Lyme Disease

Lyme Disease - Bug's Beginnings

• Etiology: Spirochetes:
  • Borrelia burgdorferi sensu lato complex (main cause):
    • B. burgdorferi sensu stricto (N. America)
    • B. afzelii, B. garinii (Europe, Asia)
  • Borrelia mayonii (N. America, less common)
• Vector: Transmitted by Ixodes ticks (e.g., deer tick - I. scapularis, I. ricinus, I. persulcatus).
• Reservoirs: Primarily small rodents (e.g., white-footed mice); deer are important tick hosts.
• Epidemiology:
  • Endemic in USA (Northeast, Upper Midwest). Increasing incidence in Europe & Asia.
  • India: Rare. Awareness crucial for imported cases or potential misdiagnosis.

⭐ Borrelia burgdorferi is a Gram-negative spirochete transmitted by Ixodes ticks.

Word Count: 79

Lyme Disease - Rash Report

• Early Localized Stage (3-30 days post-tick bite): Characterized by:
  • Erythema Migrans (EM): The hallmark rash.
    • Site: Appears at/near tick bite location.
    • Appearance: Expanding, annular (ring-like) red patch or macule.
    • Classic: Central clearing common, creating a "bull's-eye" (targetoid) appearance.
    • Size: Typically enlarges to >5 cm in diameter.
    • Symptoms: May feel warm to touch; usually not painful or pruritic.
    • 📌 Mnemonic: EM = Expanding Macule.

    ⭐ Erythema migrans (EM) is the pathognomonic skin lesion of early Lyme disease, seen in 70-80% of US cases.

  • Associated Systemic Symptoms (Flu-like):
    • Fever, chills, fatigue, headache.
    • Myalgias (muscle pain), arthralgias (joint pain).

Lyme Disease - Spreading Symptoms

Early Disseminated (Weeks to Months)

• Neurologic (Lyme Neuroborreliosis - LNB): Aseptic meningitis, cranial neuritis (esp. facial nerve palsy - CN VII, can be bilateral), radiculoneuritis.
• Cardiac: Carditis (AV block - 1st, 2nd, 3rd degree), myopericarditis.
• Musculoskeletal: Migratory arthralgias/myalgias.
• Ocular: Conjunctivitis, uveitis.

Late Disseminated (Months to Years)

• Arthritis: Mono- or oligoarticular, large joints (esp. knee).
• Chronic LNB: Encephalopathy, polyneuropathy.
• Skin: Acrodermatitis Chronica Atrophicans (ACA) - primarily Borrelia afzelii (Europe).

📌 Mnemonic: 'ABC of Lyme': Arthritis, Bell's Palsy (Facial), Carditis.

⭐ Lyme carditis most commonly manifests as fluctuating degrees of atrioventricular (AV) block.

Lyme Disease - Test & Treat Tactics

Diagnosis:

• Clinical: EM endemic = diagnostic.
• Serology (Two-tier): EIA/IFA → Western Blot (IgM/IgG <30d; IgG >30d).
• CSF (LNB): Pleocytosis, intrathecal Ab.
• PCR: Biopsy (EM), CSF, synovial (low blood sensitivity).

⭐ For Lyme disease diagnosis, serologic tests are not recommended for patients with EM if they reside in a high-prevalence area, as diagnosis is clinical; testing may be falsely negative early on.

CDC Two-Tier Serological Testing:

Treatment Regimens:

Prophylaxis:

• Doxycycline 200mg (1 dose): tick ≥36h, high-risk, within 72h removal.

PTLDS:

• Persistent symptoms; unclear mechanism; no prolonged antibiotics.

High‑Yield Points - ⚡ Biggest Takeaways

• Causative agent: Borrelia burgdorferi, a spirochete.
• Vector: Transmitted by Ixodes ticks (deer ticks).
• Stage 1 (Early Localized): Hallmark is Erythema migrans (targetoid or bull's-eye rash).
• Stage 2 (Early Disseminated): Neurologic (e.g., bilateral Bell's palsy, meningitis) and cardiac (e.g., AV block) manifestations.
• Stage 3 (Late Disease): Arthritis (especially large joints like the knee) is common; chronic encephalopathy.
• Diagnosis: Clinical diagnosis supported by two-tier serology (ELISA followed by Western blot).
• Treatment: Doxycycline is standard; Amoxicillin for children/pregnant women. IV Ceftriaxone for severe/late manifestations_.