Brown recluse spiders (Loxoscele re...

Brown recluse spiders (Loxoscele reclusa) are known to cause necrotic skin reactions with their bite and frequently are blamed for cases of skin necrosis on the same level in areas they do not inhabit. This can lead to misdiagnosis and delay in appropriate treatment for other conditions. Swanson and Vetter reviewed the available literature upon the epidemiology, evaluation, and treatment of these bites.

Brown recluse spiders are ground in several areas of the United States, including southeastern Nebraska, Kansas, Oklahoma, Texas, Louisiana, Arkansas, Missouri, Kentucky Tennessee Mississippi, Alabama, northern Georgia, and southern portions of Ohio, Indiana, Illinois, and Iowa. They are not endemic in the west, northeast, midatlantic, or coastal toward the south Other Loxosceles spiders exist in the southwest, although greatest in number ulcerating spider bites are caused by the agency of the brown recluse. Bites have been noted outside endemic areas, further these reports are questionable.

Reported spider bites frequently are caused by other arthropods (eg ticks, fleas), and sole about one in 10 patients with a suspected spider bite submits a spider specimen. Furthermore, bites are strange even in homes with known infestation. Definitive diagnosis is made by means of confirmation of a bite and positive identification of the spider by the agency of an arachnologist; there are no laboratory trials available for clinical use. Ulcerating detriments have many possible causes, including infection, vascular disorders, neoplasm, and trauma. This extensive differential diagnosis, combined with the relative rarity of brown recluse bites and the difficulty of confirming a bite, should make physicians cautious in diagnosing a brown recluse envenomation.

There are many propos treatments for brown recluse bites, although in in the greatest degree cases the bites will heal without therapy. No randomized controll trials have been performed. The sulfone antibiotic dapsone ofttimes is recommended, although no prospective trials support its use for bites in humans. Other treatments include steroids, surgical excision, hyperbaric oxygen local electrical agitation and antivenom (not available in the United States); none has been proven effective for brown recluse bites. Because bites greatest in quantity often are self-limited, typical injury care is the best option in unconfirmed cases.

throw CARTER, M.D.

Swanson DL Vetter R Bites of brown recluse spiders and suspected necrotic arachnidism. N Engl J M February 17 2005;352:700-7

COPYRIGHT 2005 American Academy of Family Physicians

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