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Can Fam Physician. 2004 August; 50: 1098–1101.
PMCID: PMC2214648

An approach to spider bites. Erroneous attribution of dermonecrotic lesions to brown recluse or hobo spider bites in Canada.


OBJECTIVE: To dispel prevalent myths surrounding diagnosis of dermonecrotic and associated conditions supposedly resulting from bites of brown recluse, hobo, or other spiders in Canada. SOURCES OF INFORMATION: Worldwide, spider bites are regularly misdiagnosed as the etiologic agents in human dermonecrosis mainly as a result of inaccurate, erroneous, or hyperbolic popular and professional literature based on inference, circumstantial evidence, inferior clinical trials, and misunderstanding of the facts regarding spider-bite envenomation. MAIN MESSAGE: A working diagnosis of "spider bite" or publishing a case history should be considered only when a spider is caught in the act of biting or otherwise reliably associated with a lesion. Accurate identification of the spider could be critical for correct diagnosis and subsequent treatment. CONCLUSION: Brown recluse spiders are not found in Canada. Hobo spiders have not been reliably implicated in dermonecrosis. Worldwide, spider-bite envenomation is an unlikely cause of dermonecrosis. Canadian physicians should give priority consideration to other, more likely, causes.

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