|
Time for a change of pace this month and a look at the weird world of marine toxins. I was chatting to my cousin the other day who has spent a considerable time in Japan and is quite an accomplished Japanese cook. I was reminded of the newspaper clipping in the UEC newsletter a while back about the Qld couple who ended up in hospital after consuming "Fugu" or puffer fish.
Tetrodotoxin(TTX) is a fascinating substance which is found in a number of marine organisms including puffer (blowfish, globefish) and toad fish, porcupine fish, blue ringed octopus ("TTX –like" substance), crabs, certain frogs, shellfish, seastars and flatworms. When humans ingest a toxin such as when dining out on puffer fish it is called a poison, when the toxin is injected (as in a blue ring bite) it is called a venom.
TTX was finally identified by joint American-Japanese research in 1964. It works by blocking nerve impulses to voluntary muscles so causing a dose-dependent flaccid paralysis: i.e. the victim remains awake but paralysed and so unable to breathe or move! A particularly unpleasant way to go! Rescuers should keep this in mind when attending to the victim and not make audible predictions of poor outcome!
First aid in TTX envenomation/poisoning may be life saving. Expired air resuscitation (EAR) will support the victim’s breathing until advanced life support can be instituted with airway protection and mechanical ventilation. This will be required for 4-8 hours until the toxin wears off. No specific antidote exists.
FUGU
The deadly nature of the toxin in Puffer fish flesh should not be underestimated. In a series of 3000 poisonings from Japan over 21 years, nearly 60% were fatal. More recent cases have had a mortality of 11%. TTX is a small molecule that is rapidly absorbed after ingestion and is not destroyed by heat or cooking.
The liver, ovaries and skin contain the greatest concentration of TTX. Interestingly, farmed fugu is not toxic which supports the theory that the toxin is produced within the fish by marine bacterium such as pseudomonas and vibrionaceae. The culture and customs surrounding the eating of fugu in China and Japan are interesting enough to be the subject of a column in itself. Fugu chefs must be licensed and undergo an intensive apprenticeship. Despite this expertise around 50 deaths occur in Japan each year. A mild episode of poisoning with just a tingle around the lips gives the diner a thrill and makes one feel more alive…………..yeah right!
BLUE RINGED OCTOPUS
Two species of Blue Ringed Octopus exist; Hapalochlaena lunulata is the larger tropical species and H. maculosa occurs around the southern half of the country. The "maculotoxin" in the venom is indistinguishable from TTX. The toxin is similar in both species and is delivered via an often painless bite from the animal’s parrot-like beak. 2 human fatalities and about 15 episodes of envenomation have occurred in Australia in the past 50 years, however the creature is not aggressive and will not bite unless handled. The female lays about 50 eggs in autumn and carries them about under her legs for 6 months. Once the eggs have hatched, the female dies. |
