Two weeks ago bird flu was first identified at a free-range egg farm in Lethbridge.

That farm was placed under quarantine, had birds destroyed, and had a restricted buffer zone established around it.

Then a further detection of bird flu was confirmed on a commercial egg farm in the Golden Plains Shire, and another in eastern Victoria.

The outbreak has prompted the state's agriculture department to order all commercial free-range egg farms in the area to house their flocks indoors for 30 days.

The strain of virus on rare occasions has been known to infect and cause disease in humans who have had close contact with infected poultry or human cases.

The Department of Health and Human Services said to date, no human cases have been reported and there is no risk of transmission through consumption of eggs and chicken meat that are thoroughly cooked.

Warrnambool and District Poultry Club secretary Jason Callaway said even backyard layers must be vigilant.

"Some basic measures are to not bring any poultry or birds onto the premises if they've come near or past the exclusion zone," he said.

"Make sure your poultry are enclosed for the time being and not in an open space where wild birds can get in, because they can transfer the flu on.

"Also making sure there's no cross-contamination in cages. I would think most serious farmers would be vigilant and know about the issues but backyarders might not be up to date with quarantine measures.

"Hopefully there's no major outbreaks, it's a concern not just for big operators but even if you get three backyard chooks infected there's the potential to spread to everyone else in the Warrnambool district."

Casaccio Egg Farm Terang operations manager Ian Sfetcopoulos said they were following strict biosecurity protocols and remaining vigilant about the outbreak.

They have 120,000 chickens on their south-west family owned and run farm.

Of those, 30 per cent, or 36,000 are free range, while 70 per cent, or 84,000, are cage layers.

"We've always followed strict biosecurity measures and while we are far enough away from the concerns at Lethbridge we've been checking all vehicles coming in or out, making sure the wheels are all properly washed and sanitised," he said.

"We feel okay about it because we're fairly isolated here in regards to distancing so we're unaffected by it.

"This is a seven day a week operation, the chickens don't stop laying so we have to keep the welfare of the birds as our top priority."

Mr Sfetcopoulos said all chooks could be moved into sheds if needed.

He said the pandemic had led to a drop in egg sales.

"We've really seen a drop with cafes in the area closing and reducing capacity," he said.

"We employ a large number of locals and support around 30 families in Terang making us one of the largest employers in town.

"We haven't stopped because we are an essential service and have been keeping all our staff on by doing a delivery service to all the major towns in the area including Warrnambool, Portland, Mortlake, Timboon and Colac.

"We hope to do home delivery in the near future, or possible a pick up, drop off point for locals where customers can order their eggs over the phone and set up a time to pick them up contact-free."

The department said last week staff and other persons who may have been exposed to infected poultry are being contacted and provided with relevant information to monitor their health and seek medical assistance if they develop symptoms.

Agriculture Victoria has ensured that movement controls are in place and the affected properties have been quarantined.

These controls prohibit the movement of birds, equipment and products within and out of the restricted area until further notice.

Kate Warner from Caravan Eggs said it was concerning to see the outbreak so close to home.

They have 8000 free range chickens on their Dundonnell property.

"We're continuing to do our strict biosecurity measures and are monitoring the situation very closely, it's a concern but all we can do is monitor it," she said.

"We've had good sales, catering has dropped off but retail is strong and steady I think because a lot of people are cooking breaky at home and things like that."

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