The alarm was raised when thousands of tiny, translucent “jellies” – now identified as salp – were found washed up along a 10-kilometre stretch of Phuket’s west coast on Sept 18, with reports that contact with the jellies resulted in a rash. (See story here.)
Yet it is now believed that the arrival of salp in such great numbers may indicate the arrival of much more harmful, possibly deadly, jellyfish: Irukandji.
Although Phuket has never suffered a box jellyfish fatality on record, what makes the Irukandji so different is that its victims are often wrongly diagnosed as suffering from food poisoning, a severe allergic reaction or anaphylactic shock, explains Dr Lisa-ann Gershwin, a globally recognised leading researcher who has spent 18 years studying jellyfish, with a focus on Irukandji species.
“The salps are not as harmless as they may seem,” Dr Gershwin told The Phuket News. “The salps themselves are not able to sting, but they co-occur and indicate the presence of small, transparent jellyfish called Irukandji that are highly dangerous.
“Salps very often co-occur with Irukandjis in tropical waters, and salps are the most visible indicator that Irukandjis are infesting,” she said.
“We know of incidents in the past at Phuket beaches where large numbers of salps are present in the water and on the beaches, and swimmers get an itchy irritation feeling, and large numbers of swimmers and bathers have become very sick, requiring hospitalisation – these are highly likely to be Irukandji syndrome, which is often wrongly diagnosed as food poisoning or allergy or anaphylactic shock – these are all common misunderstandings of what Irukandji syndrome is,” she added.
Irukandjis are translucent and tiny. Their size is roughly one cubic centimetre and they measure from 5mm to 25mm across. Their tentacles are long. At just 5mm across their tentacles can grow up to one metre in length.
Also, Irukandji syndrome leaves no mark on the body, and no chemical or physical signature in the body that can be tested post-mortem, Dr Gershwin notes.
Based on data from decades of research, Dr Gershwin and her team created a model for predicting Irukandji blooms, with their findings published in the respected Journal of the Royal Society.
“In Australia where Irukandji syndrome was first described, the most common pattern is that when salps are present and winds are calm is when these stings occur, and the days when the salps are washing up on the beach are the periods of highest risk,” Dr Gershwin explained.
“These patterns are based on decades of data and form the basis for an early warning system currently in development,” she said.
Irukandji were at one time thought to be in the northern waters of Australia only, but according to a National Geographic documentary they have since been found in waters as far north as the British Isles, Japan and the Florida coast of the United States.
There have been sightings and recorded injuries in the waters of Malaysia, and in 2012 a small and venomous Irukandji jellyfish found in the Philippines was first described to science and is now known as Malo filipina.
Dr Gershwin is also aware of the deadly effect on tourism that deaths by Irukandji stings can bring. “For example, the costs of cancelled tourism bookings following two fatalities on the Great Barrier Reef (in Queensland, Australia) in 2002 have been estimated to be in excess of US$65 million (B2.32bn), she noted in one published paper.
However, Dr Gershwin is adamant that the awareness allows beach-goers to have fun in the water – but without being stung. The trick is just to cover up when entering the water during “bloom time”.
Regardless, she urges, “The public should not become complacent about the presence of Irukandjis, as they are life threatening. The safest advice on days when salps are present is to either wear protective clothing or stay out of the water entirely.
“Also, on days when these salps are present, it is very important that anyone stung by these seemingly minor irritations should douse them with vinegar to inhibit further stinging, and they should not under any circumstances apply freshwater or any type of alcohol.”
Phuket Lifeguard Chief Prathaiyut Chuayuan told The Phuket News that he was not aware of Ms Gershwin’s assertion specifically for Phuket, but said that he knew of her work and respected her opinion. “She is probably right about the possibility of the presence of Irukandji. We will look out for them,” he said.
“We see salps every rainy season. They come and go, but we have never spotted an Irukandji. Here salps come with Portuguese man o’ war, and if we find a lot of these we may have to close the beach.”
Mr Prathaiyut reiterated that Phuket had yet to suffer a box jellyfish fatality. “I have been working in Phuket a long time and we have never had box jellyfish. We never find them here in Phuket, but in Samui they find them every other week,” he said.
In October last year, 20-year-old German tourist Thies Saskia died after being stung by a box jellyfish at Lamai Beach, Samui. Her death followed that of Chayanan Surin, 30, from Bangkok, who was stung by a box jellyfish while swimming at night during a full moon party on Koh Pha-ngan six weeks earlier.