Marine animal bites

Some marine animal bites are venomous; all bites produce wounds with a high risk of infection by marine microorganisms, especially Vibrio, Aeromonas species, and Mycobacterium marinum. Shark bites produce jagged, lacerated wounds, with partial or complete amputations of limbs, requiring the same treatment as other major trauma.

[ 1 ], [ 2 ], [ 3 ]

Cnidaria (coelenterates)

Cnidaria—corals, sea anemones, jellyfish (including stinging jellyfish), and hydroids (such as the Portuguese man-of-war)—cause more poisonings than any other marine animal. However, of the 9,000 species, only about 100 fish are poisonous to humans. Cnidaria have multiple, highly developed stinging structures on their tentacles (stinging cells) that can penetrate human skin; upon contact, a single tentacle can launch thousands of stinging cells into the skin.

Different species of Cnidaria have different lesions. Typically, lesions initially appear as small linear papular eruptions that rapidly coalesce into one or more discontinuous lines, occasionally surrounded by a raised area of hyperemia. Pain is immediate and may be severe; itching is common. Papules may enlarge, suppurate, bleed, and scaly. Systemic manifestations include general weakness, nausea, headache, muscle pain and spasms, lacrimation and rhinitis, increased sweating, pulse changes, and pleuritic pain.

In North American waters, the Portuguese man-of-war has caused several fatalities. In the Indian and Pacific Oceans, the most dangerous and also causing several fatalities are members of the Cubomedusae order, especially the sea wasp Chironex fleckeri) and the box jellyfish Chiropsalmus quadrigatus).

To stop the burning sensation caused by the stinging cells, vinegar and baking soda in a 50:50 ratio are applied to the sting of box jellyfish and Portuguese man-of-war. Fresh water can activate undischarged stinging cells. The tentacles should be removed immediately using forceps or by removing them with a double-gloved hand. Treatment is supportive. Minor burns can be treated with NSAIDs or other analgesics; opioid analgesics are used for severe pain. Painful muscle spasms can be relieved with benzodiazepines. Intravenous fluids and epinephrine can be used as initial empirical treatment for shock. Antidotes are available for C. fleckeri and box jellyfish stings, but they are ineffective against the North American species.

Swimmer's eruption is a burning, itchy, maculopapular rash that affects swimmers in some Atlantic regions (e.g., Florida, Caribbean, Long Island). The rash is caused by the bite of the larvae of the sea anemone Edwardsiella lineata. The rash usually appears in areas where swimwear presses against the skin. Symptoms disappear when the larvae are washed off.

[ 4 ], [ 5 ]

Stingrays

In the past, stingrays were responsible for about 750 stings per year along the North American coast; current statistics are unknown, and most cases go unreported. The venom is contained in one or more spines on the dorsal side of the animal's tail. Injuries usually occur when an unwary swimmer walking along the bay bottom steps on a ray buried in the sand, causing the animal to lift its tail up and forward and drive a dorsal spine (or spines) into the victim's foot or leg. The spines' integumentary sheaths rupture, releasing the venom into the victim's tissues, causing immediate, intense pain. Although the pain is often limited to the injured area, it can escalate rapidly, reaching its greatest intensity after about 90 minutes. In most cases, the pain gradually diminishes over 6 to 48 hours, but may occasionally persist for days or weeks. Fainting, general weakness, nausea and restlessness are characteristic and may be partly due to peripheral vasodilation. Lymphangitis, vomiting, diarrhoea, sweating, generalised cramps, inguinal or axillary pain and respiratory distress have been reported. The wound is usually ragged, lacerated, bleeds profusely and is often contaminated with integumentary membranes. The wound edges are often discoloured and localised tissue destruction is likely to occur in several areas. There is some swelling. Open wounds become easily infected. Lesions of the extremities should be flushed with salt water. An attempt should be made to remove integumentary membranes if visible in the wound. The extremity should be immersed in water for 30 to 90 minutes (as hot as the patient can tolerate without developing a burn) to inactivate the venom. The wound should be re-examined for membrane remnants and cleaned, under local anaesthesia if necessary. In case of injuries to the torso, a thorough examination is necessary to exclude puncture of internal organs. Treatment is symptomatic. Tetanus prophylaxis is necessary, the injured limb should be elevated for several days. Antibiotic therapy and surgical closure of the wound may be required.

Mollusks

Mollusks include cones (including cone snails), octopuses, and bivalves. Conus californicus is the only known dangerous cone in North American waters. Its sting causes local pain, swelling, redness, and numbness that rarely progress to shock. Treatment is generally symptomatic. Local treatment plays a minor role, with local injections of epinephrine and neostigmine methyl sulfate unsupported. Severe Conus stings may require mechanical ventilation and antishock measures.

Cone snails are a rare cause of poisoning of divers and shell collectors in the Indian and Pacific Oceans. The snail injects venom through a harpoon-like tooth when suddenly disturbed (such as when cleaning a shell or being placed in a bag). The venom contains multiple neurotoxins that block ion channels and neurotransmitter receptors, causing paralysis that is usually reversible but has been fatal. Treatment is symptomatic and includes local immobilization with a pressure bandage, hot water immersion, and tetanus prophylaxis. In severe cases, respiratory support may be required.

Bites from the North American octopus are rarely serious. Bites from the blue-ringed octopus, more common in Australian waters, cause tetrodotoxin intoxication with localized sensory loss, neuromuscular paralysis, and respiratory failure. Treatment is symptomatic.

Sea urchins

Most injuries caused by sea urchins occur when the spines remain embedded in the skin, causing local skin reactions. Without treatment, the spines may migrate into deeper tissues, forming granulomatous nodules, or they may become embedded in bone or nerve. Muscle and joint pain and dermatitis may occur. A few sea urchins (e.g., Globiferous pedicellariae) have venomous organs with calcareous jaws that can penetrate human skin, but they rarely cause serious injury.

The diagnosis is usually obvious from the history. A bluish discoloration at the entry site may help locate the spines. If they cannot be visualized, radiographs are taken. Treatment consists of immediate removal of the spines. Vinegar dissolves most superficial spines; soaking the wound in vinegar several times a day, applying a wet vinegar compress, or a combination of both is usually sufficient. Sometimes a small incision must be made to extract the spine. Care must be taken because the spine is very fragile. A spine that has migrated deeper into the tissue is removed surgically. After the spines are removed, pain may persist for many days; persistence of pain for more than 5 to 7 days should raise suspicion of infection or a retained foreign body.

G. pedicellariae bites are treated by washing with menthol balm.