THEME: Summer hazards Marine envenomations Part 2 – Other marine envenomations BACKGROUND Australian waters contain a variety of venomous creatures, including jellyfish, stinging fish, blue-ringed octopus, sea snakes, cone snails and stingrays. B Nimorakiotakis, OBJECTIVE Part 2 of this article focusses on common marine envenomations other than K D Winkel jellyfish stings. B Nimorakiotakis, DISCUSSION Even though mortality from these envenomations is low, there is a high level of MBBS, FACEM, is morbidity especially with stonefish and other stinging fish envenomations. Some Staff Specialist, envenomations, however, are serious enough to require antivenom treatment and deaths still Epworth Hospital, occasionally occur. and Fellow, The Australian Venom Research Unit, Department of Pharmacology, the University of Melbourne, Victoria. tion when they pick it up or step on it. The venom contains tetrodotoxin (also found in puffer fish K D Winkel, MBBS, BMedSc, PhD, flesh) that is secreted in the saliva of the octopus. FACTM, is Director, It causes blockade of neuronal sodium channels The Australian leading to weakness, numbness or paraesthesia, Venom Research Unit, Department of breathing difficulties and ultimately, respiratory Pharmacology, the paralysis. University of Melbourne, Victoria, Symptoms and signs of blue- and President elect, ringed octopus envenomation the Australasian College of Tropical Figure 1. Blue-ringed octopus Medicine. Photo courtesy of Vern Draffin • Pain is not a prominent feature of the bite • Within 10 minutes, symptoms of poisoning Blue-ringed octopus begin to develop; initially weakness and numb- (Haplochlaena spp.) ness about the face or neck, difficulty breathing, The blue-ringed octopus is a small, usually incon- nausea and vomiting spicuous, brown coloured octopus that develops • In severe cases, there is rapid progression to brilliant blue ring shaped markings when dis- flaccid paralysis and apnoea. The patient may turbed (Figure 1). The genus is found throughout be completely paralysed and unable to respond, Australian coastal waters; the southern blue- sometimes with fixed dilated pupils, but the sen- ringed octopus (H. maculosa) in southern regions, sorium is often intact, and care should be taken and the greater blue-ringed octopus (H. lunulate) to avoid negative remarks that the alert patient in more tropical areas. A third species, the blue- may hear. lined octopus (H. fasciata) has also been described along the east coast of Australia. This genus has First aid and treatment been associated with severe neurotoxic envenoma- • Remove victim from the water tion resulting in respiratory failure and human • If victim is apnoeic, support breathing with fatalities.1-3 The blue-ringed octopus is found in expired air respiration and urgently transfer to tidal rock pools and is very attractive, especially to hospital children and tourists who are at risk of envenoma- • A pressure immobilisation bandage should be Reprinted from Australian Family Physician Vol. 31, No. 12, December 2002 • 975 n Marine envenomations part 2 – other marine envenomations Figure 2. Stonefish (Synanceia spp.) Figure 3. Stonefish camouflaged in sand applied to the affected limb (as for land snakes) • Endotracheal intubation and artificial ventila- • Systemic effects of the venom may include tion may be required until the effects of venom muscle weakness, paralysis and shock. wear off (typically this takes 24–48 hours). There is no antivenom available for blue-ringed First aid and treatment octopus envenomation, however, although two • Bathing or immersing the stung area in hot fatalities have been reported,4 these envenoma- water may be effective tions are uncommon. • Hospitalisation for intravenous narcotic analge- sia +/- local anaesthetic (without adrenaline) Stinging fish infiltration or regional block may be required Stonefish (Synanceia spp.) • Definitive management consists of administra- Stonefish (Figure 2) are found throughout the tion of stonefish antivenom (produced by CSL world, and may be described as the world’s most Ltd, Australia, from the venom of S. trachynis), dangerous stinging fish. The two Australian which is usually given intramuscularly species, Synanceia trachynis and S. verrucosa, are • Indications for antivenom include: found commonly throughout tropical Indo- – severe pain Pacific waters. They are extremely well – systemic symptoms or signs of envenomation camouflaged and dig themselves into the sur- (weakness, paralysis) rounding sand or mud, making them almost – multiple punctures indicating the discharge impossible to see (Figure 3). Thirteen dorsal of several spines and thus injection of a spines project from venom glands along their larger amount of venom. (Recommended back; with venom involuntarily expelled when antivenom dose is one ampoule for 1–2 spine the spine is pressed. Stonefish venom, unlike punctures, two ampoules for 3–4 spine punc- other marine venom, is purely for defence. tures, three ampoules for greater than four Fatalities have been recorded in the Indo-Pacific spine punctures) region, but not in Australian waters. • Tetanus prophylaxis should be undertaken depending on the patient’s immunisation status. Symptoms and signs of stonefish Severe stings may produce an area of tissue necro- envenomation sis, particularly if antivenom administration is • Despite the presence of myotoxic, neurotoxic delayed. This may require surgical debridement or and cardiotoxic components of the venom in even skin grafting. Consideration should also be experimental models, human envenomation is given to the presence of broken spines within the characterised by: wound, which should be X-rayed if in doubt. – immediate extremely painful sting with pain extending rapidly up the limb Other venomous fish – associated rapid local swelling Australia has numerous stinging fish distributed • The severity of symptoms is related to the spine around its coastline (Figure 4). Many of these fish penetration depth and the number of spines are found in tropical waters, but others are present involved in temperate waters. 976 • Reprinted from Australian Family Physician Vol. 31, No. 12, December 2002 Marine envenomations part 2 – other marine envenomations n Cone shells (Conus spp.) Cone shells are predatory marine snails better referred to as cone snails (Figure 5). They live mainly in shallow tropical and subtropical reef waters of the Indo-Pacific. There are more than 600 varieties that have been identified worldwide; more than 70 seen in tropical and subtropical waters of Australia. All are venomous; with the venom injected by radula teeth resembling small Figure 5. Cone shell Figure 4. Lionfish harpoons held in their proboscis (Figure 6). Cone shell venom is diverse and complex in its action. It consists of numerous neurotoxic peptides that act Symptoms and signs of fish envenomation pre- and post-synaptically to give rise to neurologi- cal symptoms. • The major clinical feature of fish stings is imme- Over recent years the venom of the cone shells diate severe pain which may be prolonged and has been studied extensively. Pharmaceutical difficult to manage even with narcotic analgesia companies are now utilising the selectivity and • The pain will usually subside within 24 hours, potency of conus derived peptides in the manu- Figure 6. Cone shell but swelling may persist for several days. facture of medications for pain, epilepsy and harpoon in proboscis other disorders.8 First aid and treatment • Immersion of the affected area (almost always a Symptoms and signs of cone hand or foot) in hot (not scalding) water shell envenomation • Infiltration of the wound with local anaesthetic • Stings are usually as a result of cone handling (without adrenaline) agents provides dramatic • Initially there is sharp pain, with the stung area relief in most cases, although occasionally a becoming swollen and pale regional nerve block will be required • Numbness may follow as well as signs of neuro- • Tetanus prophylaxis should be updated, and the logical impairment including weakness, lack of wound examined for signs of infection or retained coordination, and visual and speech distur- foreign material in the form of broken spines bances • Stonefish antivenom could be of use for scor- • Less common systemic symptoms include pion fish type stings, but requires further clinical nausea and generalised pruritus. assessment. Based on in vitro evidence of the potential for stone- First aid and treatment fish antivenom to neutralise lionfish (Pterois volitans) • Remove victim from the water venom toxicity, an aquarium worker was recently • Pressure immobilisation first aid should be treated with this antivenom – to good clinical effect – applied and left in place until resuscitation facil- for a significant lionfish spike to her thumb.5 ities are available, as assisted ventilation may be required to avoid hypoxia Bacterial infections • There is at present no antivenom for cone Zoonotic bacterial infections can be a problem. shell stings Humans tend to have good natural immunity to • The wound should be regarded as potentially marine bacteria, and most fish associated wound contaminated and tetanus prophylaxis should be infections tend to be self limiting.6 Infections are updated if required. mixed, and comprise mainly of genera vibrio, pseudomonas and aeromonas. Minor wounds can Stingrays be treated with early and efficient simple cleaning Stingrays are found throughout the world and so of the wound with an antibacterial solution.