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Tick Paralysis

Tick paralysis (TP) is a condition that was first documented in Australia in 1824 in association with an engorging female tick. TP afflicts wild animals, livestock, pets, and humans. It is characterized by ascending paralysis that usually begins in legs with muscle weakness, loss of coordination and sensation, and potentially death from respiratory failure due to paralysis of chest muscles. The cause is now known to be an unidentified protein toxin (or toxins) in tick saliva, not a disease agent. Early recognition of the cause and prompt removal of the engorging female tick typically results in complete recovery.

Causative agent

  • An unidentified protein toxin (or toxins) in tick saliva.

Geographical distribution of cases

  • Australia, South Africa, Asia, Europe, and North America.
  • In North America, it occurs mostly in the Pacific Northwest and western Canada, but also in the eastern U.S.

Symptoms of infection

  • Progressive, ascending paralysis that starts in the legs, beginning with muscle weakness and eventually resulting in loss of motor coordination and loss of sensation in the legs.
  • The condition eventually can extend to the trunk, back muscles, and muscles of the chest.
  • Advanced stages may result in an inability to sit up, move limbs, chew, swallow, and speak.
  • The condition progresses rapidly and death due to respiratory failure may ensue in 24-48 hours.

Reservoir of toxin(s)

  • Not applicable because the condition is not due to a disease-causing agent

Vectors of the toxin(s)

  • Dermacentor variabilis, American dog tick, in the eastern U.S.
  • Dermacentor andersoni, Rocky Mountain wood tick, in the western U.S.

Mode of transmission

  • Via the bite of a female adult tick that has been feeding for days, typically engorging along the spinal cord.

Diagnosis of infection

  • Symptoms, together with onset in late spring and early summer.

Treatment of infection

  • Removal of the engorging tick; if done soon enough, recovery may be complete within 48 hours.
  • NOTE: if paralysis has progressed, complete recovery may take up to six months after tick removal.

Prevention of infection

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