ARTHROPOD BITES AND STINGS

TICK BITES AND TICK PARALYSIS

• Epidemiology: Ticks are important carriers of vector-borne diseases (e.g., Lyme disease, babesiosis, anaplasmosis, ehrlichiosis) in the United States.
• Etiology: While ticks feed on blood from their hosts, their secretions may produce local reactions, transmit diverse pathogens, induce a febrile illness, or cause paralysis. Soft ticks attach for <1 h; hard ticks can feed for >1 week.
• Clinical features: Except for tick-borne diseases, most manifestations of tick bites are self-limited following tick removal.
  • Tick-induced fever, in the absence of pathogen transmission, is associated with headache, nausea, and malaise and usually resolves ≤36 h after the tick is removed.
  • Tick paralysis is an ascending flaccid paralysis due to a toxin in tick saliva that causes neuromuscular block and decreased nerve conduction.
    • Weakness begins symmetrically in the lower extremities ≤6 days after the tick’s attachment and ascends symmetrically, causing complete paralysis of the extremities and cranial nerves.
    • Deep tendon reflexes are decreased or absent, but sensory examination and LP yield normal findings.
    • Tick removal results in improvement within hours; failure to remove the tick may lead ultimately to respiratory paralysis and death.