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Warning Against Dermal Therapies Using Heat or Other Vasodilator
Spider bites and tick bites need careful diagnostic differentiation in clinical and forensic investigation, particularly if associated with severe systemic illness. This article, continuing part I of the Winter 2007 issue of The Forensic Examiner, compares envenomation by brown spiders (Sicariidae), six-eyed crab spiders (Sicariidae), and sac spiders (Clubionidae) to tick-transmitted or other zoonotic illnesses, including babesiosis (with notes on Rocky Mountain spotted fever), Lyme disease, tularemia, Ebola hemorrhagic fever, and African tick-bite fever. Spider bites, compared to tick bites, are more readily necrotic and present sooner with systemic symptoms. Vasodilation therapies, facilitating the venom's entry into the blood at bite sites, are warned against.
Sicariidae, Genus Loxosceles
Recent reviews from the United States (Hogan, Barbara, & Winkel, 2004; Swanson & Vetter, 2005; Wendell, 2003) and Brazil (da Silva et al., 2004), as well as recent clinical and epidemic-logical studies from Tennessee, United States (Sams et al., 2001), and Santa Catarina, Brazil (Sezerino et al., 1998), have addressed the public health threat of necrotic and systemic loxoscelism, with yet some uncertainties and controversies regarding therapies.
Within the United States, the web-weaving brown recluse spider, Loxosceles redusa (Gertsch & Mulaik, 1940) of the Sicariidae, inhabits mainly the southcentral region, roughly reaching from a northern line of demarcation (southeastern Nebraska to southern Ohio) south to the Gulf of Mexico, excepting Florida and southwestern Texas (Swanson & Vetter, 2005; Vetter 2000, 2005). From bordering regions, suspected bites have been reported from the Chicago area (Erickson, Hryhorczuk, Lipscomb, Burda, & Greenberg, 1990), Montana (Lee, Buker, & Petersen, 1969), and Idaho (Wand, 1972).
The spider's brown body, marked by a sunken cephalothorax, reaches about 10 mm in length in the female; males are somewhat smaller. Immobilized at temperatures around 5°C, the species retreats in a silken tube during winter and appears most active in summer and early fall (Hire, Gladney, Lancaster, & Whitcomb, 1966). It may enter homes seeking dark, secluded places. For correct identification, the six eyes are important, occurring as pairs in the 100 Loxosceles species worldwide and contrasting with the eight eyes of most spiders (Swanson & Vetter, 2005).
Loxosceles laeta of South America is the larger species. It is known to cause, more frequently than...