Clinical Management of Envenomation by Australian Carybdeid Cubozoan, Hydrozoan, and Scyphozoan Jellyfish

Abstract

The waters surrounding the continent harbor numerous species of jellyfish classified as carybdeids, hydrozoans, and scyphozoans. Some of the carybdeids, small jellyfish with single tentacles arising from each of the four corners of a cuboid bell, have only relatively recently been identified. The stings of carybdeids cause a clinical syndrome known as “Irukandji syndrome” – the delayed onset of severe pain in association with hypertension and sometimes progressing to acute cardiac failure, resembling Takotsubo cardiomyopathy and necessitating mechanical ventilation and inotropic support. The severe syndrome is consistent with endogenous release of catecholamines by toxins acting on sodium channels and by cytolytic toxins causing pore formation of cardiac cells. Although initially recognized in Australia and typified by the sting of Carukia barnesi, it is being increasingly recognized in victims of stings by similar jellyfish in other oceanic regions. Some protein toxins of Carukia barnesi and Malo kingi have a molecular mass of 43–46 kDa and have some homologies with cytolytic pore-forming toxins of chirodropids Chiropsalmus quadrigatus and Chironex fleckeri and homologies with ion channel neurotoxins of sea anemones. A hydrozoan jellyfish, Physalia physalis, found in Australian waters but distributed widely throughout the world, is the most frequent cause of mild jellyfish stings. Its protein toxins are known to be cytolytic, acting by cell membrane poration and allowing cellular entry of calcium. Numerous other jellyfish of the class Scyphozoa in Australian waters include Pelagia noctiluca, Cyanea capillata, and Aurelia aurita. At present, no specific therapy exists for stings by any of these jellyfish and toxins of all remain to be comprehensively identified and studied.