Updated Guidelines for Stinging Insect Hypersensitivity

The American College of Allergy, Asthma and Immunology (ACAAI) has updated guidelines for diagnosing and treating stinging insect hypersensitivity.RecommendationsSpecific summary statements in the Practice Parameter include the following:

• Persons who have had a systemic reaction to an insect sting are at greater risk for subsequent systemic sting reactions. Venom immunotherapy (VIT) can significantly lower this risk.
• Acute reactions to stings should be managed symptomatically:
  • Acute systemic reactions to insect stings should be treated like any anaphylactic reaction, with epinephrine injection, supportive treatment, and transport to an emergency department. Symptoms may include chest tightness; difficulty breathing; edema of the tongue, throat, nose, and lips; dizziness; and/or loss of consciousness. Complications may include shock and heart failure.
  • For patients who have a history of only cutaneous systemic reactions, antihistamines and close observation may be appropriate initial therapy for cutaneous systemic symptoms.
  • However, delaying epinephrine administration may result in fatal sting reactions.
  • For large local reactions, treatment may include antihistamines, cold compresses, and a brief course of oral corticosteroids, in severe cases. Antibiotics are usually not required.
• For patients with a suspected systemic reaction to an insect sting, consultation with an allergist-immunologist is recommended. This is especially true for patients who:
  • Need education about their risk for another reaction if they are stung, emergency and preventative treatment options, and/or how to avoid insect stings;
  • Have a comorbid condition, such as high blood pressure or pulmonary disease, or require regular use of a medication (eg, beta-blockers or angiotensin-converting enzyme inhibitors) that might complicate a potential reaction to a sting; or
  • Request referral for more detailed information or specific testing.
• Patients who have a history of systemic reactions to insect stings should:
  • Be informed regarding insect avoidance in ways to avoid insect stings;
  • Carry epinephrine and be educated regarding proper use and indications for emergency self-treatment;
  • Have specific immunoglobulin E (IgE) testing for stinging insect sensitivity;
  • Be considered for immunotherapy; and
  • Consider wearing a medical identification bracelet or necklace.
• Patients who are candidates for VIT should undergo immediate hypersensitivity skin tests to stinging insect venoms, with the following special considerations:
  • Except in special circumstances, skin tests should be used for initial measurement of venom-specific IgE, rather than in vitro assays.
  • Patients who have a severe allergic reaction but negative skin test responses at 6 weeks or longer after the sting reaction should have further testing (in vitro testing, subsequent skin testing, or both) and baseline testing of serum tryptase.
  • The degree of sensitivity shown by skin and serologic testing for venom-specific IgE does not correlate consistently with the severity of a reaction to a sting.
  • For sensitivity to imported fire ants, skin testing is performed with whole-body extracts.
• For all patients who have had a systemic reaction to an insect sting and who have specific IgE to venom allergens, VIT is recommended, with the following special considerations:
  • VIT is usually not needed in children 16 years or younger who have had cutaneous systemic reactions without other systemic findings after an insect sting.
  • The need for immunotherapy in adults who have had only cutaneous reactions to an insect sting is controversial, but these patients are usually considered candidates for VIT.
  • VIT is typically not needed in patients with only large local reactions to stings, but it may be considered in those with frequent, unavoidable exposure to stinging insects.
• All patients who have had a systemic reaction to a sting from a fire ant and who have positive skin test responses or allergen-specific serologic test results should have immunotherapy with imported fire ant whole-body extract. However, immunotherapy may be considered for children with only cutaneous manifestations who live in areas where fire ants are prevalent, because the natural history of fire ant hypersensitivity in these children has not been completely elucidated.
• VIT should usually be continued for at least 3 to 5 years once it is started. Most patients can then safely discontinue immunotherapy, but some patients may need to continue it longer or even indefinitely, based on the following:
  • High-risk factors include near-fatal reaction before or systemic reaction during VIT, honeybee allergy, increased baseline serum tryptase levels, underlying medical conditions and concomitant medications, and frequent exposure.
  • Quality-of-life considerations include limitation of activities and/or anxiety regarding being stung.
  • Optimal duration of immunotherapy with imported fire ant whole-body extracts has not been completely determined.

"There remain some unmet needs in the diagnosis and treatment of insect sting hypersensitivity," the guidelines authors write. "Improved diagnostic accuracy with better positive predictive value might await studies to validate new tests, such as those using recombinant allergens or epitopes or those designed to detect basophil activation or basophil sensitivity. Similarly, there is a need for a better predictor of relapse after stopping VIT."A complete description of the disclosures of the guidelines authors is available at the Journal of Allergy & Clinical Immunology Web site .J Allergy Clin Immunol. 2011;127:852-854.e23. Abstract