Backyards have become Australia’s frontline against the fast‑moving bird flu outbreak, with pet and poultry owners urged to do all they can to protect their beloved domestic animals.

It came as the national tally of confirmed or presumed cases of the deadly H5 strain of the virus topped 230 and the federal government announced a vaccination program for birds in captivity and zoos.

The virus has not yet spread beyond wild birds but authorities have warned that what happens in suburban yards and smallholdings in coming weeks will be critical to keeping the deadly strain at bay.

Most of the nation’s confirmed cases are in South Australia, with the state count rising to 163 following another 11 detections in wild seabirds.

The latest cases confirmed by CSIRO’s Australian Centre for Disease Preparedness in Geelong include a cormorant as well as greater crested terns and gulls found along the Limestone Coast, Kangaroo Island, the Yorke Peninsula and Adelaide’s coastline.

“We have been abundantly clear that Australians should expect to see more spread and larger numbers, particularly of dead birds, and mass mortalities around the country from the H5 bird flu,” Agriculture Minister Julie Collins said on Tuesday.

“We have been very clear it will continue to spread across the country.”

She said reporting of the number of bird flu cases would change due to the spread of the virus among species. Counting the overall tally was no longer the most accurate picture of how the disease was spreading.

“Our reporting will evolve to focus on confirmed H5 events and the developments that matter most, where the disease is spreading, new locations or species affected in emerging areas of risk,” Collins said.

Attention has also shifted from remote seabird colonies to household pets and backyard flocks as authorities look to ensure they don’t act as a bird flu bridge between wildlife and humans.

“It’s now important to really focus in on our domestic animals and what we can do practically to keep them safe,” RSPCA SA chief executive Marcus Gehrig said in Adelaide.

Owners should look at containing cats indoors or in secure outdoor enclosures so did not interact with wildlife and wild birds, which had been shown globally to pose a particular risk, he said.

“Our backyard birds and poultry, they are very susceptible to bird flu, and the prognosis there is typically death,” he said.

Owners are also urged to keep flocks separate from native wildlife and to ensure feeders and their water sources are separated.

“We know cats that are left to roam prey on wildlife and now, more than ever, it’s important to keep them indoors,” SA Environment Minister Emily Bourke said.

International reports of H5 infections in dogs are infrequent but increase when exposed to sick or dead birds.

State biosecurity director Georgie Cornish urged people to keep their pet birds away from wild birds by adjusting aviaries or keeping them inside.

Simple hygiene and securing feed and water from wildlife was key to avoiding the spread, she said.

Commercial producers are advised to undertake voluntary housing orders and other precautions.

Adelaide dog and chicken owner Anthony Abley installed enclosed feeders and drinkers that exclude wild birds and vermin, including a treadle feeder that opens only when his hens step on it.

He said his family planned to move the flock into a smaller, fully netted run to further reduce contact with wild birds as the season progressed.

Collins again warned people not to touch sick or dead birds. They should instead be reported via the national hotline listed at birdflu.gov.au.

Environment Minister Murray Watt said more mass mortalities of birds were inevitable.

“That will be a very distressing thing for Australians and as a government we are determined not only to protect our birds as best we can also to support Australians through what is going to be a very difficult journey,” he said.

“Where it is possible to vaccinate wild birds we will do so, but the priority is to vaccinate birds that are in captivity and in zoos and other institutions.

“We are taking this step now because, of course, the situation regarding bird flu in Australia is escalating.”

The federal government has stressed that “the risk to human health remains low”. It has invested more than $113 million to boost Australia’s H5 preparedness as part of a wider $2 billion biosecurity package.

-with AAP