Farms infected with bird flu could rise as risk to human health remains low

The detection at the property near Meredith is the fourth case of bird flu reported in Victoria since late May, with one agricultural leader warning more infected properties could likely be detected in coming days.

"This detection is not unexpected and is the result of comprehensive and ongoing surveillance activities within the restricted and control areas," Agriculture Victoria said.

More than half a million birds have been destroyed since the first outbreak on a property near Meredith with the H7N3 strain, while a second property at Terang linked to the first property was detected with the H7N9 strain.

Since then, a Farm Pride Foods' site at Lethbridge, plus a fourth property at Meredith have also tested positive for the disease.

Farm Pride Foods, an ASX-listed company, said about 80,000 free-range hens - or about 8 per cent - of the company's production capacity had been destroyed since the H7N3 strain detection this week.

The company said it would seek compensation from the Emergency Animal Disease Compensation Scheme in the wake of the depopulation.

"Farm Pride has a further separate site with approximately 40,000 free-range hens in the Lethbridge area which is also subject to monitoring and testing," a Farm Pride Foods spokesperson said.

La Trobe Institute of Molecular Science research fellow Emma Grant, a viral immunologist with research focusing on immune responses to viruses, said the risks associated with human health remained low.

"Threats from a human perspective are very limited," Dr Grant said.

"The biggest threat is to the agriculture sector and that's why there's been a lot of focus on containing the spread and preventing further outbreaks."

"It's not of concern to human health, but from an agriculture perspective it's obviously concerning when we see these outbreaks."

Dr Grant said the strains of avian influenza detected in Victoria did not easily infect humans.

"There are lots of different strains of avian influenza, and some are classified as high pathogenicity avian influenzas and some are low pathogenicity influenzas," she said.

"High pathogenicity diseases can cause greater disease in animals and the strains seen in Victoria have been classified by the Australian government.

"All of the avian influenzas find it hard to bind to human cells, and only in instances of repeated and constant exposure to diseased animals do we see these transmissions from animals to humans occur."

Victorian Farmers Federation vice-president Danyel Cucinotta, an egg farmer at Werribee, said there was no simple solution to halt the spread of the virus.

"This latest detection is unsurprising and I wouldn't be surprised if we continue to find further farms affected in the coming days," Ms Cucinotta said.

"Unfortunately, you can have the best biosecurity in the world, but we can't stop wild birds flying over the country.

"That is the risk in putting more birds out on the ground and having free range systems."

Ms Cucinotta said she was an advocate for a hybrid of three production systems in the poultry industry, which included free range, barn or cage-free and cage-system farms.

"I'm an advocate for all three production systems and you need to balance all three systems to ensure an effective and efficient food supply chain," she said.

Bird owners are urged to report unexplained bird deaths to the VicEmergency Hotline on 1800 226 226.