Local wound treatment includes cold compresses along with elevation of the affected extremity. Topical steroids and antihistamines can improve pruritus.

Bees, Wasps, Hornets, and Yellow Jackets

These insects belong to the Vespidae and Apidae families and are responsible for most insect-related anaphylaxis. These insects are found throughout the United States. All are capable of stinging; however, the Africanized honeybee, an aggressive hybrid resulting from an experiment intended to enhance honey production, is of the most concern. The danger arises from the multiple stings inflicted because of the species’ “swarm-and-attack” behavior; their venom is no different from that of other honeybees.¹⁷ Hymenoptera venom includes histamine, dopamine, noradrenalin, 5-hydroxytryptamine, hyaluronidase, phosphomonoesterase, alpha-D-glucosidase, phospholipase A and B, kinins, and peptides, including melitin (thought to be responsible for hemolysis and rhabdomyolysis) and apamin (thought to be responsible for neurotoxicity).¹⁸

Most stings cause transient pain, itching, and swelling. There can be delayed onset of a large local sting reaction that causes induration and edema extending beyond the sting site to the entire affected extremity. These reactions can continue to increase for 24 to 48 hours after the envenomation and take 3 to 10 days to resolve.¹⁷

Systemic reactions, including anaphylaxis, present with the above findings, in addition to other cutaneous, vascular, respiratory, musculoskeletal, and renal findings, either in isolation or in combination. Cardiac findings include bradycardia, dysrhythmias, angina, and myocardial infarction.
¹⁷
Nausea, vomiting, diarrhea, fatigue, and dizziness can occur. Hemolysis, rhabdomyolysis, and transient liver transaminase elevation have also been reported with massive envenomation.¹⁹ Acute kidney injury, with or without rhabdomyolysis or intravascular hemolysis, can also occur.²⁰

Anaphylaxis is a severe, potentially fatal, systemic allergic reaction that occurs suddenly after contact with an allergy-causing substance.²¹ Although there are no universally accepted diagnostic criteria, most authorities agree that skin or mucosal involvement and involvement of either respiratory compromise (e.g., dyspnea, wheeze-bronchospasm, stridor, hypoxemia) or reduced blood pressure or other associated symptoms of end-organ dysfunction (e.g., hypotonia [collapse], syncope, incontinence) would suggest anaphylaxis.²¹

Management of anaphylaxis includes intramuscular epinephrine, oxygen, and inhaled beta-adrenergic agents (albuterol), aggressive fluid resuscitation with multiple 10- to 20-mL/kg fluid boluses under pressure, H1 and H2 antihistamines, and corticosteroids.

CRITICAL DECISION

What is the most important initial treatment for a patient who presents with anaphylaxis from insect envenomations?

Epinephrine is the treatment of choice for anaphylaxis. Intramuscular injection in doses of 0.01 mg/kg (maximum dose, 0.5 mg) given every 5 to 15 minutes as necessary is recommended for controlling symptoms and maintaining blood pressure.²¹ Although studies have not been performed in patients experiencing anaphylaxis, both children and adults have faster absorption with higher peak plasma epinephrine levels when epinephrine is administered intramuscularly in the anterolateral thigh versus subcutaneously or intramuscularly in the deltoid.²¹