Insect Allergy

Systemic reactions to insect stings are reported by 3% of adults and can be fatal even on the first reaction. Large local reactions are more frequent than systemic reactions, but rarely dangerous. The chance of a systemic reaction to a sting is low (5-10%) in children and adults with a history of large local reactions and in children with mild (cutaneous) systemic reactions, and varies between 30% and 65% in adults with previous systemic reactions, depending on the severity of previous sting reactions. Venom sensitization can be detected in 20% of normal adults, so the history is most important in clinical evaluation. Venom skin tests are most sensitive for diagnosis but the serum-specific IgE test is an important complementary test. The level of venom-IgE detected by the skin test or serum test does not, however, reliably predict the severity of a sting reaction. Baseline serum tryptase is elevated in many patients with sting anaphylaxis, and should be evaluated as a predictor of severe reactions. Venom immunotherapy is safe and is 75-98% effective in preventing sting anaphylaxis; it also significantly reduces the risk of large local reactions. Most patients can discontinue treatment after 5 years, with very low residual risk of a severe sting reaction.