Avian Influenza Factsheet

Background

The Australian Government has been aware of this strain of the disease since its emergence in 1996 and again when it took hold in many Asian countries in 2003.

2003-05
The Australian Government has been aware of this highly pathogenic strain of the virus since its emergence in 1996 and again when it re-emerged in many Asian countries in 2003.

Between December 2003 and July 2005 highly pathogenic avian influenza (H5N1) outbreaks occurred in poultry and other birds in Korea, Japan, Vietnam, Thailand, Cambodia, Laos, Indonesia, China, and Malaysia.

In late 2005 it spread to Russia, Kazakhstan, Romania, Mongolia, Turkey and Croatia. Also during this period outbreaks increased in Indonesia, Vietnam and China.

2006
Highly pathogenic avian influenza H5N1 spread even further in 2006, to Western Europe, Africa, the Middle East and Hong Kong. Low pathogenic strains were also reported in the United Kingdom and in several states of America.

The most severely affected country in 2006 was Indonesia.  It now has the highest human case and death toll in the world from avian influenza H5N1 infection - overtaking Vietnam which reported no human cases or deaths in 2006.  

Other countries that had major outbreaks in poultry were Sudan, Nigeria, Egypt, Thailand and China.

Avian influenza infections were also reported in cats and some wild carnivores that had eaten raw infected birds.

2007
2007 saw the human avian influenza death toll climb to over 200 people with most deaths still occurring in Asian countries including Indonesia and China.

Countries which had H5N1 outbreaks in birds for the first time included Japan, the Czech Republic and Ghana. Small outbreaks occurred in Hong Kong, Germany, Poland, and the African nations of Lagos, Togo and Benin.

The larger outbreaks in birds occurred in Vietnam, Indonesia, China, Myanmar and in the Middle Eastern countries of Bangladesh, Pakistan, Afghanistan and Kuwait.

Britain had a major outbreak in February with the source of the infection identified as contaminated meat imported from Hungary. Britain suffered a second major outbreak in Suffolk in November.

France had a number of detections of the disease in wild birds but none in domestic birds.

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What is Avian Influenza (bird flu)?

Avian Influenza (AI) is a viral disease of birds. There are many strains of AI virus that cause infections of different severity. These range from low pathogenic or mild, to highly pathogenic strains that are associated with severe disease and high mortality in poultry.

The disease occurs worldwide. 

What is H5N1?

H5N1 is a particular strain of highly pathogenic avian influenza.

Human Health

Generally, humans are not affected but the H5N1 strain of the virus can infect humans who come in close contact with infected birds. Accurate statistics on human deaths caused by H5N1 can be found on the WHO website Link to a non-government site.

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

People are not infected through eating cooked chicken meat and eggs. Good handwashing after contact with raw products should always be followed.

Clinical signs and symptoms of avian influenza in humans include fever, sore throat, respiratory distress, pneumonia and in some cases death.

The WHO has concerns that this strain may mutate and gain the capacity to spread from person to person, potentially causing a pandemic of influenza in humans. However, worldwide investigations currently provide no evidence of human to human transmission.

If avian influenza were to pose a significant threat (direct or indirect) to Australia’s human population, the Australian Government would activate the Australian Action Plan for Pandemic InfluenzaPDF [345kb]. This plan provides direction for the development of actions by all Australian Governments, their agencies and emergency services in the event of such an occurrence.

Additional public health information about avian influenza is available on the Australian Government Department of Health and Ageing website.

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Susceptible Species

All bird species are thought to be susceptible, with reports showing it to occur in more than 140 species including domestic poultry - chickens, turkeys, pheasants, partridges, quail, pigeons, ducks, geese, guinea fowl and ostriches - and wild birds.

Many species of wild birds and waterfowl (especially geese, ducks and swans) carry the virus but generally show no signs of disease. If they or their excretions come into contact with, and infect domestic poultry (domestic chickens, turkeys, quail etc), the virus may mutate and become highly pathogenic.

Other mammals

AI viruses usually only infect birds but pigs, tigers, leopards and domestic cats and dogs have also been infected with H5N1. So far, all cases of H5N1 infection in other mammals has involved close contact with, or the consumption of raw infected birds.

Clinical Signs in Birds

The clinical signs are variable and depend on a range of factors including the virulence of the virus, the species and age of the birds infected, the presence of concurrent diseases, and the environment.

In very severe forms, such as H5N1, the disease appears suddenly and birds die quickly. 

Common signs to look for are:

  • sudden death in several birds
  • ruffled feathers
  • unusual head or neck posture
  • inability to walk or stand
  • relunctance to move, eat or drink
  • droopy appearance
  • respiratory distress
  • diarrhoea
  • swollen head, wattle or comb, and
  • a drop in egg production.
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Persistence of the Virus

Environmental conditions have a marked effect on the duration of infectivity of the virus outside the bird. Avian influenza virus can survive and retain infectivity for at least 35 days at 4° Celcius in manure. The disease can also survive in water for many days, if not weeks, depending on temperature. The virus can remain infective for several days in carcases at ambient temperature and up to 23 days if refrigerated. The virus can survive in poultry meat products but is destroyed by adequate heating (eg. normal cooking temperatures). Freezing poultry does not kill the virus.

Has Avian Influenza ever occurred in Australia?

The H5N1 strain has never been reported in Australia.  There have been five outbreaks of other avian influenza strains in commercial bird flocks in Australia, all of which were successfully eradicated.  The last reported case was in 1997 in Tamworth, NSW.  Previous outbreaks occurred in commercial poultry farms in Victoria (1976, 1985 and 1992) and Queensland (1994). There have been no cases of avian influenza viruses infecting humans, reported in Australia.

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The Quick Key Facts

  • Avian influenza and human pandemic influenza are different diseases. 
  • Avian influenza virus of birds does not easily cause disease in humans.  There have been over 280 human deaths from avian influenza in the world since the H5N1 virus first emerged in 2003.
  • There is only the most remote possibility of a human pandemic influenza developing in Australia as a result of migratory birds carrying avian influenza virus to Australia.  If human pandemic influenza develops as a result of mutation of an avian influenza virus, it will most likely occur somewhere else in the world and any spread to Australia would be from international travellers.
  • Surveillance continues to show H5N1 avian influenza virus is not present in Australia.  Waterfowl, which are the normal hosts of avian influenza and are thought to have had a role in the spread of the H5N1 virus in Europe, Asia and Africa, do not migrate to Australia. A number of species of wading birds do migrate to Australia but they are not the normal hosts or spreaders of avian influenza. Australia’s strict quarantine measures prevent the disease coming into Australia through imported birds or poultry products.
  • There is little risk of people in Australia being affected by avian influenza through normal contact with birds.  As always, practice good personal hygeine when handling birds.
  • Aviary birds, caged birds and back yard birds are at little risk if simple measures such as preventing them mixing with wild birds and protecting their feed and water supply are adopted. 
  • Australia is well prepared to deal with a case of avian influenza should it occur in poultry here. There have been five minor incidents of avian influenza in Australia, the last being in 1997. Each was eradicated before the disease was able to signficantly spread. Workers involved with diseased poultry did not become infected with avian influenza in any of these outbreaks.
  • Australia has a surveillance program to detect incursions of avian influenza.
  • There is little risk of people in Australia being affected by avian influenza through normal contact with birds. As always, practice good personal hygiene when handling birds.
  • Health and agricultural simulation exercises have been held to better prepare Australia in responding to a case of avian influenza should it occur.
  • Public alarm about avian influenza and confusion between avian influenza and human pandemic influenza may unnecessarily damage Australia's poultry industry.
  • Eggs, meat and poultry products in Australia remain safe.
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