Marine Envenomations 

Marine Envenomations

Key Points

• Maintain awareness of regional marine animals responsible for potential envenomation and knowledge about management options, including how to obtain antivenom
• Envenomation is most common in regions where contact with humans is greatest, including coastal waters, and in temperate to tropical waters
• Patients at increased risk of severe envenomation include children, patients of advanced age, and patients with significant comorbidity
• Clinical presentation is species specific but, in general, marine organisms capable of envenomation deliver toxin by 3 primary mechanisms
  • Discharge of microscopic harpoon-like apparatuses from the cell wall (nematocyst) of specialized cells (ie, cnidocyte), often located on tentacles of jellyfish, anemones, and Portuguese man-of-war, and found on the surface of fire coral
  • Penetrating injury from venom-containing spine-like structures with or without barbs (eg, Echinodermata [sea urchins, sea stars]), fish of the Scorpaenidae family (eg, scorpion fish, stone fish, lionfish), fish of the Trachinidae family (eg, weeverfish), stingrays, and cone snails
  • Bites from the venomous beak of the blue-ringed octopus and fangs of venomous sea snakes
• Diagnosis is determined by clinical presentation (eg, characteristic wound, geographic region envenomation occurred, identification of animal) after exclusion of alternate cause (eg, trauma or nonvenomous bite)
  • Imaging (radiography, ultrasonography, MRI) may be indicated to assess for presence of retained foreign bodies (eg, spines, barbs) associated with some species, particularly when a retained foreign body is suspected despite thorough wound exploration
• Manage significant or potentially fatal envenomation in consultation with medical toxicologist and/or regional poison control center for additional diagnostic and management considerations
• Immediate transport for definitive care and observation is important in potentially fatal envenomation (eg, box jellyfish, Irukandji jellyfish, cone snail, blue-ringed octopus, venomous sea snake)
• Treatment of marine envenomation may be initiated based on nature of wound (eg, puncture from spines, rash from discharge of nematocysts) and region in which wound occurred, despite lack of identification of the specific marine animal responsible for envenomation. Table 2 summarizes preferred management options for most significant marine envenomations
• Decontamination is species specific but usually involves
  • Application of hot water. Effective for many marine toxins, as most toxins encountered in marine envenomation are heat labile; therefore, hot water is a reliable and effective neutralization technique in many instances and may diminish risk of further toxin release in some Cnidaria (North American jellyfish, fire coral) species
  • Application of acetic acid (vinegar). May minimize discharge of nematocysts from cnidocyte cells of certain Cnidaria species (eg, box jellyfish); however, use is controversial and may exacerbate pain in some species (Portuguese man-of-war, many North American species of Cnidaria)
  • Manual removal of tentacles and debris, and removal of toxin-containing spines and/or barbs
• Antivenom is available for severe stonefish reactions and envenomation by sea snakes and box jellyfish
• Pressure immobilization is used in attempt to minimize systemic absorption of some potentially fatal toxins (eg, cone snail, blue-ringed octopus, venomous sea snake)
• Other pertinent aspects of management include pain control, selective use of prophylactic antibiotics covering bacteria specific to marine environments (eg, ciprofloxacin, trimethoprim/sulfamethoxazole, doxycycline), meticulous wound care, and tetanus prophylaxis as indicated
• Prevention is important as many marine envenomations occur after improper handling or touching of marine life by snorkelers, scuba divers, shell collectors, or aquarium owners, and by unintentionally stepping on organisms on the ocean floor or underwater rocky surfaces

Alarm Signs and Symptoms

• Acute life-threatening envenomation may occur from box jellyfish, Irukandji jellyfish, stonefish, cone snails, blue-ring octopus, and sea snakes
  • Prepare for advanced supportive care following envenomation as many marine toxins may result in neurologic manifestations (eg, flaccid paralysis) and cardiopulmonary collapse
• Delayed wound healing and secondary wound infection are common
  • Carefully evaluate for retained material and foreign body in patients presenting with a secondary wound infection
  • Prescribe antibiotics for appropriate wounds that cover typical skin microbes (eg, Staphylococcus, Streptococcus) and well as pathogens prevalent in marine environments (eg, Vibrio species)
• Maintain awareness that an otherwise benign envenomation in a healthy adult may cause serious illness in patients at high risk for severe reactions
  • Children and the elderly, particularly those with significant comorbidity, are at higher risk for worse outcomes resulting from envenomation

Basic Information

Terminology

• Marine envenomation
  • Process by which venom or toxin is introduced via bite, sting, or puncture after contact with a marine animal
  • May be caused by both invertebrate and vertebrate organisms¹
    • Invertebrates include the phylum Cnidaria (jellyfish, Portuguese man-of-war, anemones, fire coral), Mollusca (snails and octopods), Echinodermata (sea stars, sea urchins), and Porifera (sponges)
    • Vertebrates include cartilaginous (Chondrichthyes) and bony fish (Osteichthyes), and sea snakes (family Elapidae, subfamilies hydrophiinae and laticaudinae)
• Irukandji syndrome
  • Syndrome of autonomic excess and severe pain that occurs following envenomation by one of several, highly venomous species of box jellyfish collectively referred to as Irukandji jellyfish (eg, Carukia barnesi, Malo kingi)²
  • Jellyfish species that may cause this reaction are notoriously tiny and contact with these organisms may go unnoticed or feel like an innocuous insect bite
  • May require large amounts of analgesia, sympatholytic, and vasodilator support
• Seabather’s eruption
  • Eruption caused by larval stages of certain Scyphozoan jellyfish and sea anemones
  • Usually develops minutes to hours after swimming and may last up to a couple of weeks³
  • Presents as discrete areas of skin irritation or papules resembling mosquito bites, usually in the distribution of covered areas of the body (larvae get trapped under bathing suit or wetsuit)³

Epidemiology

• Figure 1. Climate zones.

• Ubiquitous and worldwide distribution is characteristic of most marine fauna responsible for envenomations
• Concentration of some animals is characteristically higher in certain regions
  • Irukandji jellyfish is native to northern Australian seas
  • Crown-of-thorns sea star is mainly found in Indo-Pacific seas
  • Stone fish, scorpion fish, and lionfish (Scorpaenidae) are native to the Indo-Pacific seas
    • Lionfish were introduced to Caribbean Sea and Atlantic Ocean and have spread largely throughout the region
  • Weeverfish (Trachinidae) common in European and African seas
  • Blue-ringed octopus and sea snakes are indigenous to Indo-Pacific seas and do not inhabit Caribbean waters
• Most marine envenomations occur in tropical and subtropical seas, some occur in temperate climates, and few in polar regions (Figure 1)
• Envenomations are most common in regions where contact with humans is greatest including
  • Coastal waters
  • Temperate to tropical waters
• Envenomations may occur secondary to inadvertent or intentional contact with marine animals
  • Venom-containing marine creatures are not characteristically aggressive by nature and do not seek to harm humans

Etiology and Risk Factors

Etiology

• Figure 2. Invertebrate animals and characteristic identifying wounds: A-B, scyphozoan “true” jellyfish; C-D, hydrozoan (Portuguese man-of-war); E-F, anemone; G-H, box jellyfish; I-J, sea urchin; K-L, sea star; M, cone snail; N-O, blue-ringed octopus. P-Q, sea sponge.A, Photo credit: Dan90266. https://www.flickr.com/photos/dan90266/37269957/; B, Photo credit: Jmarchn. https://en.wikipedia.org/wiki/Jellyfish; D, From Dinulos J. Habif’s Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 7th edition. Elsevier Inc; 2021.; E, Photo credit: Nhobgood. https://en.wikipedia.org/wiki/Condylactis_gigantea; F, From Tsai H-S et al. Acute skin manifestation of sea anemone envenomation. J Emerg Med. 2021;60(4):536-537. https://doi.org/10.1016/j.jemermed.2020.11.025.; G, Photo credit: Guido Gautsch. https://en.wikipedia.org/wiki/Box_jellyfish; H, From Auerbach PS et al. Dermatological progression of a probable box jellyfish sting. Wilderness Environ Med. 2019;30(3):310-320.; I, https://en.wikipedia.org/wiki/Sea_urchin#/media/File:Paracentrotus_lividus_profil.JPG; J, Photo credit: Yugyug. https://en.wikipedia.org/wiki/Sea_urchin_injury#/media/File:Sea-urchin-injury.jpg; K, Photo credit: Jon Hanson. https://en.wikipedia.org/wiki/Crown-of-thorns_starfish#/media/File:Crown_of_Thorns-jonhanson.jpg; L, From Lakshmanan P et al. Management of crown-of-thorns starfish injury. Foot Ankle Surg. 2004;10(3):155-157.; M, From Favreau P et al. Marine snail venoms: use and trends in receptor and channel neuropharmacology. Curr Opin Pharmacol. 2009;9(5):594-601.; N, Photo credit: Jens Petersen. https://en.wikipedia.org/wiki/Blue-ringed_octopus#/media/File:Hapalochlaena_lunulata2.JPG; O, https://www.tandfonline.com/doi/pdf/10.1080/15563650701601790; P, Photo credit: Kirt L. Onthank. https://commons.wikimedia.org/wiki/File:Spongilla_lacustris.jpg; Q, From Isbister GK et al. Clinical effects of stings by sponges of the genus Tedania and review of sponge stings worldwide. Toxicon. 2005;46(7): 782-785, Figure 2.
• Figure 3. Vertebrate animals and characteristic identifying wounds: A-B, stingray; C-D, lionfish; E-G, stonefish; H-I, weeverfish; J-K, sea snake; L, scorpionfish.A, Photo credit: Barry Peters. https://commons.wikimedia.org/wiki/File:Southern_stingrays_at_stingray_city.jpg; B, Photo credit: Symac. https://en.wikipedia.org/wiki/Stingray_injury#/media/File:Stingray_injury.jpg; C, Photo credit: Jean-Marc Kuffer. https://www.flickr.com/photos/54452028@N00/192796211; D, From Hobday D et al. Denaturing the lionfish. Eplasty. 2016;16:ic20.; E, Photo credit: Karelj. https://commons.wikimedia.org/w/index.php?curid=19147608; F, From Isbister GK. Venomous fish stings in tropical northern Australia. Am J Emerg Med. 2001; 19(7):561-565.; G, From Dall GF et al. Severe sequelae after stonefish envenomation. Surgeon. 2006;4(6):384-385.; H, Photo credit: Hans Hillewaert. https://en.wikipedia.org/wiki/Lesser_weever; I, From Peters W et al (eds). Tropical Medicine and Parasitology. 5th ed. Mosby; 2002.; J, Photo credit: Jon Hanson. https://www.flickr.com/photos/jonhanson/90795890/; K, From Auerbach P et al. Auerbach’s Wilderness Medicine. 7th ed. Elsevier Inc; 2017, Figure 36-79.; L, Photo credit: Wilfried Berns. https://commons.wikimedia.org/wiki/File:Grosserdrachenkopf-02.jpg
• Venom delivery may occur through several mechanisms
  • Nematocyst delivery
    • Organisms of phylum Cnidaria may contain specialized cells called cnidocytes; phylum Cnidaria is divided into 4 primary groups (Figure 2)
      • Cubozoans: box jellyfish and Irukandji jellyfish
      • Scyphozoans: true jellyfish
      • Hydrozoans: Portuguese man-of-war, fire corals, and feather hydroids
      • Anthozoans: soft corals and anemones
    • Cnidocytes are frequently located on tentacles and each tentacle may contain thousands of cnidocytes
    • The specialized cell (ie, cnidocyte) contains a unique cell wall organelle called a nematocyst (cnidocyst) that is responsible for venom delivery into the dermis
    • Direct contact/physical pressure, osmolality changes, and chemical changes may trigger the nematocyst to discharge a microscopic harpoon-like barb coated with venom that then may penetrate victim or prey
  • Spines
    • Numerous marine organisms utilize spines to deliver venom (Figure 3)
      • Organisms of the phylum Echinodermata (eg, sea urchins, sea stars) may have spines resembling thin needles; spines are composed of calcium carbonate, do not have barbs, and notoriously break easily causing a retained foreign body in an apparent innocuous puncture wound
      • Cone snails of the Conus genus have a long flexible feeding tube (proboscis) that protrudes out of the head of the snail and contains a barbed, venom-containing, harpoon-like apparatus called a radula
      • Stingrays of the Chondrichthyes class have venom-containing retro-serrated barbed spines at the end of a long thin tail that may detach in the victim causing retained foreign bodies
      • Fish of the Scorpaenidae family (eg, scorpion fish, stone fish, lionfish) have venomous dorsal spines without barbs; venom release is usually triggered by pressure
      • Fish of the Trachinidae family (eg, weeverfish) also have venomous dorsal spines lacking barbs; venom release is usually triggered by pressure
      • Catfish (numerous species) typically inhabit fresh waters and have venomous spines; venom release is usually triggered by pressure⁴
  • Bites
    • Other marine animals inject venom via bites
      • Cephalopods of the Hapalochlaena genus (eg, blue-ringed octopus) inject venom via a bony beak
      • Venomous sea snakes of the Elpaidae family inject venom via fangs; human envenomation most often involves Beaked (E. schistosa) and Yellow-bellied sea snakes (Hydrophis platurus)⁵

Risk Factors

• Inadvertent contact with venomous marine life may occur when entering various marine ecosystems (eg, swimming or wading in an ocean, snorkeling and scuba diving, fishing)
• Intentional handling of marine organisms in the ocean or an aquarium
  • Shell collectors may be at increased risk for cone snail envenomation
  • Fisherman may be bitten by sea snakes or stung by fish containing venomous spines when caught on the reef and reeled into boat
• Risk factors for severe envenomation include
  • Pediatric age groups
  • Advanced age groups
  • Patients with significant comorbidity (eg, preexisting cardiac insufficiency, respiratory disease)
  • Envenomation occurring in the Indo-Pacific region, specifically in waters near Australia

Risk Models and Risk Scores

• Mild envenomation
  • Limited to pain and soft tissue symptoms at injection site
• Severe envenomation
  • Associated with systemic symptoms (eg, paralysis, coma, cardiorespiratory failure)

Diagnosis

Approach to Diagnosis

• Diagnosis is determined by clinical presentation (eg, characteristic wound, geographic region envenomation occurred, identification of animal) after exclusion of alternate causes (eg, trauma or nonvenomous bite, sting, puncture)
• Obtain radiographic studies (eg, radiographs, ultrasound, CT, MRI) to evaluate for retained foreign bodies when appropriate based on clinical scenario
  • Imaging is recommended for any significant marine puncture wound⁶
    • Initial imaging is typically radiography and/or ultrasonography to assess for foreign bodies⁷
    • CT or MRI is often useful when clinical suspicion remains high for foreign bodies not found on wound exploration or visible on initial studies⁶
  • Retained foreign bodies from the following marine animals are common
    • Spines from Scorpaenidae (eg, stonefish, scorpion fish, lionfish), Trachinidae (eg, weeverfish), sea urchin and crown-of-thorns sea star, stingray barbs
• Laboratory studies are not routinely indicated in the absence of systemic toxicity⁶
• Individualize additional specific ancillary testing based on clinical presentation
  • Obtain routine laboratory evaluations (eg, CBC, complete metabolic panel) in patients presenting with signs of systemic envenomation (eg, abnormal vital signs, respiratory distress, and neurologic manifestations)
  • Baseline testing (eg, creatine kinase, electrolytes, BUN/creatinine, urinalysis) to allow follow-up for development of acute kidney injury and rhabdomyolysis in patients with suspected sea snake envenomation
  • Indications to perform an ECG may include patients with arrhythmia/dysrhythmia, hemodynamic instability, and suspected Irukandji syndrome⁸
  • Measurement of compartment pressure with concern for compartment syndrome

Workup

History

• Venomous marine animal may or may not be seen when injury occurs
• Injuries sustained on lower extremity while wading are often the result of stonefish or scorpionfish, echinoderm (eg, sea star, sea urchin), or stingray envenomation
• Delayed presentation, rather than immediate development of symptoms, may occur with sea snake and blue-ringed octopus envenomation⁶
• Characteristic presentation patterns of certain envenomation include
  • Linear marks suggest exposure to nematocyst-covered tentacles
  • Immediate severe pain at site of rash followed by rapid progression to cardiopulmonary collapse may suggest box jellyfish envenomation
  • Delayed systemic manifestations (eg, sense of impending doom, diffuse severe pain, diffuse muscle spasms, cardiopulmonary collapse) within 30 minutes to 2 hours of minor or unnoticed sting(s) suggest Irukandji syndrome²
  • Immediate and intense local pain with scrapes, linear marks, lacerations, and/or patchy erythema suggests trauma from fire coral
  • Multiple pruritic, insect-bite–like lesions suggest seabather’s eruption (contact with larval forms of certain sea anemones and Scyphozoan jellyfish)
  • Mild to moderately painful puncture followed by onset of neurologic symptoms (eg, paresthesia, weakness) suggest neurotoxin envenomation by a cone snail
  • Relatively painless puncture followed by onset of neurologic symptoms (eg, paresthesia, weakness) suggest neurotoxin envenomation by a blue-ringed octopus or venomous sea snake
  • Immediate, intense pain, with rapid and significant localized reaction is typical of Scorpaenidae (eg, stonefish, scorpionfish, lionfish) and Trachinidae (weeverfish) puncture
  • Multiple punctures with minor to moderate burning pain with intensification over hours suggests sea urchin or crown-of-thorns starfish exposure; associated purple discoloration may or may not be present
  • Pain out of proportion to appearance of puncture wound or laceration on lower extremity may suggest stingray envenomation

Physical Examination

• Nonspecific findings can include localized contact eruptions (eg, wheal and flare reactions, urticarial lesions)
• Characteristic findings associated with contact with nematocysts
  • Whip-like tentacle marks may present as multiple erythematous linear markings; cross hatch pattern is characteristic of box jellyfish
  • Sudden onset of unexplained hypertension, tachycardia, and diaphoresis suggest Irukandji syndrome
  • Linear abrasions and lacerations associated with erythema, edema, urticaria, and vesicles suggest fire coral exposure; regional reactive lymphadenopathy often develops
  • Seabather’s eruption may present with multiple discrete erythematous macules and papules resembling multiple insect bites, often distributed in area covered by swimming apparel
  • Irukandji jellyfish stings may go unnoticed or present with discrete papules at sites of contact with individual organisms
• Characteristic findings associated with certain lacerations include
  • Gaping lower extremity wound, often bleeding, with dusky, cyanotic, blue wound edges may suggest traumatic stingray injury
• Characteristic findings associated with certain puncture wounds include
  • A single punctate ischemic site (eg, pallor, cyanosis), similar to a wasp sting, is typical of cone snail envenomation; neuromuscular paralysis may ensue
  • Multiple punctures with an erratic pattern with or without purple discoloration and occasional retained fragments indicate sea urchin injury
  • Ischemic puncture wound with surrounding red halo and significant swelling is typical of scorpionfish envenomation
  • Edema out of proportion to appearance of puncture wound may suggest stingray envenomation
  • Relatively painless puncture followed by onset of neuromuscular paralysis suggests a blue-ringed octopus bite
  • Fang marks accompanied by the onset of neurologic symptoms (eg, ptosis, bulbar palsy, ascending flaccid paralysis) suggest sea snake envenomation

Laboratory Tests

• Basic metabolic panel
  • May be indicated to assess for acute kidney injury and electrolyte abnormalities associated with rhabdomyolysis (eg, hyperkalemia) and acute kidney injury in patients with suspected sea snake envenomation
• Creatinine kinase
  • May be indicated to evaluate for development of rhabdomyolysis in patients with sea snake envenomation
• Urinalysis
  • May be indicated to evaluate for the development of rhabdomyolysis and acute kidney injury in patients with sea snake envenomation

Imaging Studies

• Maintain a low threshold for radiographic investigation to aid in identification and removal of retained spine and other material in marine puncture wounds; options include
  • Radiograph
    • Often initial study obtained
    • Very limited data suggest that radiographs may be the most sensitive imaging method to identify retained stingray barbs⁹
  • Ultrasonography
    • May aid in both identification and real-time removal
  • MRI and CT
    • CT and MRI are considered by most experts as the gold standards to detect foreign bodies in marine puncture wounds⁶
    • May be needed when wound exploration and other imaging modalities fail to identify suspected foreign bodies
    • Very limited data suggest that MRI may be the most specific imaging method to identify retained stingray barbs⁹

Diagnostic Procedures

• Compartment pressures
  • May rarely be necessary in patients with significant swelling after marine envenomation with clinical suspicion for compartment syndrome
  • May complicate stingray puncture wounds and trauma
• Surgical exploration
  • Deep or extensive puncture wounds require surgical debridement or spine extraction if not easily removed
  • Puncture wounds near joints or structures prone to serious infection may require surgical exploration and management
  • Deep puncture wounds to potentially vital structures involving the chest, abdomen, neck, and groin require evaluation in the operating room by trauma surgeons trained in management of penetrating thoracoabdominal injury

Diagnostic Tools

• ECG
  • May be indicated based on clinical picture to assess dysrhythmias/arrhythmias, hemodynamic instability (significant hypertension, hypotension), and suspected Irukandji syndrome⁸

Differential Diagnosis

Key Points

• Maintain awareness of regional marine animals responsible for potential envenomation and knowledge about management options, including how to obtain antivenom
• Envenomation is most common in regions where contact with humans is greatest, including coastal waters, and in temperate to tropical waters
• Patients at increased risk of severe envenomation include children, patients of advanced age, and patients with significant comorbidity
• Clinical presentation is species specific but, in general, marine organisms capable of envenomation deliver toxin by 3 primary mechanisms
  • Discharge of microscopic harpoon-like apparatuses from the cell wall (nematocyst) of specialized cells (ie, cnidocyte), often located on tentacles of jellyfish, anemones, and Portuguese man-of-war, and found on the surface of fire coral
  • Penetrating injury from venom-containing spine-like structures with or without barbs (eg, Echinodermata [sea urchins, sea stars]), fish of the Scorpaenidae family (eg, scorpion fish, stone fish, lionfish), fish of the Trachinidae family (eg, weeverfish), stingrays, and cone snails
  • Bites from the venomous beak of the blue-ringed octopus and fangs of venomous sea snakes
• Diagnosis is determined by clinical presentation (eg, characteristic wound, geographic region envenomation occurred, identification of animal) after exclusion of alternate cause (eg, trauma or nonvenomous bite)
  • Imaging (radiography, ultrasonography, MRI) may be indicated to assess for presence of retained foreign bodies (eg, spines, barbs) associated with some species, particularly when a retained foreign body is suspected despite thorough wound exploration
• Manage significant or potentially fatal envenomation in consultation with medical toxicologist and/or regional poison control center for additional diagnostic and management considerations
• Immediate transport for definitive care and observation is important in potentially fatal envenomation (eg, box jellyfish, Irukandji jellyfish, cone snail, blue-ringed octopus, venomous sea snake)
• Treatment of marine envenomation may be initiated based on nature of wound (eg, puncture from spines, rash from discharge of nematocysts) and region in which wound occurred, despite lack of identification of the specific marine animal responsible for envenomation. Table 2 summarizes preferred management options for most significant marine envenomations
• Decontamination is species specific but usually involves
  • Application of hot water. Effective for many marine toxins, as most toxins encountered in marine envenomation are heat labile; therefore, hot water is a reliable and effective neutralization technique in many instances and may diminish risk of further toxin release in some Cnidaria (North American jellyfish, fire coral) species
  • Application of acetic acid (vinegar). May minimize discharge of nematocysts from cnidocyte cells of certain Cnidaria species (eg, box jellyfish); however, use is controversial and may exacerbate pain in some species (Portuguese man-of-war, many North American species of Cnidaria)
  • Manual removal of tentacles and debris, and removal of toxin-containing spines and/or barbs
• Antivenom is available for severe stonefish reactions and envenomation by sea snakes and box jellyfish
• Pressure immobilization is used in attempt to minimize systemic absorption of some potentially fatal toxins (eg, cone snail, blue-ringed octopus, venomous sea snake)
• Other pertinent aspects of management include pain control, selective use of prophylactic antibiotics covering bacteria specific to marine environments (eg, ciprofloxacin, trimethoprim/sulfamethoxazole, doxycycline), meticulous wound care, and tetanus prophylaxis as indicated
• Prevention is important as many marine envenomations occur after improper handling or touching of marine life by snorkelers, scuba divers, shell collectors, or aquarium owners, and by unintentionally stepping on organisms on the ocean floor or underwater rocky surfaces

Alarm Signs and Symptoms

• Acute life-threatening envenomation may occur from box jellyfish, Irukandji jellyfish, stonefish, cone snails, blue-ring octopus, and sea snakes
  • Prepare for advanced supportive care following envenomation as many marine toxins may result in neurologic manifestations (eg, flaccid paralysis) and cardiopulmonary collapse
• Delayed wound healing and secondary wound infection are common
  • Carefully evaluate for retained material and foreign body in patients presenting with a secondary wound infection
  • Prescribe antibiotics for appropriate wounds that cover typical skin microbes (eg, Staphylococcus, Streptococcus) and well as pathogens prevalent in marine environments (eg, Vibrio species)
• Maintain awareness that an otherwise benign envenomation in a healthy adult may cause serious illness in patients at high risk for severe reactions
  • Children and the elderly, particularly those with significant comorbidity, are at higher risk for worse outcomes resulting from envenomation

Basic Information

Terminology

• Marine envenomation
  • Process by which venom or toxin is introduced via bite, sting, or puncture after contact with a marine animal
  • May be caused by both invertebrate and vertebrate organisms¹
    • Invertebrates include the phylum Cnidaria (jellyfish, Portuguese man-of-war, anemones, fire coral), Mollusca (snails and octopods), Echinodermata (sea stars, sea urchins), and Porifera (sponges)
    • Vertebrates include cartilaginous (Chondrichthyes) and bony fish (Osteichthyes), and sea snakes (family Elapidae, subfamilies hydrophiinae and laticaudinae)
• Irukandji syndrome
  • Syndrome of autonomic excess and severe pain that occurs following envenomation by one of several, highly venomous species of box jellyfish collectively referred to as Irukandji jellyfish (eg, Carukia barnesi, Malo kingi)²
  • Jellyfish species that may cause this reaction are notoriously tiny and contact with these organisms may go unnoticed or feel like an innocuous insect bite
  • May require large amounts of analgesia, sympatholytic, and vasodilator support
• Seabather’s eruption
  • Eruption caused by larval stages of certain Scyphozoan jellyfish and sea anemones
  • Usually develops minutes to hours after swimming and may last up to a couple of weeks³
  • Presents as discrete areas of skin irritation or papules resembling mosquito bites, usually in the distribution of covered areas of the body (larvae get trapped under bathing suit or wetsuit)³

Epidemiology

• Figure 1. Climate zones.

• Ubiquitous and worldwide distribution is characteristic of most marine fauna responsible for envenomations
• Concentration of some animals is characteristically higher in certain regions
  • Irukandji jellyfish is native to northern Australian seas
  • Crown-of-thorns sea star is mainly found in Indo-Pacific seas
  • Stone fish, scorpion fish, and lionfish (Scorpaenidae) are native to the Indo-Pacific seas
    • Lionfish were introduced to Caribbean Sea and Atlantic Ocean and have spread largely throughout the region
  • Weeverfish (Trachinidae) common in European and African seas
  • Blue-ringed octopus and sea snakes are indigenous to Indo-Pacific seas and do not inhabit Caribbean waters
• Most marine envenomations occur in tropical and subtropical seas, some occur in temperate climates, and few in polar regions (Figure 1)
• Envenomations are most common in regions where contact with humans is greatest including
  • Coastal waters
  • Temperate to tropical waters
• Envenomations may occur secondary to inadvertent or intentional contact with marine animals
  • Venom-containing marine creatures are not characteristically aggressive by nature and do not seek to harm humans

Etiology and Risk Factors

Etiology

• Figure 2. Invertebrate animals and characteristic identifying wounds: A-B, scyphozoan “true” jellyfish; C-D, hydrozoan (Portuguese man-of-war); E-F, anemone; G-H, box jellyfish; I-J, sea urchin; K-L, sea star; M, cone snail; N-O, blue-ringed octopus. P-Q, sea sponge.A, Photo credit: Dan90266. https://www.flickr.com/photos/dan90266/37269957/; B, Photo credit: Jmarchn. https://en.wikipedia.org/wiki/Jellyfish; D, From Dinulos J. Habif’s Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 7th edition. Elsevier Inc; 2021.; E, Photo credit: Nhobgood. https://en.wikipedia.org/wiki/Condylactis_gigantea; F, From Tsai H-S et al. Acute skin manifestation of sea anemone envenomation. J Emerg Med. 2021;60(4):536-537. https://doi.org/10.1016/j.jemermed.2020.11.025.; G, Photo credit: Guido Gautsch. https://en.wikipedia.org/wiki/Box_jellyfish; H, From Auerbach PS et al. Dermatological progression of a probable box jellyfish sting. Wilderness Environ Med. 2019;30(3):310-320.; I, https://en.wikipedia.org/wiki/Sea_urchin#/media/File:Paracentrotus_lividus_profil.JPG; J, Photo credit: Yugyug. https://en.wikipedia.org/wiki/Sea_urchin_injury#/media/File:Sea-urchin-injury.jpg; K, Photo credit: Jon Hanson. https://en.wikipedia.org/wiki/Crown-of-thorns_starfish#/media/File:Crown_of_Thorns-jonhanson.jpg; L, From Lakshmanan P et al. Management of crown-of-thorns starfish injury. Foot Ankle Surg. 2004;10(3):155-157.; M, From Favreau P et al. Marine snail venoms: use and trends in receptor and channel neuropharmacology. Curr Opin Pharmacol. 2009;9(5):594-601.; N, Photo credit: Jens Petersen. https://en.wikipedia.org/wiki/Blue-ringed_octopus#/media/File:Hapalochlaena_lunulata2.JPG; O, https://www.tandfonline.com/doi/pdf/10.1080/15563650701601790; P, Photo credit: Kirt L. Onthank. https://commons.wikimedia.org/wiki/File:Spongilla_lacustris.jpg; Q, From Isbister GK et al. Clinical effects of stings by sponges of the genus Tedania and review of sponge stings worldwide. Toxicon. 2005;46(7): 782-785, Figure 2.
• Figure 3. Vertebrate animals and characteristic identifying wounds: A-B, stingray; C-D, lionfish; E-G, stonefish; H-I, weeverfish; J-K, sea snake; L, scorpionfish.A, Photo credit: Barry Peters. https://commons.wikimedia.org/wiki/File:Southern_stingrays_at_stingray_city.jpg; B, Photo credit: Symac. https://en.wikipedia.org/wiki/Stingray_injury#/media/File:Stingray_injury.jpg; C, Photo credit: Jean-Marc Kuffer. https://www.flickr.com/photos/54452028@N00/192796211; D, From Hobday D et al. Denaturing the lionfish. Eplasty. 2016;16:ic20.; E, Photo credit: Karelj. https://commons.wikimedia.org/w/index.php?curid=19147608; F, From Isbister GK. Venomous fish stings in tropical northern Australia. Am J Emerg Med. 2001; 19(7):561-565.; G, From Dall GF et al. Severe sequelae after stonefish envenomation. Surgeon. 2006;4(6):384-385.; H, Photo credit: Hans Hillewaert. https://en.wikipedia.org/wiki/Lesser_weever; I, From Peters W et al (eds). Tropical Medicine and Parasitology. 5th ed. Mosby; 2002.; J, Photo credit: Jon Hanson. https://www.flickr.com/photos/jonhanson/90795890/; K, From Auerbach P et al. Auerbach’s Wilderness Medicine. 7th ed. Elsevier Inc; 2017, Figure 36-79.; L, Photo credit: Wilfried Berns. https://commons.wikimedia.org/wiki/File:Grosserdrachenkopf-02.jpg
• Venom delivery may occur through several mechanisms
  • Nematocyst delivery
    • Organisms of phylum Cnidaria may contain specialized cells called cnidocytes; phylum Cnidaria is divided into 4 primary groups (Figure 2)
      • Cubozoans: box jellyfish and Irukandji jellyfish
      • Scyphozoans: true jellyfish
      • Hydrozoans: Portuguese man-of-war, fire corals, and feather hydroids
      • Anthozoans: soft corals and anemones
    • Cnidocytes are frequently located on tentacles and each tentacle may contain thousands of cnidocytes
    • The specialized cell (ie, cnidocyte) contains a unique cell wall organelle called a nematocyst (cnidocyst) that is responsible for venom delivery into the dermis
    • Direct contact/physical pressure, osmolality changes, and chemical changes may trigger the nematocyst to discharge a microscopic harpoon-like barb coated with venom that then may penetrate victim or prey
  • Spines
    • Numerous marine organisms utilize spines to deliver venom (Figure 3)
      • Organisms of the phylum Echinodermata (eg, sea urchins, sea stars) may have spines resembling thin needles; spines are composed of calcium carbonate, do not have barbs, and notoriously break easily causing a retained foreign body in an apparent innocuous puncture wound
      • Cone snails of the Conus genus have a long flexible feeding tube (proboscis) that protrudes out of the head of the snail and contains a barbed, venom-containing, harpoon-like apparatus called a radula
      • Stingrays of the Chondrichthyes class have venom-containing retro-serrated barbed spines at the end of a long thin tail that may detach in the victim causing retained foreign bodies
      • Fish of the Scorpaenidae family (eg, scorpion fish, stone fish, lionfish) have venomous dorsal spines without barbs; venom release is usually triggered by pressure
      • Fish of the Trachinidae family (eg, weeverfish) also have venomous dorsal spines lacking barbs; venom release is usually triggered by pressure
      • Catfish (numerous species) typically inhabit fresh waters and have venomous spines; venom release is usually triggered by pressure⁴
  • Bites
    • Other marine animals inject venom via bites
      • Cephalopods of the Hapalochlaena genus (eg, blue-ringed octopus) inject venom via a bony beak
      • Venomous sea snakes of the Elpaidae family inject venom via fangs; human envenomation most often involves Beaked (E. schistosa) and Yellow-bellied sea snakes (Hydrophis platurus)⁵

Risk Factors

• Inadvertent contact with venomous marine life may occur when entering various marine ecosystems (eg, swimming or wading in an ocean, snorkeling and scuba diving, fishing)
• Intentional handling of marine organisms in the ocean or an aquarium
  • Shell collectors may be at increased risk for cone snail envenomation
  • Fisherman may be bitten by sea snakes or stung by fish containing venomous spines when caught on the reef and reeled into boat
• Risk factors for severe envenomation include
  • Pediatric age groups
  • Advanced age groups
  • Patients with significant comorbidity (eg, preexisting cardiac insufficiency, respiratory disease)
  • Envenomation occurring in the Indo-Pacific region, specifically in waters near Australia

Risk Models and Risk Scores

• Mild envenomation
  • Limited to pain and soft tissue symptoms at injection site
• Severe envenomation
  • Associated with systemic symptoms (eg, paralysis, coma, cardiorespiratory failure)

Diagnosis

Approach to Diagnosis

• Diagnosis is determined by clinical presentation (eg, characteristic wound, geographic region envenomation occurred, identification of animal) after exclusion of alternate causes (eg, trauma or nonvenomous bite, sting, puncture)
• Obtain radiographic studies (eg, radiographs, ultrasound, CT, MRI) to evaluate for retained foreign bodies when appropriate based on clinical scenario
  • Imaging is recommended for any significant marine puncture wound⁶
    • Initial imaging is typically radiography and/or ultrasonography to assess for foreign bodies⁷
    • CT or MRI is often useful when clinical suspicion remains high for foreign bodies not found on wound exploration or visible on initial studies⁶
  • Retained foreign bodies from the following marine animals are common
    • Spines from Scorpaenidae (eg, stonefish, scorpion fish, lionfish), Trachinidae (eg, weeverfish), sea urchin and crown-of-thorns sea star, stingray barbs
• Laboratory studies are not routinely indicated in the absence of systemic toxicity⁶
• Individualize additional specific ancillary testing based on clinical presentation
  • Obtain routine laboratory evaluations (eg, CBC, complete metabolic panel) in patients presenting with signs of systemic envenomation (eg, abnormal vital signs, respiratory distress, and neurologic manifestations)
  • Baseline testing (eg, creatine kinase, electrolytes, BUN/creatinine, urinalysis) to allow follow-up for development of acute kidney injury and rhabdomyolysis in patients with suspected sea snake envenomation
  • Indications to perform an ECG may include patients with arrhythmia/dysrhythmia, hemodynamic instability, and suspected Irukandji syndrome⁸
  • Measurement of compartment pressure with concern for compartment syndrome

Workup

History

• Venomous marine animal may or may not be seen when injury occurs
• Injuries sustained on lower extremity while wading are often the result of stonefish or scorpionfish, echinoderm (eg, sea star, sea urchin), or stingray envenomation
• Delayed presentation, rather than immediate development of symptoms, may occur with sea snake and blue-ringed octopus envenomation⁶
• Characteristic presentation patterns of certain envenomation include
  • Linear marks suggest exposure to nematocyst-covered tentacles
  • Immediate severe pain at site of rash followed by rapid progression to cardiopulmonary collapse may suggest box jellyfish envenomation
  • Delayed systemic manifestations (eg, sense of impending doom, diffuse severe pain, diffuse muscle spasms, cardiopulmonary collapse) within 30 minutes to 2 hours of minor or unnoticed sting(s) suggest Irukandji syndrome²
  • Immediate and intense local pain with scrapes, linear marks, lacerations, and/or patchy erythema suggests trauma from fire coral
  • Multiple pruritic, insect-bite–like lesions suggest seabather’s eruption (contact with larval forms of certain sea anemones and Scyphozoan jellyfish)
  • Mild to moderately painful puncture followed by onset of neurologic symptoms (eg, paresthesia, weakness) suggest neurotoxin envenomation by a cone snail
  • Relatively painless puncture followed by onset of neurologic symptoms (eg, paresthesia, weakness) suggest neurotoxin envenomation by a blue-ringed octopus or venomous sea snake
  • Immediate, intense pain, with rapid and significant localized reaction is typical of Scorpaenidae (eg, stonefish, scorpionfish, lionfish) and Trachinidae (weeverfish) puncture
  • Multiple punctures with minor to moderate burning pain with intensification over hours suggests sea urchin or crown-of-thorns starfish exposure; associated purple discoloration may or may not be present
  • Pain out of proportion to appearance of puncture wound or laceration on lower extremity may suggest stingray envenomation

Physical Examination

• Nonspecific findings can include localized contact eruptions (eg, wheal and flare reactions, urticarial lesions)
• Characteristic findings associated with contact with nematocysts
  • Whip-like tentacle marks may present as multiple erythematous linear markings; cross hatch pattern is characteristic of box jellyfish
  • Sudden onset of unexplained hypertension, tachycardia, and diaphoresis suggest Irukandji syndrome
  • Linear abrasions and lacerations associated with erythema, edema, urticaria, and vesicles suggest fire coral exposure; regional reactive lymphadenopathy often develops
  • Seabather’s eruption may present with multiple discrete erythematous macules and papules resembling multiple insect bites, often distributed in area covered by swimming apparel
  • Irukandji jellyfish stings may go unnoticed or present with discrete papules at sites of contact with individual organisms
• Characteristic findings associated with certain lacerations include
  • Gaping lower extremity wound, often bleeding, with dusky, cyanotic, blue wound edges may suggest traumatic stingray injury
• Characteristic findings associated with certain puncture wounds include
  • A single punctate ischemic site (eg, pallor, cyanosis), similar to a wasp sting, is typical of cone snail envenomation; neuromuscular paralysis may ensue
  • Multiple punctures with an erratic pattern with or without purple discoloration and occasional retained fragments indicate sea urchin injury
  • Ischemic puncture wound with surrounding red halo and significant swelling is typical of scorpionfish envenomation
  • Edema out of proportion to appearance of puncture wound may suggest stingray envenomation
  • Relatively painless puncture followed by onset of neuromuscular paralysis suggests a blue-ringed octopus bite
  • Fang marks accompanied by the onset of neurologic symptoms (eg, ptosis, bulbar palsy, ascending flaccid paralysis) suggest sea snake envenomation

Laboratory Tests

• Basic metabolic panel
  • May be indicated to assess for acute kidney injury and electrolyte abnormalities associated with rhabdomyolysis (eg, hyperkalemia) and acute kidney injury in patients with suspected sea snake envenomation
• Creatinine kinase
  • May be indicated to evaluate for development of rhabdomyolysis in patients with sea snake envenomation
• Urinalysis
  • May be indicated to evaluate for the development of rhabdomyolysis and acute kidney injury in patients with sea snake envenomation

Imaging Studies

• Maintain a low threshold for radiographic investigation to aid in identification and removal of retained spine and other material in marine puncture wounds; options include
  • Radiograph
    • Often initial study obtained
    • Very limited data suggest that radiographs may be the most sensitive imaging method to identify retained stingray barbs⁹
  • Ultrasonography
    • May aid in both identification and real-time removal
  • MRI and CT
    • CT and MRI are considered by most experts as the gold standards to detect foreign bodies in marine puncture wounds⁶
    • May be needed when wound exploration and other imaging modalities fail to identify suspected foreign bodies
    • Very limited data suggest that MRI may be the most specific imaging method to identify retained stingray barbs⁹

Diagnostic Procedures

• Compartment pressures
  • May rarely be necessary in patients with significant swelling after marine envenomation with clinical suspicion for compartment syndrome
  • May complicate stingray puncture wounds and trauma
• Surgical exploration
  • Deep or extensive puncture wounds require surgical debridement or spine extraction if not easily removed
  • Puncture wounds near joints or structures prone to serious infection may require surgical exploration and management
  • Deep puncture wounds to potentially vital structures involving the chest, abdomen, neck, and groin require evaluation in the operating room by trauma surgeons trained in management of penetrating thoracoabdominal injury

Diagnostic Tools

• ECG
  • May be indicated based on clinical picture to assess dysrhythmias/arrhythmias, hemodynamic instability (significant hypertension, hypotension), and suspected Irukandji syndrome⁸

Differential Diagnosis

Table 1. Differential Diagnosis: Clinical presentations that are similar to marine envenomations.

Condition	Description	Differentiated by
Dry bite	Bite of venomous sea snake, no venom delivered	Puncture wounds present with lack of development of systemic manifestations
Terrestrial snake bite	Envenomation by terrestrial snake that is swimming in the water	Without specimen (animal), it may be very difficult to clinically differentiate from sea snake envenomation Abnormal coagulation studies may suggest envenomation by a terrestrial snake
Decompression sickness	Diving injury (eg, decompression sickness, arterial gas embolism) can present similarly to some marine envenomation with rashes, cardiopulmonary collapse, paresthesia, paralysis, weakness, mental status changes, and syncope	Differentiation may be difficult and is often clinical according to history and presence or lack of bites or stings Decompression sickness is usually precipitated on ascent at the conclusion of a dive
Exacerbation of underlying comorbidity	Exacerbation of any number of underlying comorbid conditions may result in a presentation similar to a serious marine envenomation	Suspect based on individualized clinical presentation in patient with serious underlying comorbidity Differentiation depends on underlying condition
Trauma	Any trauma not involving marine envenomation (cut on coral or rock, without any toxin injection)	Local skin injury alone

Treatment

Approach to Treatment

• Significant trauma and severe envenomation
  • Follow established trauma protocols for significant trauma secondary to stinging apparatus
  • Follow established procedures for medical stabilization in severe envenomation
  • Involve a medical toxicologist and/or poison control center (1-800-222-1222 in the United States) early in management of severe and potentially life-threatening envenomation⁶
• General principles for envenomation associated with potentially fatal and serious reactions
  • Envenomation by cone snail, blue-ringed octopus, and venomous sea snake may be fatal and expedient management is required
    • Severe box jellyfish envenomation may be rapidly fatal in as little as 5 to 30 minutes²
    • Stonefish envenomation may be serious
  • Transport all patients for emergent definitive care when cone snail, blue-ringed octopus, and venomous sea snake bites are probable
    • Maintain a low threshold for transport of patients who have sustained box jellyfish and severe stonefish envenomation as definitive medical care may be required
  • Apply pressure immobilization of the affected area in effort to diminish systemic absorption of potentially fatal injected toxins
    • Recommended for bites of sea snakes, blue-ringed octopus, and cone snails
    • Pressure immobilization is NOT recommended in the cases of Cnidaria (eg, box jellyfish) envenomation and scorpionfish envenomation
  • Antivenom
    • Available for envenomation caused by box jellyfish, venomous sea snakes, and stonefish (not available for cone snail or blue-ringed octopus)
      • Early administration of antivenom is recommended for box jellyfish and sea snake envenomation
      • Antivenom is recommended for serious reactions associated with stonefish envenomation
    • Comprised of hyperimmune horse or sheep globulin, therefore, the potential for adverse effects is high
      • Premedicate with diphenhydramine, when possible
      • Monitor for adverse effects (eg, acute anaphylaxis, serum sickness) after use
    • Administer antivenom in consultation with a medical toxicologist whenever possible
  • Close medical observation for cardiopulmonary decompensation is recommended for a minimum of 6 to 8 hours following cone snail, blue-ringed octopus, and sea snake envenomation⁶²¹
  • Table 2 outlines management options for envenomation resulting from marine animals with the potential to cause serious and fatal envenomation
  • If sea snake antivenom is unavailable, Tiger snake antivenom can be used⁸
• General principles of treatment of marine animals that deliver toxin via spines (ie, puncture wounds)
  • Hot water immersion may help with pain
  • Consider infiltration of local anesthetic without epinephrine (0.5% bupivacaine, 1%-2% lidocaine) around wound⁷
  • Perform meticulous local wound care (eg, copious irrigation, cleaning, wound exploration) with attention to removal of any spines and residual foreign material
    • Real time ultrasound may help localize foreign bodies at the time of removal
  • Prophylactic antibiotics may be indicated for high-risk wounds (eg, large, deep, potential joint violation, contaminated)
    • Include coverage for Vibrio species as well as commonly encountered bacterial skin flora
  • Apply pressure immobilization for punctures at increased risk for serious envenomation (eg, cone snail, sea snake, blue-ringed octopus)
  • Table 2, section B, outlines management options for marine envenomation resulting from animals with spines
• General principles of treatment of marine animals that deliver toxin via nematocysts
  • Ensure that medical personnel use personal protective equipment (eg, double glove) to prevent contact with undischarged nematocysts
  • Avoid rubbing the area of envenomation to minimize discharge of still-active nematocysts¹⁰
  • Decontaminate to avoid any potential for further toxin exposure
    • Tentacles are coated with nematocysts. Without proper decontamination prior to tentacle removal, undischarged nematocysts may fire and expose medical personnel and patient to additional toxin
    • Controversy exists as to the best initial method to neutralize toxins and minimize discharge of nematocysts from cnidocyte cells, and preferred methods may differ among species (data are limited)¹⁷²⁵
      • Hot water immersion is preferred by many experts over acetic acid for many jellyfish stings, particularly North American jellyfish envenomation¹⁴¹⁵
        • Exceptions may include box jellyfish and Irukandji envenomation, as some experts recommend ice and acetic acid over hot water immersion²¹²
      • Consider application of acetic acid on a case-by-case basis¹⁴¹⁵
        • Acetic acid may irreversibly inhibit discharge of nematocysts from cnidocyte cells in certain species (eg, box jellyfish, certain species of scyphozoan jellyfish); in other species, some evidence exists that acetic acid may stimulate nematocyst discharge and worsen pain¹⁴
        • Many experts advocate avoidance of acetic acid application in Portuguese man-of-war envenomation⁶¹⁵
      • Hot water immersion versus application of ice packs is another general area lacking clear definitive recommendation
        • Limited data suggest that hot water immersion may have some advantages over ice packs for the treatment of envenomation by certain species of Cnidaria, particularly Portuguese man-of-war and most North American scyphozoan¹⁵¹⁶¹⁷
        • Cold is recommended first instead of heat for some stings, including from box and Irukandji jellyfish
      • Consensus does exist regarding avoidance of certain methods that most experts regard to worsen the discharge of nematocysts
        • Strategies that promote osmotic shifts or pressure changes will worsen the discharge of nematocysts and exacerbate symptoms²⁵
        • Avoid alcohol, methylated spirits, and fresh water¹³
        • Little evidence supports the use of urine/urea or meat tenderizer to diminish symptoms; most experts recommend avoidance of these strategies
  • Remove tentacles and any other foreign material
    • Wash off adherent tentacles with sea water or saline flush; avoid freshwater because freshwater can cause further release of venom from nematocysts
    • Manually remove tentacles with forceps or tweezers while using personal protective equipment (eg, gloves) or a barrier (towel)
      • Ensure prevention of secondary spread of toxins; any surfaces that come into direct contact with tentacles (eg, glove, towel) may become coated with nematocysts
    • Remove spicules from sponges and bristles from bristle worms (eg, fire worms) by applying and removing adhesive tape, rubber cement, commercial deep-cleaning strips for pores, or glue-soaked gauze (allow glues to dry before peeling back)⁷
    • Careful scraping of the skin with a razor blade, dull knife, or tongue blade may aid in the removal of remaining nematocysts
  • Hot water immersion
    • May denature heat-labile toxins and aid in pain control with certain envenomation (eg, Portuguese man-of-war, some common jellyfish); role in box jelly envenomation is less clear, although appears to be somewhat effective²⁶²⁶
  • Local care
    • Provide basic wound care: clean with soap and water, apply bandage or dressing
  • Table 2, section A, outlines management options for marine envenomation resulting from animals with nematocysts
• Additional general management considerations
  • Pain control
    • Hot water immersion may be an effective pain relief technique for some marine envenomations, particularly those caused by venom delivered by some organisms with nematocysts (eg, North American scyphozoans [jellyfish], Portuguese man-of-war, fire coral) and venom delivered by spines (eg, stonefish, scorpionfish, lionfish, sea urchins, crown-of-thorns sea star, stingrays)
    • Use topical or local anesthetic infiltration or regional nerve blocks with lidocaine/bupivacaine without epinephrine as clinically indicated for intractable pain
      • Do not use anesthetic prior to hot-water immersion, as it may lead to thermal injury
      • Maintain care in the dosing of pediatric patients; exact dosages depend on formulation used
    • Oral options include acetaminophen and NSAIDs; opioids may be needed in select instances
    • Fentanyl may be the preferred parenteral opioid, given the absence of histamine effects and relative hemodynamic stability compared with other opioids⁶
  • Prophylactic antibiotics
    • Indications may include
      • Large lacerations or gaping wounds, deep punctures, wounds closely approximated to joints, and wounds at high risk for retained foreign body²⁷
      • Any significant wound or puncture in an immunocompromised patient⁷
    • Preferred prophylactic antibiotics cover typical skin bacterial flora (eg, Staphylococcus, Streptococcus) and microbes specific to marine ecosystem (eg, Vibrio species)
    • Recommended empiric options typically include either ciprofloxacin, trimethoprim/sulfamethoxazole, or doxycycline
  • Tetanus prophylaxis
    • Update tetanus prophylaxis as per established guidelines²⁸
    • Likelihood of tetanus exposure in a marine environment is much less than in a terrestrial environment in wounds contaminated with soil²⁷
  • Corticosteroids
    • Topical mild to moderate potency formulations are commonly used for mild to moderate local skin inflammatory reactions, eczematous, and indolent eruptions⁷¹²
    • Indications for systemic dosing of corticosteroids may include
      • Severe Cnidaria (eg, fire coral, Portuguese man-of-war) reactions
      • Severe local inflammation
      • Acute allergic reactions and antivenom treatment complications (eg, anaphylaxis, serum sickness)

Drug Therapy

• Prophylactic and empiric antibiotics for marine wounds
  • Trimethoprim/sulfamethoxazole is favored over ciprofloxacin and doxycycline in children due to undesirable side effects²⁹
  • Trimethoprim/sulfamethoxazole
    • Adult dose: 160/800 mg PO twice daily for 5 to 7 days⁷¹²²⁹
    • Child dose: 8 to 12 mg/kg/day of trimethoprim component PO divided twice daily for 3 to 5 days.⁷ Maximum daily dose of trimethoprim component is 160 mg
  • Ciprofloxacin
    • Adult dose: 500 mg PO twice daily for 3 to 5 days⁷¹²
    • Child dose: 20 to 40 mg/kg/day PO divided twice daily for 3 to 5 days. Maximum daily dose is 1.5 g³⁰
  • Doxycycline
    • Adult dose: 100 mg PO twice daily for 3 to 5 days⁷¹²
    • Child (8 years and older) dose: 4.4 mg/kg/day PO divided twice daily for 3 to 5 days. Maximum daily dose is 200 mg³⁰
• Corticosteroids
  • Prednisone (or equivalent corticosteroid)
    • Adult dose: 60 to 100 mg PO daily with a gradual taper over 10 to 14 days¹²
    • Child dose: 2 to 5 mg/kg/dose PO daily with a gradual taper over 10 to 14 days.¹² Maximum daily dose is 50 mg
• Antivenom⁸³¹
  • Anaphylaxis prevention measures
    • Slow administration (1 vial over a minimum of 5 minutes) of antivenom is recommended³²
    • Premedicate with IV or IM diphenhydramine, when possible; however, studies have shown little effect in reducing adverse reactions using antihistamines alone³³
      • Diphenhydramine dosing
        • Adult dose: 50 to 100 mg IV/IM
        • Child dose: 1 mg/kg/dose IV/IM. Maximum dose is 50 mg per dose
    • Keep epinephrine at bedside during antivenom administration in case an urgent need for use arises⁶
  • Antivenom dosing is not weight-based
    • Intent is to neutralize the venom introduced into the patient (which is not changed by the weight of the patient)
  • Box jellyfish antivenom
    • Available only in Australia; some experts consider its benefit to be questionable
    • Indications for use include severe refractory pain, cardiovascular collapse, and severe systemic effects (eg, respiratory distress, mental status changes, arrhythmias, cardiogenic shock)⁶
      • Dosing: one vial delivered intravenously/intraosseously over 5 minutes or 3 vials delivered intramuscularly at 3 different injection sites. Repeat as necessary every 10 minutes up to 3 times, then every 2 to 4 hours until progression of systemic manifestations ceases¹²
      • Continued cardiopulmonary resuscitation efforts are recommended until administration of at least 6 vials of antivenom⁶
  • Sea snake antivenom
    • Indications for use include first clinical sign or symptom of envenomation⁶
    • Dosing: initial dose 1 to 3 vials; up to 10 vials may be required¹²
  • Stonefish antivenom
    • Indications for use include severe pain recalcitrant to standard analgesic measures, presence of systemic effects, and severe local reaction²⁶¹⁸
    • Dosing: one vial delivered intravenously or intramuscularly to neutralize one or two significant punctures; repeat once for recurrent pain or serious systemic effects¹²

Nondrug and Supportive Care

• Care at site of envenomation
  • Avoid handling creatures at the scene of envenomation because they may still pose a risk of danger even when not alive
  • Do not rinse envenomation wounds by an animal with nematocysts with fresh water; fresh water may cause unfired nematocysts to discharge
• Acetic acid application
  • May stabilize any unfired nematocysts remaining on the skin
  • May be recommended in certain regions, especially Indo-Pacific regions, for Cnidaria envenomation
  • However, use is controversial for Portuguese man-of-war and certain species of North American Cnidaria; many experts discourage its use after Portuguese man-of-war exposure, owing to concern for further nematocyst discharge⁶
• Hot water immersion
  • May denature and inactivate heat-labile toxins (ie, thermolysis) and aid in pain control
  • Data suggest benefit with Portuguese man-of-war¹⁶ and likely beneficial for most Cnidaria envenomation (eg, common/minor jellyfish, fire coral envenomation);¹⁴ however, the role of hot water in box jelly envenomation is less clear²
    • Many experts favor the use of hot water immersion for box jellyfish envenomation due to some anecdotal evidence supporting efficacy and low risk of harm
  • Indicated for venomous fish puncture wounds, echinoderm wounds, and stingray injuries²
  • Procedure involves submersion of the affected area in hot water to tolerance (maximum 45 °C) for 30 to 90 minutes or as needed for pain relief²
  • Testing of hot water on contralateral unaffected area of skin is prudent to avoid inadvertent scalding²⁷
• Ice
  • Application of ice is recommended by some experts instead of hot water immersion for box jellyfish envenomation²
• Pressure immobilization
  • Used for envenomation with potential for serious morbidity and mortality (eg, cone snail, blue-ringed octopus, venomous sea snake)
    • Pressure immobilization is not recommended for use with box jellyfish envenomation or other Cnidaria stings,¹³ and is not typically recommended for venomous fish stings
  • Intent is to prevent rapid systemic dissemination of toxin before antivenom can be administered
  • Involves application of elastic bandage with wide margin over the envenomation site at venous-lymphatic occlusive pressure followed by immobilization of extremity³⁴

Treatment Procedures

• Deep puncture wounds to thoracoabdominal, neck, and groin regions
  • Stabilize any visible foreign body in any potentially vital anatomic location
  • Further evaluation, foreign body removal, and definitive treatment are indicated in the operating suite by a trauma surgeon
• Puncture wounds involving barbs and spines
  • Wound care requires meticulous exploration and copious irrigation
  • Remove any foreign body or material found in the wound
  • Imaging (radiographs, ultrasonography, MRI) may help locate foreign bodies and aid in retrieval
  • Sea urchin spines
    • Spines are extremely brittle and may crack and crumble with attempts at removal
    • Vigilant attention to the removal of spines adjacent to joints or tendons is prudent; however, thin retained fragments that are not associated with symptoms are often resorbed or extruded. Many experts suggest a reasonable approach is to observe closely on prophylactic antibiotics when thin spines cannot be successfully removed, or when removal proves to be impractical⁷
    • Note that discoloration in puncture may indicate retained dye without residual spine; discoloration usually resolves in 1 to 2 days in the absence of retained spine¹²
    • Delayed removal may be necessary if self-extrusion does not occur and granuloma formation develops despite prudent local care (eg, daily soaks with Epsom salt or vinegar)³⁵
• Deep puncture wounds of hands and feet
  • May require surgical exploration in consultation with a clinician with experience in management of such wounds
• Lacerations involving venomous marine organisms
  • Avoid suturing, when possible, in lieu of secondary intention or delayed primary closure due to risk of infection⁷
  • Carefully observe wound for ulceration, necrosis, and secondary wound infection with or without retained foreign body

Admission Criteria

• Standard trauma and toxicologic emergency admission criteria apply and include patients who present with any of the following:
  • Significant penetrating thoracoabdominal, neck, and groin wounds³⁶
  • A need for cardiopulmonary support
  • Requirement for antivenom administration
  • Envenomation by any sea snake, due to the need to monitor for progressive and delayed neurotoxicity⁸
  • Systemic toxicity (eg, persistent vital sign abnormalities, laboratory abnormalities, clinical distress)⁶
  • Severe, persistent, or worsening manifestations⁸
  • A need for pain control, particularly with Irukandji syndrome²

Special Considerations

Seabather’s Eruption

• Wash with soap and water, apply vinegar, and perform local care³
• Topical steroid cream may help with symptomatic care and diminish the inflammatory reaction
• Launder swimsuit with hot water and detergent then dry with heat (machine or sun)

Follow-up

Monitoring

• Potentially fatal envenomation
  • Monitor patients following cone snail, blue-ringed octopus, and sea snake envenomation in an emergency or inpatient setting with close observation for cardiopulmonary decompensation for a minimum of 6 to 8 hours⁶²¹
  • Discharge is appropriate if pain is controlled and patient is asymptomatic⁶
• Sea snake envenomation
  • Individualize monitoring for development of rhabdomyolysis (creatinine kinase, electrolytes) and acute kidney injury (urine output, BUN and creatinine, urinalysis) in patients with sea snake envenomation
• Irukandji syndrome
  • Individualize cardiac monitoring and assess for myocardial injury (eg, EKG changes, elevated troponins), when clinically indicated, in patients with Irukandji syndrome²
• Antivenom requirement
  • Monitor patients clinically for complications associated with the use of antivenom (eg, acute anaphylaxis, serum sickness)
  • Follow up to evaluate for any signs of serum sickness is recommended within 1 week⁶
• Wound checks
  • Wounds require close follow-up and observation. Secondary wound infection is common, and the development of ulcerations, worsening pain, and necrosis may require specific and individualized treatment
  • Most experts recommend wound reevaluation following significant marine wounds in 1 to 3 days with further individualized periodic assessments until healed⁶⁷²⁷

Complications

• Wound complications
  • Wound infection
    • May develop, particularly with penetrating injuries from spines, necessitating meticulous wound care and antibiotics covering both typical skin microbes (eg, Staphylococcus, Streptococcus) and marine organisms (Vibrio species)
    • Other bacteria known to inoculate marine wounds include Erysipelothrix rhusiopathiae and Mycobacterium marinarum⁷
      • Mycobacterium marinarum infection tends to be delayed and may occur with increased frequency in immunocompromised patients; usually presents as a nonhealing granulating wound
    • Vibrio parahaemolyticus and Vibrio vulnificus are characteristically responsible for rapidly progressive cellulitis and myositis⁷
    • Risk for wound infection is increased for unclean/contaminated, larger, and deeper wounds
    • Recommended oral empiric antibiotic options for infected wounds include ciprofloxacin, trimethoprim/sulfamethoxazole, or doxycycline for 7 to 14 days; parenteral options include ceftazidime, gentamicin, ciprofloxacin, ceftriaxone, cefuroxime, and cefoperazone (available outside of the US)⁷
    • Maintain a low threshold to assess for retained foreign body or material; evaluation may include
      • Wound exploration, debridement, and copious irrigation
      • Imaging (eg, radiographs, ultrasonography, MRI/CT)
    • Aerobic and anaerobic wound culture with susceptibilities; notify the laboratory of the intent to identify potential marine pathogens (adjustments, such as adding NaCl to the culture medium, may be necessary)⁷
  • Delayed wound healing and granuloma formation
    • Marine wounds are notorious for delayed wound healing and granuloma formation
    • Risk for delayed wound healing is increased in the presence of microscopic retained foreign bodies and with puncture wounds secondary to dermonecrotic effects of the venom
  • Post inflammatory hyperpigmentation
    • May develop following injury caused by discharge of nematocysts
    • Advise sun avoidance and liberal use of sunscreen to help prevent hyperpigmentation⁷
• Allergic and anaphylactic reactions
  • May occur following any marine envenomation, particularly among patients with previous sensitization to venom antigens (ie, second or subsequent exposure to the same or similar venomous toxin)⁶
    • Acute anaphylactic reactions (most described with Portuguese man-of-war stings) with deaths have been reported
  • Treat in standard fashion based on established guidelines (eg, antihistamines, corticosteroids, epinephrine, IV fluids)
• Antivenom adverse effects
  • Anaphylaxis
    • Hyperimmune globulin is a biological product (IgG) derived from animal (eg, sheep, horse) serum; therefore, the risk of anaphylaxis with administration is estimated between 2.4% and 11%³⁷
    • Onset of manifestations (eg, urticaria, vomiting, facial and airway edema, bronchospasm, hypotension) typically occur within 15 to 30 minutes of administration and may occur up to 6 hours following administration³²
    • Slow administration of antivenom (maximum rate of 1 vial over 5 minutes) and pretreatment with diphenhydramine may blunt anaphylactic reactions³²
    • Epinephrine infusion along with continued extremely slow administration of antivenom (in 0.1-0.2 mL aliquots) is recommended in patients with anaphylaxis secondary to antivenom¹²
  • Serum sickness
    • Results from the formation of IgG antibodies in response to antigens in the antivenom. This leads to the deposition of immune complexes, which triggers increased vascular permeability, complement activation, mast cells degranulation, and proteolytic enzyme release
    • Presents clinically within 8 to 24 days as fever, rash, arthralgias, joint swelling, and lymphadenopathy³⁸
    • May develop in up to 24% of patients following antivenom administration³⁷
    • Management often involves systemic corticosteroids until symptoms resolve, followed by a 2-week taper¹²
• Box jellyfish delayed sensitivity reaction
  • Delayed hypersensitivity rash may develop within 2 weeks of envenomation³⁶
  • Manage with topical corticosteroids³⁶
• Death
  • Box jellyfish and Irukandji jellyfish
    • Both Chironex fleckeri (Australian box jellyfish) and Carukia barnesi (Irukandji jellyfish) have been documented to cause deaths in Australian waters³⁶
    • There have been 79 deaths attributed to C. fleckeri since first report in 1883 and 2 deaths attributed to C. barnesi. Children account for the last 10 deaths reported in the Australian Northern Territories³⁹
  • Cone snail
    • There have been 36 confirmed human deaths, although the actual number is likely much higher⁴⁰
  • Stonefish
    • Thought to be the cause of several deaths in the Indo-Pacific region; however, no deaths in Australia have been documented since antivenom became available decades ago
  • Blue-ringed octopus
    • Only a handful of confirmed deaths are known as documented in Australia and Singapore
  • Venomous sea snake
    • The overall death rate is 3%, but mortality is up to 25% in severe envenomation¹²
  • Stingray
    • There have been at least 17 reported deaths worldwide, including in New Zealand, Texas, California, Fiji, and Australia⁴¹
    • Most deaths were attributed to penetrating trunk injury

Prognosis

• The majority of marine envenomations are mild resulting in contact dermatitis or small puncture wound
  • Expedient recovery is typical with minimal to no intervention²
• Severe envenomation
  • A rare occurrence, but when severe envenomation does occur, survival is typical with supportive care alone

Referral

• Indications for immediate transport for definitive medical care and observation include envenomation by the following sea animals/conditions
  • Concern for severe or anaphylactic reaction
  • Deep puncture wounds near vital structures (eg, potential for joint violation or bone involvement) or significant penetrating trauma, especially to the thoracoabdominal region
  • Stonefish envenomation associated with systemic symptoms or severe pain
  • Box jellyfish or concern for Irukandji syndrome
  • Cone snail envenomation
  • Blue-ringed octopus envenomation
  • Sea snake envenomation
• Significant envenomation
  • Manage in consultation with medical toxicologist and/or regional poison control center for additional diagnostic and management considerations
• Penetrating trauma to thoracoabdominal, groin, or neck region
  • Manage any significant or deep penetrating wounds and/or potential foreign bodies involving vital structures (eg, thorax, abdomen, groin, neck) in consultation with trauma surgeon
• Orthopedic trauma
  • Manage any puncture or foreign body potentially involving bone or joint in consultation with orthopedic surgeon

Screening and Prevention

Prevention

• Recommend the following basic preventative measures
  • Avoid touching or interacting with marine fauna and reef ecosystem while swimming, snorkeling, diving, fishing, or shell collecting
  • Avoid touching, standing, or walking on the ocean floor, rocky surfaces, and reef
  • Wear protective gear that covers all exposed skin while in the ocean
  • Avoid swimming and bathing in areas where dangerous jellyfish are found

Author Affiliations

Tyler Willing, DO
Medical Toxicology Fellow and Emergency Medicine Physician
Emergency Medicine
Medical Toxicology
Lehigh Valley Health Network

Andrew Koons, DO
Emergency Medicine Physician and Medical Toxicologist
Emergency Medicine
Medical Toxicology
Lehigh Valley Health Network

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