The population growth along coastal areas has made exposure to hazardous marine fauna increasingly common. The popularity of home aquariums generates additional exposures inland. Marine fauna can inflict injury through direct traumatic bite or envenomation, usually via a stinging apparatus.
Marine trauma includes bites from sharks, barracudas, moray eels, seals, crocodiles, needlefish, wahoos, piranhas, and trigger fish. Shark bites may also cause substantial tissue loss with hemorrhagic shock and delayed infection. Minor trauma is usually due to cuts and scrapes from coral that can cause local stinging pain, erythema, urticaria, and pruritus. Marine wounds can be infected with routine skin flora, such as Staphylococcus and Streptococcus, along with bacteria unique to the marine environment. The most serious halophilic organism is the gram-negative bacillus Vibrio, which can cause rapid infections marked by pain, swelling, hemorrhagic bullae, vasculitis, and even necrotizing fascitis and sepsis. Immunosuppressed patients, particularly those with liver disease, are susceptible to sepsis and death (up to 60%) from Vibrio vulnificus. Another bacterium, Erysipelothrix rhusiopathiae, implicated in fish handler's disease, can cause painful, marginating plaques after cutaneous puncture wounds. The unique marine bacterium Mycobacterium marinum, an acid-fast bacillus, can cause a chronic cutaneous granuloma 3 to 4 weeks after exposure.
Numerous invertebrate and vertebrate marine species are venomous. The invertebrates belong to 5 phyla: Cnidaria, Porifera, Echinodermata, Annelida, and Mollusca.
The 4 classes of Cnidaria all share stinging cells, known as nematocysts, which deliver venom subcutaneously when stimulated. The most common effect is pain, swelling, pruritus, urticaria, and even blistering and necrosis in severe cases. The Hydrozoans include hydroids, Millepora (fire corals), and Physalia (Portuguese man-of-war). The latter causes a linear erythematous eruption and rarely can cause respiratory arrest, possibly from anaphylaxis. In addition to local tissue injury, the Scyhozoans (true jellyfish) include Atlantic Ocean larval forms that can cause a persistent dermatitis under bathing suits lasting days after exposure (Seabather's eruption). The Cubozoans (box jellyfish), in particular Chironex fleckeri in Australia and Chiropsalmus in the Gulf of Mexico, can cause death after severe stings. A Hawaiian species, Carybdea, has been implicated in painful stings but no deaths. Another Australian box jellyfish, Carukia barnesi, can cause Irukandji syndrome, characterized by diffuse pain, hypertension, tachycardia, diaphoresis, and even pulmonary edema. The most innocuous cnidaria are the Anthozoans (anemones) that occasionally cause a mild local reaction.
Porifera (the sponges) can produce a stinging, pruritic dermatitis. Spicules of silica or calcium carbonate can become embedded in the skin along with toxic secretions from the sponge. Echinodermata include sea urchins and sea stars. Sea urchin spines produce immediate pain with trauma; some contain venom that leads to erythema and swelling. Retained spines can lead to infection and granuloma formation. The crown-of-thorns sea star, Acanthaster planci, has sharp rigid spines that cause burning pain and local inflammation. Annelida include bristle and fire worms, which embed bristles in the skin, causing pain and erythema. Mollusca include gastropods and octopuses. Both ...