Temperature effects on box jellyfish venom: a possible treatment for envenomed patients?

Objective: To determine the effect of temperature on lethality of venom from Chironex fleckeri (the potentially fatal box jellyfish). Design: Venom extracted from nematocysts of mature Chironex fleckeri specimens was exposed to temperatures between 40degreesC and 58degreesC for periods of two, five or 20 minutes, and then injected into freshwater crayfish (Cherax quadricarinatus) to assess lethality. Main outcome measure: Venom lethality, assessed as time to cardiac standstill in crayfish after intramuscular injection. Results: Venom lethality was significantly affected by both temperature (F-7,F-34 = 21915; P < 0.0001) and time of exposure (F-2,F-34 = 9907; P < 0.0001). No significant loss of lethality was seen after exposure to temperatures less than or equal to 39degreesC, even after 20 minutes' exposure. At temperatures greater than or equal to 43degreesC, venom lost its lethality more rapidly the longer the exposure time. Venom was non-lethal after exposure to 48degreesC for 20 minutes, 53degreesC for five minutes, and 58degreesC for two minutes. Conclusion: Exposure to heat dramatically reduces the lethality of extracted C. fleckeri venom. Although heat application may be of limited use in treating C. fleckeri envenoming because of the speed of symptom onset, its use in other box-jellyfish envenomings, such as Irukandji syndrome, requires investigation.