Marine Envenomations: Recognizing and Managing Sea Creature Stings
Marine envenomations are an uncommon but important consideration in water sports including swimming, diving, scuba, fishing, surfing, wakeboarding and others. They occur predominantly in tropical waters. Most envenomations occur not as an attack but act of self defense when an animal perceives danger. There are over 100,000 species, 100 of which are known to be poisonous. In general, marine envenomations are not well studied and thus many guidelines are based on case reports or case series.
Nematocysts (Phylum: Cnidaria)
Image 1. Example of seabather’s eruption (courtesy of the Dr Andrew Schmidt)
Seabather’s eruption. This a non-specific dermatitis secondary to nematocyst exposure. Symptoms include pruritic papules resembling insect bites in the distribution of swimsuit which often occurs during a shower after swimming in ocean as fresh water ruptures larvae. Treatment includes bathing the skin with acetic acid 5%, or lidocaine-containing first aid remedy. Swimmers should be careful to wash the swimsuit with hot water and detergent, then machine or sun dry
Image 2. Two examples of portuguese man-of-war
Portoguese man-of-war (Physalia physalis and Physalia utriculus). Found primarily in the Atlantic, Indian and Pacific oceans and stings common in southern US. Not a true jellyfish, formed by colonies of siphonophore with each unit a specialized animal of the same species. Tentacles grow up to 30m (atlantic), 3m (pacific) depth. Symptoms include local sharp pain immediately after the sting, followed by an erythematous maculopapular linear rash, local edema, and numbness. The rash improves at 24 hours, complete resolution by 72 hours. Complications are rare but include skin necrosis, cardiorespiratory collapse, and rarely death. There is no antivenom. Treatment consists of removing tentacles, preferably with forceps or gloved hand. The affected areas should be immersed in hot water (45°C) for 10–20 min preferred over local application of ice-packs for pain control . Avoid using vinegar or methylated spirits (can increase nematocyst firing). Topical anesthetics can be considered after successful removal of all tentacle fragments. Use oral or parenteral analgesics if pain persists.
Image 3. Two examples of fire coral
Fire corals. These have a worldwide distribution among reef crests and shallow waters (except hawaii). Symptoms include immediate pain and urticaria, sometimes progressing to hemorrhagic or ulcerating lesions. Pain resolves by 90 minutes, local symptoms by 72 hours. Less commonly more severe systemic symptoms include nausea, vomiting, muscle cramps, dyspnea, anxiety, abdominal pain, and headache. There is no antivenom. Treatment primarily revolves around applying acetic acid 5% (vinegar) to the skin. Consider steroid cream or an oral antihistamine for symptomatic relief and oral corticosteroids if severe.
Box Jellyfish (Chironex fleckeri). Sometimes referred to as sea wasp and marine stinger. Seen primarily tropical indo-pacific ocean however there are reports in the southeast united states as well. These occur most often during the Australian summer: 92% of the stings took place between October 1 and June 1 (i.e., stinger season). 83% of stings occur in shallow water (<1 m)  between 3-6pm and 8% of stung patients required hospitalization. Box Jellyfish sting is a medical emergency due to its potential lethality and should be treated as such. There are at least 67 deaths in Australia and most people die 20 minutes after sting. Up to 25% of people die, more than sharks.
Irukandji jellyfish (Carukia barnesi). Much smaller jellyfish, ranging from 3 to 19 mm seen in northern and western coasts of australia. Initial Symptoms are simply a wheal, local erythema at the sting site. Patients can go on to develop a phenomenon known as ‘Irukandji syndrome’ between 20m and 2hr after sting. Thought to be sympathetic nervous system stimulation presenting with sympathomimetic toxidrome. Symptoms include severe abdominal, chest, limbs, or back pain; generalized muscular pain, hypertension, tachycardia, vomiting, nausea, diaphoresis, piloerection, and local erythema. Complications include hypertensive crisis, hemodynamic decompensation with abnormal ECG and elevated troponins, cardiac failure, and death. Treatment consists of hot water shower as tolerated for 10–20 min, vinegar irrigation, antihypertensive therapy, magnesium sulfate i.v., and pain management (including local use of cold packs/ice and opiates). Do not use pressure immobilization bandages. There is no antivenom currently but ongoing research. Antihypertensives include phentolamine and magnesium sulfate should be considered [1, 8].
Image 5. Turtle grass (left) and giant see anemone (right)
Image 6. Typical mechanism of a stringray injury (left) and example of puncture wound in foot (right)
Stingrays (Family: Dasyatidae). Responsible for up to 2000 ED visits annually . Seen in tropical warm waters and are found practically all over the world. Anatomically, they are a flat cartilaginous fish with caudal appendages harboring bilaterally retroserrate barbs and associated venom glands. Injury pattern has 2 phases: mechanical, due to barbed stinger at end of whiplike tail and venomous, due to gland at the tail base is injected into the victim. Venoms are variable and contain serotonin, 5’-nucleotidase, and phosphodiesterase. Toxin may induce peripheral vasoconstriction, bradycardia, tachycardia, atrioventricular block, and seizure activity.
Image 7. A stonefish.
Stone fish (Family: Scorpaenidae). Most venomous of the spine fish, venom comparable to potency of cobra venom. Resides in the Indopacific ocean and can grow up to 38 cm in length and weigh 1.5 kg. It’s body is covered in spines that release venom from mechanical pressure (i.e. someone steps on it). Symptoms include severe pain and edema at the site of sting, headaches, severely painful cyanotic puncture, wound, necrotic ulceration. Complications include weakness, syncope, dyspnea, hypotension, and hallucinations, altered mentation, fever, nausea, vomiting, seizures, paralysis, heart block, heart failure, pulmonary edema, death can occur within 6 hours.
Image 8. A scorpion fish (left) and lion fish (right)
Lionfish & Scorpion fish (Family: Scorpaenidae). Venom is weaker than stonefish. The scorpion fish is second most toxic, found in the coastal waters of the Atlantic Ocean (usually Brazil, Uruguay, and Argentina) and is understudied fish due to its limited global distribution . The lionfish is the 3rd most toxic spine fish and injury often occurs to the hands of people handling fish. Note the catfish is likely the most common but far less poisonous and thus under-reported. Symptoms include sharp, intense, throbbing pain at the site of injection which can radiate, peaks at 60-90 minutes. Symptoms can be broken down into three grading categories. First is mild with erythema, pallor, ecchymosis or even cyanosis are the first events that present, and result from the increased capillary permeability. Second is vesicle formation, as an effect of the toxins. Finally, one can see local necrosis observed within days, which is considered a grave complication and requires debriding. Treatment is the same as the stonefish except there is no antivenom.
Image 9. Two examples of sea urchins.
Sea urchins. They have globular bodies covered by calcified spines either rounded at the tip or hollow and venom-bearing. There are many species with various venoms including steroid glycosides, hemolysins, proteases, serotonin, and cholinergic substances. They typically present with painful puncture wounds with severe local muscle aching lasting up to 24 hours. Frequently, spines break off into the victim causing granuloma formation or synovitis. Systemic symptoms include nausea, vomiting, paresthesias, weakness, abdominal pain, syncope, hypotension, and respiratory distress. Secondary infections are common. Chronically, patients may develop granulomas. Treatment includes hot water (45°C) immersion and irrigation and exploration of only superficial wounds. If concerned, considered operative irrigation especially with joint involvement. Note that the spines are hard to remove and can “tattoo” the skin making it hard to tell if there is a retained foreign body.
Image 10. Two examples of the crown of thornes starfish
Star fish. The crown-of-thorns starfish (Acanthaster planci) is particularly venomous and produces a toxic slime that coats the spines. Its venom is hemolytic, myonecrotic, hepatotoxic, and anticoagulant. Initial symptoms include puncture wounds with immediate pain, bleeding, and edema. Wounds can become dusky and tenosynovitis may develop. Multiple punctures can cause systemic reactions with paresthesias, nausea, vomiting, lymphadenopathy, and paralysis. In most cases, pain resolves in 30 minutes to 3 hours. Retained spines can cause granulomas. Treatment includes hot water (45°C) immersion and irrigation and exploration of only superficial wounds.
Image 11. The cone snail.
Cone shells/snails (Conus geographus). Their venom gland, teeth at end of proboscis (nose) and contains a conotoxin or neurotoxin that acts as a neuromuscular blockade which blocks potassium, sodium and calcium channels. Initial symptoms include severe pain at the site of sting, muscular paralysis. Complications include palpebral ptosis, speech difficulty, and swallowing impairment, and eventually respiratory arrest in occurs as fast as 40 min up to 5 h and typically lasts 12 to 36 hours. 50 deaths reported in the literature with a mortality rate as high as 25% .
Image 12. Two examples of the blue ringed octopus.
Blue Ringed Octopus (Hapalochlaena lunulata). This animal is seen in shallow waters throughout Indo-Pacific oceans. Injury typically occurs when picked up out of the water by humans. They carry a tetrodotoxin which inhibits voltage gated sodium channels leading to paralysis. Symptoms can include flaccid paralysis, hypotension and less commonly respiratory failure and death. There is no antivenom. Treatment is generally supportive including mechanical ventilation if necessary. The limb should have a pressure bandage to minimize toxin spread. Most individuals can expect complete recovery in 2 – 4 days.
Image 13. The Mexican beaded lizard (left) and Gila monster (right)
Lizard bites (Helodermatidae). Caused by either the mexican beaded lizard or gila monster, both of SE US, Mexico and Central America. Venom delivered by the bite from glands in the lower jaw. Generally causes localized, rarely systemic effect. Note teeth can be left behind in wound as a foreign body and nidus for infection. Symptoms include crush and puncture wounds, local erythema and pain. Much less commonly, systemic features including weakness, hypotension, diaphoresis. Treatment is mostly supportive and includes removal of the animal, imaging to identify foreign bodies, irrigating copiously, tetanus and prophylactic antibiotics.
Image 14. The sea snake.
Sea snake (family Hydrophiidae). These are known to inhabit tropical Pacific and Indian oceans. Their venom is a neurotoxins acting at the acetylcholine receptor, and hemolytic and myotoxic compounds that cause muscle necrosis, hemolysis, and renal tubular damage. Approximately 80% of bites do not result in envenomation due to small, easily dislodged fangs. Initial symptoms include painless pinhead-sized fang marks and roughly 30-60 minutes later, muscle pain and stiffness, nausea, vomiting, ascending paralysis, respiratory failure, muscle necrosis, renal failure. There is an antivenom which reduces mortality rate to 3%, it is as high as 25% if not receiving antivenom. Apply a pressure immobilization dressing, maintain airway and breathing and admit to hospital. These patients require close monitoring of electrolytes and urine out as they may develop rhabdomyolysis, renal failure and hyperkalemia.
Read More: https://wikism.org/Marine_Envenomation_(Main)