ABSTRACT
Hymenoptera venom extracts are used for diagnostic testing, both in vivo and in vitro, and as allergy vaccines for venom immunotherapy (VIT) to prevent anaphylactic reactions to stinging insects. Intradermal venom skin tests and serum venom-specific IgE are complementary tests in patients with a history of anaphylaxis. VIT is indicated to reduce the risk of reaction from about 50% to less than 5% for vespids (yellow jacket, hornet, wasp) and less than 15% for honeybee. Baseline serum tryptase should also be measured because more than 10% of cases have an underlying mast cell disorder that is associated with greatly increased risk. VIT usually begins with weekly injections for 2–6 months, but the full dose can be achieved in a few days with a rush regimen that is equally safe and effective. Maintenance doses are given monthly but can be increased to 2–3 months over several years. VIT can be discontinued after 5 years in most patients with less than 3% chance of anaphylaxis to a future sting. Some patients have high-risk factors and should not stop VIT because they have more than 30% chance of anaphylaxis. Anaphylaxis can also occur from stinging ants, most commonly imported fire ants (IFAs, Solenopsis spp.) in the United States and other parts of the world. Other species of ants can also cause anaphylaxis. Purified venom extracts are not available for IFA, but whole-body extracts contain sufficient allergen to be useful for diagnosis and immunotherapy. There are fewer studies of IFA immunotherapy, but recommendations are generally extrapolated from the experience with VIT.
