#19,236
Four days ago Western Australia announced the discovery of a suspected H5N1 infected bird in Perth (collected 6/30). To date, more than 1,000 dead birds have been reported in WA alone, but collection and testing takes time, and so only a small percentage have been processed.
And testing - particularly of bird or animal remains - can be difficult, as the ability to detect the virus can degrade over time.
Normally, after a local lab detects the H5 virus, Australian samples are sent to the national CSIRO lab for confirmation. In the case of the above mentioned Perth sample, after nearly a week - while they confirmed H5 - they were unable fully sequence the virus.
However, WA's Chief Veterinary Officer Dr Katie Webb announced today, “This case will be considered as ‘presumed positive’ based on the available test results, species involved, coastal location and the broader epidemiological picture.”
So far WA has received more than 1,000 reports of dead birds, but due to the high volume, the DPIRD has prioritized 172 for further investigation. Of those already processed in WA, 5 have tested positive and 64 have tested negative.
As with any disease surveillance system - whether in birds, livestock, or people - confirmed cases will represent only the tip of the pyramid.
In the case of H5N1 in birds:
- Only a percentage of birds will sicken and die (varies by species)
- Only a fraction of those birds will be seen, reported, and collected
- Of those, only a subset will be prioritized for testing
- And of that group, some may not have detectable levels of virus
While 7 cases detected across 3 Australian states may not sound like much, it is actually a pretty strong signal that multiple incursions of HPAI have likely occurred in recent weeks.
This update from the Western Australian government website:
WA responding to ‘presumed positive’ H5 bird flu case in Perth
Media release
Additional testing of the previously reported migratory giant petrel found in the Whitfords - Mullaloo beach area has determined the case is a ‘presumed positive’ detection of the serious H5 bird flu strain.
Last updated: 6 July 2026
Additional testing of the previously reported migratory giant petrel found in the Whitfords - Mullaloo beach area has determined the case is a ‘presumed positive’ detection of the serious H5 bird flu strain.
Testing at CSIRO’s Australian Centre for Disease Preparedness has confirmed the petrel had an influenza virus of the H5 subtype.
The case has been classified as a presumed positive because viral sequencing to confirm the virus as H5 bird flu was not able to be achieved.
The inability to obtain a sequence may be due to a range of factors, including the level of decomposition of the carcass.
WA Acting Chief Veterinary Officer Dr Katie Webb said it was considered highly likely the bird was infected with H5 bird flu, but this could not be definitively proven at this stage.
“This case will be considered as ‘presumed positive’ based on the available test results, species involved, coastal location and the broader epidemiological picture,” Dr Webb said.
“This does not change our response in WA. We are treating this the same as a positive case based on the available epidemiological and laboratory evidence.”
This presumed positive case adds to the six confirmed positive detections of H5 bird flu nationally, including four in WA on the southern and south west coasts, one in South Australia and one in New South Wales.
Importantly, there is no evidence the virus has spread beyond these individual migratory seabirds, but we ask the community to be alert and follow advice about reporting sick or dead wildlife.
People should AVOID and not handle the animals, RECORD and take photos or a video and REPORT to the Emergency Animal Disease (EAD) Hotline on 1800 675 888.
There have been more than 1000 reports from WA to the EAD hotline since Friday 19 June. Of these reports, 172 have been prioritised by DPIRD for further investigation or testing based on the risk of H5 bird flu.
To date, a total of 64 negative test results have been recorded across the State.
More information is available on the Australian Government's Bird flu (avian influenza) website.
