One of the most famous misdiagnoses occurred recently in New York when a 7-month-old who had contracted cutaneous anthrax was initially diagnosed as having a brown recluse spider bite, even though these spiders are not native to New York. (The Diagnosis of Brown Recluse Spider Bite Is Overused for Dermonecrotic Wounds of Uncertain Etiology)
Two new studies in this issue find new methods to help accurately diagnose brown recluse spider bites. One study unveils the first assay (a Loxosceles species ELISA) that physicians can use to accurately test for the presence of the spider venom in a patient who was possibly bitten. Emergency physicians from the University of Michigan Medical Center in Ann Arbor and a dermatologist from the University of Missouri Health Sciences Center developed the assay. (A New Assay for the Detection of Loxosceles Species [Brown Recluse] Spider Venom)
In another study, a similar University of Michigan team of emergency medicine investigators found preliminary evidence that invasive biopsies may not be necessary to identify suspected brown recluse spider bites. Using the newly developed Loxosceles ELISA assay, the investigators find venom is detectable in hair, fluid from the wound and in skin biopsies in an animal model at least seven days after venom inoculation, but venom was not detectable in serum samples. (Detection of Loxosceles Venom in Dermal Lesions: A Comparison of 4 Venom Recovery Methods)
The studys authors said although the less invasive collection of venom from a victims hair or fluid from the wound contains far less venom then the biopsy, it is clinically irrelevant as long as some venom is detectable to make a diagnosis.