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Chapter 21
ARTHROPOD ENVENOMATIONS
Recommendations are considered Category 1A, except where indicated Category 2, by
the WMS Panel of Expert Reviewers
I. GENERAL INFORMATION
In the United States, arthropods (invertebrates with jointed legs and segmented bodies)
cause more deaths by envenomation than reptiles. Hymenoptera (bees, wasps, etc.), the
Arachnida (spiders and scorpions), and Chilopoda (centipedes) cause the most significant
envenomations.
Neither Latrodectus (North American black widow, Australian red-back, New Zealand
kati, South African knoppie) nor Loxosceles (brown recluse) are aggressive toward
humans. These spiders live in crevices under ground cover, trash piles, barns, porches,
and outside toilets. Prevention includes inspection, clearing, and care, especially around
these areas. Nearly half of all bites could be prevented if toilets and clothing were
inspected prior to use. The Northwest "Hobo"spider (Tegenaria agrestis) has systemic
and local reactions similar to mild cases of loxoscelism (Vest DK in Auerbach PS:
Wilderness Medicine, Mosby, 200l)
II. GUIDELINES FOR ASSESSMENT AND TREATMENT
A. Stinging Insects: The most common insect stings are from the Hymenoptera. Although
it takes about 300 to 500 stings to make a lethal dose of the complex venom,
hypersensitivity, which occurs in approximately 1% of the general public, may result in a
life-threatening anaphylactic reaction from a solitary sting. This is more common in
adults than in children.
The Hymenoptera comprise four families: 1) honeybees, which account for the
most stings and leave the stinger attached to their victims, 2) bumblebees, 3) hornets,
yellow jackets, and wasps and 4) fire ants, whose alkaloid venom results in a sterile,
burning, vesicular lesion.
Nearly all Hymenoptera stings result in local pain, swelling, and redness. The
honeybee stinger should be removed as soon as possible by the most expedient means to
prevent the injection of still more venom. The site may be treated locally with gentle
cleansing, application of cold, elevation, and immobilization. Calm the patient. Common
remedies, such as applying a slurry of baking soda or meat tenderizer, often reduce pain.
Commercial "sting sticks" containing a topical anesthetic like xylocaine may be used.
Oral aspirin or ibuprofen usually helps control pain. The use of a non-invasive suction
cup, the Sawyer Extractor, helps alleviate pain and is effective in removing a portion of
the venom if applied within three minutes. (Category 2)
Patients with serious allergic reactions have pruritis, hives, angioedema, and early
upper airway obstruction with respiratory distrees. For these individuals apply a light
constrictive band (not a tourniquet) proximal to the site. Oral antihistamines (such as
diphenhydramine) may be helpful. If the patient is carrying injectable epinephrine,
