Epidemiology:

• Tick-Borne: Ixodes ticks
• Peak Incidence: I. dammini tick in NE US (Massachusetts to Mayland) and midwest (Minnesota/Wisconsin)
  • Immature I. dammini has white-footed mouse as preferred host/mature tick has white-tailed deer as preferred host
  • Other species of Ixodes ticks seen in western US, Europe, Asia, Australia
• Season: most cases occur during summer months
• Incidence: 1000 cases are acquired each summer in US
• Age: affects all ages
• Sex: no sex predominace

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Etiology

• Borrelia burgdorferi

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Diagnosis

• CBC:
• Blood c/s:
• ELISA: requires Western blot confirmation
• Western Blot: required for diagnsosis of disseminated ot late-stage disease
• PCR: useful for detecting active disease in joints
  • May be positive in patients with active CNS disease
• Lyme Urine Ag: unreliable and of no clinical value

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Clinical

Clinical Stages of Lyme Disease:
1) Stage 1: Early/Localized Infection: occurs 3-32 days (average 7-10 days) after infection
a) Erythema Migrans (75% of cases): bullseye rash at bite site (usually thigh/groin/axilla) -> progresses to warm (although not often painful) erythema migrans
-Rash may last up to 3-4 wks, although pts usually do not notice the non-pruritic skin lesions
b) Non-Specific Rash:
c) Influenza-Like Illness Without Rash:

2) Stage 2: Disseminated Infection: occurs weeks-months after onset of Erythema Migrans
a) Multiple Annular Skin Lesions:
b) Arthralgias/Myalgias:
c) Malaise/Fatigue:
d) Neuro Involvement (15% of cases/occurs after weeks-months):
–Aseptic Meningitis: LP with lymphocytic pleocytosis (WBC usually around 100)/elevated protein/normal-slightly decreased glucose
–Facial Palsy:
–Encephalitis:
–Neuropathy (see [[Phrenic Neuropathy]])
– Acute/Chronic Hypoventilation (see Acute Hypoventilation, [[Acute Hypoventilation]] and Chronic Hypoventilation, [[Chronic Hypoventilation]])
–Myelitis:
–Headache: may be severe
e) Cardiac Involvement (8% of cases/occurs after weeks, lasting only a few wks, but may recur):
–Myocarditis:
–Heart Blocks: AV blocks, complete heart block
–LV Dysfunction/CHF:
–Arrhythmias: VT

3) Stage 3: Persistent Infection: occurs months-years after onset of infection
a) Large Joint Oligoarticular Arthritis (60% of cases):
–Lasts wks-months in each joint
–Typically involves the knee
–Arthrocentesis: WBC count 500-110k (average 25k), neutrophil-predominant
b) Neuroborreliosis:
–Subtle Encephalopathy (with abnormal CSF):
–Axonal Polyneuropathy:
–Leukoencephalitis (rare):
c) Chronic Skin Involvement: acrodermatitis chronica atrophicans (mostly in elderly women/more common in Europe)

4) Post-Lyme Syndrome: debilitating chronic illness (fatigue, neurocognitive symptoms, etc.) following Lyme treatment (not due to chronic Lyme infection)
-Randomized trial of antibiotics in tis group showed no improvement
[Klempner, 2001, NEJM]

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Treatment

• Prevention:
  • Avoid Tick Bites:
• Antibiotic Prophylaxis: PO Amoxacillin or Doxycycline x 10-14 days can be considered for ticks attached for >24 hrs with bite occurring in hyperendemic area
  • However, most experts do not believe that this regimen is efficacious (given risk of antibiotic SE), regardless of length of tick attachment
  • Single-Dose Antibiotic Prophylaxis: single 200 mg dose of Doxycycline given within 72 hrs of tick bite in endemic area decreases incidence of acute Lyme from 3.2% (placebo) to 0.4%, with only minor adverse SE
    [Nadelman, 2001, NEJM; 345: 79-84]
• Antibiotic Treatment:
  • Early Disease:
    • PO: Amoxacillin or Doxycycline x 21 days
      • Alternative PO: Cefuroxime or Erythro or Clarithro x 21 days
    • IV: Ceftriaxone 2 g qday x 14 days
      • Alternative IV: cefotaxime or PCN-G x 14 day
• Late Disease:
  • Carditis: Ceftriaxone 2 g IV qday x 21 days or PCN-G IV x 14 days
  • Facial Nerve Palsy: PO Doxycycline or amox x 21 days
  • Other Neuro: Ceftriaxone 2 g IV qday x 21 days or PCN-G IV x 14 days
  • Arthritis: PO Doxycycline x 21 days or PCN-G IV x 14 days

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References

Steere AC. Lyme Disease (Medical Progress). New Engl J Med 1989; 321(9):586-596
Vlay SC, Dervan JP, Elias J, et al. Ventricular tachycardia associated with Lyme disease. Am Heart J 1991; 121:1558-1660