With more more than 500,000 chickens already slaughtered due to an outbreak of bird flu at three Victorian farms, many Australians are rightly concerned about the safety of the food they eat. 

Tensions were heightened when a child returning from India was confirmed as Australia's first case of avian influenza A(H5N1) - bird flu - which has caused widespread bird deaths around the world.

Coles shoppers have been limited to buying two cartons of eggs due to supply chain issues caused by the outbreak in Victoria, leading to increased scrutiny of the crisis gripping Australia's poultry farms.

With bird flu also capable of spreading to cows, the major question on people's minds is, can bird flu be caught through eating chicken and eggs, or drinking milk?

How safe is chicken?

Since last month, there have been four outbreaks in Victorian poultry farms (three with H7N3 bird flu, one with H7N9), and one in Western Australia, H9N2).

These bird flu strains can infect humans, but this is very rare and is generally caused by close contact with infected live birds or contaminated areas.

This means there is very little chance of bird flu being caught from chicken meat.

But, as Professor Enzo Palombo of Swinburne University wrote on The Conversation, 'it is timely to remind people to handle chicken meat with caution as many dangerous pathogens, such as salmonella and campylobacter, can be found on chicken carcasses'.

Chicken meat should always be handled carefully when shopping, transporting it home and storing it in the kitchen. 

It is a good idea to use a cool bag when transporting meat, and to refrigerate or freeze it within two hours.

Avoid washing the chicken before cooking to prevent the spread of disease-causing microbes around the kitchen.

Finally, cook the chicken thoroughly as viruses such as bird flu cannot survive cooking temperatures.

What about eggs? 

Flu viruses can contaminate chicken eggs and potentially spread bird flu. 

The viruses can get in through the eggshell because influenza virus particles are smaller (100nanometres) than the pores in eggshells (at least 200nanometres).

This means the viruses will not be removed by cleaning the outside of the egg, so it is best to cook the eggs, rather than eating them raw.

The US Food and Drug Administration recommends cooking poultry, eggs and other animal products to the proper temperature and preventing cross-contamination between raw and cooked food.

Is milk safe?

In Australia, where bird flu has not been reported in dairy cattle, it is safe to drink milk and milk products because it is pasteurised. 

'Although there is little direct research on whether pasteurisation inactivates H5N1 in milk, we can extrapolate from what we know about heat inactivation of H5N1 in chicken and eggs,' the professor wrote.

'So we can be confident there is no risk of bird flu transmission via pasteurised milk or milk products.'

More than 80 dairy herds in at least nine American states have been infected with the H5N1 version of the bird flu virus.

Infected birds can shed the virus in their saliva, nasal secretions and faeces, so bird flu can contaminate animal-derived food products during processing and manufacturing.

But Prof Palombo wrote that 'the spread of bird flu among cattle, and possibly to humans, is likely to have been caused through contact with contaminated milking equipment, not the milk itself'.

The test used to detect the virus in milk is highly sensitive, which means it can detect very low levels of bird flu genetic material (RNA). 

But the test does not distinguish between live or inactivated virus, just that the RNA is present, so from that test alone, it's not possible tell if the virus found in milk is infectious and capable of infecting humans.

In conclusion, Prof Palombo said 'If you consume pasteurised milk products and thoroughly cook your chicken and eggs, there is nothing to worry about as bird flu is inactivated by heat.'