Solution to box jellyfish venom
Scientists have discovered how to block the action of the venom of the lethal box jellyfish family.
Using a new extraction technique to isolate the stinging cells, or nematocysts, from the tentacles of two species of the box family, including the north Queensland resident Chironex fleckeri, University of Hawaii researchers Angel Yanagihara and Ralph Shohet were able to isolate the venom components at unprecedented concentrations and purity. This has enabled them to examine in detail how this potent cocktail of chemicals, to which at least 100 people fall victim worldwide each year, exerts its lethal effect.
Using samples of freshly-donated human blood, the researchers confirmed that the venom components attack red blood cells by assembling tiny pore structures that punch holes through the cell membranes. This causes the cells to swell and then burst open, releasing into the bloodstream large amounts of potassium, which is normally kept locked away inside cells. This, Yanagihara and Shohet speculated, could disrupt the electrical activity of the heart.
To test this, they administered varying doses of their purified venom samples to mice, which rapidly developed escalating potassium levels, changes to the electrocardiogram consistent with potassium toxicity and cardiac arrest. This is almost certainly the cause of death in the majority of human victims that receive lethal envenomations, which is not difficult given that the tentacles can be metres long and are each loaded with half a million venom-laden nematocysts.
Next, the researchers tested a range of different treatments to attempt to mitigate the effects of the venom, including using doses of the antivenom traditionally prescribed in emergencies for box jellyfish stings, and a range of metal salts, including zinc gluconate.
Zinc, they found, was extremely effective - in fact more so than the antivenom - at deactivating the venom toxins and preventing the dangerous rise in potassium. The duo conclude their paper, published this week in PLoS One, by suggesting that zinc treatments should be tested on larger animals regarded as good models for humans, like pigs, and also topical application of zinc to sting sites might help to reduce the subsequent venom load by disabling undischarged stinging cells. The result, they suggest, might be many lives saved...