10.22 Marine envenomations

agk’s Library of Common Simple Emergencies

Presentation

After swimming in the ocean and coming into contact with marine life, the patient may seek medical attention because of local pain or swelling or skin discoloration. Marine animal envenomations can be divided into two major categories: puncture wounds and focal rashes. Severe envenomations can be accompanied by systemic symptoms like vomiting, paralysis, seizures, respiratory distress and hypotension, but this review is limited to the more common local injuries.

• Puncture wounds:
  • A laceration of the leg with blue edges suggests a stingray attack. There is immediate, local, intense pain, edema of soft tissue, and a variable amount of bleeding. The pain peaks after 30 to 60 minutes, may radiate centrally, and may last 48 hours.
  • A single ischemic puncture wound with a red halo and rapid swelling suggests a scorpionfish envenomation. The pain is immediate, intense and radiating. Untreated, the pain peaks 60 to 90 minutes after the sting, persists for at least 6 to 12 hours, and sometimes for days.
  • Multiple punctures in an erratic pattern with or without purple discoloration or retained fragments are typical of a sea urchin sting. The venomous spines can innflict immediate and intense burning pain with severe muscle aching. The area surrounding the puncture wounds may be red and swollen.
• Focal rashes:
  • Contact with a bristleworm is followed by an intense red, itchy rash.
  • Contact with feather hydroids and sea anemones induce a mild reaction, consisting of instantaneous burning, itching and urticaria. The reaction may be delayed and can include the appearance of papules, hemorrhagic vesicles or zoster-like reactions 4 to 12 hours after contact.
  • The sting of the fire coral induces intense burning pain, with central radiation and reactive regional lymphadenopathy.
  • Most of the jellyfish with suspended tentacles create “tentacle prints” or a whip-like pattern of darkened reddish brown, purple or frosted and cross-hatched stripes in the precise areas of skin contact. Vesiculation and skin necrosis may follow.

What to do:

• Puncture wounds:
  • To relieve pain and perhaps attenuate some of the thermolabile protein components of the venom, soak the wound in hot (not scalding) water (approximately 45 degrees C or 113 degrees F) for 30 to 90 minutes or longer is required for pain control.
  • During hot water treatment, infiltrate into or around the wound with 0.5% bupivacaine or 1% or 2% lidocaine without epinephrine to provide further pain control. When necessary, add narcotic analgesics.
  • Irrigate the wound as soon as possible with normal saline or dilute 1% povidone-iodine solution (add 10% Betadine to 0.9% NaCl in a 1:10 ratio) and remove visible pieces of spine or debris.
  • Obtain x rays if there might be any radio-opaque fragments like sea urchin spines retained.
  • When anesthesia is complete and pain has been controlled, then thoroughly explore, debride and irrigate open wounds. Remove fragile sea urchin spines using the technique for superficial sliver.
  • Suture lacerations loosely or, better, pack open for delayed primary closure.
  • Ensure current tetanus prophylaxis.
  • Prescribe prophylactic antibiotics except for minor abrasions, superficial punctures and superficial lacerations. Ciprofloxacin 500 mg bid x 3-5 days for adults or trimethoprim-sulfamethoxazole are most appropriate for coverage of pathogenic marine microbes. The genus Vibrio is particularly common in the ocean and poses a serious risk for immunosuppressed patients. Injuries with potential for serious infection include large lacerations, deep puncture wounds (particularly near joints) and retained foreign material. Recomended initial parenteral antibiotics include cefoperazone, cefotaxime, ceftazidime, chloramphenicol, gentamycin and tobramycin.
  • For infected wounds obtain both aerobic and anaerobic cultures, and alert the clinical microbiology laboratory that standard antimicrobial susceptibiliy testing media may need to be supplemented with NaCl to permit growth of marine bacteria. Institute the above antibiotics except for minor wound infections with the classic appearance of erysipelas, which can be treated with erythromycin or cephalexin. Prescribe antibiotics for 7-14 days.
  • Follow up all wounds in 1-2 days with periodic revisits until healing is complete.
• Focal rashes:
  • For fire coral, jellyfish, hydroid or sea anemone stings, decontaminate the area with a liberal soaking of 5% acetic acid (vinegar). The leading alternative is 40-70% isopropyl (rubbing) alcohol. Apply continuously for 30 minutes or until the pain disappears.
  • After decontamination, remove any visible large tentacles with forceps or doubly-gloved hands. Remove small particles by applying shaving foam or some equivalent and gently shaving the area with a safety razor, dull knife or plastic card, then clean with an antibacterial soap and flush with water or saline solution.
  • Treat any generalized allergic reactions with antihistamines, corticosteroids and epinephrine.
  • When irritation from sponges, bristle worms or other marine creatures cause erythematous or urticarial eruptions, it usually means tiny spicules and spinules are embedded in the skin. Dry the skin and apply the sticky side of a piece of adhesive tape to the affected area and peel the tape back to remove these particles.
  • Residual inflamation can be treated with topical corticosteroids like Aristocort A 0.1% or 0.5% cream or Topicort emollient cream or ointment 0.25% (dispense 15 grams and apply tid-qid). A topical steroid in combination with a topical anesthetic can be additionally soothing (eg Pramosone cream, lotion or ointment 2.5% or Zone-a-cream 1% tid-qid).
  • Check wounds for infection in two and seven days.

What not to do:

• Do not use fresh water to decontaminate jellyfish stings. It may cause microscopic cysts to swell and rupture and trigger additional stinging.
• Do not use topical or systemic corticosteroids for puncture wounds unless there is an allergic reaction.
• Do not constrict limbs tightly.

Discussion

Any wound acquired in the marine environment can become infected, and this is particularly likely if the wound is large, a puncture, or contaminated with bottom sediment or organic matter.

Stingray victims are generally innocent beach walkers who step on the back of the ray, which reflexively strikes upward with its tail, inflicting a penetrating wound along the upper foot, ankle, or lower leg. The anatomical structure of the stingray’s back causes a deep, jagged, painful wound that may contain fragments of barb located proximal to the tail.

Scorpionfish, lionfish and stonefish stings occur in divers and fishermen, and sometimes keepers of marine aquariums or those involved in illegal tropical fish trade. Catfish stings are common when the fish are handled or kicked. Certain catfish species produce a venom in glands at the base of the dorsal spine, but most do not, and catfish venom causes only mild local pain, redness and swelling. Of more concern is the wound caused by the spine and the likelihood of infection.

Sea urchin victims are stung when the step on, handle, or brush up against these sessile creatures. The sea urchin secretes a toxin on the surface of its spines, which is transferred into the wound when they penetrate the skin. The brittle spines also tend to break off and remain in the wound.

References:

• Auerback PS: Marine env envenomation. N Eng J Med 1991;325:486-493.

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