INSECT STING ALLERGY

Abstract

Venom immunotherapy is highly effective prophylaxis for individuals at risk for insect sting anaphylaxis. Venom immunotherapy should be administered to all patients who have had a serious anaphylactic sting reaction (e.g., throat edema, dyspnea, hypotension, shock, loss of consciousness) and have positive venom skin tests. Children who have dermal (hives, edema) reactions only have a very benign course and do not require venom immunotherapy. Adults with similar mild sting reactions also appear to have a benign course, but data are still insufficient to recommend withholding venom immunotherapy. A positive venom skin test has been defined as a reaction to venom concentrations of 1.0 μg/mL or less. Reactions to only this top concentration of 1.0 μg/mL should be interpreted with caution, as nonspecific reactions may occur with this dose. Venom immunotherapy is usually administered with all venoms to which there is a positive skin test. Immunologic studies suggest that these multiple positive reactions are due to venom cross-reactivity. If the culprit insect can be identified, single venom therapy is effective. Recommended maintenance doses are 100 μg of single venoms and 300 μg of mixed vespid venoms. A lower dose, 50 μg of single venoms, appears to be adequate. After 1 year of therapy, the 4-week interval between maintenance doses can be extended to 6 and even 8 weeks, without loss of effectiveness or increased reactions. Recommendations for duration of therapy are evolving. Venom immunotherapy 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.