Avian Influenza (AI) is a highly contagious, viral disease of birds.
All commercial, domestic and wild bird species are susceptible to infection, but disease outbreaks occur more frequently in chickens and turkeys. Many species of wild birds, including waterfowl (geese, ducks and swans) and seabirds, can carry the Avian Influenza virus but generally show no signs of the disease.
There are many subtypes or strains of the Avian Influenza virus. Some strains, known as Low Pathogenic Avian Influenza (LPAI), will only cause mild signs in domestic poultry. Other, more serious strains, known as Highly Pathogenic Avian Influenza (HPAI), will spread rapidly through a poultry flock and cause severe disease and high mortalities. Examples of subtypes causing recent outbreaks of HPAI overseas are the H7N7, H5N1 and H5N2 subtypes.
Why is an outbreak of Avian Influenza serious in Australia?
Avian Influenza is highly contagious from bird to bird and an outbreak of one of the highly pathogenic types could cause very high mortality rates in infected poultry. Significant economic losses occur in outbreaks of Avian Influenza in commercial poultry flocks. On rare occasions, Avian Influenza viruses can be transmitted to humans.
How is Avian Influenza spread?
The most common way that Avian Influenza infection is spread is via the faeces of diseased birds. The virus can also be present in other bodily fluids, such as nasal/eye discharge and blood. Susceptible birds may become infected when they have contact with contaminated secretions or droppings from other infected birds. This could include susceptible birds becoming infected by drinking water or eating food contaminated by the droppings of diseased birds. Infection could also spread by indirect methods such as clothing, footwear or equipment contaminated by droppings or secretions from infected birds.
Preventing susceptible birds having contact with secretions or droppings from infected birds is important for preventing outbreaks of Avian Influenza.Avian Influenza viruses appear to circulate in waterfowl (ducks, geese and swan) throughout the world. Waterfowl generally carry the virus without themselves being diseased. Fortunately, the waterfowl that are the normal hosts of Avian Influenza virus, and have spread the highly pathogenic avian influenza (HPAI) virus across Asia and Europe, do not migrate to Australia. The wading birds that migrate to Australia are not the normal hosts or spreaders of the disease. However, the risk that a locally circulating LPAI strain will become a virulent HPAI strain remains. Australia's strict biosecurity measures are also aimed at preventing the disease being transported to Australia by means other than wild birds.
Is HPAI present in Australia?
From time to time, less virulent strains of Avian Influenza virus, known as Low Pathogenic Avian Influenza (LPAI) viruses are detected in wild birds in Australia.
These generally harmless Avian Influenza viruses occur worldwide, wherever there are wild waterfowl (ducks, geese and swans).
Outbreaks in domestic birds of the more virulent Highly Pathogenic Avian Influenza (HPAI) do occur very occasionally and require emergency responses by government and industry. Surveillance is conducted continually in Tasmania and across Australia of both wild and domesticated birds, to ensure risk assessments are up to date.
It is important to distinguish LPAI viruses from HPAI viruses which can cause severe disease. Historically these are of the H5 and H7 LPAI virus strains which mutate to a virulent (ie severe) HPAI strain if they get into a large bird flock and start to "passage" from bird to bird. For this reason commercial poultry producers must keep wild birds out of their sheds and enclosures and prevent contamination of feed and water. It is also why we would seek to eradicate the disease if we diagnosed a LPAI H5 or H7 in a commercial poultry unit.
What is the likelihood of the HPAI Avian Influenza virus entering Australia and causing disease?
The waterfowl that are the normal hosts of Avian Influenza, and have spread the H5 or H7 virus strains across America, Asia and Europe, do not usually migrate to Australia. The wading birds that migrate to Australia are not the normal hosts or spreaders of the disease. However, the risk that a locally circulating LPAI strain will become a virulent HPAI strain remains.
Australia's strict biosecurity measures are aimed at preventing the disease being transported to Australia.
How close is Avian Influenza to Australia?
Outbreaks of HPAI occur intermittently, often on a seasonal basis, around the world. For the latest information on these HPAI outbreaks, go to the website of the
World Organisation for Animal Health (OIE).
There has never been an Avian Influenza outbreak in Tasmanian poultry. While on occasion LPAI strains of Avian Influenza virus have been detected in wild birds in Tasmania, these detections have not been associated with outbreaks of the disease to date. Outbreaks of HPAI have occurred on Mainland Australia in recent years. However, to date each incident has been eradicated before the disease could spread. There were no reported cases of human health problems associated with any of these outbreaks.
How would Australia cope with an outbreak of Avian Influenza in poultry?
Australia is well prepared to deal with a case of Avian Influenza in poultry.
Outbreaks of HPAI in poultry in Australia, have been controlled before the disease could spread widely. No person became sick from the Avian Influenza virus in any of the outbreaks. Good surveillance, early detection, and rapid, effective stamping out have characterised every outbreak in Australia so far. Planning, preparedness and response procedures continue to be refined and improved at both national and state levels.
Australia's eradication plans include personal protection and treatment measures to protect people working on infected properties and other people at risk of infection with the virus.
What safety measures are in place to prevent Avian Influenza entering Australia?
Biosecurity Australia has strict guidelines for the importation of all live animals and/or animal products in order to protect Australia from any exotic disease threat. Officials routinely screen all international flights for animals or animal products. Particular attention is being paid to eggs, egg products, poultry meat, poultry vaccines, feathers and similar items. All international mail is also routinely screened. Maximum use is being made of X-ray machines and detector dog inspections. Luggage and mail items may be physically opened and checked.
Commonwealth and state departments rapidly investigate all suspected Avian Influenza reports.
A nationwide
toll free
Emergency Disease Watch Hotline is operated all hours in order to detect any potential Avian Influenza outbreaks, tel.:
1800 675 888
Staff from Commonwealth, State and Territory departments are trained and experienced so they can rapidly detect, isolate and control any exotic disease outbreak.
Unlike some other parts of the world where outbreaks have occurred recently, Australia has high biosecurity standards on commercial poultry farms. These strict standards provide significant protection against the disease infecting local poultry.
What can the broader community do to help reduce the risk of Avian Influenza?
It's important that visitors to Australia and Australians returning from overseas do not bring potentially infected material into the country. NRE Tas and Biosecurity Australia officers are on high alert as part of the national effort to prevent Avian Influenza entering Australia. They are on particular alert for poultry and poultry-related products - for example, birds nests, noodles with egg or chicken, mooncakes with egg yolk and fly tying materials made from feathers.
Biosecurity officers are screening 100 per cent of all international flights from high risk countries. All international mail is also being screened. Maximum use is being made of X-ray machines and detector dog inspections. Luggage and mail items are physically opened and checked.
For more information on biosecurity restrictions for international travellers, importers and exporters, please visit the Australian Government's website:
Biosecurity in Australia.
Does NRE Tas do any AI surveillance in wild birds?
Surveillance to detect any HPAI virus in wild birds is an important part of prevention. The Commonwealth government funds such surveillance by the States (including Tasmania). This includes collecting swabs from ducks that are shot during the duck season or shot/trapped at any time for crop protection.
Members of the public should report wild bird mortality events to NRE Tas on tel. 1300 368 550, or email
AnimalDisease.Enquiries@nre.tas.gov.au
Can anything be done to stop the spread of Avian Influenza in wild birds?
The
World Health Organisation agrees with the
Food and Agriculture Organisation of the United Nations and the
World Organisation for Animal Health (OIE) that control of Avian Influenza infection in wild bird populations is not feasible and should not be attempted.
Wild waterfowl have been known for some time to be the natural reservoir of Avian Influenza viruses. Migratory birds can carry these viruses, in their low pathogenic form, over long distances but do not usually develop signs of illness and rarely die of the disease.
The instances in which highly pathogenic Avian Influenza viruses have been detected in migratory birds are rare and the role of these birds in the spread of highly pathogenic Avian Influenza remains poorly understood.
What is the risk of other animals being infected by Avian Influenza virus?
There is worldwide evidence that the Avian Influenza virus can infect a range of non-human mammals, including pigs, cats, mink, seals and whales. This list is expected to change over time as the virus adapts to other niches.
A small number of cats (including both domestic cats and larger cats in zoos) have been infected with Avian Influenza virus after exposure to infected birds. In some countries affected by Avian Influenza, cat owners are advised to ensure that contact between cats and wild birds or poultry is avoided.
For further information: