Tick paralysis is an acute, progressive, ascending motor paralysis caused by a salivary neurotoxin produced by certain species of ticks. Humans (especially children), a wide variety of other mammals, and birds may be affected. Human cases of tick paralysis caused by the genera Ixodes , Dermacentor , and Amblyomma have been reported from Australia, North America, Europe, and South Africa; these 3 plus Rhipicephalus , Haemaphysalis , Otobius , and Argas have been associated with paralysis in animals.