What is avian influenza?
Avian influenza is a disease of birds (mostly commercial chickens and turkeys) which is caused by a virus. It has received a lot of attention in recent years because since 2004 one particular strain of the virus (the H5N1 strain, which some people refer to as ‘bird flu’) has spread widely through Asia and in some other countries, where it has also been seen to cause serious disease, and some deaths, in a relatively small number of humans who have had direct contact with sick or dead birds which have been infected with this particular virus. At present (March 2014), Australia is free from avian influenza. However, this has not always been the case, and Australia has had nine outbreaks of avian influenza (of a different strain to the H5N1 type) in commercial poultry flocks (meat chickens, egg chickens and ducks) over the past 50 years. On every occasion, Australia has been well prepared to quickly spot the infection and to take action to get rid of it. On each occasion, the outbreak has immediately been controlled and eradicated. Should the H5N1 strain ever get into Australia’s poultry flock, it would be expected to be equally quickly identified and eradicated.
What is avian influenza A (H5N1)?
This is the designation of the virus that emerged in 2004 in China and South-East Asia. This particular strain is highly lethal to poultry and remains of concern to poultry.
The WHO has identified the main risk of transmitting the highly virulent H5N1 strain of AI as the movement of live birds through local markets, where vendors bring large numbers of birds for breeding or eating. The virus can survive in faeces, on feathers, eggs or meat. The spread of H5N1 has lessened compared to the height of its impact around 2006-07 but the virus remains a major issue in a number of countries where it has become endemic, including Egypt, Indonesia and Viet Nam. However, despite the time that has now passed, the virus remains restricted to animal to animal transmission and the rare transmission to a person, but the latter requires close interaction between sick birds and the person. The change in the virus to make it able to be transmitted between people has fortunately not eventuated.
What about H7N9 in China?
In March/April 2013, China reported human infections with H7N9 with severe symptoms and high mortality. This new virus did not spread readily in poultry and did not affect the health of poultry that was infected. This was very different from the H5N1 virus. The virus continuesd to infect small numbers of people in some of the south eastern provinces of China during the winter of 2013-14, but has not spread to other countries (as of April 2014).
What is happening in the US?
In early 2015, a new strain called H5N2 took hold in poultry in the US. By May 2015, over 20 farms, mostly turkey but also layer farms, were affected and had to be quarantiened and the birds culled. This strain, while highly infectious to poultry, does not affect people. As with all avian influenza, there is no food safety issue associated with these outbreaks.
It is believed that the virus is being spread by wild birds as has been the case with other strains. Increased biosecurity measures on farms is the main action that is used to limit the further spread.
For more information see our dedicated Avian Influenza webpage and the Department of Agriculture website.