Tick paralysis

Tick paralysis is caused by injection of a neurotoxin by blood-feeding female ixodid ticks and by some Argas species. The neurotoxin, which may be different in different species, affect synapses in the spinal cord and blocks the neuro-muscular junctions. The first symptoms appear 5-7 days after attachment of the female tick. One single female tick is sufficient to kill an adult human. In the beginning, the paralysis affects the legs and then ascends to the trunk, arms, and head within a few hours. The most important tick species involved in human tick paralysis are Ixodes holocyclus (in Australia), Dermacentor andersoni (in western North America) and D. variabilis (in eastern North America). Removal of the tick, including its mouth-parts, usually leads to quick and complete recovery, except in cases involving I. holocyclus which may become worse by removal of the tick. Thus, in Australia an anti-toxin is injected intravenously and allowed to circulate in the body before removing the tick (Kettle 1995).

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