A number of spiders can cause spider bites that are medically important. Almost all spiders produce venom but only a few are classified as "venomous" and able to cause significant harm to humans.[1] Two medically important spider genera have a worldwide distribution—Latrodectus and Loxosceles. Others have a limited distribution.
Medical reports have been criticized for poor evidence. In the last century, both white tailed and wolf spiders were considered medically significant, only to be recanted.[2] Only ten genera (Phoneutria, Atrax, Latrodectus, Loxosceles, Sicarius, Hexophthalma, Hadronyche, Illawarra, Macrothele and Missulena) are considered medically significant.[citation needed] Bites of these spiders have a range of severity, with only a minority having severe symptoms. Deaths by verified spider bites are exceedingly rare (e.g. not one in Australia since 1979).[3]