Q&A: Bird flu
Concern is growing about a mutant strain of the deadly H5N1 bird flu virus that is spreading in Asia and beyond.
Existing vaccines appear to be powerless against the new strain.
What is bird flu?
Avian influenza, or 'bird flu', is an infectious disease caused by viruses that normally infect only birds
There are many different types or strains.
The one concerning experts at the moment is the "highly pathogenic" H5N1 strain - this means that it is highly likely to cause disease.
What is the concern?
There have been over 565 cases of human infection with H5N1 since it first appeared in 2003, killing 331 of them, according to the UN World Health Organization.
Most of these have been in south east Asia, and have been associated with close contact with diseased birds.
Birds shed the virus in their faeces and so close contact with their immediate living environment can spread disease.
There is also the potential that the virus could spread directly from person to person.
H5N1 Highly Pathogenic Avian Influenza virus was eliminated from most of the 63 countries infected at its peak in 2006, but it remained endemic in six nations. Outbreaks have risen since then, with almost 800 cases recorded between 2010 and 2011.
Is it possible to stop bird flu coming into a country?
No. Wild birds do not recognise natural boundaries. But measures such as exclusion zones and bringing poultry indoors are designed to stop the virus taking hold.
The UN's Food and Agriculture Organisation has urged heightened readiness and surveillance. There is concern about spread of the new bird flu virus to Korea, Japan, Malaysia and elsewhere in Asia. Australia is not presently on the high alert list.
Can the virus be passed on through eating poultry or eggs?
No. The virus is easily destroyed by cooking, so even if it was present it would be destroyed.
Is there a vaccine or treatment?
Scientists have made a vaccine for H5N1. As with all flu vaccines, it is a "best guess" vaccine based on the strain experts predict will be most problematic. However, flu viruses are able to rapidly change or mutate, rendering such vaccines powerless. WHO says new H5N1 candidate vaccine viruses will be developed as the viruses continue to evolve and announced as they become available.
In addition to vaccines there are also antiviral drugs, like Tamiflu, that can treat and minimise infection.
Does the seasonal flu jab protect against avian flu?
No. The seasonal flu jab does not protect against avian flu. Seasonal or winter flu is a highly infectious and very common viral illness that is spread readily between people by coughs and sneezes.
Is bird flu different to swine flu?
Yes. Bird flu, as the name suggests, originates in birds and is called H5N1. Swine flu originates in pigs and is a different type of flu, called H1N1. Both have caused outbreaks and deaths in humans.