Irukandji Syndrome

A number of species of small and virtually invisible jellyfish will produce this potentially lethal reaction in humans if contact is made. These jellyfish including Carukia barnesii are found in warmer tropical waters off the northern coast of Australia.

Carukia Barnesi, a tiny jellyfish, is typically less than 1cm across the body, and has a single tentacle on each corner, reaching up to about 1 meter long. Both its body and its tentacles are armed with stinging cells (nematocycts) which contain mini harpoons that inject toxins into prey. They are found mostly in deep reef waters but can be swept inshore by prevailing currents. Most cases of stings are reported between November and May but they have been recorded on the East Coast in every month although more notably in the summer.

Symptoms of envenomation

Initial contact with the jellyfish is often deceptively minor with mild local pain only and often with no visible tentacle contact marks on the skin. Approximately 30 minutes later the unsuspecting victim will develop cramping muscle pain and pain in the back and abdomen. Onset of nausea, vomiting, generalized sweating and a sensation of overwhelming anxiety then occur. Precipitous elevation in blood pressure can lead to heart and lung complications including pulmonary oedema (fluid in the lungs) and occasional deaths from cardiac arrest or bleeding within the brain have been reported.

First Aid in the field

Any potential victim should be safely removed from the water ensuring no risk of envenomation to First Aid givers. Basic Life Support should be commenced and assistance sought immediately.

The affected area should be flooded in Vinegar. Vinegar will not reduce the pain or reverse envenomation already occurred but will inactivate and prevent further firing of nematocysts that may come into contact with the skin. Ensure the victim (or bystanders) does not rub the envenomated skin as this will potentially activate firing of more nematocysts.

There is no antivenom available for the Irukandji syndrome and affected victims require hospital treatment until symptoms resolve.