Australia’s deadly avian flu outbreak has spread to a new species. For three weeks the virus had only spread among egg laying chickens, but on Thursday evening authorities confirmed it had reached a duck farm.
The highly contagious H7N3 strain has now been detected at six farms across Victoria, resulting in the destruction of hundreds of thousands of birds. Its spread has impacted the supply of eggs, with Coles supermarkets announcing a temporary limit of two cartons per customer nationwide, except in Western Australia.
The strain impacting Victoria is a different variant to H5N1 which has spread to at least 48 wild and domestic mammal species as well as poultry and migratory birds.
While the current outbreak of H7N3 has so far been restricted to poultry, when it comes to H5N1, there have also been rare cases in humans. In March a boy returning to Australia from India was discovered to be infected.
Is the H5N1 bird flu strain a danger to humans?
In the United States, where the H5N1 strain has infected dairy herds as well as poultry farms, virologist Dr Jenna Guthmiller has warned the virus is being allowed to spread “uncontrolled”.
“We are just seeing the tip of the iceberg. The number of people who are at risk of being exposed to this is really very high,” she told Yahoo News a week ago.
While there hasn’t been human-to-human transmission of the virus there is growing concern H5N1 could evolve into a pandemic.
“The virus is always adapting to new hosts, and the early animal-to-human infections we have seen are giving the virus opportunities to learn how to thrive in the human body,” McMaster University’s Associate Professor Matthew Miller wrote in The Conversation.
Can the spread of avian flu be stopped?
The duck farm where H7N3 was detected supplied both meat and eggs, and all birds will be killed and disposed of.
While the virus can remain in droppings, water, feathers, eggs and meat for long periods, authorities maintains poultry products bought in supermarkets remain safe to eat.
In Victoria, to stop the spread of H7N3, movement controls are in place in designated areas near Terang, Meredith and Lethbridge.
Permits are required in these areas to control the transport of birds, poultry products, feed and equipment.
But some experts believe the only way to prevent strains of avian flu from mutating and spreading is to reform farming practices.
Peter Stevenson OBE, the chief policy advisor at Compassion in World Farming, told Yahoo in May there is a “very, very strong link” between poor animal husbandry and the rise of zoonotic pandemics.
“In the large poultry sheds there are a huge number of birds which are hosts for the virus. It can move very quickly amongst them, perhaps mutating as it does so,” he said.
“That highly pathogenic bird flu can then get out of the poultry sheds, for example, through ventilation systems, and infect wild birds. So you’re getting a virus that’s continually evolving.”
Bird owners are urged to report any cases of unexplained bird deaths to the VicEmergency Hotline on 1800 226 226.
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