Key to medically relevant Italian spider bites: a practical quick recognition tool for clinicians

Spider bites are often overestimated because there are no specific clinical or histopathological aspects that characterize them, and skin lesions that resemble a spider bite are often wrongly considered to be a "true spider bite". However, even in case of a true spider bite, it is almost impossible to confirm the biting species, since very often neither physicians nor patients are trained in spider identification.

The aim of this report is to provide clinicians with a rapid and simple recognition of the few Italian medically relevant spiders, in order to take relative medical measures in case of spider bites.

We defined spiders of considerable medical relevance the ones that cause local symptoms with possible systemic involvement, while we defined spiders with mild medical relevance the ones whose bite is not a medical emergency but is particularly painful or can cause lasting symptoms. We focused on the identification of the four spider taxa of major clinical interest through a brief descriptive, photographic and graphic guide, in association to dermatological manifestations.

Spiders of considerable medical relevance are Loxosceles rufescens and Latrodectus tredecimguttatus, while spiders of less severe medical relevance are Steatoda paykulliana, S. nobilis, S. grossa, Cheiracanthium punctorium, Amblyocarenum spp. and Macrothele calpeiana (the presence of the latter in Italy is only accidental and very sporadic). The only species capable of causing necrosis is Loxo-sceles rufescens, while Latrodectus tredecimguttatus can cause more systemic symptoms.

With the aim of promoting a first and rapid recognition of the species, we performed a morphological usable aspect for an initial and quick recognition according to an identification key.