Chapter 207

The marine environment is increasingly important for recreation, industry, and communications and is dangerous to humans for several reasons: we can’t breathe in it, we can’t see in it, and swimming must be learned. The marine environment is also remote to points of definitive health care. Marine fauna can inflict injury through trauma (often with infection) or envenomation. Many marine animals have developed venomous systems of defense and predation.

There is little information on the epidemiology of marine injuries and envenomations. One U.S. study reviewed >6 years of aquatic animal exposures reported to poison control centers. The most common exposures were to jellyfish (31%), stingrays (16%), venomous fish (including lionfish, catfish, and others) (28%), and gastropods (6%).1 However, these percentages are likely to be biased toward more severe injuries and do not include common minor injuries, such as envenomation by Physalia species, seabather’s eruption, and sea urchin stings. In the U.S., thousands of cases of minor jellyfish stings occur yearly from Physalia species (Portuguese man-of-war) and Chrysaora species. There is less information on traumatic injuries except for details of shark attacks, which are maintained in the International Shark Attack File. The file reports almost 1000 attacks since 1990, with just over 10% being fatal.2

### Shark Attacks

Sharks are from the subclass Elasmobranchii of the class Chondrichthyes (“cartilaginous fishes”), which also includes skates and rays. Sharks are top-level predators and are well equipped to inflict severe injuries. There are about 400 species of shark, and human attacks have been described for >30 species. Certain species, such as the white shark (Carcharodon carcharias), the tiger shark (Galeocerdo cuvier), and several Carcharhinus species, appear to be disposed to human attacks. Despite the public perception, the risk of shark attack is extremely small compared with almost any other injury. There are probably between 70 and 100 shark attacks worldwide each year, with between 5 and 15 deaths.2,3 The mortality of shark attacks has fallen from 40% in the 30 years following World War II to current rates of approximately 10% to 20%.2 Death is usually a result of lack of prehospital resuscitation, hemorrhagic shock, or drowning.

Three general types of unprovoked shark attack are described: (1) hit-and-run attacks, in which the victim is seized and released, or slashed on an extremity, before the victim has any time to react; they often occur in shallow water and account for approximately 80% of shark attacks; (2) sneak attacks, or the “out-of-the-blue” attacks, usually involving divers or swimmers in deeper water; and (3) bump-and-bite attacks, in which the shark circles and bumps the victim prior to attacking.3 These last two types tend to occur in deeper water, are characterized by multiple and sustained attacks, involve bigger sharks, and cause the majority of deaths by shark attack.

The direct traumatic effects of a shark attack depend upon the severity and ...

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