Lyme disease


  • Tick Borne - Ixodes black-legged ticks
  • Endemic Areas: NE, E US Coasts
  • Caused by spirochete Borrelia burgdorferi
  • The spirochete Borrelia mayonii has been a new strain implicated in cases in the midwest[1]
  • Peak in May to Aug
  • Stages: Early localized infection, early disseminated, and late disseminated

Clinical Features

3 Distinct Stages - Not all patients suffer all stages, and stages may overlap with remissions between stages

Early Localized Infection (7-14d)

  • Erythema Chronicum Migrans: Occurs at site of tick bite, beginning with red macule that expands outward. Starts 3-30 days after bite and occurs in 70-80% of cases
  • Erythema migrans rash more often without central clearing
  • Fatigue, low grade fever, migrating arthralgia, lymphadenopathy, headache, nausea/vomiting, abdominal pain

Early Disseminated Infection (Days to weeks)

Late Disseminated Infection (Months to Years)

  • Arthritis: Monarticularule outligoarticular asymmetric arthritis (large joints-commonly knee)
    • Brief episodes separated with complete remission
    • Migratory pattern may occur
  • Nervous System: Subtle encephalopathy, fatigue, polyneuropathy

Differential Diagnosis


Tick Borne Illnesses


  • ELISA if positive obtain confirmatory Western blot
  • PCR
  • Cultures, serologies
  • LP with lymphocytic pleocytosis, elevated protein, normal glucose, + spirochete antibody, paired serum/CSF serologic tests,PCR
    • Must be performed in patients with neuro findings (facial nerve palsy, meningoencephalitis, etc)
    • CNS Lyme disease will be treated with ceftriaxone
  • Arthrocentesis, serologic testing of fluid


No risk when duration of attachment <24 hrs


  • Adult: Doxycycline 200mg PO x1
  • Child >8: 4mg/kg up to 200mg PO x1
  • Give if all of the following are met:
    • Tick is adult/nymphal I. scapularis
    • Tick was attached >36 hours based on degree of engorgement or exposure time
    • Prophylaxis can be given within 72 hrs after time tick was removed
    • Local rate of infection in ticks >20%
    • Doxycycline is not contraindicated
  • Old vaccine has little to no efficacy after 1 year

Early Localized Infection

  • Treat before serologic testing if endemic area if + erythema migrans rash
    • Doxycycline 100mg PO BID x 14-21 days[3]
      • Acceptable for all pediatric patients when used for 21 days or less
      • Also treats human granulocytic ehrlichiosis
    • Amoxicillin 500mg PO TID x 14-21 days
      • Preferred in pregnant, lactating
    • Cefuroxime axetil 500mg PO BID x 14-21 days
    • Macrolides-not first line
  • Jarisch-Herxheimer like reaction can occur in first 24 hrs of treatment (fevers, chills, myalgia, tachycardia)

Early Disemminated

Lyme Meningitis

Cardiac Disease




  • Early Disease
  • Late Disease: If chronic neurologic/arthritic manifestations may be able to manage as outpatient
  • Follow up with primary care, rheum, ID


  • Lyme carditis-cardiac monitoring
  • Prominent neurologic symptoms for IV antibiotics and further care

See Also

CDC: Lyme Disease


  1. Pritt BS, Mead PS, Johnson DKH, et al.Identification of a novel pathogenic Borrelia species causing Lyme borreliosis with unusually high spirochaetaemia: a descriptive study. Lancet Infectious Disease. Published Online: 05 February 2016.
  2. Signs and Symptoms of Lyme Disease, CDC, page last reviewed: June 16, 2015.
  3. Shapiro, E. (2014) ‘Lyme disease’, New England Journal of Medicine, 371(7), pp. 683–684.
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