ARTHROPOD BITES AND STINGS
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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.
- Ticks should be removed with forceps applied close to the point of attachment, which should then be disinfected.
- Pts bitten by a deer tick in Lyme disease–endemic regions can receive a prophylactic oral dose of doxycycline (200 mg) within 72 h of tick removal.
- Tick removal within 36 h of attachment usually prevents transmission of the agents of Lyme disease, babesiosis, anaplasmosis, and ehrlichiosis.