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Tick paralysis

Daniel J Sexton, MD
Section Editor
Stephen B Calderwood, MD
Deputy Editor
Jennifer Mitty, MD, MPH


Ticks transmit a number of infections to humans and other animals. However, the toxins of various ticks can also cause a disease known as tick paralysis, which can be confused with both infectious and noninfectious conditions.

Tick paralysis was first described by explorers in the Australian outback in 1824 [1]. Eighty-eight years later, the disease was recognized to occur in western Canada [2]. Tick paralysis has subsequently been found to affect humans and domestic and wild animals worldwide, although most cases occur in Australia and North America. Although it is a rare disease in humans, tick paralysis is important to recognize because it can be fatal or nearly fatal [3]. However, if diagnosed promptly, this illness can be cured with the combination of tick removal and supportive care.


There is no national surveillance system for tick paralysis and reliable information on incidence does not exist. However, the disease appears to be uncommon based upon available literature and clinical experience. As an example, only 33 cases were reported in Washington State in the 50 years between 1946 and 1996, even though tick paralysis was a reportable disease in this state until 1998 [4]. Most cases in North America occur in the western regions of the United States and Canada, but the illness has also been seen in the eastern, southeastern, and south central United States. In addition, cases have been reported in Argentina [5], and in urban areas in travelers returning from endemic areas [6,7].

Four cases of tick paralysis were reported in patients from north central Colorado in 2006 [8]. The clustering of these cases was unusual because in previous years, on average, only one case per year was reported from Colorado. Another unusual characteristic of this cluster was the age distribution of cases: only one of four cases occurred in a child. Previous case reports noted that tick paralysis was more likely to occur in children under the age of 10 years because tick toxins are more likely to cause symptoms in individuals with a smaller body mass.

Females are affected more often than males, possibly because ticks are more likely to remain undetected following attachment to individuals with long hair. As with other tick-borne diseases, most cases occur in the spring and early summer months [9].


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Literature review current through: Sep 2016. | This topic last updated: Feb 2, 2016.
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  1. Scott, E. Hume and Howell's journey to Port Phillip. R Aust Histo Soc J and Proc VII; 1921:289.
  2. Edlow JA, McGillicuddy DC. Tick paralysis. Infect Dis Clin North Am 2008; 22:397.
  3. Schaumburg HH, Herskovitz S. The weak child--a cautionary tale. N Engl J Med 2000; 342:127.
  4. Dworkin MS, Shoemaker PC, Anderson DE. Tick paralysis: 33 human cases in Washington State, 1946-1996. Clin Infect Dis 1999; 29:1435.
  5. Remondegui C. Tick paralysis cases in Argentina. Rev Soc Bras Med Trop 2012; 45:533.
  6. Gordon BM, Giza CC. Tick paralysis presenting in an urban environment. Pediatr Neurol 2004; 30:122.
  7. Inokuma H, Takahata H, Fournier PE, et al. Tick paralysis by Ixodes holocyclus in a Japanese traveler returning from Australia associated with Rickettsia helvetica infection. J Travel Med 2003; 10:61.
  8. Centers for Disease Control and Prevention (CDC). Cluster of tick paralysis cases--Colorado, 2006. MMWR Morb Mortal Wkly Rep 2006; 55:933.
  9. Centers for Disease Control and Prevention (CDC). Tick paralysis--Washington, 1995. MMWR Morb Mortal Wkly Rep 1996; 45:325.
  10. Gothe R, Kunze K, Hoogstraal H. The mechanisms of pathogenicity in the tick paralyses. J Med Entomol 1979; 16:357.
  11. Lysyk TJ. Tick paralysis caused by Dermacentor andersoni (Acari: Ixodidae) is a heritable trait. J Med Entomol 2010; 47:210.
  12. Wilkinson PR. Differences in paralyzing ability and sites of attachment to cattle of Rocky Mountain wood ticks (Acari: Ixodidae) from three regions of western Canada. J Med Entomol 1985; 22:28.
  13. Felz MW, Smith CD, Swift TR. A six-year-old girl with tick paralysis. N Engl J Med 2000; 342:90.
  14. Krishnan AV, Lin CS, Reddel SW, et al. Conduction block and impaired axonal function in tick paralysis. Muscle Nerve 2009; 40:358.
  15. Cooper BJ, Spence I. Temperature-dependent inhibition of evoked acetylcholine release in tick paralysis. Nature 1976; 263:693.
  16. Grattan-Smith PJ, Morris JG, Johnston HM, et al. Clinical and neurophysiological features of tick paralysis. Brain 1997; 120 ( Pt 11):1975.
  17. ROSE I. A review of tick paralysis. Can Med Assoc J 1954; 70:175.
  18. Vedanarayanan V, Sorey WH, Subramony SH. Tick paralysis. Semin Neurol 2004; 24:181.
  19. Bow, MR, Brown, JH. Tick-borne diseases of man in Alberta. Can Med Assoc J 1946; 53:459.
  20. Pearn J. Neuromuscular paralysis caused by tick envenomation. J Neurol Sci 1977; 34:37.
  21. Engin A, Elaldi N, Bolayir E, et al. Tick paralysis with atypical presentation: isolated, reversible involvement of the upper trunk of brachial plexus. Emerg Med J 2006; 23:e42.
  22. Greenstein P. Tick paralysis. Med Clin North Am 2002; 86:441.
  23. Crawford P, Mitchell D. Tick paralysis as a cause of autonomic dysfunction in a 57-year-old female. South Med J 2009; 102:190.
  24. Burke MS, Fordham LA, Hamrick HJ. Ticks and tick paralysis: imaging findings on cranial MR. Pediatr Radiol 2005; 35:206.
  25. Vedanarayanan VV, Evans OB, Subramony SH. Tick paralysis in children: electrophysiology and possibility of misdiagnosis. Neurology 2002; 59:1088.
  26. Diaz JH. A 60-year meta-analysis of tick paralysis in the United States: a predictable, preventable, and often misdiagnosed poisoning. J Med Toxicol 2010; 6:15.