Pediatric emergency medicine trisk 2003 2003
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Systemic reaction is most common in small children and occurs within 24 to 48
hours. Symptoms may include fever, chills, malaise, weakness, nausea, vomiting,
joint pain, morbilliform eruption with petechiae, intravascular hemolysis,
hematuria, and renal failure.
Management. Treatment varies with the clinical stage of the bite. There is no
specific serologic, biochemical, or histologic test to diagnose envenomation
accurately. Many of the presumed bites outside the endemic range are caused by
other spiders ( Table 90.19 ) or other conditions. Pediatric conditions that have
been misdiagnosed as brown recluse bites include infections with staphylococci
or streptococci, herpes simplex, herpes zoster, erythema multiforme, Lyme
disease, fungal infection, pyoderma gangrenosum, chemical burn, poison ivy/oak,
and localized vasculitis. Unless the spider is brought for identification, definitive
diagnosis cannot be made. Table 90.19 lists the spiders found in the United States
known to cause necrotic lesions. An algorithm for management of suspected
brown recluse spider bites is shown in Figure 90.18 . Serious complications are
rare in adults. Most victims will heal with supportive care. Occasionally surgical
excision and skin grafting are required, especially if bites occur over fatty tissue.
Studies of treatment with steroids, heparin, dapsone, and HBO have found no
significant effects on venom-induced necrosis. Current recommendations are to
limit the use of dapsone to adults with proven brown recluse bites. Dapsone
should not be used in children due to the risk of methemoglobinemia. Antivenom
is not yet commercially available. For systemic manifestations, vigorous
supportive care is needed. Most deaths are caused by hemolysis and respiratory
failure. Successful use of plasma exchange for profound hemolysis in a child has
been reported. A CBC and platelet count should be obtained. Evidence of
hemolysis should be sought, as well as monitoring of hemoglobin, urine
sediment, BUN, and creatinine levels. Patients with neutropenia require a
conservative approach with close monitoring and local wound care.
Latrodectism (Bite of the Black Widow Spider). Current evidence. In the United
States, there are five black widow (Latrodectus) species in all states except
Alaska. There are more than 2,500 bites each year. The bite of Latrodectus
mactans is the leading cause of death from spider bites in the United States. The
spider is shiny black, with a brilliant red hourglass marking on the ventral surface
of the abdomen of mature females. It may be present on the male, but the male is
not a threat because it is only one-fourth the size of the female, and its fangs are
unable to penetrate human skin. The webs are usually found in corners or out-ofthe-way places. The female is not aggressive unless guarding her egg sac or
