Another migratory giant petrel bird found near Esperance is suspected of being the State’s fourth positive case of the deadly H5 bird flu.

It was one of five deceased petrels found by a member of the public on Roses Beach, 30km west of the town in WA’s south, with samples from the four other birds returning a negative result to preliminary testing in Perth.

The samples have all been sent to CSIRO’s Australian Centre for Disease Preparedness in Geelong to confirm the results and determine if the suspected positive bird was indeed another case of the H5 strain making it to the West Australian shore.

So far just two cases have been formally confirmed in WA, a brown skua and giant petrel found in the same area, east of Esperance.

Results are still pending from of an earlier suspected positive detection in a giant petrel found at Quindalup, near Busselton.

Another giant petrel found in South Australia was also confirmed on Wednesday as that State’s first case of H5 avian influenza.

All cases have so far come from migratory birds with no indications of cases in poultry and no evidence of large-scale deaths in any wildlife.

Since June 19, there have been 375 reports to the Emergency Animal Disease hotline with 43 prioritised for further investigation and testing because of bird flu fears.

Agriculture Minister Jackie Jarvis said positive cases remained isolated.

“We have seen absolutely no evidence of any spread of this disease, it is only single migratory birds that have been found on beaches,” she said.

“If the situation changes, then the testing rule will continue, but as I said we’ve had lots of reports, 12 negative cases.

“We expect that the negative cases will increase as the testing is done, and so that’s an important part of the surveillance.”