Imma Perfetto
Cosmos science journalist
Concern is rising in Australia about the global outbreak of bird flu.
Today in Victoria, the Government has advised preliminary tests have confirmed the presence of avian influenza on an egg farm near Meredith, following an investigation of poultry deaths. The farm has been placed under quarantine.
This comes after yesterday’s announcement by the Victorian Department of Health that a child had made a full recovery after contracting the H5N1 virus overseas.
The egg farm preliminary results indicate that it is not the much feared highly pathogenic avian influenza (HPAI) A H5N1 virus clade 2.3.4.4b, according to a statement made by the Australian Government Department of Agriculture, Fisheries and Forestry.
Clade 2.3.4.4b has been spreading globally, causing widespread outbreaks in bird populations and even spreading to marine mammals, however it has not yet been detected in Australia.
Samples from the affected farm have been delivered to the CSIRO’s Australian Centre for Disease Preparedness at Geelong for further tests to determine the strain and whether it is a high pathogenicity avian influenza (HPAI) virus.
Victoria’s Chief Veterinary Officer, Dr Graeme Cooke, told the ABC that the variant detected was H7N7.
Cooke says: “poultry farmers, backyard flock and bird owners are urged to report any cases of unexplained bird deaths to the 24-hour Emergency Animal Disease Hotline on 1800 675 888, or to your local vet.”
Bob Doneley, a professor in avian and exotic pet service and a registered specialist in bird medicine at the University of Queensland, says: “avian influenza viruses are classified by a combination of two groups of surface proteins: haemagglutinin or “H” proteins, of which there are 16 (H1 to H16), and neuraminidase or “N” proteins, of which there are nine (N1 to N9).
Many different combinations of “H” and “N” proteins are possible – in fact, mathematically there are 170 different combinations possible. Each combination is considered a different subtype and can be further broken down into different strains.
“Avian influenza viruses are further classified by their pathogenicity, low or high, based upon the ability of a particular virus strain to cause disease in chickens,” Doneley says.
According to Doneley, HPAI viruses in poultry are usually H5 or H7 subtypes of Type A influenza and the viral strain most likely to cause human disease and fatalities is H5N1.
Associate Professor Sanjaya Senanayake, a specialist in infectious diseases and associate professor of medicine at The Australian National University, says in Victoria, surveillance will have to be ramped up to identify other poultry populations infected with H7N7.
“Hopefully large culls won’t be needed,” Senanayake says. “From a human health perspective, it is vital to terminate this H7N7 outbreak as soon as possible, otherwise more infections give the virus more opportunities to mutate.
“Infection from poultry to farmed pigs is of particular concern, as pigs can act as the perfect mixing pot of human and avian flu viruses, leading to a strain of flu that can then move between humans easily.
“Despite having “COVID fatigue” and not wanting to hear the word “pandemic” again, the next pandemic could be just around the corner, and a strain of bird flu is a likely candidate. Unlike the early days of COVD, at least with H5N1, there are already human vaccines and antivirals.”
