The notoriety of shark attacks seems undeserved when the statistics are examined.1 Fewer than 100 attacks are reported annually worldwide, with 10 or fewer fatalities. Of approximately 370 shark species, only 32 have been definitely implicated in human attacks, the majority by the tiger, great white, blue, mako, hammerhead, bull, and grey reef sharks.
Two general attack behaviors have been described: feeding and agonistic. Feeding attacks appear to be the result of mistaking a human for a pinniped or other common shark prey. Such attacks often terminate as soon as the shark realizes the mistake. Agonistic attacks seem to be defensive or territorial-protective.
Shark attack wounds range from severe dermal abrasions (due to sharkskin denticles) following a "bumping" to massive tissue loss with fractures and hemorrhage. Such injuries occur from razor-sharp teeth on jaws brought together with an estimated force approaching 18 tons/in2 tooth to tooth. "Hit-and-run" attacks occur in the majority of instances, and 70 percent of victims are bitten only once or twice. The lower extremity is most frequently injured, followed by the upper extremity. Death is usually the result of hemorrhagic shock or drowning.
As with other resuscitative endeavors, the ABCs are fundamental, with special attention to hemorrhage control, volume resuscitation, and rewarming as needed. Tetanus toxoid and tetanus immunoglobulin should be administered as indicated. Prophylactic intravenous antibiotics are empirically recommended to counter a potential Vibrio species infection. Third-generation cephalosporins, trimethoprim-sulfamethoxazole, chloramphenicol, ciprofloxacin, norfloxacin, or an aminoglycoside may be given. Meticulous wound care is most appropriately performed in the operating room for adequate surgical exploration, irrigation, and débridement of wounds. To minimize tissue destruction associated with an infection, wounds may be packed open for delayed primary closure or closed around drainage systems.
It has been suggested that most shark attacks could be prevented if a few precautionary measures were taken: (1) avoid swimming in river mouths, low-visibility waters, or shark-infested waters; (2) avoid wearing bright or shiny clothing, jewelry, or equipment; (3) avoid swimming with an open (bleeding) wound; and (4) obey beach authorities and posted warnings.
The great barracuda (Sphyraena barracuda) is the only barracuda species implicated in human attacks. Attacks are generally by solitary fish and occur only in tropical climes. Moray eels, found in tropical-to-temperate waters, can inflict severe puncture wounds or lacerations, commonly to the hands of inquisitive divers. Other marine vertebrates known to cause traumatic injuries to humans include giant groupers, sea lions, seals, crocodiles, alligators, needlefish, wahoos, piranas, and triggerfish. Wounds resulting from interactions with such creatures are a combination of crush injury, abrasion, puncture, and laceration. Treatment of such injuries is analogous to that of shark bites, with an emphasis on irrigation, removal of foreign bodies (e.g., teeth), and allowing adequate wound drainage (e.g., leaving puncture wounds open).
Coral cuts are probably the most common injuries sustained underwater. The initial reactions to a coral cut are stinging pain, erythema, and pruritus, most commonly on the hands, forearms, elbows, and knees. Within minutes, a break in the skin may be surrounded by an erythematous wheal, which fades over 1 to 2 h.
With or without treatment, the local reaction of red, raised welts and local pruritus may progress to cellulitis with ulceration and tissue sloughing. The wounds heal slowly over 3 to 6 weeks. In extreme cases, the victim develops cellulitis with lymphangitis, reactive bursitis, local ulceration, and wound necrosis. Coral poisoning usually refers to systemic malaise, fever, diarrhea, and general inanition associated with a wound from coral.
Coral cuts should be promptly and vigorously irrigated to remove all foreign matter. Any fragments that remain can become embedded and increase the risk of infection or foreign-body granuloma. If stinging is a major symptom, there may be envenomation by nematocysts. A brief rinse with dilute acetic acid (vinegar) or papain solution may diminish the discomfort. If a coral-induced laceration is severe, it should be closed with adhesive strips, rather than sutures, if possible. Sharp débridement each day for 3 to 4 days is preferable if the wound is deep. For superficial (no fat showing) wounds, utilize daily saline solution or dilute povidone-iodine wet-to-dry dressing changes, or apply a topical antiseptic under a nonadherent dressing.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.