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Systemic allergic reactions to insect stings are estimated to occur in about 1 percent of children and 3 percent of adults. In children, these reactions usually are limited to cutaneous signs, with urticaria and angioedema; adults more commonly have airway obstruction or hypotension. Epinephrine is the treatment of choice for acute anaphylaxis, and self-injection devices should be prescribed to patients at risk for this allergic reaction. Stinging insect allergy can be confirmed by measurement of venom-specific IgE antibodies using venom skin tests or a radioallergosorbent test. Patients with previous large local reactions have a 5 to 10 percent risk of experiencing systemic reactions to future stings. Patients with previous systemic reactions have a variable risk of future reactions: the risk is as low as 10 to 15 percent in those with the mildest reactions and in some children, but as high as 70 percent in adults with the most severe recent reactions. Because of demonstrated efficacy (98 percent), venom immunotherapy is recommended for use in patients who are at risk for severe systemic reactions to future insect stings. Venom immunotherapy is administered every four to eight weeks for at least five years. Immunotherapy may be needed indefinitely in patients at higher risk for recurrence of anaphylaxis after treatment is stopped. (Am Fam Physician 2003;67:2541-6. Copyright(C) 2003 American Academy of Family Physicians.)
Insect stings usually cause transient local inflammation and occasional toxic reactions. However, allergic hypersensitivity can result in more severe local reactions or generalized systemic reactions.1 Large local reactions are usually late-phase IgE-mediated allergic reactions, with severe swelling (eight to 10 inches in diameter) developing over 24 to 48 hours and resolving in two to seven days. Systemic reactions also are IgE mediated and may cause one or more signs and symptoms of anaphylaxis, including generalized urticaria, angioedema, throat tightness, dyspnea, dizziness, and hypotensive shock. Compared with adults, children have a higher frequency of isolated cutaneous reactions to insect stings and a lower frequency of vascular symptoms and anaphylactic shock.2
Morbidity and mortality from insect sting anaphylaxis can be virtually eliminated by appropriate patient education about the risk of recurrent reactions and the use of preventive and protective measures. Family physicians have an important role in identifying patients who are at risk for...