Venomous aquatic animals are hazardous to swimmers, surfers, divers, and fishermen. Exposures include mild stings, bites, abrasions, and lacerations. Severe envenomations can be life threatening. This article reviews common marine envenomations, exploring causative species, clinical presentation, and current treatment recommendations. Recommendations are included for cnidaria, sponges, bristle worms, crown-of-thorns starfish, sea urchins, venomous fish, stingrays, cone snails, stonefish, blue-ringed octopus, and sea snakes. Immediate and long-term treatment options and management of common sequelae are reviewed. Antivenom administration, treatment of anaphylaxis, and surgical indications are discussed.
Key points
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Know the marine organisms in your clinical practice area.
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Be prepared to treat anaphylaxis and acute life-threatening envenomations from box jellyfish, irukandji jellyfish, stonefish, cone snail, blue-ringed octopus, or sea snake.
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Know where and how to obtain antivenom.
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Decontamination is species specific and includes removing tentacles, embedded spines, and foreign bodies.
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Attempt pain control with species-specific treatments, including 5% acetic acid (vinegar), hot water immersion, and saline rinse.
Introduction
Venomous aquatic animals are hazardous to swimmers, surfers, divers, and fishermen. Most marine exposures are mild, so victims may not seek medical care. These exposures include mild stings, bites, abrasions, and lacerations. Severe envenomations from box jellyfish, irukandji jellyfish, cone snails, blue-ringed octopus, stonefish, or sea snakes can be life threatening. In these cases, rapid effective treatment improves immediate outcomes (decrease pain, stabilize systemic symptoms, treat anaphylaxis) and minimizes secondary complications (local allergic response, infection, wound complications). Treatment recommendations evolve in response to acquisition of data, clinical observations, and expert opinion. This article outlines recent management and treatment recommendations for marine envenomations. For the treatment of all envenomations, apply appropriate tetanus immunization. Consider prophylactic or therapeutic antibiotics.
Introduction
Venomous aquatic animals are hazardous to swimmers, surfers, divers, and fishermen. Most marine exposures are mild, so victims may not seek medical care. These exposures include mild stings, bites, abrasions, and lacerations. Severe envenomations from box jellyfish, irukandji jellyfish, cone snails, blue-ringed octopus, stonefish, or sea snakes can be life threatening. In these cases, rapid effective treatment improves immediate outcomes (decrease pain, stabilize systemic symptoms, treat anaphylaxis) and minimizes secondary complications (local allergic response, infection, wound complications). Treatment recommendations evolve in response to acquisition of data, clinical observations, and expert opinion. This article outlines recent management and treatment recommendations for marine envenomations. For the treatment of all envenomations, apply appropriate tetanus immunization. Consider prophylactic or therapeutic antibiotics.
Sponges
Epidemiology
Sponges (phylum Porifera) are acellular creatures that attach to the ocean floor. They carry spicules of silicon dioxide or calcium carbonate. Many produce dermal irritants known as crinotoxins. Typical offenders include the fire sponge ( Tedania ignis ), poison bun sponge ( Fibularia nolitangere ), and red moss sponge ( Mammillaria prolifera ).
Presentation
Spicules and crinotoxins enter the skin, causing edema, vesiculation, joint swelling, and stiffness. Mild reactions subside within 7 days. Extensive exposure may induce fever, chills, malaise, dizziness, nausea, muscle cramps, and formication. Retained spicules can result in persistent bullae that take months to heal. Delayed systemic erythema multiforme or dyshidrotic eczema may develop. In severe cases, surface desquamation may follow.
Treatment
Remove spicules using adhesive tape, a thin layer of rubber cement, or facial peel. Apply 5% acetic acid (vinegar) soaks. Steroid cream or an oral antihistamine may provide symptomatic relief. Consider systemic corticosteroids for severe allergy, erythema multiforme, or dyshidrotic eczema. Arrange wound checks because infections may develop requiring antibiotic therapy ( Table 1 ).
| Species | Presentation | Treatment |
|---|---|---|
| Portuguese man-of-war; blue bottle | Local pain, skin blisters, nausea, vomiting, abdominal pain, muscle cramps, dyspnea | Remove tentacles Hot water (upper limit 45°C) immersion |
| Box jellyfish | Excruciating pain, hypotension, paralysis, respiratory failure, cardiac arrest, skin blisters and necrosis | Apply acetic acid 5% then remove tentacles Support airway and breathing Antivenom if severe symptoms Avoid hot water immersion or pressure immobilization |
| Irukandji jellyfish | Catecholamine release, muscle pain, abdominal pain, hypertension, troponin leak, heart failure, pulmonary edema | Remove tentacles Apply acetic acid 5% Cardiac monitoring Blood pressure control ( avoid β-adrenergic blockers ) Respiratory support |
| Jellyfish | Mild pain, irritant dermatitis | Remove tentacles Apply acetic acid 5%, lidocaine-containing product, or hot water (upper limit 45°C) immersion |
| Seabather’s eruption | Pruritic papules resembling insect bites in distribution of swim suit | Treat skin with acetic acid 5%, or lidocaine-containing first aid remedy Wash swim suit with hot water and detergent, then machine or sun dry |
| Sea anemone | Erythema and pruritus Petechiae, blisters, and ulceration | Acetic acid 5% May require prolonged wound care |
| Feather hydroid; fire coral | Stinging pain, urticaria, petechiae, ulceration, residual hyperpigmentation | Acetic acid 5% May require prolonged wound care |
| Sponge | Pruritic irritant dermatitis, blisters, delayed desquamation | Remove spicules with tape, rubber cement, or facial peel Acetic acid 5% |
| Bristle worm | Painful urticarial rash | Remove bristles with tape, rubber cement, or facial peel Acetic acid 5% |
Cnidaria
The phylum Cnidaria is divided into four main groups: (1) hydrozoans, including feather hydroids, fire corals, and Portuguese man-of-war; (2) scyphozoans, such as true jellyfish; (3) anthozoans, such as soft corals and anemones; and (4) cubozoans, such as box jellyfish and irukandji.
Hydroids and Fire Coral
Epidemiology
Hydrozoans are multiorganism colonies of diverse configurations. Feather hydroids are plumelike species found in tropical waters. Fire coral has an appearance similar to hard coral. An example is Millepora , distributed in shallow tropical waters and dangling tiny nematocyst-bearing tentacles. The stinging tentacle-bearing Portuguese man-of-war ( Physalia physalis ) and blue bottle ( Physalia utriculus ) are widely distributed.
Presentation
Feather hydroids and fire coral cause immediate pain and urticaria, sometimes progressing to hemorrhagic or ulcerating lesions. Pain usually resolves by 90 minutes and inflammation resolves by 1 week, with occasional residual hyperpigmentation. Portuguese man-of-war and bluebottle envenomations cause immediate intense pain and linear rashes, with vesiculation and necrosis. Pain improves within hours, and local symptoms resolve within 72 hours. More severe systemic symptoms include nausea, vomiting, muscle cramps, dyspnea, anxiety, abdominal pain, and headache.
Treatment
For feather hydroid and fire coral envenomations, apply acetic acid 5% (vinegar) to the skin. Consider steroid cream or an oral antihistamine for symptomatic relief; if the reaction is eczematous or indolent, administer systemic corticosteroids. Portuguese man-of-war and bluebottle envenomation treatment is controversial. Acetic acid 5% is shown to worsen cnidocyst discharge in vitro, although some patients report symptomatic relief. A lidocaine-containing product may be equally effective. Recent research supports rinsing with seawater or saline followed by hot water (45°C) immersion. Consider topical steroid cream or ointment; an antihistamine; and for severe reactions, a systemic corticosteroid taper over 14 days (see Table 1 ).
Jellyfish
Epidemiology
Scyphozoans are single-organism jellyfish that range in size from 2 cm to 2 m across the bell and have different forms, including free-floating larva, sessile polyp, and large swimming medusa ( Fig. 1 ). Mauve stingers ( Pelagia ) are common in US Pacific Ocean coastal waters. The large lion’s mane jellyfish ( Cyanea capillata ) inhabits cold Arctic and Pacific waters. Stinging larval forms of multiple species are found in warm waters; these notably include pinhead-sized larvae of the thimble jellyfish ( Linuche unguiculata ).
Presentation
Contact with tentacles causes stinging pain and localized erythema that resolve in hours to days. Contact with the larval forms can cause seabather’s eruption; pruritic papules resembling bug bites in a bathing suit distribution (within which larvae are trapped) itch and annoy for 2 to 14 days. Other symptoms include fever, headache, chills, malaise, vomiting, conjunctivitis, and urethritis.
Treatment
Management of scyphozoan stings is identical to that for any cnidarian sting, namely, topical acetic acid 5%, hot water immersion, and corticosteroid or antihistamine cream, and in severe cases a systemic corticosteroid. A lidocaine-containing product may be effective as a topical decontaminant. To minimize or prevent seabather’s eruption, change swimwear on leaving the water. Use a hot water laundering scrub with detergent and full drying before reuse (see Table 1 ).
Sea Anemones
Epidemiology
Sea anemones and soft corals have tentacles loaded with stinging cnidocytes and secrete mucus that may contain cytolytic and hemolytic toxins, neurotoxins, cardiotoxins, and proteinase inhibitors.
Presentation
Victims experience painful skin lesions with central pallor and a halo of erythema and petechial hemorrhage, sometimes progressing to vesiculation and necrosis. Rare systemic reactions include fever, chills, malaise, weakness, nausea, vomiting, muscle spasm, and syncope. Mild envenomations resolve within 48 hours. Severe reactions may become indolent, leading to hyperpigmentation, hypopigmentation, or keloid formation.
Treatment
Treatment of anemone envenomation is similar to that for cnidarian sting (discussed previously). Severe dermatitis may require prolonged wound care with debridement and antibiotics for secondary infection (see Table 1 ).
Box-Shaped Jellyfish
Epidemiology
Some highly venomous box-shaped jellyfish inhabit tropical waters. These include the Hawaiian box jellyfish ( Carybdea alata ), Japanese box jellyfish ( Chironex yamaguchi ), and Australian box jellyfish ( Chironex fleckeri ). Each delivers potentially deadly venom.
Irukandji jellyfish are 1 cm to 2.5 cm box jellyfish and include Carukia barnesii and Malo species. The “irukandji syndrome” is local vasoconstriction and high blood pressure attributed to sympathetic nervous system stimulation.
Presentation
Box jellyfish stings are excruciating with rapid blistering, muscle spasm, hypotension, and sometimes paralysis. Victims collapse in 1 to 2 minutes from respiratory failure and cardiac arrest. Most deaths occur 5 to 20 minutes after the sting. Skin necrosis is common.
Irukandji envenomation symptoms begin 20 to 30 minutes post sting with muscle pain, abdominal and chest pain, nausea, vomiting, and respiratory failure. Massive catecholamine release causes severe hypertension and tachycardia, leading to cardiomyopathy, pulmonary edema, cerebral edema, troponin leak, and hypokinetic heart failure. Two deaths have occurred because of intracerebral hemorrhage. Symptoms resolve in 6 to 24 hours.
Treatment
If box jellyfish sting is suspected, support the airway and provide artificial ventilation. Immediately flood sting sites with 5% acetic acid (vinegar) for at least 30 seconds before removing adherent tentacles. Avoid contamination of rescue personnel. Administer specific antivenom one vial intravenous (IV) or introsseous 5 minutes, or three vials intramuscular (IM) at three different sites. Repeat as needed every 10 minutes up to three times immediately and then once or twice every 2 to 4 hours until there is no further progression of systemic symptoms. Antivenom use is under scrutiny because of poor efficacy noted during in vitro studies. However, until further notice it remains recommended.
For irukandji envenomation, in addition to standard cnidarian envenomation treatment measures and supportive therapy, serum troponin and cardiac monitoring should be obtained. β-Adrenergic blockers should not be used because these might contribute to unopposed α-adrenergic stimulation and myocardial ischemia (see Table 1 ).
Annelid worms
Epidemiology
Bristle worms (phylum Annelida, class Polychaeta) are covered with chitinous bristles that easily penetrate skin.
Presentation
Human contact causes bristles to break off into the skin, causing pricking sensation and urticarial rash with rare necrosis. Pain remits with a few hours, but urticaria may last for 2 to 3 days and skin discoloration for up to 10 days. Secondary infection and cellulitis may occur.
Treatment
Bristles should be removed with tape, facial peel, or a thin layer of rubber cement. Next, apply acetic acid 5% soaks. If the inflammatory reaction is severe, consider an oral antihistamine or corticosteroid (see Table 1 ).
Starfish and sea urchins
Epidemiology
The phylum Echinodermata includes starfish and sea urchins. The crown-of-thorns starfish ( Acanthaster planci ) is particularly venomous and produces a toxic slime that coats the spines ( Fig. 2 ). Venom is hemolytic, myonecrotic, hepatotoxic, and anticoagulant.
Sea urchins have globular bodies covered by calcified spines either rounded at the tip or hollow and venom-bearing ( Fig. 3 ). They may have pedicellariae (modified spines with flexible heads) that grasp to envenom. Various urchin venoms have been found to contain steroid glycosides, hemolysins, proteases, serotonin, and cholinergic substances.
Presentation
Crown-of-thorns starfish cause puncture wounds with immediate pain, bleeding, and edema. Wounds become dusky and tenosynovitis may develop. Multiple punctures can cause systemic reactions with paresthesias, nausea, vomiting, lymphadenopathy, and paralysis. Pain resolves in 30 minutes to 3 hours. Retained spines can cause granulomas.
Sea urchins cause painful puncture wounds with severe local muscle aching lasting up to 24 hours. Frequently, spines break off into the victim. A spine in a joint can cause synovitis. Systemic symptoms include nausea, vomiting, paresthesias, weakness, abdominal pain, syncope, hypotension, and respiratory distress. Secondary infections are common. Granulomas may develop.
Treatment
The puncture wounds should immediately be immersed in hot water to tolerance (upper limit 45°C) for 30 to 90 minutes or until there is significant pain relief. Local anesthetic infiltration or a nerve block may be required. Wounds should be irrigated and explored and spines removed if they are easily reached. Dark discoloration may indicate dye in the tissues in the absence of a spine. If this is the case, the discoloration disappears in 24 to 48 hours. If spines have entered a joint or are close to neurovascular structures a surgeon should be consulted and the joint splinted. Radiography, ultrasound, computed tomography, or MRI may be helpful in spine localization and removal. Reactive neuropathy may respond to a systemic corticosteroid. Secondary infections are common. Granulomas from retained spine fragments may require excision or ablation, and arthritis from retained spines may require synovectomy ( Table 2 ).
| Species | Presentation | Treatment |
|---|---|---|
| Crown-of-thorns starfish | Dusky puncture wound, pain, bleeding, edema Multiple punctures cause nausea, vomiting, paresthesias | Hot water to tolerance (maximum 45°C) for 30–90 min Local anesthetic Locate retained spines Surgical removal if spines near nerve, tendon, or joint |
| Sea urchin | Red, purple, or black puncture wounds; local muscle aching; edema Multiple punctures cause nausea, vomiting, paresthesias | Hot water to tolerance (maximum 45°C) for 30–90 min Local anesthetic Locate retained spines Surgical removal if spines near nerve, tendon, or joint |
| Cone snail | Puncture wound resembling bee sting, local cyanosis, limb paresthesias, paralysis, respiratory failure, cerebral edema, coma | Pressure immobilization Support breathing Consider edrophonium, 10 mg IV, for paralysis Consider naloxone, 2–4 mg, for severe hypotension Hot water to tolerance (maximum 45°C) for 30–90 min Local anesthetic Remove retained radula |
| Blue-ringed octopus | Painless small puncture wounds, facial numbness, paralysis, respiratory failure | Support breathing Supportive care |
| Lionfish and scorpionfish | Painful puncture wound, blistering, nausea, vomiting | Hot water to tolerance (maximum 45°C) for 30–90 min Local anesthetic or nerve block Locate retained spines Surgical removal if spines near nerve, tendon, or joint |
| Stonefish | Severely painful cyanotic puncture wound, necrotic ulceration, altered mentation, fever, nausea, vomiting, seizures, paralysis, heart block, heart failure, pulmonary edema | Antivenom for severe envenomation Hot water to tolerance (maximum 45°C) for 30–90 min Local anesthetic or nerve block Locate retained spines Surgical removal if spines near nerve, tendon, or joint Debride necrotic tissue |
| Stingray | Dusky painful laceration, local hemorrhage and necrosis, barb lodged in victim Large envenomation: nausea, vomiting, muscle cramps, syncope, arrhythmias | Hot water to tolerance (maximum 45°C) for 30–90 min Local anesthetic or nerve block Locate retained barb Surgical removal of barb Treat retained barb as stab wound if barb in thorax, abdomen, groin, or neck Serial debridement of necrotic tissue |
| Sea snake | Painless pinhead-sized fang marks, muscle pain and stiffness, nausea, vomiting, ascending paralysis, respiratory failure, muscle necrosis, renal failure | Pressure immobilization Maintain airway and breathing Antivenom if any symptom Monitor electrolytes and urine output Alkalinize urine if myoglobinuria Dialysis as needed for renal failure and hyperkalemia |
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