Stingray Injuries in Travelers
Abstract and Commentary
By Mary-Louise Scully, MD
Sansum-Santa Barbara Medical Foundation Clinic, Santa Barbara, CA.
Dr. Scully reports no financial relationships relevant to this field of study.
Synopsis: Stingray injuries can cause debilitating, painful, and often complicated wounds, and, in rare situations, even fatalities. Knowledge of presenting manifestations and proper treatment strategies is essential.
Source: Diaz, JH. The Evaluation, Management, and Prevention of Stingray Injuries in Travelers. J Trav Med 2008;15:102-109.
Stingray injuries are an important group of problems related to marine envenomations. In this article by James H. Diaz, MD, the existing literature including case reports, case series, epidemiological investigations, and toxicological studies were reviewed in an attempt to describe the epidemiology, presenting manifestations, treatment, and possible preventive strategies for stingray injuries.
Stingrays are dorsoventrally flattened fish with wide pectoral fins that look like wings. There are approximately 150 species of stingrays that are distributed throughout the temperate and tropical oceans of the world, as well as freshwater stingrays found in the brackish waters, lagoons, and fresh water tributaries of major tropical river systems such as the Amazon in South America, the Bénoué and Niger in Africa, and the Mekong in Laos and Vietnam.
It is estimated that in the United States alone, 750 to 2,000 stingray injuries are reported each year. Stingrays generally do not "attack" humans but most often inflict injury in a purely defensive reaction when disturbed or threatened. They are often camouflaged in the bottom sand, and an unknowing swimmer or diver disturbs the fish, then the tail reflexively whips upward and thrusts the caudal spine or spines into the victim. Hence, many injuries occur on the lower extremities. Fatal stingray injuries have occurred with penetrating vascular, cervical, and thoracic injuries.
The stingray spine itself is composed of a strong, bone-like, cartilaginous material known as vasodentin. On the underside of the spine are two longitudinal grooves that contain venom-secreting glandular cells. This apparatus is then covered in a sheath of integument or epidermis that tears away when inserted into a victim. The dasyatid and urolophid stingrays cause the majority of venomous stings because they have distally placed long spines on long tails—the most efficient combination for effective stings. Giant manta rays, despite their large size, lack tail spines and are nonvenomous.
Stingray venoms have not been well studied partly because there are no venom glands as in reptiles, making it difficult to efficiently and safely extract venom to perform analysis. It would appear that stingray venoms have a variety of enzymatically active fractions that are heat labile and that include 5'-nucleotidase and phosphodiesterase. Although no specific anticoagulant properties have been identified, stingray lacerations are noted to bleed profusely initially followed by increasing pain over 15 to 90 minutes. Once the bleeding stops, the area surrounding the wound initially is erythematous but then becomes bluish gray or cyanotic in appearance. Wounds can contain bits of integument, spine barbs, and venom-secreting glandular cells, all of which require removal. Wounds must then be packed openly to allow for delayed primary closure.
In the event of a stingray injury, the first priority is to assess cardiopulmonary stability and make arrangements for immediate transport to a health care facility for injuries involving the chest or abdomen or if systemic manifestations are present. The spine should be removed only if superficially imbedded and not penetrating the neck, thorax, abdomen, or extending completely through an extremity. If the injury is appropriate for spine removal, then, once the spine is removed, the wound should be gently bathed in either sea water, clean freshwater, or sterile irrigating solution to remove all bits of retained spine, glandular material, and integument. Since stingray venoms are heat labile, some experts recommend immediate non-scalding hot water immersion. Although this has not been proven in a prospective trial, a retrospective study did find hot water immersion to be effective in decreasing the severe pain associated with stingray envenomation.2
Once the victim has been transported to a medical facility, tetanus prophylaxis should be administered and appropriate analgesics given to control pain. Any peripheral or regional nerve blocks should not include vasoconstricting agents such as epinephrine, cocaine, or phenylephrine. In many cases, surgical exploration is required for full removal of retained material or repair of vascular structures. Prophylactic antibiotics are recommended with coverage to include activity against marine Vibrio species. Despite all efforts, the degree of wound tissue necrosis can be extensive, resulting in slow healing. Both hyperbaric oxygen and application of recombinant human platelet-derived growth factor-BB (0.01% becaplermin gel) have been employed in difficult cases. Osteomyelitis and chronic granulomatous foreign body reactions can occur as complications.
Commentary
In September 2006, the devastating, fatal stingray injury of the well-known, popular naturalist Steve Irwin brought stingray injuries to the forefront of media and worldwide attention. This event occurred at Batt Reef in northeastern Queensland, Australia during the filming of a documentary entitled Ocean's Deadliest. Apparently while Irwin was swimming over a stingray, the stingray reacted by placing a spine directly into Irwin's chest, with death thought to be secondary to direct heart puncture. Fatalities from stingray injuries are rare, with a range of one to two or fewer per year in Indo-Pacific countries and the United States, to up to eight per year in South American countries with freshwater or Amazonian stingrays.1
Prophylaxis with antibiotics should include coverage for marine organisms, especially halophilic Vibrio species if the injury occurred in salt water. However, empiric coverage should also still include activity against common skin and wound organisms such as beta-hemolytic streptococci and Staphylococcus aureus. Empiric antibiotic choices might include either cephalosporins, quinolones, doxycycline, or trimethoprim-sulfamethoxazole, depending on the specifics of the incident. In patients requiring intravenous antibiotics, a third-generation cephalosporin plus doxycycline or a fluoroquinolone is appropriate. Anaerobic coverage should be included if the injury penetrated the abdominal cavity. Since these wounds can be polymicrobial, antibiotic decisions are best tailored to the specific results of wound cultures once these become available.
Unfortunately, stingray spines can readily penetrate through wet suits and rubber sneakers to cause significant injury. Therefore, if one is wading or walking in shallow waters known to be inhabited by stingrays, it is best to shuffle one's feet along the bottom to create enough disturbance to frighten off any nearby stingrays.3
References
- Diaz, JH. The Evaluation, Management, and Prevention of Stingray Injuries in Travelers. J Travel Med. 2008;15:102-109.1.
- Clark RF, et al. Stingray envenomation: A Retrospective Review of Clinical Presentation and Treatment in 119 Cases. J Emerg Med. 2007;33(1):33-37.
- Auerbach, PS. Wilderness Medicine. 5th ed. Philadelphia: Mosby Inc., 2007.
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