Advances in the Diagnosis and Treatment of Stinging Insect Allergy

Allergic reactions to insect stings occur in approximately 0.4% of the general population.1,2 Severe anaphylactic reactions may occur in sensitive patients, and estimates suggest that 40 persons die during such reactions each year in the United States.3 From the standpoint of allergy the Hymenoptera order of insects is the most important; this order includes the bees (honeybees and bumblebees), vespids (wasps, yellow jackets, and hornets), and fire ants. CLASSIFICATION OF STING REACTIONS Insect sting reactions may be grouped into immediate (within two hours) or delayed (more than two hours) categories. Immediate reactions can be subdivided into local, large local, or systemic reactions, depending on the severity and extent of the reaction. Local reactions are normal reactions—a sting will cause transient pain, redness, and swelling at the sting site. In large local reactions the reaction is much more extensive, although all signs and/or symptoms produced are contiguous with the sting site. For example, a sting on the finger may produce swelling of the entire forearm or extremity. In a systemic reaction signs and/or symptoms occur at sites remote from the sting site. For example, a sting on the finger may produce angioedema of the eyelids or generalized urticaria. Toxic reactions are nonimmunologic reactions produced when an individual is stung by multiple insects within a short period of time; signs and symptoms are those of a systemic allergic reaction, but are due to the physiologic effects of vasoactive materials in the venom. Systemic allergic reactions are immunologic reactions produced by vasoactive materials released from the blood basophils or tissue mast cells as a result of interaction between venom components and specific IgE antibodies fixed to the basophils or mast cells.