What does the NSW bird flu case mean for households and grocery lists?

Egg stock in supermarkets are down, and hundreds of thousands of chickens are set to be euthanased as bird flu wreaks havoc across Australia.

Virus strain HPAI H7N8 was detected on a large poultry egg farm in the Hawkesbury district of NSW on Wednesday.

NSW Minister for Agriculture Tara Moriarty told ABC News 8,000 birds died from the flu as it swept through the farm with 240,000 birds at the farm to be euthanased.

Premier Chris Minns said there was no reason to panic as the confirmed case was "quarantined to one particular site" and government officials were "managing the situation".

It follows — but is not connected to — an outbreak of two strains in Victoria, and a third causing concern around the world.

A low-pathogenic case of bird flu was also detected in Western Australia last month.

Professor of microbiology at Swinburne University and food health and safety expert Enzo Palombo said that while there's "never been any evidence" of the virus transmitting to food supply, there are still measures that can be taken to minimise risk. 

Here are the implications of bird flu, and how it will likely affect consumers. 

What is the H7N8 strain of bird flu?

Avian influenza, more commonly known as bird flu, is an infectious virus similar to seasonal influenza (flu) in humans.

NSW Health says it spreads predominantly through wild water birds, and there are several types that vary in how deadly it is for the animals.

The virus can occasionally, but rarely, spread to humans through contact with infected birds.

There has been a lock down of machinery, materials, animals and transport within a radius of 2 kilometres of the affected egg farm, covering three large commercial poultry farms and up to 355,000 birds will be monitored for any signs of the virus.

Most strains have not shown evidence of efficient person-to-person transmission or community spread to date, according to the World Health Organization (WHO).

HPAI stands for high pathogenicity avian influenza — meaning it is more likely to kill chickens, and has been implicated in eight successfully eradicated poultry outbreaks in Australia.

In NSW, it has been eradicated three times, most recently in regional town Young in the Hilltops Region in 2013.

H7N8 is different from fellow HPAI and global strain of concern H5N1, detected in a Melbourne toddler recently, as well as H7N3 and H7N9 which have caused outbreaks in Victoria.

The strain that led to the quarantine of the Greater Sydney Basin farm is understood to be a "separate spill-over event" potentially from wild birds.

"If you haven't already, get your annual flu vaccination, because the less human flu there is in the community, the less likely these events where human and bird viruses merge to be something different, can occur."

Does it relate to the current egg shortage?

Professor Palombo said more broadly, empty shelves in supermarkets can happen when supply farms are impacted, or to prepare consumers for wider anticipated egg shortages.

"[This can] help the public get used to perhaps having to find alternative supplies," he said.

The Victorian outbreak has already affected poultry supply, and led to warnings of potential shortages that could affect egg supplies nationwide.

According to the egg industry, there are more than 21 million hens in the national egg flock and more than 1 million in Victoria that will be culled to stop the bird flu spread.

In the Hawkesbury farm instance, Australian Eggs managing director Rowan McMonnies said birds on the farm would be euthanised. 

He said it would cause a "significant blow" to the farm involved and the industry at large.

Victoria, New South Wales and Queensland produce more than 350 million dozen eggs each year combined.

Ms Moriarty said NSW consumers should not be concerned about eggs and poultry products from the supermarkets "because this detection does not pose a risk to consumer health and the products are safe to consume".

President of the NSW branch of the Farmers Federation Xavier Martin said earlier this month that less than 2 per cent of Australia's hens had been impacted.

He said that buying restrictions had more to do with supermarket procurement policy than farmers.

"There's no need for any concerns, avian influenza is not new — it's been in New South Wales about a decade ago."

Peak body Australian Eggs assured consumers that there were "still hundreds of egg farms around the country" to support demand as impacted farms recover.

"These avian influenza incidents will cause some disruption to egg supply as retailers reorganise their supply," Mr McMonnies said. 

Should we be concerned about diets, coops?

Professor Palombo assured the risk of transmission through eggs and poultry meat is "so remote that it's probably not even a concern".

Regular precautions in food hygiene, handling, cooking and storing help make the risk negligible, he said.

"If the virus ever gets into the food supply, cooking the food thoroughly, as we should always do with any poultry products, will kill the virus and therefore eliminate the risk.

"Remember, the flu is a respiratory virus, it doesn't spread through food, which is one reassuring piece of good news."

People most at risk are those in close contact with live infected birds, like at farms or abattoirs, Professor Palombo said.

"In terms of the general public, there's been no evidence of this virus being able to spread to humans unless they are in very deep contact or close contact with infected [birds]."

The professor said people with backyard chickens could also be more vigilant watching the health of themselves and their birds.

"If they see any signs of distress, symptoms like diarrhoea or respiratory symptoms, contact your authorities and report those," he urged.