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Hymenoptera Stings

The insect order Hymenoptera includes the stinging ants, bees, and wasps, which are characterized by the presence of a modified ovipositor (stinger) at the end of the abdomen through which venom is injected. Various members of the order can be found throughout the world.

Venoms and Effects

Hymenoptera venoms, mixtures of proteins and vasoactive substances, are not very potent. Most stings result in only local pain, redness, and swelling, followed by itching and resolution. Some patients experience a large local reaction in which swelling progresses beyond the sting site, possibly involving the entire extremity. Approximately 0.4-0.8% of children are at risk for acute, life-threatening reactions due to hymenoptera venom sensitivity. Each year, an estimated 50-150 people in the USA die of allergic anaphylaxis caused by hymenoptera stings (Chapter 64). Rare cases of delayed serum sickness can follow hymenoptera stings. Finally, with the spread of Africanized honey bees (Apis mellifera scutellata), massive stinging episodes resulting in systemic venom toxicity (hypotension, respiratory failure, shock, hemolysis, and renal failure) appear to be increasing in Latin America and the southwestern U.S. states.

Management

Children with typical local reactions can be treated with application of cold compresses and with analgesics and antihistamines as needed. Children with large local reactions should also receive a 5-day course of oral corticosteroids and a prescription for an epinephrine autoinjection kit (and instructions in its use) prior to discharge. Patients presenting with urticaria, angioedema, wheezing, or hypotension should be treated aggressively for an immediate hypersensitivity reaction with intramuscular epinephrine (0.01 mg/kg, up to 0.3-0.5 mg of 1 : 1000 formulation), airway management as needed, oxygen, intravenous fluids, antihistamines, and corticosteroids. Children suffering massive stinging episodes should undergo treatment similar to that for allergic anaphylaxis.

Disposition

Children with local reactions (limited or large local) can be discharged with continued care as outlined previously and instructions for wound precautions. More difficult disposition decisions are involved for children with systemic manifestations. Children with only diffuse urticaria, who are stable after a period of observation, can be discharged in the care of a responsible adult to continue antihistamines and steroids and to carry an epinephrine self-administration kit. These children seem to be at little risk for progressing to systemic anaphylaxis with future stings. Children suffering more than simple hives (e.g., wheezing, evidence of laryngeal edema or cardiovascular instability) should be admitted for 24 hr of observation and should receive a referral to an allergist for testing for hymenoptera venom sensitivity and possible immunotherapy. Immunotherapy reduces the risk of systemic anaphylaxis from future stings in high-risk patients from somewhere between 30 and 60% to less than 5%.

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