Allergy

Stinging Insect Immunotherapy

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Stinging Insect Immunotherapy, Hymenoptera Bite Immunotherapy

  • Epidemiology
  1. Anaphylaxis to Hymenoptera bites (Stinging Insects) are responsible for at least 50 U.S. fatalities yearly
  2. Incidence of systemic reaction to Stinging Insect
    1. Adults: 3%
    2. Children: 1%
  • Background
  1. See Stinging Insect
  2. Usually only Insects of Hymenoptera cause Anaphylaxis
  3. Distinct InsectVenoms (allergy specific to types)
    1. Honeybee and Bumblebee Venom
    2. Yellow Jacket and Hornet Venom
    3. Polistes Wasp
    4. Fire ants
  • Findings
  1. Intradermal Testing
    1. Requires each venom type be tested (see background)
    2. Venom dose varies from 0.001 to 1.0 mcg/ml
    3. Do not test without history of reaction
    4. Test Sensitivity: 65-80%
      1. False Negatives: Too early after bite (<6 weeks)
  2. RAST testing
    1. May be useful to clarify Skin Testing
    2. Sensitivity level does not correlate with reaction
  • Management
  1. Acute Reactions
    1. See Stinging Insect Reaction
    2. See Anaphylaxis
    3. See Allergic Reaction
  2. Immunotherapy with venoms
    1. Protects in 98% of cases against severe reaction
    2. Mixed vespid venom higher efficacy than individual
    3. Local reactions occur in 50% of patients
      1. Most often occurs at starting doses <50 mcg
    4. Titrate up to maintenance dosing
      1. Individual venom: 100 mcg
      2. Mixed vespid venom: 300 mcg
    5. Continue maintenance for at least one year
      1. Once on full dose, dose monthly
      2. May ultimately be spread to every 6-8 weeks
  3. Monitoring during Desensitization
    1. Consider skin retesting every 2-5 years
    2. Venom skin tests after Desensitization
      1. Negative at 5 years: <20% of cases
      2. Negative at 7-10 years: 50-60%
  • Prognosis
  • Future Risk of Systemic Reaction
  1. Skin-test confirmed recurrence risk declines with time
    1. Initially: 50%
    2. Year 3-5: 35%
    3. Year 10: 25%
  2. Risk decreases with duration of Desensitization
    1. Reactions uncommon on Desensitization maintenance
    2. Reactions after Desensitization are usually more mild
    3. Desensitization stopped <2 years: High Reaction Risk
    4. Desensitization stopped 5 years: 10% Reaction Risk