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A virus that causes parrots to drop their feathers and can eventually kill them is widespread in Victoria and is pushing some native species toward extinction, scientists fear.
The virus, which is endemic to Australia, attacks a parrot's feathers, claws and beak, causing the feathers to fall out, the beak to grow too large to eat with and the tissue to rot. In the worst cases, it can leave a bird entirely featherless.
A sulphur-crested cockatoo suffering the effects of beak and feather virus.Credit: J.M. Martens
It mainly affects psittaciformes, the order of birds that include cockatoos, parrots and lorikeets, many of which are already endangered by human activity.
The Australian government recognised beak and feather disease virus as an extinction threat in 2005 and launched plans to develop a vaccine.
But 15 years later there is still no vaccine – and no treatment for infected birds.
Several species can carry the virus with almost no symptoms – and then spread it to vulnerable species.
An infection could kill off the last few remaining orange-bellied parrots.Credit: Zoos Victoria
“Individual bird species use it against other species. You get this arms-war effect,” said Charles Sturt University veterinary pathologist Professor Shane Raidal.
“Pretty much any of the vulnerable and endangered species is impacted by this virus. It is an extinction-threat to the critically-endangered ones.”
The virus does not pose much of a threat to birds with healthy flock numbers, as they can tolerate a few deaths a year.
But in endangered species such as the orange-bellied parrot or the swift parrot, an infection could kill off the last few remaining birds.
There is no cure for beak and feather disease.Credit: J. M. Martens
The virus is also unique because of its tiny size. There are about 2000 letters in its genetic code (the virus that causes COVID-19 has about 30,000) meaning it can easily mutate and jump into other species.
On Thursday, Professor Raidal and a team of other researchers published the first high-quality study looking at how widespread the virus was in Australia.
And they found it almost everywhere they looked.
The researchers looked for evidence of the virus in seven native birds: crimson rosellas, eastern rosellas, galahs, sulphur-crested cockatoos, blue-winged parrots, rainbow lorikeets and red-rumped parrots.
The study, published in PLoS ONE, found the infection in six of the seven species they tested, including in more than 40 per cent of rosellas sampled and 20 per cent of cockatoos.
This fits with the idea that rosellas are a "reservoir species". The birds don’t get particularly sick from the virus, allowing them to spread it around widely to other species.
“It is widespread,” said Deakin University ornithologist Johanne Martens, the study’s lead author.
“Our study shows a lot of the abundant species carry it with a high prevalence, without having obvious signs.”
The virus was declared a major extinction threat by the federal government in 2005. Developing a vaccine was identified as the highest priority research action.
Professor Raidal is currently involved in that effort. He described progress as slow and halting due to a lack of focus and funding from the federal government.
A second obstacle: to develop a vaccine, scientists need to grow the virus inside live parrots and then harvest it – considered ethically unacceptable.
In 2015, a decade after the government first launched a strategy to tackle the disease, the plan was canned and replaced with a plan to develop what the government termed "non-statutory threat abatement advice".
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