Tick paralysis (toxicity) is an acute, progressive, symmetrical, ascending motor paralysis caused by salivary neurotoxin(s) produced by certain species of ticks. With some species, other signs of systemic "single organ" toxicity (eg, cardiac, airway, bladder, lung, esophagus, etc) may be seen separate to or within the classic paretic-paralysis presentation. People (usually children) and a wide variety of other mammals, birds, and reptiles 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 three plus Rhipicephalus, Haemaphysalis, Otobius, and Argas have been associated with paralysis to varying degrees in animals.