Stinging insect allergy

Insect sting anaphylaxis is a relatively common problem estimated to affect at least 0.4% of the population and is responsible for at least 40 deaths per year in the United States. The allergic reactions are mediated by IgE antibodies directed at constituents in honeybee, yellow jacket, hornet, and wasp venoms. In addition, increasing numbers of reactions occur from fire ant stings, non-winged Hymenoptera present in the Southeastern United States. The anaphylactic symptoms are typical of those occurring from any cause. Most reactions in children are mild, frequently involving dermal manifestations (hives, edema) only. The more severe reactions, such as shock and loss of consciousness, can occur at any age but are relatively more common in adults. Following sting anaphylaxis, approximately 50% of unselected patients will continue to have allergic reactions to subsequent stings. The natural history of the disease process is influenced by the severity of the anaphylactic symptoms. Children with dermal reactions only have a benign course and are unlikely to have recurrent reactions. Patients with more severe reactions are at risk for repeat anaphylaxis. Patients with a history of insect sting anaphylaxis and positive venom skin tests should have epinephrine available and are candidates for subsequent venom immunotherapy, which provides almost 100% protection against subsequent re-sting reactions. Recommendations for the duration of immunotherapy are evolving. Venom therapy can be stopped if skin test reactions become negative. For most patients, 3 years of therapy appears adequate, despite persistence of positive venom skin tests.