Medical experts reckon the three tourists who suffered heart attacks – two fatally – while snorkelling the Great Barrier Reef on Wednesday were likely stung by the deadly Irukandji jellyfish.
French nationals Danielle Franck, 74, and Jacques Goron, 74, both died while snorkelling at Michaelmas Cay north of Cairns on Wednesday, while a third person suffered a heart attack but survived.
They were among a French group of 21 elderly people, snorkelling the reef with tour company Passions of Paradise.
Their deaths have been attributed to pre-existing medical conditions exacerbated by swallowing salt water, but leading Sydney cardiologist Ross Walker believes all three may have been bitten by Irukandji jellyfish, the smallest and most venomous box jellyfish in the world.
“Two divers were affected by swallowing seawater? Give me a break,” he told News.com.au.
“Look at the facts here. You have jellyfish infested water, and the bite of the jellyfish stimulates a heart attack. I think they were more likely all bitten by Irukandji jellyfish.
“But if that gets out, then the people running the dive programs won’t get anyone in the water.”
Irukandji jellyfish are the size of a finger nail, meaning they’re practically impossible to see in the water.
“You don’t even know you’ve been bitten straight away,” said Dr Walker. “Around 30 minutes later you have symptoms and go into cardiac arrest.”
James Cook University medical education director Dr Tarun Sen Gupta agreed that an environmental factor is far, far more likely than simultaneous heart attacks.
“If someone’s having a heart attack in my office, the chance of the next person having a heart attack is one in a million,” he told the Cairns Post. “It’s a very, very rare event and I’ve never seen it in 30 years of practice.”
He, too, suggested jellyfish.
“I would think there may have been something in the water, some toxin, maybe an envenomation. I think you would have to look at that.”
Passions of Paradise CEO Scott Garden said in a statement that the company would conduct a review into the tragedy, but he was confident protocols were followed.
“We did what we could. It was a credit to our staff, and we also had a neighbouring doctor on another boat that offered assistance as well, so we did everything that we could,” he said.
“We’ve extended sympathy, obviously, to the family and friends of the two elderly French people today. And also sympathy out to our crew that have had to deal with the situation at hand.”
Association of Marine Park Tourism Operators‘ Col McKenzie described the deaths as “a rare tragedy”, and that he believed the cause of death was heart attack.
“It might just simply be a coincidence, but we may well find out that one person saw the other person being rescued and that caused the onset of the second emergency,” he said.
“We just don’t know, it’s pure speculation at this time.”