet recommends  feeding fresh drinking water from a tap or bottle, rather than a pond or dam. The virus is often transmitted in the droppings of wild birds, which contaminates food or water. Ideally, the birds should be kept separate from wild birds, but if this is difficult, the risk is too low for it to be of major concern.

5. What if my birds are showing respiratory signs of avian influenza (Bird Flu) ?

At this stage, the Victoria poultry-veterinarian suggests that most of the respiratory signs that we see at Melbourne Chicken Vet are caused by Mycoplasma and NO avian influenza or Bird Flu.  The poultry vet recommends a veterinary visit if you are concerned. The Melbourne-Bird-Vet in Burwood can take a throat swab from your pet chooks and have it tested for avian influenza. A negative result will give peace of mind to backyard owners.

6. Does this strain of avian influenza affect people?

At this stage, no human has been affected.

7. Does this strain of Bird Flu affect other pets, like dogs cats and parrots?

It’s unlikely, no precaution needs to be taken.

Melbourne Chicken Vet