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Insect stings and bites, including toxins are discussed further in Chapter 120.

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Epidemiology

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Up to 3% of the general population has bee sting allergy.1 While fatal reactions are uncommon, most of these deaths can be avoided with appropriate treatment, including venom immunotherapy. The frequency of significant reactions to stings from hymenopterids is related to the degree of potential exposure, with up to 35% of beekeepers sensitized to hymenoptera venom and rural areas in general having much higher rates than urban areas.2

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The different families of hymenopterids have different behaviors and degrees of aggressiveness. Honeybees (Apis mellifera) are minimally aggressive and will only sting if attacked, such as being accidentally grabbed or stepped on. In contrast, yellow jackets and hornets (Vespula, Dolichovespula, and Vespa spp) are more aggressive predators and will sting with less provocation. The wasps (Polistes) are less aggressive than the vespids, but tend to build their nests near buildings and under eaves, making them more likely to encounter people and so still contribute to a large number of stings.

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Four types of reactions to hymenopterid stings occur. Most people, when stung, will develop swelling, redness, and pain at the site of the sting, with a rapid onset and resolution within hours. This reaction is expected and may be managed with ice, antihistamines, and pain relief. More significantly, some patients may develop a second type of reaction, known as large local reactions, which extend beyond the site of the sting to involve the entire limb. These reactions, with swelling, erythema, and tenderness, develop slowly, over about 48 hours, and resolve over days. Large local reactions are frequently confused with cellulitis, but they rarely become infected and they do not respond to antibiotic treatment.

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Direct toxic reactions to Hymenoptera venom can also occur with large doses. Though it is difficult to predict the number of stings at which a toxic reaction will occur, these reactions have been reported to occur in as few as 50 stings. Anyone who has sustained more than 50 stings should be monitored for the complications of Hymenoptera venom overdose, which includes rhabdomyolysis and myocardial infarction. Africanized honeybees (Apis mellifera scutellata), which are indistinguishable from ordinary honeybees and do not have more potent venom, are much more aggressive about defending their nest and territory than ordinary honeybees, making toxic envenomations much more likely. Stings from this subspecies are treated as any other toxic Hymenoptera envenomation, with supportive care and monitoring for rhabdomyolysis.

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The final type of reaction is a systemic, IgE-mediated reaction, which causes anaphylaxis. This reaction is responsible for almost all Hymenoptera sting deaths. Systemic reactions develop rapidly, usually within 30 minutes of the sting, and may consist of urticaria, angioedema, wheezing, laryngeal edema, hypotension, tachycardia, and diarrhea or vomiting. Systemic reactions can be distinguished from large local reactions by involvement of ...

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