Spider poisoning in Portugal: fact or myth?.

Abstract

There are 800 known species of spiders in Portugal. Of these, only two may cause any kind of medical condition: the Mediterranean black-widow (Latrodectus tredecimguttatus) and the violin spider (Loxosceles rufescens). Both are relatively common in the country, the latter inclusively in urban areas. It is frequent in Portugal for some types of necrotic lesión to be attributed to spider bites. However, as in the rest of the world, evidences are often circumstantial. Most probably, some of the reported cases may in fact represent misdiagnoses of serious conditions such as infections by Streptococcus group A or Methicillin resistant Staphylococcus aureus. The correct diagnosis of spider poisoning must always be submitted to the following steps: (1) confirmation or observation of the biting, with verification of medical signs compatible with it; (2) the spider should be captured immediately or right after the bite, dead or alive; (3) identification of the spider by a taxonomist. It is extremely important that the medical community does not associate any necrotic lesion with a spider bite based on merely circumstantial evidence. Doing it is to neglect the real cause of such condition and to delay the effective cure. In reality, given their rarity, spider bite lesions should be relegated to the end of the differential diagnostic list of necrotic skin lesions.