Spider Bites
Spiders in the United States are generally harmless, with several exceptions. The most notable are the black widow (Latrodectus mactans) and brown recluse (Loxosceles reclusa, also found in South America) spiders. Their bites are serious but rarely fatal. Wandering spiders (Phoneutria species, found in South America), funnel web spiders (Atrax species, found in Australia), and more widely distributed spiders of the Chiracanthium species may also cause moderate to severe human reactions. Check current MEDIC CD-ROM for management of specific situations and venues.

The female black widow spider is usually identified by the red hourglass-shaped spot on its belly (fig. 5-2). Its bite causes a dull, numbing pain, which gradually spreads from the region of the bite to the muscles of the entire torso. The pain becomes severe, and a board-like rigidity of the abdominal muscles is common. Nausea, vomiting, headache, dizziness, difficulty in breathing, edema, rash, hypertension, and anxiety are frequently present. The bite site can be very hard to locate (there is little or no swelling at the site), and the victim may not be immediately aware of having been bitten. The buttocks and genitalia should be carefully examined for a bite site if the suspected victim has recently used an outside latrine. The following first aid treatment steps are suggested:

1. Place ice over the bite to reduce pain.
2. Hospitalize victims who are under 16 or over 65 (for observation).

3. Be prepared to give antivenom in severe cases.

The brown recluse spider (fig. 5-2) is identified by its violin-shaped marking. Its bite may initially go unnoticed, but after several hours, a bleb develops over the site, and rings of erythema begin to surround the bleb. Other symptoms include skin rash, fever and chills, nausea and vomiting, and pain. Aprogressively enlarging necrotic (dead tissue) ulcerating lesion (with a crusty black scab) eventually develops. Intravascular hemolysis (breakdown of the blood) is most often seen in children and may be fatal. Antivenom is not currently available.

Treatment for brown recluse spider bites includes the following:

· Debridement of lesion, followed by peroxide cleansing and Burrow's solution soaks

· Application of polymyxin-bacitracin-neomycin ointment and sterile dressing
· Dapsone 50-100 mg twice a day is used to promote healing in some cases, but only after screening for G6PD deficiency. Other antibiotics may be used to treat infection, and steroids to reduce inflammation

NOTE: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common human enzyme deficiency. A G6PD deficiency can cause a harmful reaction to a number of medications, including dapsone.

· Based upon medical consultation, excision of the lesion and optional commencement of corticosteroid therapy

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