Australia’s stinging trees are notorious for delivering excruciating pain that can last for days, weeks or even months and researchers now say they know why.
South-East Queensland’s giant stinging tree and its northern cousin, the Gympie-Gympie stinging tree are both members of the nettle family and are covered in needle-like hairs filled with toxins.
“When you brush past them, the needles act like a hypodermic syringe, penetrating your skin to inject what we now really consider a venom,” Professor Irina Vetter said.
“They’re definitely notorious for how bad the sting is and how long it can last for.
“The minimum time that it can hurt for is around six to eight hours, but the really intriguing thing is you can trigger this pain for days, weeks and in some cases even months after being exposed.”
Professor Vetter, from the University of Queensland’s Institute for Molecular Bioscience, has spent more than 10 years studying the notorious reputation of Australia’s stinging trees.
She and her team have recently discovered an entire new family of proteins, or peptides, found in the trees’ stinging hairs.
“The primary structure of them is completely novel, we’ve never seen anything like this before,” Professor Vetter said.
“The 3D shape of them looks like toxins that you would find in cone snail venom, and they do exactly the same thing.
“They act on channels in your sensory nerves, your pain-sensing nerves in the skin. They basically activate them and away you go and suffer.”
Far North Queensland trekking guide, Wayne Fitcher, is no stranger to the searing pain that follows encounters with stinging trees.
He said his most memorable experience of the plant occurred while guiding a group of schoolchildren through dense rainforest.
“Young Ryan was up front and I was trying to slow him down when he got hammered by this stinging tree that was about a metre high,” Mr Fitcher said.
“He was in shorts and a t-shirt and this damn thing got a hold of him from about his shoulder to his knee.
Thinking he was doing the right thing, Mr Fitcher said he tried to remove the plant by grabbing it by the stem.
“It was bordering on agony and that agony, in various degrees, lasted four or five months before it went away.”
Professor Vetter said the discovery about how Australian stinging trees delivered such pain could be used to create new painkillers.
“While the sting is quite painful it can actually teach us a lot about how pain works in general and hopefully how we can treat people for chronic pain in the future,” she said.
“The goal is, ultimately, to create new pain treatments — ones that work better and have fewer side effects.
“If we can use the venom from the stinging tree to do that, then even better.”
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World news – ‘He was in agony’: How the Australian stinging tree hurts — and keeps on hurting