Seawater, ice packs and urine all have one thing in common – they are all associated with treating jellyfish stings.
Now newly published research has confirmed that such antidotes are not only useless, but may actually make stings worse.
The study by scientists at NUI Galway and the University of Hawaii-Manoa evaluated the standard practice in Ireland for treating stings by the Portuguese man o' war (Physaliaphysalis) – as in rinsing with seawater and applying ice.
The results published this week in the journal Toxins suggest that man o’ war stings are no different than other jellyfish stings, and the best first aid is to rinse with vinegar to remove tentacles and then immerse in 45°C (113°F) hot water, or apply a hot pack for 45 minutes.
Last September, large numbers of Portuguese men-o-war washed up on the coastline from Cork to Donegal. NUIG jellyfish scientist and lecturer Dr Tom Doyle said that the numbers were "unprecedented", but there were very few reported stings.
“If this event had occurred during the summer months, then we may have had hundreds of stings,” he said.
In 2008, similar swarms unexpectedly hit the Bay of Biscay near Bordeaux, he said – "flooding local medical facilities with 40 sting cases in a single day".
For that reason, lack of agreement on the best first aid responses required scientific intervention, as it was important that lifeguards knew how to respond.
"Without solid science to back up medical practices, we have ended up with conflicting official recommendations around the world, leading to confusion and, in many cases, practices that actually worsen stings and even cost lives," Dr Christie Wilcox, lead author of the paper and post-doctoral fellow with the Pacific Cnidaria (marine species) research laboratory at University of Hawaii-Manoa, said.
Working with her postdoctoral advisor, Dr Angel Yanagihara, she worked on a set of tissue-mimicking models to test first aid approaches.
The pair of scientists first examined box jellyfish, some of the deadliest jelly species in the world, and found that common practices such as applying urine or scraping away tentacles only made stings worse.
Dr Doyle, who set up the expert Jellyfish Advisory Group in 2008, worked on this side of the Atlantic with PhD student Jasmine Headlam, performing experiments similar to those conducted in Hawaii.
“The results from opposite sides of the world lined up beautifully: the venom delivered by a man o’ war sting was lessened if the sting site was rinsed with vinegar, regardless of which species of Physalia was used,”Dr Doyle said.
The scientists showed that vinegar inhibited the animals’ stinging cells from firing, thus safely removing tentacles and stinging cells that can remain adhered to the skin and continue to deliver venom over time.
A combined stinging capsule and venom-inhibiting spray developed with US Department of Defence funding by Dr Yanagihara, named Sting No More, was also effective. Both groups found that 45 minutes of 45°C (113°F) heat application effectively inactivated already-injected venom after rinsing away tentacles, while the application of ice packs made stings worse.
“This is quite a U-turn for me,” Dr Doyle said, given the advice he had been issuing for the past decade.
He said Beaumont Poison Centre at Beaumont Hospital in Dublin will meet with members of the advisory group to discuss the findings in the next few weeks.
Dr Doyle’s colleague and PhD student Jasmine Headlam has begun similar experimental work on the Lion’s mane (Cyaneacapillata), which is the second most venomous jellyfish after the Portuguese man-o-war in Irish waters.
It is responsible for more bad jellyfish stings in Ireland than any other species, and victims are often taken to hospital.
