Spider BitesSpiders in the United States are generallyharmless, with several exceptions. The most notableare the black widow (Latrodectus mactans) and brownrecluse (Loxosceles reclusa, also found in SouthAmerica) spiders. Their bites are serious but rarelyfatal. Wandering spiders (Phoneutria species, found inSouth America), funnel web spiders (Atrax species,found in Australia), and more widely distributedspiders of the Chiracanthium species may also causemoderate to severe human reactions. Check currentMEDIC CD-ROM for management of specificsituations and venues.The female black widow spider is usuallyidentified by the red hourglass-shaped spot on its belly(fig. 5-2). Its bite causes a dull, numbing pain, whichgradually spreads from the region of the bite to themuscles of the entire torso. The pain becomes severe,and a board-like rigidity of the abdominal muscles iscommon. Nausea, vomiting, headache, dizziness,difficulty in breathing, edema, rash, hypertension, andanxiety are frequently present. The bite site can bevery hard to locate (there is little or no swelling at thesite), and the victim may not be immediately aware ofhaving been bitten. The buttocks and genitalia shouldbe carefully examined for a bite site if the suspectedvictim has recently used an outside latrine. Thefollowing 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 byits violin-shaped marking. Its bite may initially gounnoticed, but after several hours, a bleb develops overthe site, and rings of erythema begin to surround thebleb. Other symptoms include skin rash, fever andchills, nausea and vomiting, and pain. A progressivelyenlarging necrotic (dead tissue) ulcerating lesion (witha c r u s t y b l a c k s c a b ) e v e n t u a l l y d e v e l o p s .Intravascular hemolysis (breakdown of the blood) ismost often seen in children and may be fatal.Antivenom is not currently available.Treatment for brown recluse spider bites includesthe following:Debridement of lesion, followed by peroxidecleansing and Burrow’s solution soaksApplication of polymyxin-bacitracin-neomycinointment and sterile dressingDapsone 50-100 mg twice a day is used topromote healing in some cases, but only afterscreening for G6PD deficiency.Otherantibiotics may be used to treat infection, andsteroids to reduce inflammationNOTE: Glucose-6-phosphate dehydrogenase(G6PD) deficiency is a common humanenzyme deficiency. A G6PD deficiency cancause a harmful reaction to a number ofmedications, including dapsone.Based upon medical consultation, excision ofthe lesion and optional commencement ofcorticosteroid therapyCentipede BitesCentipedes can attain sizes of over one foot inlength! Their bite, though rare, leaves two tiny redmarks and causes redness and swelling. Severe pain,swelling, and inflammation may follow, and there maybe headache, dizziness, vomiting, irregular pulse,muscle spasm, and swollen lymph nodes. Nolong-term effects are usually seen. Treat discomfortwith acetaminophen, cool packs, and elevation of theaffected limb to heart level.5-10THE “BLACK WIDOW” SPIDERA. TOP VIEWB. UNDERSIDESCORPIONBROWN RECLUSEHM3f0502Figure 5-2.—Black widow and brown recluse spiders andscorpion.
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