Creatures of the Deep: Marine Animal-Acquired Injuries and Envenomations
Authors: Angela F. Gardner, MD, FACEP, Assistant Professor, Department of Surgery/Emergency Medicine, University of Texas Medical Branch, Galveston; and Paul S. Auerbach, MD, MS, FACEP, FAWM, Professor of Surgery, Division of Emergency Medicine, Stanford University School of Medicine, Palo Alto, CA.
Peer Reviewer: Frank LoVecchio, DO, MPH, Banner Poison Control Center, Maricopa Medical Center, Department of Emergency Medicine, Phoenix, AZ.
Does the ocean fascinate you? Can you watch the surf for hours? Many will answer "yes." Perhaps it is something about the origin of life from the sea. Do you scuba dive or snorkel? I don't, but can understand the attraction. But if you do, after reading this article, you can join me in being grateful that we are land-based mammals rather than ones that reside in the ocean. We are pleased to present this review of marine animal-associated injuries and envenomations written by Drs. Gardner and Auerbach, two well-known experts.
J. Stephan Stapczynski, MD, FACEP, Editor
Seventy percent of the earth's surface is covered by ocean. In this marine environment lives four-fifths of the world's organisms, estimated to be about 275,000 species. About 80% of the world's human population lives near a coast. By the year 2010, it is estimated that 127 million U.S. citizens will live near an ocean.1
With the ease of travel and mobility, people injured in the marine environment may present for medical attention far inland. Additionally, growth of the marine aquarium industry has resulted in importation of dangerous aquatic species. As the chances for injury increase, so does the need for every emergency physician to be familiar with the basics of treating marine-acquired injuries.
Because marine-acquired wounds have not been studied to the same extent as land-acquired wounds, empirical observations and extrapolation from the traumatic wound literature are important contributors to many recommendations for clinical management.
Manner of Injury
Although treatises of marine injuries traditionally describe therapeutic intervention by type of animal involved, it is also useful from a practical standpoint to categorize by type of injury that presents to the emergency department (ED). In this manner, dangerous marine animals can be divided into the following groups:
- those that disrupt the skin (bite, puncture, sever, amputate, or deliver electric shock without envenomation);
- those that sting (envenomation);
- those that cause skin eruptions without envenomation; and
- those that cause allergic reactions.
For the purposes of this publication, the first two will be discussed.
First aid. First, address the airway, breathing, and circulation. The patient should have a patent airway, spontaneous breathing, and an adequate blood pressure to assure perfusion of the tissues. Anticipate anaphylaxis.
Wound Management. Whether bite, abrasion, or puncture, any open wound to the skin should receive appropriate wound care.
Wound Irrigation. The wound should be irrigated with an appropriate diluent at a pressure of 10-20 PSI. Sterile saline is the diluent of choice, if available. Sterile water or hypotonic saline may be used if sterile normal saline is not available. Recent research indicates that tap water may be used with efficacy in some wounds. Although this has not been specifically studied in wounds acquired in a marine environment, it is likely completely effective.2,3 Irrigation with sea water has a hypothetical risk of infection and so should be avoided.
A minimum of 150-200 cc should be used to irrigate each wound. If the wound is from a stingray spine, there may be residual organic material and likely venom in the wound. If the wound is still painful at the time of irrigation, use warm (45°C, 113°F) saline for irrigation. If a thermometer is not available to measure the water temperature, the saline should be as warm as can be tolerated by the patient (tested on uninjured and intact skin) without causing a burn injury.
Wound Anesthesia. Use local infiltration with 1% lidocaine, 0.5% bupivocaine, or a regional nerve block to achieve anesthesia of the wound. These methods have no deleterious effects on tissue healing. Topical anesthetics such as those containing epinephrine to cocaine are less desirable because they worsen wound healing as a result of local vasoconstriction.
Wound Debridement. Sharp dissection and removal of devitalized tissue results in improved healing. Remove obvious debris such as sand, vegetation, spines, or teeth. Imaging via radiograph, ultrasound, CT, or MRI may help locate foreign bodies either preoperatively or perioperatively. Proper debridement should be accomplished in a sterile field, if necessary within an operating room.
Wound Closure. The decision about whether to suture a wound balances the risk of infection with the need for an adequate cosmetic result. The presence of venom and potentially virulent microorganisms, inability to irrigate adequately and early, and delay to definitive treatment all contribute to the high potential for infection. Wounds to the hands, feet, and wrists; puncture or crush wounds; wounds to areas of poor vascularity such as fat; and wounds to persons who are immunocompromised all carry an increased risk of infection. If the decision is made to close the wound, it ideally should be closed loosely enough to allow for adequate drainage. Absorbable sutures and layered closures should be avoided in contaminated wounds to prevent a foreign body reaction.1
Tetanus Prophylaxis. The anaerobic bacterium Clostridium tetani is ubiquitous in the environment and potentially can enter any break in the skin. Proper immunization with tetanus toxoid virtually eliminates risk of disease. Administer tetanus prophylaxis according to Table 1.
Antibiotic Use. There is little scientific evidence to support the prophylactic use of antibiotics for all marine injuries. However, certain conditions dramatically increase the chances of infection, including deep or puncture wounds, large wounds, crush injuries, bite wounds, and multiple wounds.4-6 Any person in an immunocompromised state is also at increased risk for developing infection.
The most common pathogens retrieved from marine injuries are Staphylococcus aureus and Streptococcus pyogenes, presumably from the introduction of normal flora from the patient's skin through disruption of the integumentary system.6,7 Marine organisms implicated in skin and soft-tissue infections include Vibrio species, Aeromonas hydrophila, Pseudomonas species, Plesiomonas species, Erysipelothrix rhusiopathiae, Mycobacterium marinum, and other microbes.
Vibrio vulnificus has been implicated in serious, sometimes fatal soft-tissue infections occurring after marine-associated cutaneous wounds. Erythematous lesions may progress to hemorrhagic bullae with high fever, bacteremia, hypotension, and septic shock. The incubation period from wounding to severe systemic illness may be as short as 8-24 hours. The mortality rate from systemic Vibrio infections approaches 50%, with death occurring within 48 hours of admission to the hospital.8 Patients with a wound exposure to warm seawater and concurrently existing liver disease, chronic renal disease, alcoholism, diabetes, malignancy, or other type of immunocompromise are at high risk for rapidly progressive systemic infection.9-11 Patients with Vibrio vulnificus infections and septicemia require hospitalization.12
During warm summer months, Vibrio species are present in 50% of certain oyster beds. The Centers for Disease Control and Prevention received 302 V. vulnificus infection reports from the gulf coast states from 1988-1995. From 1981-1992, the Florida Department of Health and Rehabilitative Services reported 125 persons with V. vulnificus infections.
Tetracyclines are the oral antibiotics of choice for treating V. vulnificus infections if the drugs are administered early in the course and the victim does not require parenteral antibiotics. The recommended oral doses are doxycyline 100 mg twice daily or tetracycline 500 mg four times daily. Other recommended oral treatment regimens include ciprofloxacin 500 mg or 750 mg daily by mouth or trimethoprim-sulfamethoxazole (double strength) twice daily. Studies of U.S. coastal waters during four different seasons suggest that Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, and Bacillus species are also important seawater pathogens, and recommend penicillin or ampicillin plus levofloxacin for empiric therapy.13
Monitor all marine-acquired wounds closely for signs of infection and be prepared to treat early and aggressively with parenteral antibiotics.
Injuries from Nonvenomous Marine Animals
Sharks. In April 2008, a 66-year-old man sustained a shark bite in the waters of the Pacific Ocean near San Diego, triggering numerous news reports in the media for more than 48 hours. It is a familiar story, since shark attacks hold enormous fascination for the media, scientists, water enthusiasts, and the public. About one-third of the annual number of worldwide shark attacks each year occur in U.S. coastal waters. The International Shark Attack File (ISAF), maintained by the International Elasmobranch Society and the Florida Museum of Natural History, is an authoritative collection of analyzed reports of shark attacks dating back to the mid-1500s. Each year there are 6-10 deaths reported worldwide attributed to shark attacks. Florida alone reports 20-30 "minor" attacks each year, and is the area of greatest number of attacks in the United States.1 The most commonly reported attackers are the great white (Carcharodon carcharias), bull, and tiger (Galeocerdo cuvieri) sharks. Positive identification of an attacking species is often very difficult, since most victims do not see the attacker well enough to make an accurate identification and since even trained scientists have difficulty differentiating certain species, especially with requiem shark attacks. Retained tooth fragments can aid in identification, but this happens relatively infrequently.
Sharks are natural predators equipped with numerous finely honed senses (detecting electrical fields, vibration, chemicals in the water, etc.) intended to locate prey. There is some controversy about whether sharks can differentiate distinct colors (such as International Orange), but it is clear that they prefer colors to black. Most human attacks are "hit-and-run" attacks in which the shark is investigating to determine if the victim is edible prey. Humans are not preferred prey, but certain human swimming behaviors may be similar to those of the seals, penguins, and sea turtles preferred by sharks. For large sharks, a human may just be the appropriate size to incite interest. There are known reef sharks that will attack in defense of their territory, but human bites are largely considered to be inquisitive in nature.
The odds of being attacked by a shark along the North American coastline is 1 in 11.5 million, according to ISAF data. Most attacks occur during the summer, in warm (20°C, 68°F) waters, during evening and nighttime feeding, and in recreational areas. Sharks show a predilection for bright, shiny, and reflective surfaces. They have been known to attack surfboards, buoys, and boat propellers. Sharks have attacked swimmers on surfboards (black on white), especially in migratory seal habitats.
Sharks do not chew their food, but anchor it on the bottom teeth then use the serrated upper teeth to slash, aided by swinging the head from side to side. One exception to this is the cookie-cutter shark, which leaves circular 5-6 cm tissue defects where a bite has been made. For shark bites upon living victims, the legs and buttocks are the areas most commonly bitten, followed by hands and arms. Shark attacks historically have been fatal in 15-25% of cases, but advances in prehospital care and major trauma treatment have been instrumental in reducing that number to 10% in the past decade.
Treatment. The most significant risks are exsanguination and hypovolemic shock, followed by drowning. For this reason, it occasionally may be necessary to constrict arterial vessels or compress wounds while the victim is still in the water. Following this, remove the patient from the water and arrange for transport to the nearest medical center capable of treating major trauma. Selective use of tourniquets or pressure points may be necessary, with attention to preventing ischemia in the affected tissues. Keep the patient warm and well-oxygenated during transport. Start two large-bore IVs.
Examine the patient carefully for signs of cervical, intrathoracic, or intraabdominal injuries.
Replace lost blood volume with packed red blood cells. The exact ratio of crystalloid to blood products for shark injuries has not been determined, but it makes sense to follow guidelines established for acute blood loss.
Administer tetanus toxoid 0.5 cc IM and tetanus immune globulin 250-500 units IM, to cover for inoculation of Clostridium into the wound.
Shark bites are presumed to contain heavy contamination with seawater, plant debris, sand, shark teeth, and shark mouth flora. For this reason, administer an IV third-generation cephalosporin, trimethoprim-sulfamethoxazole, a fluoroquinolone, an aminoglycoside, or some reasonable combination.
For signs of early septicemia, particularly in an immunocompromised patient, consider meropenem or imipenem-cilastin IV.
Proper operative management of penetrating shark wounds is imperative. The operating room allows for the wide debridement of devitalized tissue and for the copious irrigation necessary to remove debris. This is difficult to accomplish in an emergency department setting.
Wounds should be closed loosely with multiple drains or packed open to await delayed primary closure.
Recovery from a shark bite is a lengthy and often complicated process, requiring attention appropriate for the multiple trauma patient.
Barracuda. The great barracuda lives in all tropical waters and is reputed to grow up to 50 kg (110 lbs) and 2.5 m (8.2 ft). Barracuda are swift, usually solitary swimmers and equally swift attackers. They seldom attack divers, but have been reported to attack in murky waters, especially when attracted to shiny objects. They have been reported to attack people dangling their legs from a boat, cleaning their hands in the water, or attempting to free fish from a net or hook. They are attracted to jewelry, fishing spears, and other metallic objects.
The barracuda has a narrow, elongated mouth with two rows of nearly parallel, razor-sharp teeth. The wounds inflicted by the barracuda are v-shaped, in contrast to the crescent-shaped wounds inflicted by sharks.
Treatment. Except for differences in the magnitude of injury, barracuda wounds are treated identically to those of the shark. The major issues are tissue loss, blood loss, and wound infection.
Moray Eels. Moray eels are found in tropical, subtropical, and some temperate waters. In U.S. waters, the most commonly observed species are the California, spotted, and green morays.
Moray eels have very poor vision and locate prey using their sense of smell. They are easily intimidated and seldom strike unless cornered or provoked. Aquarium owners who house morays must handle them with care to prevent attack. When they do attack, the moray eels are forceful and vicious. They are equipped with long, retrorse, sharp teeth in narrow, vise-like jaws. They are quite tenacious and may bite multiple times or cling to the prey. Most moray eel bites occur on the hand.
Treatment. Moray eels may cling to the victim, requiring forceful removal. Pulling the eel off without breaking the jaws or decapitating the animal may result in significant loss of tissue. After removing the head, the primary wound should be explored.
Inspect and, if necessary, explore the wounds thoroughly for debris and retained moray teeth. Obtain radiographs or other imaging studies if necessary, reevaluate for retained teeth, and assist in their removal.
Irrigate wounds copiously with normal saline.
For isolated small bites, wounds may be left open and allowed to drain. If the bite resembles a dog bite, it can be loosely closed with nonabsorbable sutures or staples. Extensive wounds require surgical evaluation and debridement.
The moray eel has a host of symbiotic organisms in the oral flora. Because of this, prophylactic antibiotics should be started on most moray eel bites. In all cases, the wounds should be re-examined at 24 and 48 hours, since infections from the bite of a moray eel may last for months or years.1,14
Sea Lions. Sea lions and seals are usually mild-mannered mammals with two exceptions: during mating season and when protecting their pups. Divers, aquarium workers, and persons protecting seal habitats have been bitten.
Treatment. Treatment of the bite wounds is similar to that for shark bites. However, the risk of post-traumatic infection differs from that of sharks, both in presentation and sequelae.
Seal finger, also known as spekk finger or blubber finger, occurs after a bite wound from a seal. It also can occur if even a minor wound comes into contact with a seal mouth or pelt. The affliction has a typical incubation time of four days, but may occur between 1 and 15 days. Severe pain is the initial symptom, followed by swelling, stiffness, and a furuncle. If untreated, the digit continues to swell and develops a brown, violet hue. Tenosynovitis and articular destruction have been noted. Painless, nonsuppurative lymphandenitis may develop. The etiology is thought to be Mycoplasma species, possibly phocidae or phocacerebrale.1
Recommended therapy is oral tetracycline 1.5 g initially, followed by 500 mg four times daily for 4-6 weeks. Fluoroquinolones or macrolide antibiotics may be useful if tetracycline is not available. Beta-lactam antibiotics and cephalosporins are not thought to be useful.1 Early antibiotics are essential for successful treatment.
Alligators and Crocodiles. Alligators and crocodiles are long-bodied loricans with ferocious reputations. The American alligator Alligator mississippiensis most commonly attacks swimmers, waders, and fishermen. The attacks usually occur in water but may occur on land. There were 343 alligator attacks resulting in 13 deaths between 1948 and 2003 in Florida, yielding a mortality rate of 4%; by comparison, the shark attack fatality rate during the same time period was 1.7% (ISAF data). American crocodiles (Crocodylus acutus) are found in the southern tip of Florida, and they attack even less frequently than alligators do.
Both species kill by dragging their prey beneath the water and drowning them. They also kill by biting the prey, then waiting for it to die and decay. The meat is easier to tear off after the prey is dead.
Crocodiles and alligators have relatively weak muscles that open the jaw but strong jaw-closing muscles that can sever an outboard boat propeller. The resulting injury is a largely contaminated crush injury, usually of an extremity.
Treatment. Cleanse and irrigate the wound thoroughly, using copious irrigation with normal saline.
Explore the wound for retained debris and possible teeth.
Surgical debridement may be required for large areas of devitalized tissue.
Provide adequate tetanus prophylaxis.
Antibiotic coverage has not been extensively studied in this population, but is assumed to be similar to that of other marine-acquired injuries. For large, contaminated wounds, consider prophylaxis against Aeromonas hydrophila, Pseudomonas, and Vibrio. In addition, coverage against anaerobes such as Bacteroides is prudent.1
Other Species. There are numerous other species that have been implicated in human injury, including the needlefish, giant octopus, mantis shrimp, and triggerfish. The numbers of injuries are small and often result from territorial invasion or provocation. Killer whales have been reported to "pursue" and batter a human, but one publicized incident occurred in captivity when a whale pursued its trainer. Sea lore attributes attacks to giant clams, colossal squid, and giant manta rays, but actual cases have yet to be substantiated. Divers may sustain significant abrasions when brushing against the dermal skin of the manta ray, but aggressive manta ray behavior has not been noted.
There are two groups of marine electric fish: the electric rays and the stargazers. Generally, the ventral side of an electric ray is negatively charged and the dorsal side is positively charged. An electrical discharge is produced reflexively on contact with the animal in an amount of 8-220 volts. Although the amperage is low, the electrical injury may be enough to stun an adult human and lead to drowning. The imperative is to remove the victim from the water. Anecdotally, recovery is reported to be uneventful.
Stony Corals. The true stony corals have calcerous outer skeletons with razor-sharp edges, pointed horns, or both. Nearly 1,000 species are found in colonies or as individual polyps from surface waters to depths between 20 fathoms (120 ft) and 83 fathoms (500 ft). They generally are found in waters of 20°C (68°F) or higher.
Coral cuts are probably the most common injuries sustained under water.1 Divers, snorkelers, underwater photographers, and spear fishermen handle or brush against these living reefs, resulting in injury to themselves and to the coral. Divers without gloves commonly sustain cuts to the hands. Knees, elbows, and forearms are also frequent sites of coral cuts. The initial reaction is pain, stinging, erythema, and pruritis. The break in the skin may develop a wheal, which fades over 1-2 hours. "Coral poisoning" is the description given to the erythema and wheal when it is accompanied by fever, gastroenteritis, and/or malaise. With or without treatment, the injury may develop blisters and cellulitis. Low-grade fever may be present. The wounds heal slowly over 3-6 weeks and may develop ulceration and skin sloughing. If chronic dermal granulomatous changes develop, infection with Mycobacterium, such as marinum or haemophilum, should be suspected.1
Treatment. Initial. All new coral cuts should be scrubbed vigorously then irrigated copiously with a forceful stream of sterile saline or disinfected fresh water to remove tiny fragments of foreign material ("coral dust"). If stinging persists, the wound may be rinsed briefly with diluted acetic acid (household vinegar) or isopropyl alcohol 20%, noting that these are normally tissue toxic in open wounds and should be used solely for decontamination of suspected coelenterate envenomation. Follow this topical decontamination with a freshwater or saline rinse.
Subsequent Wound Care. There are a number of approaches to subsequent wound care; none have been evaluated by prospective trial. They are:
- twice-daily wet to dry dressings using sterile saline and sterile dressings;
- application of a nontoxic antibiotic (antiseptic) ointment (e.g., mupirocin, bacitracin) and a nonadherent dressing (e.g., Telfa);
- application of a half- or full-strength antiseptic solution, followed by a powdered antibiotic such as tetracycline. This has largely fallen out of favor.
If the laceration is severe, close loosely with adhesive strips. In all cases, debride the wound daily for 3-4 days, removing devitalized tissue.
These wounds typically heal in a 4- to 15-week period, requiring close observation for wound infection, lichenoid papule formation, or systemic symptoms.
Envenomation by Aquatic Invertebrates
Sponges (Phylum Porifera). There are approximately 5000 known species of sponges. Sponges are acellular animals that attach to the sea floor or to coral beds. Sponges have internal collagenous skeletons of "spongin." Embedded in the connective tissue matrices are spicules of calcium carbonate (calcite) and silicon dioxide (silica). Sponges may be colonized by other sponges, algae, hydrozoans, mollusks, coelenterates, annelids, crustaceans, echinoderms, and fish. These secondary inhabitants may be responsible for the local necrotic skin reaction and dermatitis known as maladie des plongeurs, or sponge diver's disease.
There are two general syndromes produced by contact with sponges. The first is a pruritic dermatitis similar to that seen with plant-induced allergic dermatidities and the second is an irritant dermatitis secondary to penetration of the skin by the small calcium or silicone spicules of the sponge.
The most common offender is the Hawaiian or West Indian fire sponge (Tedania ignis), found off the Hawaiian islands and the Florida keys. Other culprits include Fibula (or Neofibularia) nolitangere, the "poison bun sponge," and Microciona prolifera, the red moss sponge. F. nolitangere is found in deep water and grows in clusters, with oscula (openings) wide enough to accommodate a diver's fingers. M. prolifera is found in the waters off the coast of the northeastern United States.
Divers without proper gloves sometimes handle sponges, which are friable and may crumble, injuring the hand. Any exposed skin may be abraded by contact with the sponge. Ten minutes to a few hours later, the affected area begins to itch and burn. This progresses to joint swelling, soft-tissue edema, vesiculation, and stiffness. Without treatment, mild reactions usually subside in 3-7 days. Rarely, erythema multiforme or anaphylactoid reactions may occur, developing 7-14 days after the exposure.
The second type of dermatitis is caused by spicules from the sponge breaking off in the skin. Most sponges have spicules and some have crinotoxins that enter the tiny wounds caused by the spicules. In severe cases of sponge dermatitis, the skin may subsequently desquamate 10 days to 2 months after the initial injury. Rarely, recurrent eczema and persistent arthralgias follow. There is no proven medical intervention to retard this process, although administration of potent topical or systemic steroids may be helpful for the eczema.
Treatment. It is virtually impossible to distinguish the two types of dermatitis on initial clinical examination. Therefore, it is prudent to treat both types. It is important to perform the initial decontamination as soon as possible, since delay and/or incomplete initial decontamination may lead to the formation of bullae. If these bullae become purulent, healing may extend for months.
Gently dry the skin.
Remove the spicules using adhesive tape, a thin layer of rubber cement, or a facial peel.1
Apply 5% acetic acid (vinegar) soaks for 10-30 minutes every 6-8 hours. Isopropyl alcohol is a reasonable second choice.
After completion of the initial decontamination, apply a mild emollient cream or steroid preparation.
If the allergic or eczematous component is severe, use a systemic glucocorticoid, beginning with a moderately high dose (prednisone 60-100 mg) tapered over 2-3 weeks.
Severe itching may be relieved by an antihistamine.
Anecdotal remedies for management of sponge envenomation include antiseptic dressings, broad-spectrum antibiotics, methdilazine, pyribenzamine, phenobarbital, diphenhydramine, prome-thazine, topical carbolic oil, or zinc oxide. None of these have been shown to have any proven efficacy in the treatment of sponge dermatitis.
Coelenterates (Phylum Cnidaria). There are at least 100 members of the coelenterates that are dangerous to humans, a small portion of the approximately 10,000 species. Coelenterates ("hollow gut") organisms are one of the lowest forms of life. Medically significant coelenterates with the venom-charged stinging apparatus, known as a nematocysts, are called Cnidaria. Those without nematocysts are called acnidaria.
Classification. The Cnidaria can be divided into three main groups:
- Hydrozoans, e.g., Portuguese man-of-war;
- Scyphozoans, e.g., true jellyfish; and
- Anthozoans, e.g., soft corals (alcyonarians), stony corals, and anemones.
An alternative categorization by Fenner15 divides jellyfish into three main classes:
- Schyphozoanstrue jellyfish, which have a transparent bell and tentacles arranged at regular intervals around the bell;
- Cubozoansbox jellyfish, which have a bell with tentacles only at the four corners. (These are further subdivided into: Carybdeids with only one tentacle at each corner, e.g., Irukandji; and Chirodropids with more than one tentacle at each corner); and
- Other jellyfish, which includes the hydrozoans. (This includes Physalia [Portugese man-of-war] species.)
It is important to distinguish this difference in classification when reviewing the pertinent literature. Although the identification and treatment of deadly cnidarians found only in Indo-Pacific waters if fascinating, this publication will emphasize those that could be seen by emergency physicians in the United States.
Venom Apparatus. For clinical purposes, all stinging species in this phylum are somewhat related, so the clinical features of coelenterate syndromes are fairly constant, with a spectrum of severity. The basis of the venom apparatus is the cnidocyte. The cnidae (nematocysts, spirocysts, and ptychocysts) are nonliving intracytoplasmic stinging organoids that are encapsulated in this living cell called the cnidocyte. Cnidocytes line the epithelial surfaces of the tentacles and/or the area near the mouth and are triggered by contact with the victim. The nematocyst is contained within a cnidoblast (outer capsule) and is attached to a cnidocil (single, pointing trigger). The nematocyst is filled with fluid and a coiled tubule (nema). When the cnidocil is triggered by physical contact, the operculum opens and the venom-bearing tubule is everted in less than 3 microseconds. The thread penetrates the epidermis and upper dermis and delivers venom into the circulation of the victim. Theoretically, a human encounter with a Portugese man-of-war could trigger several million stinging cells.16
Factors affecting the severity of a coelenterate envenomation include season, species (venom potency), number of nematocysts triggered, size of the animal, size of the victim, age of the victim, location and surface area of the sting, and health of the victim. Brief envenomation may result in only mild dermatitis, while severe envenomation can result in mortality. Clinicians should suspect coelenterate envenomation in all near-drownings, diving accidents, and collapses that occur in a marine setting.
Treatment – Mild envenomation/dermatitis. Rinse the wound immediately with sea water. Do not use fresh water. It is believed that nonforceful fresh water rinsing or rubbing will cause nematocysts to discharge, worsening the injury.
Recent studies indicate that a hot fresh water shower with a forceful stream applied by lifesavers at the beach can reduce the pain of envenomation.17,18 It may be that the mechanical effect of the water dislodges the nematocysts and/or tentacle fragments, preventing worsening of the injury.
Remove any visible tentacle fragments with forceps. If absolutely necessary, a gloved (double thickness of surgical gloves) hand or the relatively keratinized surface of the palm of the hand can be used to remove tentacle fragments.
Decontaminate using the appropriate solution. There is a great deal of variety in recommendations for the "appropriate" solution for immediate decontamination. Acetic acid 5% (vinegar) is the solution of choice for treating Chironex fleckeri. It may not be as useful against Chrysaora or Cyanea. Sodium bicarbonate is reported to be effective against the sea nettles (Chrysaoara quinquecirrha) found in the Chesapeake Bay and the coastal Atlantic waters of the United States. Isopropyl alcohol and dilute ammonium hydroxide also have been used with some clinical success. A slurry of papain (meat tenderizer) has been recommended by some for sting of thimble jellyfishes that cause seabather's eruption. Lime or lemon juice may be effective. The following are not effective: perfume, aftershave lotion, high-proof liquor, formalin, ether, or gasoline.
Flood the area with the decontaminant for at least a few minutes. More time may be required for most decontaminants, but if using papain, remove it after 5 minutes and do not use it on delicate or thin skin.
Cold Pack/Hot Pack. Commercial cold packs traditionally have been recommended, applied over a thin cloth or plastic membrane. Recent studies indicate that hot water immersion may be equally or more effective for certain species in the Indo-Pacific, but this has not yet been confirmed for U.S. coastal species.17,19,20
Remove the remaining (perhaps "invisible") nematocysts using shaving cream and a razor. In a primitive setting, make a paste of sand and sea water and "shave" the area using a sharp shell or piece of wood.
Anesthetize the area using a topical anesthetic ointment (lidocaine, 2.5%) or spray (benzocaine, 14%). Antihistaminic cream (diphenhydramine or tripelennamine) or a mild topical steroid (hydrocortisone, 1%) also may be soothing. Administer pain medication as needed.
Tetanus prophylaxis is required.
No prophylactic antibiotics are required. Wounds should be checked at 3 days and 7 days for signs of infection. If a lesion develops ulceration, apply a thin layer of mupirocin daily.
NOTE: A jellyfish sting involving the cornea should be referred immediately to an ophthalmologist. Do not use standard decontaminating solutions in the eye.
Treatment – Moderate to Severe Envenomation. The prime offenders in this group are the anemones, Physalia species, and scyphozoans. The targets of treatment are to provide supportive care for systemic symptoms, provide adequate pain relief, and treat the dermatitis. Treatment of the dermatitis is identical to that for a mild envenomation.
Provide supportive treatment based on the signs and symptoms.
Treat hypotension with prompt IV administration of crystalloid. However, do not discontinue the decontamination while starting fluids because it is important to continue to interrupt further venom release into the victim.
Hypertension is an occasional side effect of a cubomedusan envenomation, such as that from the Irukandji. Although this is more typically reported from the Indo-Pacific, there is a reported Irukandji-type death from the Gulf of Mexico. The hypertension is felt to be secondary to the release of circulating catecholamines. Treat with phentolamine 5 mg IV initial dose followed by an infusion of up to 10 mg/hr.
Manage bronchospasm and wheezing as an allergic component. Arterial blood gases may be useful to guide oxygen administration by mask.
Seizures are usually self-limited and can be managed with IV diazepam. They rarely recur after the first 48 hours.
Monitor older patients for arrhythmias and obtain an electrocardiogram.
Obtain a urinalysis to check for hemoglobinuria, which occurs when the venom of certain Physalia species attaches to red blood cell glycoprotein sites, causing red cell lysis. If hemoglobinuria is present, alkalinize the urine with sodium bicarbonate and administer a loop diuretic (furosemide) or mannitol to maintain a moderate diuresis of 30-50 cc/hr.
To date, the only coelenterate antivenom available is for the box-jellyfish Chironex fleckeri.
Phylum Echinodermata. This phylum includes starfish, sea cucumbers, sea urchins, sea lilies, and brittle stars. Only the first three are of significant medical interest.
Starfish are stellate, simple, free-living organisms covered with calcium carbonate spines. The crown-of-thorns starfish (Acanthaster planci) is injurious to humans and is found throughout the Pacific and the Gulf of California. The venom of A. planci covers the sharp, thorny spines. The venom has hepatotoxic, myonecrotic, and anticoagulant effects.
The thorns can penetrate a thick diver's glove or reef slipper. There is immediate severe pain, initial blanching followed by erythema, mild edema, and copious bleeding. Multiple puncture wounds may result in systemic symptoms including nausea, vomiting, paresthesias, lymphadenopathy, and muscular paralysis.
Treatment. Immediately immerse the wound in hot water to tolerance (45°C, 113°F) for 90 minutes. If a thermometer is not available, first place a noninjured extremity into water of the same temperature to determine the patient's tolerance and avoid burning the envenomed tissue, which may have an altered sensory perception of heat.21
Irrigate the wound copiously with normal saline.
Explore the wound for retained fragments. The thorns of A. planci are very sturdy and usually do not leave fragments. However, if a smaller starfish is encountered, the tips may break and become embedded foreign bodies. If there is a suspicion of retained thorns, obtain a radiograph of the affected extremity.
Allow the wound to heal without sutures.
Granulomas from retained starfish spines may require surgical excision after the wounds have healed.
Sea Urchins. There are approximately 600 species of sea urchins, roughly 80 of which are venomous to humans. The venom is contained in the hollow spines and in the triple-jawed pedicellariae. Most people are injured when they step on, handle, or brush up against a sea urchin. The long, needle-like spines of the sea urchin break off easily and may remain in the wound.
The puncture-type wound is immediately intensely painful. The burning pain rapidly becomes local muscle aching and the skin develops erythema at the site. The external surfaces of the spines of some species (Diadema setosum or Strongylocentrotus purpuratus) carry a purplish-black dye that may be deposited in the wound(s) and leave the false impression that there is a retained spine in the wound.
If a spine invades a joint space, tenosynovitis may develop rapidly. If spines are deeply embedded or if there are multiple spine fragments, systemic symptoms may develop. These include nausea, vomiting, paresthesias, numbness, muscular paralysis, abdominal pain, hypotension, and respiratory distress. Frank neuropathy suggests direct contact with a peripheral nerve. Spines that break off near the finger- or toenail may cause a subungual or periungual granulomatous nodular lesion.
Treatment. Immediately immerse the affected extremity in hot water to tolerance (45°C, 113°F) for 30-90 minutes.
Remove any pedicellariae still attached to the skin. This is accomplished with shaving cream and a razor.
Remove any of the long, needle-like spines that are easily retrieved. Very thin spines may be absorbed in 1-21 days but thick, calcified spines must be removed from the tissues.
Obtain soft-tissue-technique radiographs, ultrasound, or an MRI to localize retained spines.
Retained spines in the hands or feet potentially could intrude upon a joint or blood vessel or could be in a location to cause chronic inflammation if they remain. If it is determined that the retained spines should be removed, they should be removed by a qualified surgeon using an operating microscope as soon as possible after the injury.
Injuries that involve interphalangeal joints should be splinted to prevent further fragmentation of the retained spines. Retained spines become a nidus for granuloma formation. These granulomas may be excised at a later date.
Sea Cucumbers. Sea cucumbers are free-living bottom-dwellers found in both shallow and deep waters. The animals extrude tentacles that may contain a cantharidin-like liquid toxin known as holothurin. On occasion, the body walls of the animals contain the toxin. Normally, holothurin is diluted by the surrounding sea water. Injury may occur when sea cucumbers are handled for food preparation.
Holothurin produces contact dermatitis similar to that caused by starfish. If ingested, holothurin is a potent cardiac glycoside and may cause death. Holothurin in the water from recent handling of sea cucumbers can contact the cornea when a diver clears his mask. The resulting inflammation may be severe.
Treatment. Treat the contact dermatitis in the same fashion as dermatitis from starfish. Because sea cucumbers feed on coelenterates and excrete the venom, contact may cause a dermal reaction. Flood the wound with 5% acetic acid (vinegar) for decontamination.
For eye exposures, anesthetize the eye with 1% proparacaine, then irrigate the affected eye with 100-250 cc of normal saline to remove debris. Perform a slit lamp examination to determine the presence of corneal injury. Examine the anterior chamber and iris for involvement. Prompt referral to an ophthalmologist is imperative.
Annelid Worms (Phylum Annelida). Most marine worms are carnivorous free-moving organisms that live from the tidal zone to depths of 16,000 feet. The bristleworm (Hermodice carunculata), which releases chitinous, irritating bristles upon contact, is improperly handled by divers and home aquarists.
The bite or sting of an annelid worm may result in intense pain and inflammation, accompanied by an urticarial, erythematous rash. Some spines are too small to be visualized with the naked eye, and most, regardless of size, are easily broken off into the skin.
Symptoms are self-limited, but the inflammation may last 7-10 days.
Treatment. Dry the skin without abrading or rubbing.
Remove the spines using adhesive tape, a facial peel, or a thin layer of rubber cement.
After spine removal, douse the area with 5% acetic acid (vinegar), dilute ammonia, or 70% isopropyl alcohol.
Severe inflammation can be treated with a topical corticosteroid.
Mollusks (Phylum Mollusca). The phylum Mollusca contains more than 45,000 members. Of the 5 main classes, three pose a danger to humans:
- Pelecypodsscallops, oysters, clams, and mussels;
- Gastropodssnails and slugs; and
- Cephalopodssquids, octopuses, and cuttlefish.
Mollusks are also implicated in poisonous ingestions.
Cone Snails (Cone Shells). There are 500 species of marine snails that are thought to be venomous, but fewer than two dozen species have been reported to cause human envenomations.22 The brightly colored geometric patterns on the shells are a lure for shell collectors.
Venomous cone snails hunt prey and protect themselves using a harpoon-like radula located at the tapered end of the shell within a proboscis that may extend more than 3 times the length of the shell.23,24 The snail contracts a muscular pharynx and launches the radula. Unlike the passive discharge of a nematocyst in a coelenterate, the extension of the proboscis and launching of the radula is under the voluntary control of the cone snail.
Through a combination of alpha and mu conotoxins, which act both presynaptically and postsynaptically, effective neuromuscular paralysis may result from only minute inoculations of toxin. The wound may or may not produce initial pain, but paresthesias at the site rapidly affect the limb, the perioral area, and then the entire body. Death is attributed to diaphragmatic paralysis or cardiac failure.
Treatment. There is no specific antivenom. The pressure-immobilization technique for venom sequestration has been suggested but has not been proven effective as a first-aid measure.
Cardiovascular and respiratory support are life-saving in this envenomation.
Inspect the wound for a foreign body (the radula) and remove it if present.
Numerous topical therapies have been suggested, but none has proven beneficial by scientific standards.
One reasonable approach suggested is the use of edrophonium (10 mg IV in an adult) as empiric therapy for paralysis. Choose a relatively weak group of muscles for which strength can be objectively tested and inject 2 mg IV. If there is improvement, inject 8 mg IV.
Adverse reactions to edrophonium, such as salivation, nausea, diarrhea, and muscle fasciculations, can be treated with atropine 0.6 mg IV.
Octopuses. Octopuses and cuttlefish are cephalopods that are usually harmless and shy. The media has created the image of a giant octopus surrounding its prey with its tentacles, but the truth is that the most dangerous of the octopuses are less than 10-20 cm (4-8 inches) in length.
Octopus bites are rare, but can result in severe envenomation. The most venomous of these is the blue-ringed octopus found only in Australasian waters. The common octopus Octopus vulgaris is nonvenomous. The Octopus joubini sometimes frequents empty containers or submerged bottles in the waters of the Caribbean.
The venom apparatus of the octopus is composed of the salivary ducts, buccal mass, beak, and salivary glands. It is located on the central ventral surface surrounded by tentacles. Maculotoxin from the blue-ringed octopus has at least one component identical to tetrodotoxin.
Most octopus bites occur on the hand, acquired while handling the animal. The bite itself consists of one or two puncture marks and may initially go unnoticed. Sometimes local urticarial reactions occur, and profuse bleeding at the site is caused by a local anticoagualant effect. Local reactions are minimal compared with the systemic effects.
For a blue-ringed octopus bite, within 5-10 minutes of the bite, paresthesias develop and ascend the affected limb. Perioral numbness develops between 10 and 30 minutes, leading rapidly to total flaccid paralysis and respiratory collapse.
Treatment. The mainstay of therapy is respiratory support.
Pressure-immobilization has been proposed for the local injury and should be used.
Provide immediate ventilatory support, including endotracheal intubation and mechanical ventilation.
The effects of the venom last between 4 and 10 hours. If no anoxia occurs during that time, recovery should occur within 2-4 days.
Summary. Treatment of marine envenomations by invertebrates can be difficult, especially since the exact culprit is not always reliably identified by the victim. Figure 1 provides a useful algorithm for the treatment of envenomations.
Aquatic Vertebrate Envenomation
Stingrays. The "devil ray" or the "demon of the deep" has been recognized as venomous since ancient times. It is the most commonly incriminated group of fish involved in human envenomations. Twenty-two species of rays are found along the U.S. coast, eight in the Pacific, and 14 in the Atlantic.
About 2000 stingray injuries occur each year in the United States, most caused by members of the family Dasyatidae. Most injuries occur in the summer and autumn months when vacationers take advantage of the surf. Coincidentally, that is the time that rays congregate to spawn. In the southeastern United States, the southern stingray (Dasyatis americana) is a frequent stinger. On the west coast, the round stingray (Urolophus halleri) has that distinction. There are no known freshwater species in the United States.
Rays vary from small (several inches) to large (12 ft x 6 ft) and have a flattened, wide body with large pectoral fins. They are bottom-feeders and tend to stay on the bottom of the sea, partially submerged in the sand. For this reason, a frequent cause of injury is stepping on the body of the animal, causing the whip-like tail to reflexively snap up and thrust a spine into the unwary human, causing a puncture wound or laceration. (See Figure 2.) There are occasional abrasions reported by divers who "hitch a ride" on large manta rays, but these are caused by the rough dermis of the creature, not by envenomation. In certain parts of the world, stingrays are hand-fed by tourists. Since the ray feeds by suctioning water and prey through the ventral opening, a "hickey" can be caused by its attempt to "vacuum" the food from the hand of the unsuspecting tourist, or a direct bite by the animal.
The venom apparatus is a bilaterally retroserrated spine and the enveloping integumentary sheath. There may be up to 4 spines on the tail of a single ray. The spines are attached to the dorsum of the tail. Along the edges of the spines are hollow grooves that contain soft venom glands.
A stingray wound is both a mechanical wound and an envenomation. The cartilagenous spine and strength of the strike combine to cause significant tissue damage. Most injuries involve the lower extremity. There are also reported injuries to the upper extremity, abdomen, and thorax. In very rare cases, the heart may be injured directly. In addition, a detached stingray spine may be used as a combat weapon.
Envenomation is accompanied by immediate intense local pain with variable edema and bleeding. The pain radiates centrally, peaks at 30-60 minutes, and may last for 48 hours. Systemic symptoms include nausea, vomiting, diarrhea, diaphoresis, vertigo, tachycardia, headache, syncope, seizures, muscle cramps, fasciculations, generalized edema, paralysis, hypotension, arrhythmias, and death.
Treatment. Treatment is aimed at combating the effects of the venom, relieving pain, and preventing subsequent infection.
First, as in all marine injuries, remove the victim from the water. Muscle contractions and fasciculations may be caused by the venom and/or pain, causing problems for a swimmer.
Immediately soak the injury in nonscalding hot water (45°C, 113°F) for 30-90 minutes. If hot water is not available, irrigate the wound with nonheated water or saline. If sterile water or saline is not available, use tap water. The goal is to remove as much of the venom and organic material as quickly as possible. In addition, the heat may attenuate some of the thermolabile components of the venom or interrupt nerve impulse transmission. It has no proven effect on the ultimate degree of tissue necrosis.
There is no indication for additives for the soaking solution.
During the hot water soak, explore the wound and remove any visible portions of the sting or its integumentary sheath. Note: The exception is a penetrating injury of the chest or other body location where the presence of the spine may be occluding a blood vessel with the propensity to bleed torrentially. These should be removed in the operating room under sterile conditions with adequate preparation for uncontrolled bleeding or other catastrophic events.
There is no role for cryotherapy, steroids, or antihistamines.
Initiate pain control as soon as possible during the first soaking period. Parenteral narcotics may be required. Local infiltration with 1% or 2 % lidocaine or bupivicaine 0.25-0.50% without epinephrine may be needed. A regional nerve block can be used.
Upon completion of the soaking procedure, explore the wound in a sterile fashion.
Excise hemorrhagic fat and obviously devitalized tissue.
Pack the wound for a delayed primary closure or close loosely around adequate drainage. An alternative includes excising the wound and packing it with an alginate dressing.25
Provide tetanus prophylaxis.
Prescribe prophylactic antibiotics to prevent secondary infection. To cover Vibrio species implicated in cases of stingray infection,26 administer oral doxycycline 100 mg twice daily, tetracycline 500 mg four times daily, or trimethoprim-sulfamethoxazole double-strength twice daily. Ciprofloxacin 500 mg or 750 mg daily is an alternative. Topical becaplermin gel was used with some success in one patient who suffered prolonged healing.27
Obtain an MRI if a retained foreign body is expected and none is seen on plain radiographs. Stingrays have cartilaginous endoskeletons, so spine fragments may not be visible without advanced imaging.
Obtain surgical consultation for repair of vascular injuries, lacerated nerves and tendons, and for all stab wounds of the abdomen, thorax, or neck.28,29
Observe patients who are not being admitted for 3-6 hours to make sure that systemic symptoms do not develop.
Venomous Fish. The family Scorpaenidae is divided into three groups:
- Pteroisthe zebrafish, lionfish, and butterfly cod;
- Scorpaenascorpionfish, bullrout, and sculpin; and
These fish dwell in tropical and, less often, in more temperate waters. Two fish that sting in a similar manner are the Pacific ratfish and the Atlantic toadfish.
Zebrafish (lionfish, turkeyfish) have been imported to the United States to dwell in home aquariums. They have now been spotted in the Atlantic Ocean from North Carolina to Florida.
The scorpionfish proper (Scorpaena) are found on the tip of southern Florida, in the Gulf of Mexico, off the coast of southern California, and in Hawaii.
Stonefish are not indigenous to U.S. waters.
Venom is associated with venom glands in the 12 dorsal, 2 pelvic, and 3 anal spines. The ornate, plumelike, and beautiful pectoral fins of these fish are nonvenomous. Each venomous spine is covered with an integumentary sheath that covers a hollow groove on the anterolateral portion of the spine. When the fish is handled, or more often, stepped on, it erects the dorsal spine and flares the pectoral and anal fins. If provoked in the water, the stonefish may attack.30,31
As with stingray injuries, the majority of injuries occur when a person steps on the fish. Most reported envenomations in the United States result in painful local wounds. Severe systemic effects and fatalities are rare.
The patient experiences immediate excruciating pain at the site, which quickly spreads to the entire limb and regional lymph nodes. The pain peaks at 90 minutes and may last up to 12 hours. Mild subsequent pain can persist for weeks. Occasionally, vesicles form in the region of the original puncture wound. This may be followed by skin sloughing, cellulitis, and surrounding hypesthesia.
Systemic symptoms include nausea, muscular weakness, respiratory distress, and hypotension.
Treatment. Remove the victim from the water.
Remove any visible spines immediately to prevent further penetration and breakage.
Immerse the affected limb into nonscalding water (45°C, 113°F) for 30-90 minutes.
Provide pain relief with local anesthesia using lidocaine 1-2% or bupivicaine 0.25-0.5% without epinephrine. Regional anesthesia also may be effective. Systemic narcotics may be needed for pain control, especially if the envenomation is in an area that is difficult to immerse in hot water.
After immersion, explore the wound in a sterile environment. Spine fragments in critical areas such as joints, weight-bearing surfaces, and in proximity to nerves and vessels, usually should be removed.
Remove any foreign material directly with forceps then irrigate copiously with warm normal saline.
Wide excision usually is not necessary. It has been required in cases of severe extensive necrosis associated with stonefish envenomation.
Provide tetanus prophylaxis.
Prophylactic antibiotics are needed if the wound is very deep or involves the hand or foot. Appropriate antibiotics include oral doxycycline 100 mg twice daily, tetracycline 500 mg four times daily, trimethoprim-sulfamethoxazole double-strength twice daily, or ciprofloxacin 500-750 mg twice daily.
Stonefish Antivenom. There is antivenom available from the Australian Venom Research Unit, Department of Pharmacology, University of Melbourne, Parkville, Vic 3052, Australia. Telephone: 61-3-934447753. The antivenom is no longer available at Sea World in San Diego. Regional poison centers may be of value in locating the closest supply of antivenom.
The antivenom is hyperimmunized equine-derived antisera, so there are risks of allergic reaction and serum sickness in the recipient. Skin testing has traditionally been recommended prior to administration. Australian sources recommend pretreatment rather than skin testing to save time.32 Subcutaneous epinephrine and an intramuscular antihistamine are recommended, followed by an intramuscular corticosteroid for known hypersensitivity. If the patient has a history of hypersensitiviy to equine products, the risk of the antivenom must be weighed carefully against the risk of the envenomation.
Following premedication, administer the antivenom as follows: 1 ampule (2000 U) IV for every 1-2 punctures, up to 3 ampules for more than 4 punctures.
Slow IV administration requires dilution in 50-100 cc of normal saline and administration over at least 20 minutes.
The Commonwealth Serum Laboratories (CSL) stonefish antivenom is recommended only for prediluted IM use. This route may not be ideal in serious envenomations because of erratic and unpredictable absorption.33,34
Sea Snakes. Sea snakes are probably the most abundant reptiles on earth, and all of the 52 species are venomous. Fortunately, Hawaii is the only state in the United States that has sea snakes (Pelamis platurus).
Sea snakes have two to four hollow maxillary fangs and a pair of associated venom glands. The proteinaceous venom is highly toxic and contains stable neurotoxins that are often more potent than those of terrestrial snakes.
The patient is usually in the water or handling nets when the snake strikes. The bite site may exhibit the traditional fang marks, but these are often overlooked initially since there is little or no local pain on envenomation. Symptoms can develop in as little as 5 minutes, but typically evolve over 8 hours. Symptoms include euphoria, malaise, anxiety, muscle aching, sialorrhea, and a "thick tongue." Ascending flaccid or spastic paralysis ensues, followed by nausea, vomiting, myoclonus, muscle spasm, ophthalmoplegia, trismus, and bilateral painless swelling of the parotid glands.
Severe systemic envenomations develop symptoms rapidly over 2 hours. Victims complain of loss of vision, then become cool and cyanotic. Acute renal failure, respiratory failure, and coma ensue. The mortality rate is 25% untreated and 3% overall.
Treatment. Remove the victim from the water.
Immobilize the wound and keep the victim as calm as possible. The pressure-immobilization technique should be used.35
Sea snake antivenom is required if envenomation is present or highly suspected.
Intensive care management is necessary for sea snake envenomations. Respiratory collapse secondary to paralysis is anticipated, and endotracheal intubation and mechanical ventilation will likely be needed.
Treat myoglobinuria by alkalinizing the urine with sodium bicarbonate and a loop diuretic. Progressive nephropathy may require hemodialysis.
Repeat electrolyte monitoring will guide the administration of fluids and electrolyte supplements. Hyperkalemia secondary to rhabdomyolysis and renal failure should be anticipated and treated aggressively.
If the patient has no symptoms of systemic envenomation during the emergency department visit, observe for at least 8-12 hours before release.
Evaluation and management of the serious bite and envenomation injuries from marine animals can be summarized by some general key principles. For bite wounds, the basic principle is appropriate wound care and antibiotics directed against expected pathogens. For most envenomations, immersion in warm water will provide local relief. Many envenomations may have residual venom-containing objects in the wound that require appropriate removal. Finally, some envenomations may have serious systemic effects that necessitate a period of observation and cardiopulmonary monitoring.
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