tick bite

Epidemiology

• probability of acquiring a tick-borne infection from a tick bite even in endemic areas is low
• most persons bitten by a tick are unaware of having been bitten

Clinical manifestations

• normal reaction following any sting or bite
  • immediate local pain with swelling
  • subsides within 1-2 hours
  • pruritus that may persist for days
• local wheal & itching may occur
• associated symptoms of tick bite fever, tick paralysis, Rocky Mountain spotted fever of Lyme disease may be present
• symptoms of tick borne infections (up to 8 weeks)
  • rash
  • fever
  • arthralgias
  • headache
  • stiff neck
  • photophobia
  • facial droop

* image of tick attached to tympanic membrane [5[

Laboratory

• leukocytosis & hyperglycemia typical of stress reaction
• generally laboratory tests not useful

Differential diagnosis

• spider bite
• vasculitis

Management

• tick removal
  • firm traction with foreceps at the site of attachment
  • rupture of the tick body may permit escape of fluids containing pathogenic viruses, rickettsiae, borreliae, or the agent of tularemia
• prophylactic doxycycline 200 mg single dose if all of following criteria met:
  • tick identified as a blacklegged tick
  • antibiotics can be given within 72 hours of the bite
  • tick was attached for >=36 hours
  • tick bite occurred in a Lyme-endemic area wth B. burgdorferi prevalence > 20% (Northeast, mid-Atlantic, upper Midwest)
  • not pregnant or lactating
• otherwise, prophylactic antibiotics NOT indicated for asymptomatic tick bites
• tick-borne infections respond to antibiotic therapy started with the onset of symptoms
• patients should be counseled to observe for symptoms of tick-borne infections for up to 8 weeks

More general terms

• animal bite
• superficial injury/trauma

Additional terms

• tick
• tick borne infection
• tick fever
• tick-related allergy