Heat deactivation of the stonefish Synanceia horrida venom – implications for first-aid management

Objectives: To investigate the effects of temperature and hot water immersion time on neutralising venom lethality of the Australian estuarine stonefish (Synanceia horrida). Design: Depths of the spines were measured while venom was extracted from S. horrida individuals. The venom was then exposed to temperatures of 4OC, 37.0OC, 40.1OC, 42.3OC, 45.0OC, 47.7OC, 55.2OC, and 60.0OC for either five or 20 minutes incubation periods. Venom samples were added to cultured human cardiomyocytes and cell viability curves were produced using the ACEA’s xCELLigence real-time cell monitoring system. Main outcome measures: Determination of venom lethality on cardiomyocytes at a range of temperatures. Results: The average depth of the spine required to go into a victims’ flesh before the venom gland compressed and expelled venom was 18 mm. Cardiomyocytes exposed to heat-treated venom for five minutes required higher temperatures to neutralise 99% of the venom, namely 44.6OC in comparison to 42.1OC with an incubation time of 20 minutes. Conclusion: This study supports the use of hot water immersion therapy in the treatment of S. horrida stings. It is suggested that due to the depth of the puncture wound longer incubation times should be sought to allow heat to penetrate the deeper portions of the dermis and effectively begin venom deactivation.