Ticks are arachnids that attach to other animals at various stages of their life cycles and obtain blood for nourishment. There are 70 tick species found in Australia but only the three Ixodes species listed above cause paralysis. Tick paralysis in humans is almost exclusively associated with Ixodes holocyclus, distributed in a narrow eastern coastal strip extending from far north Queensland to Victoria.
The salivary glands of ticks excrete multiple haemostatic and anti-inflammatory agents to facilitate attachment and feeding. These include, in the case of the adult female Ixodes holocyclus, a protein neurotoxin known as holocyclotoxin. It is thought to act at the presynaptic region of the neuromuscular junction and inhibit release of acetylcholine.
- Ixodes cornuatus
- Ixodes hirsti
- Ixodes holocyclus
References
- Grattan-Smith PJ, Morris JG, Johnston HM, et al. Clinical and neurophysiological features of tick paralysis. Brain 1997; 120:1975-1987
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