Long-term analysis of Irukandji stings in Far North Queensland.

INTRODUCTION: We reviewed the occurrence, trends, definition and severity of the Irukandji syndrome for the Cairns region of North Queensland, Australia.

METHODS: A retrospective analysis of patient files from two sources was conducted: historic accounts kept by Dr Jack Barnes for the period 1942 to 1967, and records from the Emergency Unit in Cairns Base Hospital for 1995 to 2007.

RESULTS: There has been a significant increase in the length of the Irukandji season since it was first reliably recorded (15 days in 1961; 151 days in 2002); however, annual numbers of envenomations were highly variable. Traditionally, greater frequencies of Irukandji stings were reported at onshore as opposed to offshore locations. However, in recent years this trend has reversed, potentially because of increased safety protocols for beach regions. Mean Troponin I levels were higher in offshore reef envenomations compared to those from islands or coastal regions. In terms of morphine-equivalent doses, patients given fentanyl received significantly greater opioid doses compared to those given morphine or pethidine. Opioid dosage was indicative of syndrome severity and correlated with other physiological parameters measured. Five major symptoms were associated with Irukandji syndrome: pain, nausea/vomiting, diaphoresis, headache and shortness of breath. Pain was the overwhelming symptom, followed closely by nausea/vomiting.

CONCLUSIONS: The duration of the Irukandji season appears to be increasing. Conversely the number of envenomings appears to be decreasing, possibly because of improved beach management in recent years. Offshore envenomings appear to have a higher potential for more severe envenomings with five associated major symptoms.