Avian Influenza (also called Bird Flu)

An original article by Josie Pyle

The World Health Organization has reported an outbreak of Avian Influenza in birds in Asia. Millions of birds have been infected as have a small number of people, who were infected after close contact with chickens in Vietnam and Thailand. There is no evidence as yet that the virus has spread from person-to-person. 19 out of 25 confirmed cases of human infection with avian influenza have resulted in death, 12 were under 18 years and 7 were adults. All human cases have been reported from two countries, Vietnam and Thailand.

Avian influenza is a viral disease of birds. There are many strains of avian influenza virus that cause infections of different severity and some strains may be associated with severe disease and high mortality in poultry, as well as transmission to humans. Avian influenza A (H5N1) is the strain of the virus currently active in South-East Asia and is highly lethal to poultry. The virus can survive in faeces, on feathers, eggs or meat.

Avian influenza viruses can infect more than poultry.

Avian influenza viruses can infect a wide variety of birds – more than just domestic poultry. Avicultural species including pheasants, partridges, quail, pigeons, ducks, geese, guinea fowl and ostriches are susceptible, as well as wild birds. Some migratory waterfowl, sea birds, and waders are infected with AI viruses, but do not show signs of the clinical disease.

Avian influenza viruses usually only infect birds but theoretically avian influenza viruses could spread to any species susceptible to influenza viruses such as pigs and horses. In practice, this type of spread is extremely limited.

The clinical signs of avian influenza in birds.

Clinical signs vary greatly and depend on many factors but highly infective avian influenza can cause sudden death, swelling of the head, ruffled feathers, diarrhoea, haemorrhaging, nervous signs and respiratory distress. Any signs of sickness or sudden death in a substantial part of a flock should be reported immediately to the appropriate authorities.

The spread of avian influenza

The principal means by which the AI virus initiates outbreaks in domestic poultry is by wild birds, particularly ducks, contaminating food or water supplies and subsequent spread of the virus by the movements of infected live birds or contaminated feed, equipment and materials. 

Migratory birds are a potential risk of introducing exotic avian influenza viruses to Australia.

Transmission to humans occurs predominantly through the handling of live infected birds or close contact with them and their excretions.

Is Australia safe?

There have been five outbreaks of avian influenza in commercial bird flocks in Australia, all of which were successfully eradicated.  The last reported case was in 1997 in Tamworth, NSW.  Avian influenza can be carried by migratory bird species that could infect wild birds in Australia. It is highly probable that contact between wild birds, particularly ducks, and poultry was the cause of the avian influenza outbreaks in Australia in the past.

What is Australia doing about avian influenza?

Animal health authorities have had contingency plans in place for many years to minimise the impact of an outbreak of avian influenza in Australia. Commercial poultry farmers have well-developed biosecurity systems which have been strengthened in recent years. Poultry farmers are on high alert and are backed up by diagnostic facilities and response plans the equal of anywhere in the world.

Australian Government agencies with responsibility for issues such as animal and human health, quarantine and border protection have been closely monitoring and will continue to monitor the current South-East Asian avian influenza situation.

What can I do as an aviculturist?

Good biosecurity, so as to maintain a barrier between domestic birds and wild bird populations, is the single most important factor in reducing the risk of an avian influenza outbreak. Apart from preventing contact between wild and domestic birds, the water supply must also be treated, or from a known safe source.

When cleaning aviaries or poultry yards appropriate precautions such as gloves and face-masks should always be used.

Any suspicious sudden deaths, especially involving a large number of birds should be reported immediately.

Avian Influenza Hotline: 1800 675 888