Spider Venoms Potentially Lethal to Humans

Abstract

Spiders from four families [Atrax and Hadronyche (Hexathelidae), Loxosceles (Sicariidae), Latrodectus (Theridiidae) and Phoneutria (Ctenidae), with several species each] may cause severe symptoms when biting humans. This is mainly due to a combination of factors: (1) synanthropic way of living (all taxa), (2) high densities in urban areas (Latrodectus, Loxosceles, Phoneutria), (3) large body size (Atrax, Hadronyche, Phoneutria), (4) ion-channel targeting neuropeptides or other venom compounds which are very potent and/or to which vertebrates/humans are very sensitive (Atrax, Hadronyche, Latrodectus, Phoneutria), (5) a venom enzyme causing necrosis (Loxosceles) and (6) aggressive behaviour towards humans (Phoneutria). For each spider genus, envenomation symptoms, therapy, venom peculiarity and frequency of bites are described in detail. Several decades ago, fatal issues were reported for all four groups, but medical documentation as well as medical standards in many countries was poor. In the last 2–3 decades, no fatalities were reported for Atrax, Hadronyche, Latrodectus and Phoneutria. The situation with Loxosceles is less clear, but on a global scale, it is obvious that fatalities due to spider bites are now close to zero, which refers to an annual mortality of <0.001 per million humans. Thus, spiders are by far less dangerous than bees and wasps.