exerpts from - A CALL FOR PARSIMONY IN SPIDER BITE DIAGNOSES by: Richard S. Vetter and P. Kirk Visscher Department of Entomology, University of California, Riverside, CA 92521 USA click here to review full report Although some spiders listed in the report can have deleterious effects, not all bites lead to serious symptoms, and most may in fact be unremarkable. Typically, spiders bite only in defense, only once, and the bite is rarely felt. Multiple "bites" or an initially painful bite would exonerate most spiders as probable culprits. There are many arthropods which actively seek to bite humans, and these seem more logical candidates for suspicion 115. In one study of 600 suspected "spider bite cases" in southern California, 80% were caused by other arthropods, mostly ticks and reduviid bugs 115,116. Loxosceles spiders have been erroneously blamed for a variety of necrotic wounds of unknown origin, which have often turned out to have other etiological agents (Table 1). It has been estimated that 60% of "alleged brown recluse bites" occur in areas where no Loxosceles spiders are known to exist 116. There are many causative agents of necrotic wounds, many not arthropod in nature, which can be or have been confused for recluse spider bites 74,116,118-120. A call for greater parsimony in spider bite diagnoses has been made more than once 74,88,116,117,121 and excellent guidelines for "verified", "probable" and "possible" spider bite diagnoses have been put forth118. Table 1. Conditions which can cause necrotic wounds, have been misdiagnosed as or could be confused with "brown recluse spider bite" (from 73,115-117,120) | |
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