Avian influenza, or bird flu, is a contagious disease of animals caused by Type A strains of influenza. Bird flu viruses are usually specific to birds but they have, on rare occasions, crossed the species barrier to infect humans and other mammals, including pigs and sheep.
Avian influenza can infect a wide range of birds, including ducks, geese, ibis, swans, chickens, turkeys, pheasants, partridges, quail, pigeons, guinea fowl and ostriches. Signs of the disease vary, but commonly include a sudden drop in egg production, loss of appetite, diarrhoea and death. The signs vary depending on the strain of the virus and the age and species of the birds infected.
There are many different strains of avian influenza (at least 144) which exist at low levels in wild bird populations. Most are of no danger to the health of the birds, though the highly contagious and pathogenic H5N1 form of avian influenza virus is infecting and causing death in wild and domestic birds in South-east Asia, Russia, India, West Africa, Egypt, Indonesia and Europe.
Despite the recent spread of avian influenza from Asia to other areas of the world, there have been no recorded cases of the H5N1 strain of the virus in Australia. The Australian Government has been aware of the H5N1 strain of the virus since its emergence in 1997 and wild bird surveillance programs are also in place to ensure early detection and coordinated response to any outbreaks.
Avian Influenza is transmitted among birds through contact with droppings and secretions from the eyes, mouth and nose. Transmission is promoted in domestic flocks of poultry, in particular, where the density of birds is high and close contact between birds occurs regularly. The spread of the H5N1 virus has been aided in cultures where domestic birds (eg. chickens, ducks, geese) mix regularly with wild bird populations. The most likely birds associated with the intercontinental spread of the virus are migratory waterfowl, including ducks and geese.
Transmission of the H5N1 virus from birds to humans has occurred as a result of close contact with infected poultry or contaminated surfaces. Therefore, it is important when handling and dressing birds that thorough hygiene practices are adopted (see below). This includes using gloves, and disinfecting hands, clothing and any equipment which comes into contact with birds.
The H5N1 virus can survive in water and frozen for many days and, depending on temperature, for weeks. Therefore, thorough cooking of meat is required to kill the virus.
Transport of H5N1 to Australia
The spread of the H5N1 virus throughout various parts of the world has been largely associated with migratory birds, particularly waterfowl (ie. ducks, geese and swans). While a large number of migratory waders and shorebirds visit Australia each year, we receive no migratory waterfowl. Australia does, though, have nomadic waterfowl that make small-scale, random movements between Papua New Guinea and South-east Asia, where interaction may occur, however, this random movement poses significantly less risk than the mass movement of large concentrations of birds associated with full-scale migration.
The most likely risk of Australian waterfowl coming into contact the H5N1 virus is through interaction with migratory waders and shore birds which come to Australia from Asia. However, these migratory birds are much less likely to be infected as they rarely come into contact with domestic poultry. Further, the migration is energy demanding and it is unlikely a bird infected with the H5N1 strain could make the long-distance travel to Australia.
The most probable way that the H5N1 form of avian influenza could reach Australia is through the importation of infected live birds or poultry products. However, both of these routes are strictly monitored by the Australian Quarantine and Inspection Services.
Risk to duck hunters
As the H5N1 strain of avian influenza has not been detected in Australia to date, the risk to duck hunters is considered low. However, basic personal hygiene practices should be observed when handling and dressing waterfowl. Even apparently healthy waterfowl can be infected with microorganisms and parasites that can move between wildlife and people. It is recommended that hunters of all game follow these practical guidelines.
Guidelines for hunters - The safe and hygienic handling of game
- Do not handle game that is obviously sick or found dead with no obvious reason
- Keep all harvested game cool, clean and dry
- Use rubber gloves when cleaning game
- Avoid hand to face contact when dressing game and prior to washing your hands
- Do not eat, drink or smoke while cleaning game
- Wash your hands with soap and water or alcohol wipes after handling or dressing game
- Clean all tools and surfaces immediately after dressing game; use hot soapy water, then disinfect with a 10% chlorine bleach solution
- Cook game meat thoroughly (68 - 74 degrees Celsius) to kill disease and parasites. Please note that freezing will not kill the H5N1 virus
- For duck hunters using mechanical pluckers, consideration should be given to wearing a facemask to protect against pathogens
Surveillance – the Important Role of Hunters
Duck hunters can play an important role in the surveillance and reporting significant wildlife diseases, including the H5N1 virus.
Wild birds eventually die, as all animals do. So you shouldn't assume that dead birds have died of avian influenza. However, if you observe unusual circumstances, such as birds dying one after another or a group of dead birds without an obvious cause, please take the following actions:
- Do not touch or bury the dead birds.
- Take note of where the birds are on the ground and the location of where you found them. Report the details and location of the birds to your local Veterinary Surgery or DEPI Animal Health and Welfare staff immediately.
- If either cannot be contacted straight away, and there is a mass unexplained die-off, call the Emergency Animal Disease Watch Hotline on free call 1800 675 888.
The sooner veterinarians and authorities can contain a disease, the better chance industries, such as the chicken meat and egg industries, have of keeping the disease away from their birds and ultimately, retaining their markets and livelihood.
The importance of being alert to the signs of avian influenza while out in the field cannot be stressed enough. If you do come across something that looks unusual in bird populations, please report it to the Emergency Animal Disease Watch Hotline on free call 1800 675 888. Alternatively, report it to your local veterinarian or to us immediately on 136 186.
A wide variety of information on bird flu is available to the public. The Australian Government website www.daff.gov.au/birdflu offers comprehensive information that has been written by Australian veterinarians. Additionally, contact us on 136 186 for information specific to Victoria.