II. Epidemiology
- Peak Incidence in August
- Hymenoptera are most common cause of serious venom reaction (as well as for death) in U.S.
- Systemic Allergic Reaction: 5% of patients
- Anaphylaxis: <1% of patients overall (up to 3% in adults)
- Responsible for average of 62 deaths per year in U.S.
III. Types: Hymenoptera
- Hymenoptera order contains more than 100,000 species, of which only the Stinging Insects are listed here
- Usually only Insects of Hymenoptera cause Anaphylaxis
- Yellow jackets and Wasps (Vespidae family)
- Attracted to food and garbage containers
- Attack without provocation
- Stings peak in summer and autumn coinciding with population peaks
- Yellow jackets nest in the ground (crevices or burrows) or in trees or shrubs
- Wasps nest under houses, in barns, mailboxes, shrubs and tree cavities
- Disturbance of a nest may lead to attacks (>10)
- Hornets (Vespidae family)
- Nest on undersurfaces of decks and roof overhangs
- Attack in small groups (1-5) if nest disturbed
- Hornet venom is more potent and of greater volume, able to reach lethal levels with fewer stings
- Associated with higher risk of multiorgan failure and death than with other stinging Hymenoptera
- Bumblebees and Honeybees (Apidae family)
- Africanized Honeybees (Killer Bees)
- Attack in swarms of hundreds
- Pursue victims well away from the hive
- In U.S. found in Arizona, California, Nevada, New Mexico and Texas
- Fire Ants (Formicidae family, Solenopsis species)
- Fire ants are 3 to 8 mm and red-brown or black
- Nest in the ground
- Attack in swarms when nest is attacked, most typically on extremities
- Circular cluster of 6 to 7 stings is common
- Stings may result in immediate and delayed Hypersensitivity Reactions
IV. Signs: Local Reactions
- Most reactions have onset in minutes and hours and resolve within 24 hours
- Bees/Wasps (Venom contains biogenic amines)
- Fire ants (Venom contains alkaloids)
- Arc shaped lesions or circular grouping of 6-7 stings
- Sterile Pustules develop within 24 hours
- Honeybee
- Barbed Stinger remains in skin after sting
- Injection continues until Stinger removed (although most venom is injected in first minute)
- Do NOT grasp Stinger - will inject more venom
- Retained Stinger may also lead to Foreign Body Granuloma and risk for secondary infection
- Technique to remove Stinger
- Scrape sharp object (knife) horizontally over skin
- Drags Stinger out intact
- Barbed Stinger remains in skin after sting
V. Signs: Large Local Reaction
- Represents 19% of reactions
- Onset in first few days and resolves by 7 days after sting
- Erythema and induration >10 cm (>4 inches, up to 8 to 10 inch diameter)
- May be difficult to differentiate from a secondary infection
- Risk of future systemic reaction: 5 to 10%
VI. Signs: Systemic Reaction
- See Allergic Reaction
- See Anaphylaxis
- Systemic Reaction or Anaphylaxis (responsible for 17% of all anaphylactic reactions)
- See Anaphylaxis for management
- IgE mediated reaction with Angioedema, Urticaria, respiratory distress
- Onset of reaction within 20 minutes of sting
- Delayed Hypersensitivity
- Reactions include Serum Sickness, Vasculitis, Glomerulonephritis, cerebral edema, DIC, Arthritis
- Rare complication of Insect Bite
- Occurs 3-14 days after large dose of venom
- Arthralgia and fever
- Massive Envenomation
- Rhabdomyolysis
- Multiorgan failure (renal, hepatic)
- Hemolysis
- Seizures
- Pancreatitis
VII. Complications (rare - case reports)
- Vasculitis
- Nephritis
- Neuritis
- Encephalitis
- Myocarditis
- Guillain-Barre Syndrome
VIII. Differential Diagnosis
- See Insect Bite
IX. Management: Reaction
-
General measures
- Remove Stingers still embedded in skin (avoids foreign body reaction)
- Tetanus Vaccination is not needed for Hymenoptera Stings
- Systemic Allergic Reaction or Anaphylaxis Management
- See Anaphylaxis for management
- See Allergic Reaction
- Obtain history of prior Allergic Reaction history
- Obtain details of attack
- Location
- Number of stings
- Which type of Stinging Insect
- Recurrent systemic reaction in 50% of cases from future Hymenoptera Sting
- Reaction is specific to the 3 types: Bees, Fire Ants or Vespidae (wasps, hornets, yellow jackets)
- Systemic reaction risk is reduced to 3% risk with Desensitization
- Severe reaction is highest risk in small children, elderly or multiple stings
- Local Reaction
- Ice Packs or cool compresses
- Analgesics (e.g. NSAIDs, Acetaminophen)
- Unproved efficacy of:
- Antihistamines (e.g. Zyrtec)
- Topical Corticosteroids
- Topical papain (meat tenderizer) or baking soda
- Large Local Reaction
- Differentiate from Cellulitis and other vector borne conditions (e.g. Erythema Migrans)
- Prednisone or Methylprednisolone 1 to 2 mg/kg (children) up to 40 to 60 mg (adults) for 3 o 5 days
- Delayed Hypersensitivity or Serum Sickness
- Supportive care
- Systemic Corticosteroids
- Antihistamines
X. Prevention
- See Stinging Insect Immunotherapy
-
General
- Avoid floral print clothing
- Avoid floral fragrances
- Avoid walking barefoot
- Remove wasp and hornet nests when identified
- Cleanse outdoor garbage cans
- Clean eating areas of food remains
- Close food sources
- Bees
- Avoid walking through flowers
- Avoid bananas around hives (similar scent to bee alarm pheromone)
- Carbon dioxide and human sweat can also antagonize bees
- Fire Ants
- Inspect playgrounds and yards for ant mounds
- Toxic bait may target queen ant
XI. References
- Cowling and Ferreri (2019) Crit Dec Emerg Med 33(2): 17-25
- Herness (2022) Am Fam Physician 106(2): 137-47 [PubMed]
- Kemp (1998) J Postgrad Med 103(6):88-106 [PubMed]