See Also
1. Insect Bite
Epidemiology
1. 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. Usually only insects of Hymenoptera cause Anaphylaxis
2. Distinct Insect Venoms (allergy specific to types)
  1. Honeybee and Bumblebee Venom
  2. Yellow Jacket and Hornet Venom
  3. Polistes Wasp
  4. Fire ants
Signs
1. See Allergic Reaction
2. Systemic reactions (IgE mediated)
  1. Anaphylaxis
  2. Large local swelling at bite (8-10 inch diameter)
    1. Develops over 2 days
    2. Resolves within 7 days
Differential Diagnosis
1. See Insect Bite
Diagnosis: Hymenoptera venom tests
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. See Anaphylaxis
Prevention
1. See Allergic Reaction
2. See Insect Bite
3. See Prevention of Vector-borne Infection
4. 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
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
Resources
1. AAAAI Stinging Insect Allergy Prevention
  1. http://www.aaaai.org/patients/publicedmat/tips
References
1. Golden (2003) Am Fam Physician 67(12):2541

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This page was written by Scott Moses, MD. This page was last revised before 5/10/08, prior to consistent tracking of revision date. This page was last published on 6/1/2008. Please send comments and questions to the editor. Contact information may be found on the page About the Family Practice Notebook. These pages are best viewed with Microsoft Internet Explorer 6.0.