Human health impact by alien spiders and scorpions.

Abstract

Abstract Only a few alien spider species are of medical importance to humans because they are large and/or aggressive enough to inject venom and/or possess peculiar venom components. Spiders of serious medical concern include several Latrodectus (Theridiidae) and Loxosceles species (Sicariidae), numerously and globally introduced into many new areas. Loxosceles species are the only spiders that can cause severe local effects (necrosis) and both mentioned genera contain the only alien spider species that can provoke severe systemic effects. However, fatal issues are very rare. For all other spider species large enough to penetrate the human skin and introduced somewhere as alien species, 42 genera or species from 16 families are considered in detail. The venoms of these spiders cause only modest local (redness at the site of the bite, itching and swelling) and systemic (headache or nausea) effects and can be considered as harmless. In contrast to spiders, information on health issues of alien scorpions is rare and restricted to three species so far. One of them is potentially dangerous to humans, two species are not.