Stining Insect Hypersensitivity

Question 1

How many children have systemic allergic reactions to insect stings

Answer 1

0.4-0.8%

Question 2

What are stinging insects?

Answer 2

Hornets, wasps, yellow jackets, honeybees, important fire ants

Question 3

Define the 2 types of IgE mediated reactions to insect stings?

Answer 3

1. Large local reactions: swelling >10cm at sting site, increase in size over day 1-2, and resolve over 3-10d
2. Systemic reactions: anaphylaxis, usually 5-30min after

Question 4

What insects leave their stingers at the site of the sting

Answer 4

Yellow jacket - sometimes

Honeybee

Question 5

What stinging insects are aggressive

Answer 5

High

Hornet

Question 6

How do you treat large local reactions

Answer 6

Symptomatic - cold compresses, non-sedating antihistamines, oral analgesics +/- PO oral corticosteroids

Question 7

How do you treat systemic reactions?

Answer 7

IM epinephrine 0.01mg/kg
Max 0.3mg in prepubertal child
Max 0.5mg in adolescent

Then observe x 4-6h in ED

Adjuncts

• non-sedating antihistamines
• oral steroids
• bronchodilators

Question 8

How does epinephrine work?

Answer 8

Vasoconstriction
Bronchodilation
Decreasing laryngeal edema

Question 9

Which patients need longer ED observation for systemic reactions?

Answer 9

Delayed presentation to ED
More than 1 dose of epi
Patients on beta-blockers 
Patients who got beta-agonists in the ED
Patients with wide pulse pressure

Question 10

Do patients with large local reactions need EpiPens?

Answer 10

No, they just need to avoid stings

Low risk of future anaphylaxis

Question 11

What are stinging insect avoidance measures

Answer 11

Wear shoes (don’t be barefoot)
Be careful when eating and drinking outdoors
Don’t drink from opaque cans or straws 
Wear long sleeve +/- gloves outside 
Remove nest (yourself or call for help)

Question 12

How do you counsel for systemic reactions

Answer 12

1. Provide Epipen x 2
2. Educate how to use Epipen - there are no contraindications
3. MedicAlert bracelet
4. Anaphylaxis action plan for home/school/child care
5. Referral to allergist for intradermal skin testing, and need for VIT

Question 13

If skin-testing and serum-specific IgE are negative, what is the risk for future systemic reactions?

Answer 13

Minimal

Question 14

What is the benefit of VIT

Answer 14

Reduces risk from 30% to 5% for future systemic reactions

Question 15

How is VIT done?

Answer 15

sub-cu injections of venom doses weekly x several weeks, then monthly over 1-2 years, weaned eventually to q8-12wk

Question 16

What venom is used for VIT?

Answer 16

Yellow jacket - has cross reactivity - coverage for all three
Less cross reactivity for wasp, rare cross reactivity for honeybee

Question 17

In VIT who needs to always have an EpiPen?

Answer 17

1. History of near-fatal reaction
2. History of systemic reactions during treatment of severe honeybee allergy
3. Elevated baseline serum tryptase
4. Underlying medical condition
5. Persons who are likely to have frequent unavoidable exposures

Question 18

How is a serum tryptase used in stinging allergies?

Answer 18

High baseline levels = higher risk for systemic reactions in the future, and higher risk for failure of VIT

> 20ng/mL = may indicate comorbid systemic mastocytosis

Question 19

What is the risk for systemic reaction with isolated systemic cutaneous reaction?

Answer 19

Low risk
89% had less severe reactions when stung again the future
EpiPens not needed
VIT not needed