Yellowjackets, hornets, and true wasps are part of the Vespidae family. They tend to be more aggressive than bees and can sting multiple times. The Formicidae family includes fire ants, harvester ants, jack jumper ants, bulldog ants, and others. Mounds may contain between 80,000 and 250,000 ants. The red imported fire ant, Solenopsis invicta , originally migrated from South America and entered the U.S. in the 1930s. It is arguably the most medically important of the ants, both because of its potency and its aggressive behavior. The black imported fire ant, S. richteri, and the native Southern fire ant, S. xyloni, are also implicated in many envenomings. Figure 21. Red Imported Fire Ant (Solenopsis Invicta)
ant venom, which causes cell death and hemolysis and, in rodent models, can also produce cardiotoxicity, seizures, and respiratory depression. There are also various allergens that often produce no effects but can precipitate anaphylaxis in predisposed victims. Envenomations are exceptionally common and usually well tolerated. Minor local reactions include swelling extending 1–5 cm from the injection site. Onset is within minutes and typically lasts less than 24 hours. Approximately 10% of victims have more exaggerated local findings, and swelling may extend to 10 cm or more. Rhabdomyolysis may develop. Systemic toxicity may present with urticaria, tachycardia, hypotension, laryngeal edema, facial swelling, nausea, vomiting, and diarrhea. Renal failure may result from volume loss and/or rhabdomyolysis. Allergic reactions, which may affect up to 6% of the population, are often clinically indistinguishable from severe envenomations. However, the former may develop following a single sting in a susceptible victim. The latter typically requires more than 20 stings per kilogram of body weight, which is considered the minimum dose to kill 50% of victims. An important consideration in prehospital management of hymenoptera envenomations is ensuring your own safety. Because many hymenopterans are aggressive and will swarm, potential rescuers should not enter the vicinity without appropriate protective clothing. Heavy turnout gear worn by firefighters and EMS personnel can provide good protection so long as a properly fitting bee veil is also used. Hazardous material suits can also be used. Management of hymenoptera stings is primarily supportive. Ensure airway and breathing. Establish IV access. Apply cool compresses to the injection site. Aggressive fluid resuscitation may be needed to treat hypotension. Consider epinephrine for refractory hypotension. Provide analgesia with parenteral opioids. There is no role for any type of constrictive bandage or electrical therapy. There is also no urgency to remove any stingers; the venom sacs attached to the stinger empty their contents within the first 30–60 seconds. Stinger removal can be performed after any other medical conditions have been addressed. Diphenhydramine may be used to treat mild allergic reactions, but severe allergic reaction should be treated like anaphylaxis with epinephrine.
Source: Spencer Greene Between 2015 and 2017, there an average of 3,945 exposures were attributed to various hymenopterans, with 20% involving children younger than age six years old 1-3 A total of six fatalities were reported. An additional 41 victims had major effects. Hymenoptera venom is introduced through a stinger and comprises a complex mixture of toxins such as hyaluronidase and phospholipases A 2 that can cause edema, pain, and activation of the complement cascade. Bradykinin-like peptides can produce significant angioedema and vasodilation. Mellitin is the principal component of bee venom and acts as detergent to disrupt cell membranes, releasing potassium and biogenic amines. Wasp venom may contain mastoparan, which enhances histamine release, and antigen 5, which is implicated in many allergic reactions. Alkaloids such solenopsin are the major constituents of
CATERPILLAR ENVENOMATIONS
Lepidoptera is an order of insects that includes butterflies and moths, including their larval stage, caterpillars. There are more than 150,000 species worldwide. In the U.S, at least 50 species are technically venomous, and several can cause medically significant envenomings. 70 Arguably the most dangerous of the lepidopterans is the puss caterpillar, Megalopyge opercularis , which is widely distributed throughout the southern U.S. Also known as an asp, wooly asp, southern flannel moth , and wooly slug , these small, white, furry-appearing caterpillars cause envenomations throughout the year, with peaks in late spring and late autumn. Other potentially dangerous caterpillars include the spiny oak slug ( Euclea delphinii ), stinging nettle caterpillar ( Darna pallivitta ), and stinging rose caterpillar ( Parasa indetermina ). A total of 5,160 caterpillar envenomations were reported to the AAPCC between 2015 and 2017. 1-3 Out of these, 1,342 (26%) affected children younger than age six years. Individuals younger than age 20 years old for 2,473 (47.9%) stings. There was one patient with major effects and no fatalities.
Figure 22. Puss Caterpillar (Megalopyge Opercularis)
Source: Spencer Greene Caterpillar venom contains proteases, hyaluronidase, phospholipases A 2 , esterases, and kinins. 71 The venom is stored in spicules located just below the hairs of the caterpillar. There may be several thousand spicules on a single caterpillar. When there is contact with the spicules, they break, depositing the venom into tissue. Most caterpillar envenomings occur when someone inadvertently steps on or picks up the creature or when the caterpillar falls out of a tree and lands on the victim.
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