Hymenoptera (insect sting) allergy
Hymenoptera sting allergy is an IgE-mediated reaction to venom from bees, wasps, hornets, and fire ants, ranging from large local reactions to systemic anaphylaxis. Systemic reactions are treated with intramuscular epinephrine, and venom immunotherapy is the disease-modifying treatment that reduces the risk of a future systemic sting reaction to about 5 percent.
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What this article covers
- Overview
Definition: Hymenoptera sting allergy is an IgE-mediated hypersensitivity to insect venom from bees, wasps, hornets, yellow jackets, and fire ants.
- Epidemiology
Common exposure, variable sensitization: stings are frequent, but systemic allergy affects a minority.
- Risk factors
Prior systemic sting reaction: the strongest predictor of future anaphylaxis.
- Pathophysiology
IgE sensitization: an initial sting sensitizes the patient, producing venom-specific IgE on mast cells.
- Clinical features
Normal local reaction: transient pain, swelling, and redness at the site.
- Differential diagnosis
Large local reaction versus cellulitis: immediate swelling peaking over 1 to 2 days suggests allergy, whereas warmth, fever, and spreading erythema over days suggest infection.
- Diagnosis
Establish with a systemic-reaction history plus venom sensitization testing: the diagnostic basis is a clinical history of a systemic sting reaction confirmed by a positive venom skin test or…
- Management
First, treat a systemic reaction as anaphylaxis: epinephrine 0.3 to 0.5 mg IM into the anterolateral thigh, repeated every 5 to 15 minutes, with oxygen, IV fluids, and airway support.
- Complications
Fatal anaphylaxis: the principal danger, especially in adults.
- Prognosis
Excellent with venom immunotherapy: the risk of a future systemic reaction falls to roughly 5 percent, and protection often persists after a completed course.
- Prevention
Venom immunotherapy for patients with a systemic reaction and confirmed sensitization, continued for 3 to 5 years, is the definitive preventive measure.
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