Avian Influenza ("Bird Flu")
Note Number: AG1173
Andrew Cameron, Attwood
Updated: January 2012
Avian Influenza (AI)
Avian influenza is a highly contagious viral infection of birds. AI can be highly pathogenic or low pathogenic. Some highly pathogenic avian influenza viruses (HPAI), can cause sudden, high mortality (up to 100%) in domestic fowl (chickens) and turkeys. Low pathogenic avian influenza viruses (LPAI) can result in some mortality, but is often present with few or nor symptoms. The need to eradicate LPAI stems from experiences in other countries where LPAI has been allowed to remain in the population without eradication and has mutated to a more highly pathogenic form of the virus – HPAI.
LPAI has not been detected in Australia prior to this outbreak; however, the severe and widespread epidemics of HPAI in Europe in 2003 and in east Asia in 2004/5 have heightened awareness of the ongoing risk to Australia’s bird population. It appears that HPAI is now established in several countries in east Asia.
Avian Influenza: What is the Risk to Australia?
AI viruses are common in wild waterfowl throughout the world, for the most part cycling harmlessly in these well-adapted hosts.
Occasionally, exposure of wild water birds to domestic birds, especially poultry, or to their feed or water supply, can lead to the emergence of HPAI viruses which quickly and rapidly kill the exposed domestic birds.
Five outbreaks of HPAI have occurred on poultry farms in Australia: in Victoria in 1976, 1985 and 1992; in Queensland in 1994; and in NSW in 1997. On each occasion the outbreak was quickly detected and stamped out, and only a small number of farms were affected. Effective eradication measures ensured that Australia remained free of HPAI.
However, annual migration of wild birds has the potential to continually introduce new subtypes of avian influenza to Australia’s wild and free-living waterfowl. Hence there is an ever-present need for sound biosecurity to prevent wild bird exposure to domestic poultry and vigilance to enable rapid response should an outbreak of LPAI or HPAI occur.
What Species are Affected?
Domestic fowl, ducks, geese, turkeys, guinea fowl, quail, pheasants and ostriches are susceptible. Many species of wild birds, including waterfowl and seabirds can carry the virus but usually show no signs of disease.
Generally, humans are not affected, although the H5N1 subtype (a HPAI strain) prevailing in east Asia has infected and killed a small number of people who had very close contact with infected birds. People are not infected by eating chicken meat or eggs, or by contact with other infected people.
Biosecurity
What can I do to prevent Avian influenza?
Avoiding contact with wild waterfowl and their droppings minimises the risk of avian influenza outbreaks in domestic birds. Poultry producers and bird-keepers should implement basic biosecurity measures:
- bird-proofing housing and feed storage areas;
- preventing access to surface water that may have been contaminated by wild waterfowl (such as ponds, lakes, creeks, channels, dams, puddles and water troughs), and/or only using a chlorinated (2-3 PPM)water source;
- restricting access of other people to bird areas;
- ensuring visitors are only permitted to enter bird areas after donning protective clothing and going through a foot bath containing a virucidal agent effective in the presence of organic matter.
- only sourcing birds from a reputable breeder or producer, rather than from a market or place where birds have been congregated from many sources;
- inspection and cleaning bird areas at least once per week;
- regular cleaning and disinfection of feed containers;
- do not share equipment with other bird-keepers unless it has been cleaned and disinfected;
- removal of sand and grit from the aviary between batches of birds, and every few months for resident birds;
- thorough cleaning of concrete floors, walls and aviary wire and scrub down with detergent.
Preventing wild bird access is relatively straight forward where birds are enclosed in poultry houses, but may be difficult where birds range freely over open areas.
Minimising Risk at Bird Shows
While bird shows are a great opportunity for breeders and exhibitors to showcase breeds and compete for coveted titles, there is some risk of disease spread because of close contact among birds and handlers from different locations.
Basic and effective biosecurity measures at bird shows to help prevent the spread of diseases include:
- not introducing any birds to the show if there is illness in the home flock;
- cleaning and disinfection of all bird equipment, cages and containers before and after shows;
- judges and handlers taking care to disinfect hands between birds where possible; exhibitors should preferably handle their own birds only;
- ensuring show birds undergo a quarantine period before reintroduction to the home flock; while 21 days is sufficient for AI, a period of 6 weeks may be preferable as a general disease precaution;
- exhibitors and show organisers:
- maintaining records of bird movements to assist traceback in the event of a disease outbreak;
- not displaying waterfowl in pavilions or areas that house poultry, pigeons or other birds;
- consider having a veterinarian present or contactable on show days.
Vigilance
Avian influenza: signs to look out for:
LPAI:
The clinical signs of AI infection are variable and influenced greatly by the virulence of the viruses involved, the species affected, age, concurrent bacterial disease and the environment.
Clinical signs range from inapparent to mild or severe 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, dopiness, closed eyes
- death of small proportions of the chicken flocks of 3-15%.
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 gravely ill or dead within 24 to 48 hours.
Clinical signs may include:
- sudden death
- respiratory distress
- swelling and purple discolouration of the head, comb, wattles and neck
- coughing, sneezing, or rasping respiration
- rapid drop in feed intake, water intake and egg production
- typical “sick bird” signs – ruffled feathers, dopiness, closed eyes
- diarrhoea
- occasionally, nervous symptoms
What do I do if I Suspect AI?
Poultry producers and bird keepers should regularly check their birds and immediately report any unusual signs of disease to their local veterinarian or DPI Animal Health and Welfare staff.
If either cannot be contacted straight away, call the Emergency Disease Watch Hotline on 1800675888.
Note: Avian influenza is a notifiable disease. Suspicion of infection must be notified immediately to local DPI Animal Health and Welfare staff.
Australian Response to HPAI
State and Commonwealth Governments and the national chicken meat and egg industries have formally agreed to share the costs of stamping out an outbreak of LPAI and HPAI. This helps to ensure that a rapid and effective emergency response can be immediately mounted if the disease occurs. Owners are compensated if birds or property need to be destroyed to eradicate the disease.
Procedures generally include slaughter out of infected and in-contact poultry, decontamination, strict quarantine and movement controls to prevent spread of infection and tracing and surveillance to locate the extent of infection. Vaccination may be an option in some circumstances.
Further Information
Other Information Notes in this series:
- AG1155: Biosecurity guidelines for poultry producers
- AG1013: Quarantine advice for small poultry flocks
- AG1012: Common diseases of backyard poultry
Online:
The previous version of this Information Note was published April 2005.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
