Condition

Tick Paralysis

Editors: Paritosh Prasad MD

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Background Information

Description

  • life-threatening, acute ascending flaccid paralysis due to salivary neurotoxins secreted by ticks during a blood feed(
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Also called

  • tick toxicosis

Epidemiology

Geographic distribution

  • occurs worldwide but majority of cases reported in(
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    • United States
      • Rocky Mountain states
      • Pacific Northwest
      • Southeast
    • southwestern Canada
    • eastern coast of Australia

Incidence/Prevalence

  • rare(
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    • not a reportable illness so precise incidence not known and likely underestimated
    • at least 50 well-documented cases between 1946 and 2006
    • 4 cases reported in north-central Colorado in May 2006 (MMWR Morb Mortal Wkly Rep 2006 Sep 1;55(34):933)
  • Neurologic_Disordersrates in United States and Australia generally < 1 case/year (Clin Toxicol (Phila) 2015 Nov)05/31/2017 07:11:00 PM26359765 rates in United States and Australia generally < 1 case/year
    • 55 cases reported in United States between 1946 and 2014
    • 35 cases reported in Australia between 1904 and 2009
    • Reference - Clin Toxicol (Phila) 2015 Nov;53(9):874
  • most cases occur in spring and summer (peak tick season)(
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Likely risk factors

  • activities associated with potential tick exposure such as
    • hiking
    • camping
  • living in or traveling to endemic areas

Etiology and Pathogenesis

Causes

  • neurotoxin secreted from the salivary gland of some ticks (typically gravid female ticks)(
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  • over 40 species of tick, both hard- and soft-bodied, reported to cause tick paralysis, including(
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    • Dermacentor andersoni
    • Dermacentor variabilis
    • Ixodes scapularis
    • Ixodes holocyclus

Pathogenesis

  • salivary neurotoxin, holocyclotoxin, transmitted from tick to human during a blood meal(
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    • holocyclotoxin likely acts by decreasing acetylcholine release at the neuromuscular junction
    • mechanism of action thought similar to that of botulinum toxin
    • toxin from tick in Australian variant may act differently
  • as tick feeds, toxin increases in concentration(
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  • symptoms of paralysis begin about 2-7 days after bite (mean 5 days)(
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