Hymenoptera stings

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Background

  • All Hymenoptera share similar components in their venonm and patients can have allergies across the subgroups[1]
  • Most reactions are local but anaphylaxis and serum sickness are possible

Bees (Apids)

Stinging bee
  • Include Bumblebees and Honeybees
  • Barbed Stingers - remain in victims and the process of stinging kills the bee
  • Killer bees (hybridized African Bees) have small individual toxin potency but attack in large numbers with increased aggression[2]
  • Main allergen is phospholipase A2, hyaluronidase and melittin[1]
  • redness and irritation last 1-3 days

Wasps (Vespids)

Wasp.
  • Include Yellow Jackets, Hornets, and Wasps
  • Non barbed stinger - can sting multiple times and the sting does not cause the wasps' death
  • Histamine, phospholipase, antigen 5, and bradykinin similar to bees[1]
  • redness and irritation last 1-3 days

Fire Ants (Formicidae)

Fire ants
  • Alkaloid venom
  • Intense burning papules that may turn to pustules in 24hrs
  • Localized necrosis has also been reported[3]

Clinical Features

Local Reaction

Local reaction: 2 minutes after bee sting
Local reaction: 6 minutes after bee sting (stinger removed)
Local reaction: 27 after bee sting
Local reaction: 1 day after bee sting
Local reaction: Fire ant bite
  • Urticarial lesion contiguous with sting site
  • Local reaction occurring in mouth or throat can produce airway obstruction
  • Local reaction occurring around eye can result in cataract, iris atrophy, globe perf

Toxic Reaction

  • Occurs after multiple stings
  • May be delayed 8-24hrs
  • Venom mediated, not IgE
  • Resembles anaphylaxis but greater frequency of nausea/vomiting and diarrhea
    • Other symptoms: light-headedness, syncope, headache, fever, drowsiness, muscle spasms
  • Massive stings can result in renal or hepatic failure, DIC, rhabdo
  • Systemic toxicity more likely if > 50 stings
  • Median lethal dose of honeybee venom ~19 stings/kg or 500-1400 stings per human

Anaphylactic reaction

  • Majority occur within first 15min; nearly all within 6hr
  • No correlation with number of stings
  • IgE mediated, rather than direct response to the venom.
  • Shorter the interval between sting and onset of symptoms the more severe the reaction

Delayed Reaction

  • May occur 5-14d after a sting
  • Serum-sickness features (fever, malaise, urticaria, lymphadenopathy, polyarthritis)

Differential Diagnosis

Envenomations, bites and stings

Evaluation

  • Usually clinical

Management

  • Stinger Removal
    • Immediate removal is the most important principle; the method of removal is irrelevant
  • Local wound care and tetanus prophylaxis
  • Oral Antihistamines provide symptom relief for pruritus

Local Reaction

  • Ice packs diminish swelling and delays absorption of venom
  • NSAIDs and antihistamines for comfort
  • Infection is uncommon, but may present as ongoing swelling or cellulitis

Systemic reaction

Disposition

  • Normally outpatient, unless anaphylaxis or systemic toxicity
    • EpiPen should be prescribed on discharge if significant reaction

See Also

References

  1. 1.0 1.1 1.2 King TP et al. Structure and biology of stinging insect venom allergens. Int Arch Allergy Immunol. 2000;123(2):99-106
  2. Díaz-Sánchez C. et al. Suvival after massive (>2000) Africanized Honey bee stings. Arch Intern Med. 1998;158(8):925-927
  3. Fernández-Meléndez S. et al. Anaphylaxis caused by imported red fire ant stings in Málaga, Spain. J Investig Allergol Immunol. 2007;17(1):48-49

Review Questions

1. You are seeing a patient who has been stung by a bee. The risk of his developing anaphylaxis depends most upon which of the following?

the size of the bee
the size of the bee’s stinger
the nature of the most severe previous reaction experienced by the patient
Freeman TM. Hypersensitivity to Hymenoptera stings. N Engl J Med 2004; 351: 1978-1984. The risk of anaphylaxis with any event is dependent on the nature of the most severe previous reaction experienced by a patient Local reactions are best treated symptomatically with nonsteroidal antiinflammatory agents, antihistamines, and cold compresses. The definitive therapy for anaphylaxis is epinephrine by injection (0.01mg per kilogram of body weight; maximum, 0.3 and 0.5mg per dose, for children and adults, respectively), and this should be administered to any patient who has more than a cutaneous reaction. Antihistamines are often added to treat cutaneous signs and symptoms. Supplemental oxygen, beta-agonists for bronchospasm, and intravenous fluids for hypotension are sometimes indicated. Occasionally, for a reaction that does not respond to the initial dose of epinephrine, steroids (oral or intravenous) are added, although definitive support for their addition is lacking. Epinephrine auto-injectors should be prescribed for any patient who has had an anaphylactic reaction to a hymenoptera sting. The instructions for use are printed on the side of each injector, but these should be reviewed with the patient when prescribing the medication. Patients should be educated to use epinephrine if signs or symptoms beyond a cutaneous reaction develop after a hymenoptera sting, and always to seek additional medical care after using an injector. Patients should also be advised to wear a medical alert bracelet. Referral to an allergist is warranted, and skin testing should be performed for sensitivity to honeybees, wasps, white-faced hornets, yellow hornets, and yellow jackets. Venom immunotherapy should be administered for all venoms for which testing results are positive. The protective benefit is expected from the immunotherapy by the time maintenance dose is reached, usually by three to six months with standard protocols.
the amount of cutaneous erythema
whether the patient is on oral steroid treatment

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