How to identify and treat common bites and stings
A thorough history and physical are key to proper diagnosis and treatment following a patient’s encounter with an insect, arachnid, or other arthropod.
PRACTICE RECOMMENDATIONS
❯ Recommend that patients use an insect repellent, such as an over-the-counter formulation that contains DEET, picaridin, or PMD (a chemical constituent of Eucalyptus citriodora oil) to prevent flea bites. C
❯ Prescribe nonsedating oral antihistamines as first-line symptomatic treatment of mild-to-moderate pruritus secondary to an insect bite. C
❯ When indicated, refer patients for venom immunotherapy, which is approximately 95% effective in preventing or reducing severe systemic reactions and reduces the risk of anaphylaxis and death. C
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
Bee and wasp sting allergies are the most common insect venom allergic reactions. A bee sting is more likely to lead to a severe allergic reaction than a wasp sting. Allergic reactions to hornet and bumblebee stings are less common but can occur in patients already sensitized to wasp and honey bee stings.20,21
Management. Remove honey bee stingers by scraping the skin with a fingernail or credit card. Ideally, the stinger should be removed in the first 30 seconds, before the venom sac empties. Otherwise, intense local inflammation, with possible lymphangitic streaking, can result.22
For guidance on localized symptomatic care of bee and wasp stings and bites and stings from other sources discussed in this article, see “Providing relief and advanced care” on page E6.
Centipedes and spiders
Centipedes are arthropods of the class Chilopoda, subphylum Myriapoda, that are characterized by repeating linear (metameric) segments, each containing 1 pair of legs.23 Centipedes have a pair of poison claws behind the head that are used to paralyze prey—usually, small insects.23,24 The bite of a larger centipede can cause a painful reaction that generally subsides after a few hours but can last several days. Centipede bites are usually nonfatal to humans.23
Spiders belong to the class Arachnida, order Araneae. They have 8 legs with chelicerae (mouthpiece, or “jaws”) that inject venom into prey.25 Most spiders found in the United States cannot bite through human skin.26,27 Common exceptions are black widow and brown recluse spiders, which each produce a distinct toxic venom that can cause significant morbidity in humans through a bite, although bites are rarely fatal.26,27
The brown recluse spider is described as having a violin-shaped marking on the abdomen; the body is yellowish, tan, or dark brown. A bite can produce tiny fang marks and cause dull pain at the site of the bite that spreads quickly; myalgia; and pain in the stomach, back, chest, and legs.28,29 The bite takes approximately 7 days to resolve. In a minority of cases, a tender erythematous halo develops, followed by a severe necrotic ulcer, or loxoscelism (FIGURE 3; 40% of cases) or scarring (13%), or both.29,30
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