11.05 Hymenoptera (Bee, Wasp, Hornet) Envenomation

agk’s Library of Common Simple Emergencies

Presentation

Sometimes a patient comes to a hospital emergency department immediately after a painful sting because he is alarmed at the intensity of the pain or worried about developing a serious life threatening reaction. Sometimes he seeks help the next day because of swelling, redness, and itching. Parents may not be aware that their child was stung by a bee and be concerned only about the local swelling. Erythema soon after the sting, with varying degrees of localized edema, develops. Often there is a central punctate discoloration at the site of the sting, or, rarely, a stinger may be protruding. A delayed hypersensitivity reaction will produce varying degrees of edema which can be quite dramatic when present on the face. Tenderness and, occasionally, ascending lymphangitis can occur.

What to do:

• Scrape away the stinger with the back edge of a scalpel blade or a long fingernail.
• Examine the patient for any signs of an immediate, systemic, allergic reaction (anaphylaxis), such as decreased blood pressure, generalized urticaria or erythema, or wheezing.
• Apply a cold pack to an acute sting to give pain relief and reduce swelling.
• Observe the patient with an acute sting for approximately an hour to watch for the rare anaphylaxis.
• Reassure patient who has come in after 12-24 hours that anaphylaxis is no longer a problem.
• Prescribe hydroxyzine (Atarax) 50mg qid for itching.
• If an ascending lymphangitis is present, treat the patient with an appropriate antibiotic for 10 days (e.g., cephadryl (Duricef) lgm qd, cephalexin 500mg tid, dicloxacillin 500mg qid)
• If an extremity is involved, have the patient keep it elevated and instruct him that the swelling may worsen if the hand or foot is held in a dependent position. This swelling may continue for several days. Severe hand swelling may be prevented or reduced by placing the patient in a splint and compression dressing. Promptly remove any rings in cases of hand stings.

What not to do:

• Do not belittle the patient’s complaint or make him feel guilty about his visit.
• Do not send the patient with an acute sting out of the ED less than one hour after the sting.
• Do not apply heat, even if an infection is suspected--the swelling and discomfort will worsen.

Discussion

Bee stings are very painful and frightening. There are many misconceptions about the danger of bee stings, and many patients have been instructed unnecessarily to report to an ED immediately after being stung. Many of these people have only suffered localized hypersensitivity reactions in the past and are not at a significantly greater risk than the general public for developing anaphylaxis. Besides the immediate relief of pain for the acute sting, we have little more than reassurance to offer these patients. Although it is most prudent to treat an ascending lymphangitis with an antibiotic, it should be realized that after a bee sting the resultant local cellulitis and lymphangitis is usually a chemically mediated inflammatory reaction. Histamine is one of many components of hymenoptera venom: antihistamines may benefit the sting victim.

References

• Visscher PK, Vetter RS, Camazine S: Removing bee stings. Lancet 1996;348:301-302.

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