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

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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.

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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. If named because of the venomous barbs present on infections are more severe antibiotics of choice the dorsum of their tails (Figure 7). Although they include doxycycline, ciprofloxacin or cefotaxime.7 are venomous, the major clinical problem is often Figure 7. Stingray

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related to mechanical trauma from the sting itself, which may produce deep penetrating injuries or severe lacerations, or subsequent infection includ- ing tetanus. Fatalities and near fatalities from penetrating chest or abdominal wounds by stingray barbs have been recorded.9

Symptoms and signs of stingray envenomation • Envenomation may result in increasing local pain which may spread to involve the entire limb +/- swelling and a characteristic bluish- Figure 8. Sea snake white appearance of the wound • Systemic symptoms are rare, but may include have also been documented in New South Wales nausea and vomiting, salivation, diarrhoea, and Western Australia. Generally it is fishermen sweating, muscle cramps, syncope, cardiac who are most at risk as they pull in nets and sort arrhythmias and convulsions. fish, but swimmers and waders are also occasion- ally bitten. First aid and treatment • Remove victim from the water; if any major Symptoms and signs of sea snake bleeding, apply local pressure envenomation • Immersing the stung area in hot water (as for • Signs of severe envenomation include myalgia, stinging fish) may provide temporary relief vomiting, eye signs (ptosis, weakness of external • Transfer patient to a medical facility (unless eye muscles, pupillary dilatation poorly reactive very small injury to limb to light), paresis of lower motor neurone type, • Analgesia, tetanus prophylaxis X-ray, and surgi- leucocytosis, and rhabdomyolysis cal exploration and debridement may be • There is little local pain at the bite site necessary • Signs of envenomation develop rapidly (approx- • All penetrating chest and abdominal wounds imately 15–30 minutes postenvenomation). need to be explored (this should be deemed a medical emergency until proven otherwise) First aid and treatment • Infection of the contaminated wound may • Attention to basic life support is a priority develop and involve poorly characterised • Pressure immobilisation first aid should be marine bacteria requiring special culture media. used and left in situ until the patient reaches Consideration should be given to antibiotic pro- medical care phylaxis in contaminated wounds, particularly if • If there is clinical evidence of envenomation, there has been a delay between the sting and sea snake antivenom can be given (based on medical treatment beaked sea snake [Enhydrina schistosa] • No antivenom exists for stingray envenomation. venom). If this not available tiger snake antivenom may be used Sea snakes • Supportive measures such as intubation and In addition to highly venomous land snakes, ventilation for respiratory failure or the treat- Australia has the highest biodiversity of sea ment of hyperkalaemia may also be required. snakes in the world, hosting 59% of all such It has been postulated that the land based snake species (Figure 8). While predominantly concen- venom detection kit (SVDK) may be of use. A trated in warm tropical waters, Australian sea recent study looking at the reactivity of sea snake snakes are widely distributed throughout venom to the SVDK showed good reactivity to the Australia. Fortunately however, bites from these tiger venom in three of the four sea snake venoms snakes are rare and no fatalities have yet been tested.10 More research into whether this will be reported in Australia. Although most bites have useful in the ‘undifferentiated’ marine envenoma- been reported from Queensland, a few cases tion will need to be conducted.

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Conclusion Conflict of interest: none declared. Marine stings are mostly the cause of minor injuries, but offer the potential for lethal sequelae. References Most often this involves acutely painful fish stings 1. Williamson J A, Fenner P J, Burnett J W, Rifkin J F. Venomous & Poisonous Marine Creatures: A Medical that respond to analgesia and appropriate wound and Biological Handbook. Sydney: University of care in general practice. However, sea snake, New South Wales Press, 1996; 73. stingray and blue-ringed octopus bite stings should 2. Sutherland S K, Lane W R. Toxins and mode of envenomation of the common ringed or blue-banded be managed in the inpatient setting. octopus. Med J Aust 1969; 1:893–898. 3. Hopkins D.G. Venomous effects and treatment of octopus bite. Med J Aust 1964; 1:81–82. SUMMARY OF 4. Flecker H, Cotton B C. Fatal bite from octopus. Med J IMPORTANT POINTS Aust 1955; 2:329–331. 5. Church J E, Hodgson W C. Adrenergic and choliner- gic activity contributes to the cardiovascular effects • There is a high level of morbidity with of lionfish (Pterois volitans) venom. Toxicon 2002; stonefish and other stinging fish 40:787–796. envenomations. 6. Lehane L, Rawlin G T. Topically acquired bacterial zoonoses from fish: A review. Med J Aust 2000; • Tetanus prophylaxis should be undertaken 173:256–259. if required. 7. Williamson J A, Fenner P J, Burnett J W, Rifkin J F. • The blue-ringed octopus has been associated Venomous & Poisonous Marine Creatures: A Medical with severe neurotoxic envenomation and Biological Handbook. Sydney: University of resulting in respiratory failure and fatalities. New South Wales Press, 1996; 366. 8. McIntosh J M, Jones R M. Cone venom: From acci- • Pressure immobilisation and urgent transfer dental stings to deliberate injection. Toxicon 2001; to hospital is a priority for blue-ringed octopus 39(10):1447–1451. and cone shell envenomation. 9. Weiss B F, Wolfenden H D. Survivor of a stingray • First aid for fish envenomation includes injury to the heart. Med J Aust 2001; 175:33–34. immersion of the affected area in hot water, 10. Nimorakiotakis V. The diagnosis and management of local anaesthetic and tetanus update. sea snake envenomation. Clinical Risk Management Toxicology Update. Winter Symposium 2003. AFP • Minor bacterial wounds can be treated with Melbourne: June 2003. antibacterial solutions. • Antibiotic prophylaxis should be considered in contaminated stingray envenomation. • Signs of severe sea snake envenomation include myalgia, vomiting, eye signs, paresis, CORRESPONDENCE leucocytosis and rhabdomyolysis. Email: [email protected]

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