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1350 SECTION 16: Environmental Injuries Renal failure results from direct thermal injury to the kidney, rhabdomyolysis, or volume depletion. Clinically, this is manifested by oliguria, microscopic hematuria, proteinuria, myoglobinuria, and granular or red cell casts in the urine. Early volume expansion decreases the detrimental renal effects of heat stroke. Adult respiratory distress syndrome requires ongoing respiratory support. Myocardial injury may also occur. The presence of hypotension, low cardiac output, and a falling cardiac index is associated with a poor prognosis. Seizures may occur during cooling and can be controlled with benzodiazepines. Mortality correlates with the degree of temperature elevation, time to initiation of cooling measures, and the number of organ systems affected. In one prospective cohort study, the risk of death increased substantially in patients who presented with anuria, coma, or cardiovascular failure. DISPOSITION AND FOLLOW-UP OF HEAT EMERGENCIES Patients with minor heat emergency syndromes (heat edema, heat cramps, or heat stress) require only ED treatment along with clear dis charge instructions and outpatient follow-up. However, patients with underlying diseases, such as congestive heart failure or renal failure, and patients with severe electrolyte imbalance may require hospital admis sion. No decision rules exist to guide disposition decisions. Patients with heat stroke require admission to a unit providing care at a level appropriate to the patient’s condition. Patients who are intubated, are in hemodynamically labile condition, require invasive hemodynamic monitoring, or need continued cooling should be admitted to the intensive care unit. If the receiving healthcare facility is unable to provide the services needed for quality care, then transfer the patient to a higher-level facility. SPECIAL POPULATIONS The elderly have a higher mortality rate and suffer more complications with heat stroke. 7,8,15 Elderly persons who lack mobility, have preexisting medical illness, take medications that may affect thermoregulation or ambulation, live in housing that is without thermal insulation, or sleep on the top floor are particularly susceptible to heat stress. Y oung children lack adequate thermoregulatory and sweating capabilities, do not instinctively replace their fluid losses or limit exercise in extreme heat, and may be unable to remove themselves from risky environments such as a closed car in the sun. Teenagers and preadolescents are at risk because they may use poor judgment when exercising in high heat and humidity and may push themselves to the limit. Early season high school heat stroke deaths are most likely to occur during the first 4 days of practice; children require 10 to 14 days to achieve an appropriate acclimatization response.

ents are at risk because they may use poor judgment when exercising in high heat and humidity and may push themselves to the limit. Early season high school heat stroke deaths are most likely to occur during the first 4 days of practice; children require 10 to 14 days to achieve an appropriate acclimatization response. PREVENTION The Centers for Disease Control and Prevention has tips for the prevention of heat illness, 24 and the National Athletic Trainers’ Association published a position statement that details prevention strategies.13 General recommendations for the individual include (1) decreasing or rescheduling strenuous activity for cooler parts of the day; (2) wear ing light and loose-fitting clothing; (3) increasing carbohydrate intake and decreasing protein intake to decrease endogenous heat production; (4) drinking plenty of fluids, even when not thirsty; (5) avoiding alco holic beverages; (6) using salt tablets as well as fluids; (7) avoiding direct sunlight; and (8) taking advantage of the shade. Community health officials and governmental leaders should recognize the need to educate the public, coordinate and plan the implementation of these measures in advance, and avoid resorting to crisis management. REFERENCES The complete reference list is available online at www.TintinalliEM.com. Bites and Stings Aaron Schneir Richard F. Clark INTRODUCTION AND EPIDEMIOLOGY The phylum Arthropoda is the largest division of the animal kingdom. The phylum includes insects (bees, wasps, hornets, flies, mosquitoes, bedbugs, fire ants, caterpillars, fleas), arachnids (spiders, scorpions, chiggers, ticks), and crustaceans (shrimp, lobsters, crabs). Venomous bites and stings from arthropods are a significant worldwide problem. In the United States, anaphylactic reactions to Hymenoptera stings account for the most fatal arthropod envenomations, although exposures to all arthropods can result in potential emergencies. This chapter discusses the most common and serious arthropod bites, stings, and envenom ations. Tick bites are discussed in Chapter 161, “Zoonotic Infections. ”  WASPS, BEES, AND ANTS (HYMENOPTERA) Wasps, bees, and ants belong to the order Hymenoptera. More fatalities result from stings by these insects than by stings or bites by any other insect. There are three major subgroups or “superfamilies” of medical importance: (1) Apidae, which includes the honeybee and bumblebee; (2) Vespidae, which includes yellow jackets, hornets, and wasps; and (3) Formicidae, or ants. BEES AND WASPS Honeybees and bumblebees are usually docile, stinging only when pro voked. A female honeybee is capable of stinging only once (male bees have no stinger) because its stinger has multiple barbs that cause the sting apparatus to detach from the bee’s body, leading to evisceration and eventual death. Africanized honeybees, or so-called “killer bees, ” are now found in many of the southern and warmer regions of the United States, includ ing Arizona, California, Nevada, New Mexico, and Texas. These bees are hybrids of African bees that escaped from laboratories in Brazil during the 1950s and have successfully spread northward along the coasts and temperate regions of the continent. Their venom is no more toxic than that of their American counterpart, but Africanized hybrid honeybees are much more aggressive and more likely to attack in swarms. An attack from Africanized bees can lead to massive stinging, resulting in multi system damage and death from severe venom toxicity. 1,2 Most of the allergic reactions reported each year due to Hymenoptera occur from wasp, hornet, and yellow jacket stings. These arthropods typically nest in the ground (yellowjackets) in trees and shrubs (hornets) or in walls (wasps).

ve stinging, resulting in multi system damage and death from severe venom toxicity. 1,2 Most of the allergic reactions reported each year due to Hymenoptera occur from wasp, hornet, and yellow jacket stings. These arthropods typically nest in the ground (yellowjackets) in trees and shrubs (hornets) or in walls (wasps). They have volatile tempers and may be disturbed by work taking place around the nest. As with bees, only the females have adapted a stinger from the ovipositor on the posterior aspect of the abdomen. Although vespids also possess barbed stingers, they can withdraw their stingers from the victim, which permits multiple stings. Hymenoptera venom contains several components. 3 Although hista mine is one component, other substances are now recognized as more important. Melittin, a known membrane-active polypeptide that can cause degranulation of basophils and mast cells, constitutes >50% of the dry weight of bee venom. Protein enzymes such as phospholipase and hyaluronidase may account for most systemic reactions. 4,5 Because all Hymenoptera share many of these components, cross-sensitization may occur in individuals allergic to one species.  CLINICAL FEATURES The most common response to a Hymenoptera sting is a transient local reaction that can last up to several days and generally spontaneously resolves. Localized itching, pain, erythema, and swelling are common. CHAPTER Tintinalli_Sec16_p1333-1418.indd 1350 8/2/19 8:23 PM

duals allergic to one species.  CLINICAL FEATURES The most common response to a Hymenoptera sting is a transient local reaction that can last up to several days and generally spontaneously resolves. Localized itching, pain, erythema, and swelling are common. CHAPTER Tintinalli_Sec16_p1333-1418.indd 1350 8/2/19 8:23 PM CHAPTER 211:  Bites and Stings      1351 Large local reactions can increase in size over 1 to 2 days and may take 3 to 10 days to resolve, and lymphangitis may develop even in the absence of infection.6 A local reaction occurring in the mouth or throat can produce airway obstruction. Stings around the eye or on the lid may result in the development of an anterior capsule cataract, atrophy of the iris, lens abscess, globe perforation, glaucoma, or refractive changes. Anaphylaxis Symptoms range on a continuum. Most reactions develop within the first 15 minutes, and nearly all occur within 6 hours. Initial mild symptoms may progress swiftly to shock. There is no correlation between systemic allergic reaction and the number of stings. Symptoms include nausea, vomiting, and diarrhea; lightheadedness and syncope; involuntary muscle spasms; edema without urticaria; and, rarely, seizures. Respiratory distress and cardiac arrest can result. Urticaria and bron chospasm do not need to be present. In general, the shorter the interval between the sting and the onset of symptoms, the more severe is the reaction. Fatalities that occur within the first hour after the sting usually result from airway obstruction or hypotension. Organ System Effects Renal and hepatic failure and disseminated intravascular coagulation can result from massive bee stings. Creatine phosphokinase concentrations can reach 100,000 IU/L or greater in cases in which rhabdomyolysis occurs from direct venom toxicity. 2 Toxic reactions are believed to occur due to a direct multisystem effect of the venom. Symptoms usually subside within 48 hours, but may last for several days in severe cases, and some effects, such as rhabdomyolysis, can be delayed. We recommend hospital admission or observation for victims with large numbers of stings, for those with substantial comor bidities, and for those at extremes of age. Delayed Reaction A delayed reaction may appear 5 to 14 days after a sting and consist of serum sickness–like signs and symptoms of fever, malaise, headache, urticaria, lymphadenopathy, and polyarthritis. 7 Frequently, the patient has forgotten about the encounter and is puzzled by the sudden appearance of symptoms. This reaction is believed to be immune complex mediated. Unusual Reactions Infrequently, a reaction to Hymenoptera venom produces neurologic, cardiovascular, and urologic symptoms, with signs of encephalopathy, neuritis, vasculitis, and nephrosis. Guillain-Barré syndrome has been reported as a possible consequence of a Hymenop tera sting. Identification of the offending insect can be difficult, except for the honeybee, which predictably leaves its stinger with venom sac attached in the lesion. In general, definitive insect identification is unnecessary, because signs and symptoms of envenomation are similar for all species of Hymenoptera. If edema persists at the sting site, then consider secondary cellulitis. Severe local reactions on the foot or ankle can be misdiagnosed as gout if the insect sting is not visible.  GENERAL TREATMENT If the bee stinger is present in the wound, remove it. Although conventional teaching suggested scraping the stinger out to avoid squeezing remaining venom from the retained venom gland into the tissues, involuntary muscle contraction of the gland continues after evisceration, and the venom contents are quickly exhausted. Immediate removal is the important principle, and the method of removal is irrelevant.

ested scraping the stinger out to avoid squeezing remaining venom from the retained venom gland into the tissues, involuntary muscle contraction of the gland continues after evisceration, and the venom contents are quickly exhausted. Immediate removal is the important principle, and the method of removal is irrelevant. Wash the sting site thoroughly with soap and water to minimize the potential for infection. For local reactions, intermittent application of cold compresses at the site may diminish pain and swelling. Oral analgesics, including NSAIDs and antihistamines may limit discomfort and pruritus, respectively. If edema is significant, elevation and rest of the affected limb may be beneficial. Although physicians often prescribe corticosteroids for large local reactions, it is not clear there is benefit of doing so. The natural course of large local reactions is to increase in size over 1 to 2 days, take 3 to 10 days to resolve, and poten tially be associated with lymphangitic streaks; associated infections are uncommon.  ANAPHYLAXIS TREATMENT Although the initial signs and symptoms of a systemic reaction may be mild, the victim’s condition can deteriorate rapidly in a matter of min utes. Administer IM epinephrine, 0.3 to 0.5 milligram (0.3 to 0.5 mL of 1:1000 concentration) in adults and 0.01 milligram/kg in children (up to 0.3 milligram). To avoid mishaps in dosing, many EDs now stock adult and pediatric EpiPens ø , which provide a standard adult or pediatric dose (EpiPen ø , 0.3 milligram epinephrine; EpiPen-Jr ø , 0.15 milligram epinephrine for children <30 kg). Provide aggressive fluid resuscitation with crystalloids. Antihistamines, histamine-2 receptor antagonists, and steroids are also commonly given. See Chapter 14, “ Allergy and Anaphylaxis, ” for detailed discussion. Antivenoms have been studied for the treatment of mass bee attacks but are not yet commercially available.  LONG-TERM MANAGEMENT AND PREVENTIVE CARE Generally, referral to an allergist/immunologist and further testing are not recommended for localized dermal reactions, including large ones. Patients who have had an anaphylactic reaction to any stinging insect, including Hymenoptera, should (1) be educated on avoidance; (2) be prescribed, be instructed on the indications for self-administration of, and carry epinephrine; (3) be referred to an allergist/immunologist who can perform skin testing and consider initiation of venom immuno therapy; and (4) consider carrying medical identification (e.g., medical alert tag) for stinging insect hypersensitivity. Venom immunotherapy is extremely effective in decreasing the risk and degree of subsequent systemic reactions. ANTS There are five known species of fire ants ( Solenopsis) in the United States: the native species Solenopsis aurea , Solenopsis geminata, and Solenopsis xyloni, and at least two imported species, Solenopsis invicta and Solenopsis richteri. The two imported species entered the United States in the 1930s, have now become well established throughout the Gulf Coast states, and are spreading throughout the Southwest. 9 Fire ants inhabit loose dirt and breed 9 to 10 months of the year. One mature nest can produce 200,000 ants during a 3-year period, which accounts for rapid spread. The venom of the fire ant is almost entirely an insoluble alkaloid. There is possible cross-reactivity between the venoms of fire ants and those of other Hymenoptera, and individual stings may produce systemic toxicity in sensitized individuals. Fire ants are characterized by their tendency to swarm when pro voked, and they may attack in great numbers. Fire ants in a swarm most often position themselves on their victim and sting simultaneously in response to an alarm pheromone released by one or several individuals.

systemic toxicity in sensitized individuals. Fire ants are characterized by their tendency to swarm when pro voked, and they may attack in great numbers. Fire ants in a swarm most often position themselves on their victim and sting simultaneously in response to an alarm pheromone released by one or several individuals. Immobilized or elderly patients can become rapidly covered by swarms, with multiple severe stings or death. 10 Reactions to the sting include local, large local, and systemic (anaphylaxis). An immediate local reac tion typically consists of a wheal and flare and characteristically exhibits a pustule at the sting site. A large local reaction involves extension of edema, erythema, and induration from the bite site and may last sev eral days. Intense pruritus may occur with local reactions. 11 Rarely, a systemic reaction manifested by urticaria and angioedema can occur. Fatalities and other severe reactions have been reported to occur rap idly following single stings from ants, but most occur in patients with a history of prior venom allergy and prior cardiopulmonary disease, in whom injectable epinephrine was not given. 12,13 Rhabdomyolysis and renal failure have also been reported after massive fire ant stings.14 Estimated hypersensitivity to fire ant venom occurs in 16% of the general population, with some crossover with those sensitized to the stings of other Hymenoptera. Treatment of fire ant stings consists of local wound care. In systemic reactions, treat for anaphylaxis. Desensitization may be necessary in patients exhibiting potentially life-threatening reactions to these arthropods. The wearing of socks or cotton tights seems to provide more protection from fire ant stings than the use of insect repellents.  SPIDERS (ARANEAE) Although nearly 40,000 species of spiders have been described world wide, medically significant envenomations have been described in only a few dozen. Spiders are carnivores, and venom probably evolved for Tintinalli_Sec16_p1333-1418.indd 1351 8/2/19 8:23 PM

stings than the use of insect repellents.  SPIDERS (ARANEAE) Although nearly 40,000 species of spiders have been described world wide, medically significant envenomations have been described in only a few dozen. Spiders are carnivores, and venom probably evolved for Tintinalli_Sec16_p1333-1418.indd 1351 8/2/19 8:23 PM 1352 SECTION 16: Environmental Injuries TABLE 211-1 Medically Important Spider Bites and Treatment Spider Bite Features Complications Treatment Loxosceles: brown recluse spider, corner spider (worldwide distribution) Painless bite, usually firm erythematous lesion that heals with little or no scar over days to weeks Occasional hemorrhagic blister at 24 h; dermatonecrosis; systemic effects rare, mostly in children, at 24–72 h No validated treatments Widow spider: black widow, redback, button spider (worldwide distribution) Pinprick bite; pain can spread to entire extremity; target lesion 1–2 cm Acetylcholine and norepinephrine release; muscle cramps extending to trunk, back, and abdomen; hypertension, tachycardia Latrodectus  antivenom  (Merck & Co),  species  specific;  derived from  horse  serum;  Fab antivenom available  in Australia  and Mexico; Analatro ®  antivenom  in clinical trials  in United  States Armed spider: banana spider (Central and South America) Intense pain at bite site Severe pain, sympathetic and parasympathetic effects; priapism; vertigo, visual disturbances Antivenom available in Brazil Funnel-web spider (Australia) Severe pain, with wheal and erythema at site; very rapid envenomation Parasympathetic effects, muscle fasciculation; myocardial damage and pulmonary edema; cerebral edema; death can occur within minutes Compressive  elastic bandage; funnel-web spider antivenom Tarantula (worldwide) Painful bite with local erythema and edema Barbed hairs can penetrate cornea and conjunctivae; contact dermatitis from hairs Ophthalmology consult for red eye and pain Recluse spiders Areas of expansion FIGURE 211-1. Highest density range of recluse (genus Loxosceles) spiders in the United States. paralyzing prey. The vast majority of spiders pose little harm to humans because their venom-injecting fangs are too small to penetrate human skin, the amount of venom injected is too little to produce toxicity, or the venom itself has little effect on mammalian cells. Even if a reaction is elicited, it is often local, and systemic toxicity is confined to a few specific species (Table 211-1 and Figure 211-1). SPIDERS CAUSING NECROTIC ARACHNIDISM ( LOXOSCELES) Loxosceles are brown spiders that have a worldwide distribution. The highest density is shown in Figure 211-1, and of these, Loxosceles reclusa (the brown recluse spider) occupies the largest geographic area and accounts for the majority of significant envenomations. In South America, particularly Brazil, Loxosceles laeta and Loxosceles intermedia account for most significant envenomations. Envenomation outside of endemic areas is very uncommon. 16 Nocturnal Loxosceles spiders are found indoors or outdoors in dark, dry areas (e.g., basements, closets, woodpiles); they are shy but may bite when threatened. A pigmented, violin-shaped pattern on the cephalothorax of the brown recluse is often present ( Figure 211-2). However, this characteristic is consid ered unreliable and often misinterpreted. Loxosceles species are most accurately identified by their eye pattern, which consists of six paired eyes (one anterior pair and two lateral pairs); paired eyes are very close together which can give the appearance of three (rather than six) black dots. 16 Most other U.S. spiders have eight eyes arranged in two rows of four. The venom of the brown recluse contains multiple enzymes, including hyaluronidase and sphingomyelinase D, which is the major enzyme responsible for necrosis.

very close together which can give the appearance of three (rather than six) black dots. 16 Most other U.S. spiders have eight eyes arranged in two rows of four. The venom of the brown recluse contains multiple enzymes, including hyaluronidase and sphingomyelinase D, which is the major enzyme responsible for necrosis. Significant necrotic wounds are rare but possible through neutrophil activation, platelet aggregation, and thrombosis. Although both local and systemic complications of Loxosceles envenomation have been well described, the perceived threat of the brown recluse far exceeds its actual danger. For more information about recluse spiders, see the University of California, Riverside, Spider Research site (http://spiders.ucr.edu).  CLINICAL FEATURES Bites by Loxosceles spiders are described as initially painless, which often prohibits possible identification of the spider. The most common manifestation of a bite is a mild erythematous lesion that may become firm and heal with little or no scar within several days or weeks. Occasionally, a more severe local reaction occurs, beginning with mild to severe pain several hours after the bite, accompanied by localized erythema, pruritus, and swelling. A hemorrhagic blister then forms, surrounded by vasoconstriction-induced blanched skin ( Figure 211-3). By day 3 or 4, the hemorrhagic area may become ecchymotic, which leads to the “red, white, and blue” (erythema, blanching, and ecchymosis) sign. The ecchymotic area may become necrotic, with eschar formation by the end of the first week. The necrotic, slowly healing ulcers may not reach maximum size for many weeks after envenomation and Tintinalli_Sec16_p1333-1418.indd 1352 8/2/19 8:23 PM

to the “red, white, and blue” (erythema, blanching, and ecchymosis) sign. The ecchymotic area may become necrotic, with eschar formation by the end of the first week. The necrotic, slowly healing ulcers may not reach maximum size for many weeks after envenomation and Tintinalli_Sec16_p1333-1418.indd 1352 8/2/19 8:23 PM CHAPTER 211:  Bites and Stings      1353 can occasionally result in a significant cosmetic defect requiring skin grafting. Although significant systemic effects are not uncommon after bites of L. laeta, the predominant South American species, they rarely occur after bites of the brown recluse, the predominant U.S. species. Systemic effects, the hallmark of which is hemolysis, are seen more often in children and typically occur 24 to 72 hours after the bite. Other effects include nausea, vomiting, fever, chills, arthralgias, thrombocytopenia, rhabdomyolysis, hemoglobinuria, and renal failure. Disseminated intravascular coagulation and death are extremely rare. Correct diagnosis of a brown recluse envenomation without definitive spider identification is difficult. Although the presence of a consistent clinical picture in an endemic area is suggestive, it is likely that a myriad of infectious and noninfectious conditions are misdiagnosed as brown recluse bites. 16 In patients who are suspected of having been bitten and who exhibit signs and symptoms of envenomation, obtain a CBC, BUN and creatinine, and coagulation profile. Assays to detect envenomation have been used in research, but a commercial test is not currently available.  TREATMENT Treatment of a possible necrotic spider bite should include the usual supportive measures. Antibiotics are indicated if signs of infection exist, although secondary infections are uncommon. Various treatments have been advocated for brown recluse spider bites, including antihistamines, antivenom, colchicine, dapsone, hyperbaric oxygen, surgical excision, steroids, and topical nitroglycerin. None of these therapies have clear benefit, and most wounds from the brown recluse are self-limiting and heal without any medical intervention. Administration of the leukocyte inhibitor dapsone continues to be advocated by some despite lack of supporting research and known adverse effects, including hemolysis and methemoglobinemia. Early antivenom administration after envenom ation is efficacious in animal models. 17 However, antivenom’s potential utility is limited by delayed post-bite presentation, inability to identify an envenomation, and difficulty of prognosticating the (rare) develop ment of dermatonecrosis. An equine-derived antivenom is commonly used in Brazil, but its efficacy is unclear. In the United States, there is no commercially available Loxosceles antivenom. Arranging follow-up for serial wound evaluation is appropriate. If ulceration develops, referral to a surgeon is indicated. Surgical debridement should be delayed until clear margins are established, often 2 to 3 weeks after the bite. Patients with systemic symptoms following a bite warrant hospitalization. HOBO SPIDER (ERATIGENA AGRESTIS; FORMERLY TEGENARIA AGRESTIS) A native of Europe and Central Asia, the hobo or northwestern brown spider is now found in the Pacific Northwest of the United States and southern British Columbia. Hobo spiders are brown with gray markings and have a 7- to 14-mm body length and a 27- to 45-mm leg span. They live in moist, dark areas such as woodpiles and basements. Little documentation supports the occurrence of necrosis from hobo spider bites. 16 In its native European habitat, it is not considered poisonous to humans, and venom analysis comparing European to U.S. species has confirmed no unique differences. Confirmed bites have demon strated localized erythema, itching, pain, and swelling.

entation supports the occurrence of necrosis from hobo spider bites. 16 In its native European habitat, it is not considered poisonous to humans, and venom analysis comparing European to U.S. species has confirmed no unique differences. Confirmed bites have demon strated localized erythema, itching, pain, and swelling. There is no diagnostic test for hobo spider envenomation and no proven treatment. WIDOW SPIDERS (LATRODECTUS) Latrodectus or “widow” spiders have a worldwide distribution. In the United States, the black widow is the most well-known, although of the five Latrodectus species found commonly in the United States, only three (Latrodectus mactans, Latrodectus variolus, and Latrodectus hesperus) are actually black. Other varieties may be predominantly brown ( Latrodectus geometricus ) or red ( Latrodectus bishopi). An orange-red hourglass-shaped marking characterizes many of the Latrodectus species ( Figure 211-4). Female spiders are relatively large, FIGURE 211-2. Close-up look at the characteristic fiddle-shaped back marking on the brown  recluse  spider  (Loxosceles reclusa ). Note  the  eyes,  which  are  distributed  as  a  single anterior pair and two lateral pairs; the paired eyes are very close together. FIGURE 211-3. Early  brown  recluse  spider  bite  (approximately  8  hours  old)  with  a violaceous center surrounded by a faint spreading erythema. [Photograph by Lawrence B. Stack, MD. Reproduced  with  permission  from  Knoop  KJ,  Stack  LB,  Storrow  AB,  Thurman  RJ:  The Atlas of Emergency Medicine, 3rd ed, © 2009 by McGraw-Hill, Inc., New York.] FIGURE 211-4. Black widow spider (Latrodectus mactans) with offspring. Note characteristic hourglass marking on abdomen. [Photograph by Lawrence B. Stack, MD. Reproduced with permission from Knoop KJ, Stack LB, Storrow AB, Thurman RJ:  The Atlas of Emergency Medicine, 3rd ed, © 2009 by McGraw-Hill, Inc., New York.] Tintinalli_Sec16_p1333-1418.indd 1353 8/2/19 8:23 PM

tans) with offspring. Note characteristic hourglass marking on abdomen. [Photograph by Lawrence B. Stack, MD. Reproduced with permission from Knoop KJ, Stack LB, Storrow AB, Thurman RJ:  The Atlas of Emergency Medicine, 3rd ed, © 2009 by McGraw-Hill, Inc., New York.] Tintinalli_Sec16_p1333-1418.indd 1353 8/2/19 8:23 PM 1354 SECTION 16: Environmental Injuries with a body size ranging up to 1.5 cm in length and leg spans of 4 to 5 cm. The male spider is approximately one third the size of the female and lighter in color, and his bite cannot penetrate human skin. Black widow spiders are found most often in woodpiles, basements, garages, and sheds. Latrodectus will aggressively defend her web, particularly when guarding her eggs. Most black widow bites in the United States occur between April and October and are usually seen on the hands and forearms. The black widow spider injures its victim and its prey with highly potent venom. The most active component of the venom is α-latrotoxin, which acts through both calcium-dependent and calcium-independent pathways leading to receptor stimulation, pore formation, and ultimately massive release of neurotransmitters (predominantly acetylcholine and norepinephrine). 19 Acetylcholine release accounts for neuromuscular manifestations, and norepinephrine release accounts for the cardiovas cular manifestations.  CLINICAL FEATURES The severity and features of Latrodectus envenomation may vary for different widow spiders from different regions. However, in all cases, the most prominent feature of envenomation is local, regional, or generalized pain which may be associated with systemic symptoms and autonomic effects. Most Latrodectus bites are felt immediately as a pinprick sensation at the bite site, followed by increasing local pain that may spread quickly to include the entire bitten extremity. Ery thema appears approximately 20 to 60 minutes after the bite. In some bites, a small, <5-mm erythematous macule develops that may evolve into a larger target lesion with a blanched center and surrounding erythema (Figure 211-5). The clinical syndrome of envenomation is referred to as latrodectism. Victims frequently complain of cramplike spasms in large muscle groups, although physical examination of the “cramping” extremity rarely reveals rigidity. The pain often increases progressively, becomes generalized, and can involve the trunk, back, and abdomen. Localized diaphoresis near the site of envenomation can be seen. Severe abdominal wall musculature pain and cramping are well described, and in the absence of a known bite, the clinical picture can be confusing. Hypertension and tachycardia are common. Systemic symptoms include headache, nausea, vomiting, diaphoresis, photophobia, and dyspnea. Rarely reported complications include atrial fibrillation, myocarditis, priapism, and death. The pain with envenomation can be severe and intermittent and, if untreated, often lasts for a day. Occasionally, symptoms may persist for several days. Because the initial bite is typically painful with most Latrodectus species, it is common for the offending spider to be identified. In the absence of a witnessed bite, a clinical diagnosis can be made based on characteristic symptoms and signs. There is no confirmatory labora tory test. TREATMENT Cleansing of the bite site is reasonable. The optimal management of latrodectism remains controversial. 20 IV calcium had been recommended in the past, but a retrospective study did not demonstrate efficacy.21 Opioid administration is appropriate to treat pain, and benzodiazepines may also be considered. For severe envenomations, admission may be necessary to achieve adequate pain control.

odectism remains controversial. 20 IV calcium had been recommended in the past, but a retrospective study did not demonstrate efficacy.21 Opioid administration is appropriate to treat pain, and benzodiazepines may also be considered. For severe envenomations, admission may be necessary to achieve adequate pain control. Case reports, retrospective series, and anecdotal experience from those knowledgeable in managing these bites suggest efficacy of antivenom administration. 21,22 From this experience, rapid resolution of symptoms with antivenom administration and ability to discharge patients from the ED after a short observation period are possible. 21 Successful treatment of latrodectism with antivenom has been described even with administration 90 hours after envenomation.23 Additionally, case reports have detailed successful use in pregnant patients, in whom envenomation could theoretically induce preterm labor and mimic preeclampsia. 24 However, the efficacy of antivenom administra tion has been recently questioned based on two studies that, to date, are the only randomized, prospective, placebo-controlled studies using Latrodectus antivenom. In both studies, antivenom administration did not demonstrate efficacy for the primary pain endpoint chosen, although in one study, pain was more rapidly reduced than with placebo. 25,26 Latrodectus antivenom is produced in at least three countries with specificity for indigenous species: Redback ( Latrodectus hasselti) Spider Antivenom® (CSL Ltd., Melbourne, Australia), Button Spider Antivenom® (South African Vaccine Producers Institute, Edenvale, South Africa), and Antivenin Latrodectus mactans ® (Merck & Co., Inc., Whitehouse Station, NJ). It is likely that the antivenom to one species would be clinically effective in treating the bites of the others. Indications, amount, and route of administration vary according to product. Antivenin Latrodectus mactans and Button Spider Antivenom are administered IV , and Redback Spider Antivenom is typically administered by IM injection. An Australian-based study using Redback Spider Antivenom found minimal clinical difference between IV and IM routes. Anaphylaxis From Antivenom In the early years of its use, whole immunoglobulin G Antivenin Latrodectus mactans ® use in the United  States was considered safe. The only death was ascribed to administration via undiluted IV push to an asthmatic patient with known multiple medication allergies; slow administration of diluted antivenom was recommended to minimize risk. 28 However, in the past decade two additional cases of anaphylaxis to Antivenin Latrodectus  mactans ® have been described despite dilution and slow administration.29,30 In one of these cases, the anaphylaxis resulted in cardiac arrest, and despite initial successful resuscitation, the patient later died. 29 Such reactions have not been described with the Australian product that is a purified F(ab)2 antivenom. The current U.S. antivenom is available from Merck (Table  211-1). Antivenin Latrodectus Equine Immune F(ab)2 (Analatro® ), which is expected to be less immunogenic and safer than whole-antibody products, is currently commercially available in Mexico and was used in one of the randomized, placebocontrolled, double-blind studies mentioned earlier. 25 It is currently in phase III clinical trials in the United  States. The recent questions of antivenom efficacy and potential for fatal reactions, particularly with the current U.S. product, should be considered, particularly since envenomation from a Latrodectus bite is rarely life threatening itself. A thorough discussion of risk and benefits should occur with the patient. ARMED SPIDERS ( PHONEUTRIA) The armed spiders are found throughout South America and Costa Rica.

larly with the current U.S. product, should be considered, particularly since envenomation from a Latrodectus bite is rarely life threatening itself. A thorough discussion of risk and benefits should occur with the patient. ARMED SPIDERS ( PHONEUTRIA) The armed spiders are found throughout South America and Costa Rica. The majority of clinically important bites have been described in Brazil. The spiders are solitary, nocturnal, do not construct a web, and possess potent neurotoxic venom. They have been reported to hide in banana bunches during shipping and can bite workers handling these bananas at their destination. When threatened, they assume a characteristic aggressive position by raising their four front legs, displaying their fangs, bristling their leg spines, and moving to continually face their threat. The best-known armed spider, Phoneutria nigriventer (banana spider), is large, with a body size up to 3.5 cm and leg length up to 6 cm. P . nigriventer FIGURE 211-5. Black widow spider bite on the knee. [Photograph by Gerald O’Malley, DO. Reproduced with permission from Knoop KJ, Stack LB, Storrow AB, Thurman RJ: The Atlas of Emergency Medicine, 3rd ed, © 2009 by McGraw-Hill, Inc., New York.] Tintinalli_Sec16_p1333-1418.indd 1354 8/2/19 8:23 PM

o 6 cm. P . nigriventer FIGURE 211-5. Black widow spider bite on the knee. [Photograph by Gerald O’Malley, DO. Reproduced with permission from Knoop KJ, Stack LB, Storrow AB, Thurman RJ: The Atlas of Emergency Medicine, 3rd ed, © 2009 by McGraw-Hill, Inc., New York.] Tintinalli_Sec16_p1333-1418.indd 1354 8/2/19 8:23 PM CHAPTER 211:  Bites and Stings      1355 venom contains a mixture of potent neurotoxins that produce CNS, spinal cord, and autonomic effects. Most P . nigriventer bites produce no significant symptoms. Signifi cant envenomation produces local symptoms (severe pain) followed by sympathetic stimulation (tachycardia, hypertension), parasympathetic hyperactivity (nausea, vomiting, diaphoresis, salivation), spinal cord impairment (priapism), and CNS effects (vertigo, visual changes). Children and the elderly are at highest risk for serious envenomation. Pulmonary edema, shock, and death are rare. 31 Most healthy adults recover in 1 to 2 days. In most cases, supportive care is adequate. Local anesthetic infiltra tion at the bite site can control pain. A polyvalent antivenom (Instituto Butantan, São Paulo, Brazil) is available for cases of severe envenomation from P . nigriventer. FUNNEL-WEB SPIDERS ( ATRAX/HADRONYCHE) Funnel-web spiders are the deadliest spiders in the world. Fortunately, they only exist in a localized geographical location in eastern Australia, envenomations are rare (median of two per year), and no fatalities have been reported since the introduction of antivenom in 1981. 32 The spiders are so named because they construct a cylindrical web that extends into a recess, such as a burrow in the ground or a hole in a tree. Funnel-web spiders have a shiny black body and long fangs, and females can grow up to 4 cm in body length. Females stay close to their webs, but the smaller and more aggressive males tend to wander, especially during the summer following a rain. Atrax venom contains atracotoxin, which (like scorpion venom) binds to sodium channels and causes release of neurotransmitters leading to both autonomic and neuromotor effects.  CLINICAL FEATURES Atrax bites may result in local reaction with immediate pain, followed by wheal formation and surrounding erythema. Later, localized sweat ing and piloerection may be observed. The vast majority of Atrax bites do not result in significant envenomation or systemic toxicity. The onset of severe envenomation is rapid and unlikely to begin after 2 hours. 32 Symptoms and signs of systemic toxicity include perioral paresthesias, cholinergic excess (nausea, vomiting, diaphoresis, salivation, lacrimation, bronchorrhea), neuromuscular stimulation (muscle fasciculation, tremors, spasms, weakness), and CNS toxicity (altered level of consciousness). Myocardial damage with pulmonary edema may occur early after envenomation and is thought to be from massive cat echolamine release. 33 Death after Atrax robustus envenomation has been reported as a result of cardiac arrest, hypotension, or pulmonary failure occurring between 15 minutes and 3 days after a bite.  TREATMENT To reduce venom absorption and systemic toxicity from a bite on an extremity, apply a compressive elastic bandage to the entire length of the limb, and splint the extremity to prevent movement. 34 Immobilize the victim and transport promptly to the hospital. The specific treatment for systemic toxicity is Funnel-Web Spider Antivenom® (CSL Ltd., Melbourne, Australia). If the patient has signs of systemic toxicity upon arrival or develops them after the compressive elastic bandage is carefully removed, antivenom should be administered until symptoms improve. Antivenom appears effective in reversing many of the manifestations of envenomation and appears to improve mortality.

stralia). If the patient has signs of systemic toxicity upon arrival or develops them after the compressive elastic bandage is carefully removed, antivenom should be administered until symptoms improve. Antivenom appears effective in reversing many of the manifestations of envenomation and appears to improve mortality. It does not appear effective in reversing cardiac damage. Supportive therapy for hypotension (IV fluid), bronchorrhea (atropine), tremors and agitation (benzodiazepines), and hypertension and tachy cardia (β-blockers) may be necessary. TARANTULAS (THERAPHOSIDAE) Tarantulas are large, hairy spiders belonging to the family Theraphosidae that are popular as pets. The hairs found on the abdomen of most species of tarantulas in North and South America resemble a velvety covering and are used defensively. When threatened, tarantulas may flick these hairs a short distance with their two back legs. Although North American tarantula hairs rarely penetrate human skin, the hairs can imbed deeply into the conjunctiva and cornea and can cause inflammation in all levels of the eye, from conjunctiva to retina. Patients who manifest a red eye and pain after handling a tarantula should be examined to determine if offending barbed hairs are present in the cornea or conjunctiva. Although hairs are sometimes easily seen on slit-lamp examination, they may at times be very difficult to detect. Therapy includes surgical removal of the hairs and topical application of steroids to control inflammation. Ophthalmia nodosa is a granulomatous, nodular reaction that can occur in cases of ocular exposure to tarantula hairs. 35 Patients may also develop a diffuse contact dermatitis from indirect exposure to hairs while cleaning a tarantula cage. Tarantula bites occasionally occur from North and South American species, leading to localized pain and swell ing. Systemic symptoms from these species are rare. Certain Old World tarantulas in Africa and Asia, which may lack protective urticating hairs, can cause severe and persistent pain from envenomation. OTHER SPIDERS Y ellow sac spiders (Cheiracanthium) are medium-sized, typically yellow spiders that have a worldwide distribution. A few species are commonly found in homes. The most common symptom of a bite is local sharp pain. Minor erythema, swelling, and pruritus may occur at the bite site. Dermatonecrotic lesions are rare. Wolf spiders (Lycosa) are small- to medium-sized (3- to 5-mm body length) ground-dwelling spiders with a worldwide distribution. The venom produces local pain and occasionally induration and erythema, but no systemic symptoms and no skin necrosis. Jumping spiders (family Salticidae) are typically small (<15 mm), brightly colored, and very active spiders with a worldwide distribution. A bite may produce pain, swelling, pruritus, and erythema with resolu tion in 2 days. Daddy long-legs spiders (family Pholcidae) are common cellar and outbuilding dwellers along the Pacific coast and in southwestern deserts. There are no case reports of human envenomation.  SCORPIONS (SCORPIONIDAE) Scorpions have a worldwide distribution, and highly toxic species are found in Africa, India, Mexico, North Africa, South America, the Middle East, and the Caribbean island of Trinidad. The toxins of the Centruroides and Parabuthus scorpions exhibit primarily neuromuscular effects, but toxins of the Androctonus, Buthus, and Mesobuthus scorpions exhibit cardiovascular effects. 38 Several species of scorpions are found in the warmer parts of the southern United States, but most species cause little more than localized pain. In the United States, only Centruroides sculpturatus (bark scorpion), found throughout Arizona, New Mexico, and parts of Texas and California, possesses venom potent enough to cause systemic toxicity.

ns are found in the warmer parts of the southern United States, but most species cause little more than localized pain. In the United States, only Centruroides sculpturatus (bark scorpion), found throughout Arizona, New Mexico, and parts of Texas and California, possesses venom potent enough to cause systemic toxicity. CLINICAL FEATURES Most stings cause localized pain at the bite site, and systemic toxicity occurs in <10% of stings. Scorpion venom contains many toxins, but the toxins with the most serious medical effects can open neuronal sodium channels and cause prolonged and excessive depolarization. Somatic and autonomic (parasympathetic and sympathetic) systems are affected (Table 211-2). Infants and young children are at highest risk for severe systemic symptoms , which can be life threatening. Motor hyperactivity is nearly universal when symptoms are systemic and may present as restlessness or uncontrollable jerking of the extremities that appears to be seizure-like activity. Peripheral nervous system toxicity includes abnormal oculomotor function, loss of pharyngeal muscle control, uncoordinated neuromuscular activity with respiratory com promise, and tongue fasciculations. Hypersalivation is common and, combined with cranial nerve dysfunction, can threaten airway integrity. Cardiovascular toxicity from systemic envenomation includes tachycardia, hypertension, pulmonary edema, and cardiogenic shock. Tintinalli_Sec16_p1333-1418.indd 1355 8/2/19 8:23 PM 1356 SECTION 16: Environmental Injuries TABLE 211-2 Scorpion Sting Effects and Treatment Clinical Effect Pathophysiology Treatment Comments Local effects only Pain at sting site Acetaminophen, NSAID, local lidocaine without epinephrine at sting site

CLINICAL FEATURES Most stings cause localized pain at the bite site, and systemic toxicity occurs in <10% of stings. Scorpion venom contains many toxins, but the toxins with the most serious medical effects can open neuronal sodium channels and cause prolonged and excessive depolarization. Somatic and autonomic (parasympathetic and sympathetic) systems are affected (Table 211-2). Infants and young children are at highest risk for severe systemic symptoms , which can be life threatening. Motor hyperactivity is nearly universal when symptoms are systemic and may present as restlessness or uncontrollable jerking of the extremities that appears to be seizure-like activity. Peripheral nervous system toxicity includes abnormal oculomotor function, loss of pharyngeal muscle control, uncoordinated neuromuscular activity with respiratory com promise, and tongue fasciculations. Hypersalivation is common and, combined with cranial nerve dysfunction, can threaten airway integrity. Cardiovascular toxicity from systemic envenomation includes tachycardia, hypertension, pulmonary edema, and cardiogenic shock. Tintinalli_Sec16_p1333-1418.indd 1355 8/2/19 8:23 PM 1356 SECTION 16: Environmental Injuries TABLE 211-2 Scorpion Sting Effects and Treatment Clinical Effect Pathophysiology Treatment Comments Local effects only Pain at sting site Acetaminophen, NSAID, local lidocaine without epinephrine at sting site Dermatonecrosis over hours or days Local necrosis, in 20% systemic features, myoglobinuria; similar to Loxosceles spider envenomation Habromys lepturus of Iran Tachycardia, hypertension, mydriasis Excess catecholamines Antivenom*; prazosin Agitation and anxiety Neuromuscular agitation Benzodiazepines Pulmonary edema Catecholamine-induced cardiac injury, myocardial depression; cardiogenic shock Antivenom*; nitroglycerin or prazosin†; dobutamine† for cardiogenic shock Androctonus, Buthus, Mesobuthus, and Tityus scorpions Hypotension, bradycardia, salivation, sweating, abdominal pain, diarrhea, pancreatitis Cholinergic effects Atropine Tityus species Oculomotor abnormalities, uncoordinated neuromuscular activity, muscle spasms Neuromuscular excitation Antivenom*; benzodiazepines Centruroides scorpions, also Parabuthus and Tityus Multiorgan failure     Supportive care *Role of antivenom not clear once systemic toxicity established, as antivenom binds toxin but does not reverse established injury. †Role of vasodilators not clear; concern if using vasodilators with dobutamine. DIAGNOSIS AND TREATMENT Diagnosis is clinical. Laboratory studies are needed in severe envenom ation to identify organ system involvement. Treatment is described in Table 211-2. Administer opioids for pain control and short-acting benzodiazepines for sedation as needed. Scor pion antivenom directed against different species has been produced for research or clinical use in many other countries. Recommendations for use and dosing of these products vary widely. Like all animal-derived antivenom, both immediate and delayed allergic reactions, including serum sickness, are possible. A randomized, double-blind study from Arizona in children suffering from significant neurotoxic effects of Centruroides stings demonstrated that an equine-derived IV scorpionspecific antibody F(ab′) 2 resolved the clinical syndrome within 4 hours and significantly reduced the need for concomitant sedation. 39 The antivenom used, Anascorp® , is available for use in the United States but is currently quite expensive, and therefore, use should be restricted to patients with severe systemic symptoms. The most dangerous clinical manifestation of scorpion envenomation worldwide is acute heart failure and pulmonary edema. It remains unclear whether an initial massive catecholamine release and myocardial stunning is universally responsi ble for this. 40,41 It may be that in certain species, direct cardiotoxic effects of the venom can occur. Administration of the vasodilator prazosin is advocated to counteract the initial adrenergic response, and dobutamine administration may be appropriate to support cardiac dysfunction.  CHIGGERS (TROMBICULIDAE) Chigger infestations result from mite larvae feeding on host skin cells. Mites are found in almost every habitat and are 0.3 to 1.0 mm in length. The larvae attach themselves to host skin with mandibular structures. They tend to attach in areas where an obstacle such as tight-fitting clothing is met, such as at the tops of socks, the leg bands of underwear, the waistband, or the edges of a bra. Once attached, the larvae release digestive enzymes to liquefy epidermal cells. The combination of digestive enzymes secreted by the mite and subsequent host immune response produces the “chigger bite.

tting clothing is met, such as at the tops of socks, the leg bands of underwear, the waistband, or the edges of a bra. Once attached, the larvae release digestive enzymes to liquefy epidermal cells. The combination of digestive enzymes secreted by the mite and subsequent host immune response produces the “chigger bite. ” CLINICAL FEATURES Although diseases such as rickettsialpox and scruff typhus have been spread by mite vectors, the major clinical manifestation of chigger infestation is most often intense pruritus. The attached chigger may be seen initially as a bright red fleck on the skin, and it, along with the larvae, may be easily scratched off. Lesions are intensely pruritic and often appear as grouped papules or papulovesicles. The localized allergic response may last for weeks, and significant excoriation may occur at the site from intense scratching. A summer penile syndrome in children has been attributed to chiggers that manifests with acute swelling of the penis, often accompanied by pruritus. 42 The diagnosis of chigger infes tation may be difficult, because many other arthropods cause similar clinical manifestations. The history of outdoor exposure combined with the presence of signs and symptoms localized to areas of snug-fitting clothing may be helpful. TREATMENT Treatment is primarily symptomatic to control the itching and consists of oral antihistamines and topical steroids. Oral steroids may be helpful in severe cases. Chiggers themselves may be killed with permethrin and other topical scabicides. If secondary infection occurs, antibiotics are indicated.  MOSQUITOS, FLIES, FLEAS, AND LICE MOSQUITOES Mosquitoes penetrate skin with the piercing motion of a bayonet-like proboscis. The actual puncturing of the skin surface causes minimal trauma and frequently is not felt by the host. A local anesthetic is injected into the wound that causes local tissue damage and local hypersensitivity. Bites can lead to both immediate and delayed reactions. An immediate skin reaction includes redness, a wheal, and itching. A delayed reaction can occur and usually consists of edema and pruritus. The immediate reaction tends to be of short duration, whereas a delayed reaction may persist for hours, days, and even weeks. Severe local reactions with skin necrosis are possible. Patients can acquire allergy to mosquito saliva constituents and develop symptoms consisting of an escalating reaction to seasonal exposures with increasingly pronounced edematous and pruritic lesions, sometimes accompanied by fever, malaise, generalized edema, severe nausea and vomiting, and necrosis with resulting scarring. Treatment is symptomatic with antihistamines and NSAIDs. The greatest danger from mosquitoes is the transmission of disease. Even with extensive pest control programs, arbovirus infections and malaria are epidemic in many parts of the world. Chikungunya virus, dengue, Japanese B encephalitis, yellow fever, Zika virus, and various types of equine encephalitis are among the many viruses transmitted by mosquitoes. In addition, West Nile virus can be found across North America. Malaria is also encountered frequently in patients in the United States after travel and in immigrant populations from areas where malaria is endemic. Insect repellents offer some protection from mosquito bites. Tintinalli_Sec16_p1333-1418.indd 1356 8/2/19 8:23 PM

ion, West Nile virus can be found across North America. Malaria is also encountered frequently in patients in the United States after travel and in immigrant populations from areas where malaria is endemic. Insect repellents offer some protection from mosquito bites. Tintinalli_Sec16_p1333-1418.indd 1356 8/2/19 8:23 PM CHAPTER 211:  Bites and Stings      1357 FLIES (DIPTERA) Bloodsucking flies range in size from the tiny sand fly, approximately 1 to 3 mm in length, to horseflies, which can be >2 cm. All flies stab and pierce the skin, causing some degree of pain and pruritus. Several spe cies, such as deerflies, blackflies, horseflies, and sand flies, can produce allergic reactions, although these are rarely as severe as those produced by Hymenoptera venom. There is also the possibility of myiasis (infestation of tissue with fly larvae, e.g. botfly). Although rarely acquired in the United States, patients may present with cutaneous myiasis after travel to Africa and Central and South America. The diagnosis of fly bite depends chiefly on the patient’s history and knowledge of the arthropods that frequent the area of encounter. In the case of botfly, a travel history combined with recognition of a cystic-like skin lesion on exposed skin with a central pore through which the larva breathes and excretes exudate is essential to making the proper diagnosis. Treatment for most local reactions to Diptera bites is symptomatic, and treatment of systemic reactions is the same as for reactions to Hyme noptera venom. Application of cold compresses may alleviate localized edema. Secondary infection of Diptera bites can occur, and antibiotics may be necessary in some cases. Oral antihistamines may be helpful in relieving pruritus from fly bites, but topical steroids can be used when local reactions are severe, and oral steroids are indicated when systemic hypersensitivity symptoms are present. Although botfly infestation is generally a self-limited condition as the larvae will eventually exit the skin spontaneously, removal is appropriate. Application of various topical agents such as petroleum jelly that suffocate the larva may entice it to leave. Incision and removal of the entire larva is also effective. FLEAS (SIPHONAPTERA) Bites of fleas, lice, and scabies mites produce lesions so similar that diagnosis is often difficult. Flea bites are frequently found in zigzag lines, especially on the legs and in the waist area. The lesions most often have a hemorrhagic-appearing center surrounded by erythematous and urticarial patches. Flea bites are usually quite pruritic, and red spots can persist at bite sites for some time. The main concern in the treatment of these bites is the possibility of secondary infection. Children may develop impetigo as a complication. The lesions should be washed thoroughly with soap and water. Chil dren with flea bites should have their fingernails cut short to prevent scratching. To relieve discomfort and itching, local application of cala mine, cool soaks, and oral or topical antihistamines may be helpful. For severe discomfort, application of a topical steroid cream or spray may be necessary. If secondary infection develops, topical or oral antibiotics may be needed. KISSING BUGS AND BED BUGS (HEMIPTERA) The order Hemiptera includes two bloodsucking families of arthropods with medical importance. These are Reduviidae (reduviids, or “kissing” bugs) and Cimicidae (“bed bugs” and their relatives). Various species of kissing bugs are found predominantly in the southern United States and Central and South America. The common name “kissing bugs” derives from their habit of feeding at night on any exposed surface of a sleeping victim, commonly the face. Bed bugs are also nocturnal feeders, and their distribution is worldwide.

ecies of kissing bugs are found predominantly in the southern United States and Central and South America. The common name “kissing bugs” derives from their habit of feeding at night on any exposed surface of a sleeping victim, commonly the face. Bed bugs are also nocturnal feeders, and their distribution is worldwide. Recently, there has been a worldwide major resurgence in bed bug infestations, particularly in developed countries. This has been attributed to immigration, international travel, and insecticide resistance. 44 Both bugs are attracted to warm bodies and hide near beds. Bed bugs are found in nearby cracks and crevices. Kiss ing bugs of Central and South America are vectors of Chagas disease (trypanosomiasis). Current evidence does not support transmission of diseases to humans by bed bugs.  CLINICAL FEATURES Bites from both bugs are typically painless. Erythematous papules, bullae, and wheals may develop. A linear bite pattern on the skin is well described with bed bugs, and telltale brown or black patterns of excrement may be found on bed linen. A thorough search of bedding and nearby cracks and crevices will often reveal the bugs. Bed bugs are notoriously difficult to eradicate. One study demonstrated the potential for ivermectin (oral antiparasitic drug) administration to help eradicate bed bugs that are feeding on the patient.  TREATMENT Treatment of both types of bites is symptomatic. Cool compresses, topical steroids, and antihistamines can be used to relieve associated pruritus. Some individuals become highly sensitive to kissing bugs and react with systemic allergic symptoms following a bite. They should be treated as previously outlined for Hymenoptera envenomation.  CATERPILLARS AND MOTHS (LEPIDOPTERA) Lepidopterism refers to the adverse effects resulting from contact with butterflies, moths, or their caterpillars. Caterpillars, the larval stage of moths and butterflies, are responsible for most symptomatic exposures. For protection, they may have either hairs or spines that can be attached to venom glands. The spines and hairs may cause mechanical irritation, whereas the venom can produce additional symptoms. Although iso lated exposures are most common, particularly in children who may be attracted to the colored or “furry” appearance of caterpillars, there are multiple species that under the right conditions can cause “epidemics” of cutaneous or systemic exposures. A couple of moth species, most nota bly the Hylesia genus in Venezuela (responsible for the “Caripito itch”), can cause local irritant or allergic reactions. CLINICAL FEATURES Most reactions to Lepidoptera are mild and self-limited. Most caterpillars are harmless to humans. Pruritus from localized “caterpillar dermatitis” and occasional diffuse urticaria are the predominant symptoms of exposures to the hairs and venom. The puss caterpillar ( Megalopyge opercularis) is found in the southeastern United States and accounts for most of the serious envenomations in this country. After initial contact, intense local burning pain, rather than pruritus, is typical. A grid-like pattern of hemorrhagic papules may be seen within 2 to 3 hours of these exposures and may last for several days. Regional lymphadenopathy is common, and the affected limb can swell. Other potential symptoms include headaches, fever, hypotension, and convulsions. No deaths have been reported. Ingestions of the hickory tussock caterpillar ( Lophocampa caryae), found in the eastern United States, have been reported, with symptoms ranging from drooling to diffuse urticaria. Spines have been visualized in the oropharynx and even the esophagus in some of these patients, requiring endoscopy to aid in removal.

ed. Ingestions of the hickory tussock caterpillar ( Lophocampa caryae), found in the eastern United States, have been reported, with symptoms ranging from drooling to diffuse urticaria. Spines have been visualized in the oropharynx and even the esophagus in some of these patients, requiring endoscopy to aid in removal. 47 Two species of Lonomia caterpillars, found primarily in Brazil and Venezuela, are capable of causing potentially fatal coagulation defects. TREATMENT Treatment is symptomatic and supportive. Spines can be removed using adhesive tape. Antipruritic or topical anesthetic preparations, topical steroids, and oral antihistamines are typically used. For symptomatic ocular and oral exposures, removal of hairs may be necessary, and endoscopy has been described. Anaphylaxis is rare but would be treated in the typical manner. An antivenom specifically for Lonomia obliqua is available in Brazil to reverse coagulopathy.  BLISTER BEETLES (COLEOPTERA) Although the order Coleoptera includes a large number and variety of beetles, clinically significant envenomation occurs only from those that contain a vesicant (blister beetles). Blister beetles are found worldwide, including the United States. The most well-known blister beetle is the “Spanish fly” (Cantharis vesicatoria), found in Spain. Tintinalli_Sec16_p1333-1418.indd 1357 8/2/19 8:23 PM