Irukandji and Chironex fleckeri jellyfish envenomation in tropical Australia

To compare the temporal distribution of Irukandji and Chironex fleckeri stings, the demographics of victims, the prevailing physical conditions at the time of a sting, and the prevalence of unsuitable first aid strategies.

Retrospective assessment of 478 Chironex and 544 Irukandji stings in Queensland and the Northern Territory of Australia.

Adolescent and young adult males were the most common victims of Irukandji (median age 21 years) and Chironex stings (median age 16 years). Most Chironex stings occurred on the legs, while Irukandji stings were more common on the arms. Vinegar was correctly used to remove tentacles in 90.5% of Chironex stings, whereas inappropriate treatments were used in the remaining cases. Chironex stings were reported in every month in the Northern Territory, and in all months but June and July in Queensland. The peak prevalence for Chironex stings occurred in January in both areas, while the number of Irukandji stings peaked in December in Queensland and in May in the Northern Territory. Chironex stings were more common on still, cloudy days, whereas Irukandji stings were more common on still, clear days. Irukandji stings were more frequent than Chironex stings on rough days (P = .0005). Chironex and Irukandji stings were similar with respect to tides, moon phases, and rainfall.

This study failed to predict exact weather patterns or other contributing factors to reduce the risk of stings to an acceptable level, but did identify several factors that increase the incidence of stings. The "stinger-free" season reported on Chironex warning signs is inaccurate and should be changed to warn bathers that Chironex may be present year round, particularly in the Northern Territory.