A. 44 Lyme Disease Flashcards
A.44 Lyme
definition
USA - Borrelia burgdorferi, a microaerophilic spirochete bacteria
Vector Ixodes scapularis
Reservoir Host: deer, cattle, mice
Europe and asia
B. afzelii
B. garinii
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What are the 3 stages
Stage 1 - Early Localized
Stage 2 - Early Disseminated
Stage 3 - Late Disseminated
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Clinical Features of Stage 1 - Early Localized
syms occur between 3-30 days after bite
Symptom onset occurs 7–14 days after a tick bite.
Erythema migrans - A rash characterized by a circular, slowly-expanding red ring with central clearing. Pathognomonic of early Lyme disease and appears around the site of the tick bite.
Flu‑like symptoms
Fever
Headache
Fatigue, malaise, lethargy
Myalgias, arthralgias
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Clinical Features of Stage 2 - Early Disseminated
Symptom onset occurs 3–10 weeks after a tick bite.
Migratory arthralgia; can progress to Lyme arthritis if left untreated
Early neuroborreliosis - can affect the peripheral and/or central nervous system. Manifests within the first few months of infection. May include Bell’s palsy, meningitis, polyneuropathy, and/or encephalomyelitis.
Lyme carditis - A complication of early disseminated Lyme disease. Typically occurs 1–2 months after infection and manifests as AV conduction dysfunction and/or decreased cardiac contractility due to myopericarditis.
Associated signs and symptoms include chest pain, dyspnea, edema, palpitations, and syncope.
AV Block 1st to 3rd degree
Cutaneous manifestations
Multiple erythema migrans lesions
Borrelial lymphocytoma - bluish-red nodular swelling typically located on the earlobe or near the nipple
Ocular manifestations
Retinal vasculitis
Keratitis
Iridocyclitis
Uveitis
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Clinical Features of Stage 3 - Late Disseminated
Symptom onset occurs months to years after the initial infection.
Lyme arthritis - ypically affects large joints (e.g., knees, elbows). Can manifest as intermittent or persistent monoarthritis or oligoarthritis. Late neuroborreliosis - an affect the peripheral and/or central nervous system. Can include Bell palsy, meningitis, polyneuropathy, and/or encephalomyelitis. Occurs months to years after infection. Acrodermatitis chronica atrophicans - manifestation of European and Asian Lyme disease caused by infection with Borrelia afzelii. Characterized by chronic progressive atrophic dermatitis affecting the extensor surfaces of the extremities.
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Lyme Serology
Preferred testing protocol for new infections. - ELISA enzyme-linked immunosorbent assay confirmed with Western Blot
Detects IgM and IgG antibodies against Borrelia burgdorferi.
Positive Result
IgM positive, IgG negative: consistent with acute or recent infection
IgG positive: consistent with recent or remote infection
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Additional Tests to do
Further testing may be considered depending on the clinical presentation.
ECG: See “Lyme carditis.”
Lumbar puncture (LP): See “Neuroborreliosis.”
Arthrocentesis: See “Lyme arthritis.”
Laboratory studies
CBC: mild anemia, normal total WBC count with lymphopenia
Inflammatory markers: ↑ ESR
Liver enzymes: mildly elevated
Troponin: may be elevated in Lyme carditis [6]
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Oral Antibiotics
Preferred oral agents: doxycycline, amoxicillin, or cefuroxime axetil
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Indications for Oral antibiotics
Erythema migrans
Neuroborreliosis without parenchymal CNS involvement (e.g., isolated cranial nerve palsy, radiculoneuropathy, mild meningitis)
Mild Lyme carditis
Lyme arthritis Borrelial lymphocytoma Acrodermatitis chronica atrophicans
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IV Antibiotics
Preferred IV agent: ceftriaxone
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Indications for IV Antibiotics
Indications for IV therapy
Neuroborreliosis with severe meningitis or parenchymal CNS involvement (i.e., encephalitis, myelitis)
Neuroborreliosis in patients with impaired tolerance or adherence to oral therapy
Severe Lyme carditis
Treatment-resistant Lyme arthritis
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TX of Neuroborreliosis
Meningitis, radiculopathy, cranial neuropathy, and/or other peripheral neuropathy : either oral or IV antibiotics for 14–21 days
Preferred (one of the following)
Oral doxycycline (off-label)
IV ceftriaxone (off-label)
Encephalitis and/or myelitis: IV antibiotics with good CNS penetration for 14–28 days
Preferred: IV ceftriaxone (off-label)
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TX Lyme Carditis
The choice of IV or oral antibiotics depends on symptoms; patients with severe manifestations (e.g., PR prolongation > 300 ms, high-degree AV block, arrhythmias, or features of perimyocarditis) require IV antibiotics.
Mild symptoms: oral antibiotics for 14–21 days
Oral doxycycline (off-label)
Oral amoxicillin (off-label)
Oral cefuroxime axetil (off-label)
Alternative: azithromycin (off-label)
Significant cardiac involvement: IV antibiotics for 14–21 days.
Preferred: IV ceftriaxone (off-label)
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List the Complications
Heart block (may require pacemaker temporarily)
Neuroborreliosis → CN palsy, meningitis, radiculitis
Chronic arthritis
Post-treatment Lyme Disease Syndrome (fatigue, cognitive complaints) — controversial, not an indication for more antibiotics
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Patient with known Lyme disease treated 6 months ago has persistent fatigue. Should you re-treat with antibiotics?
→ No. This is Post-treatment Lyme Disease Syndrome. No benefit from additional antibiotics.
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What’s the first test in suspected Lyme carditis?
→ ECG — look for heart block. Doxy won’t fix 3rd-degree block overnight!
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You suspect neuroborreliosis. What do you do?
→ Lumbar puncture + start IV ceftriaxone. Look for lymphocytic pleocytosis, elevated protein, intrathecal antibodies.
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Do you treat the tick bite prophylactically?
→ Only if:
Ixodes tick identified Attached ≥36 hours Prophylaxis can begin within 72h of removal Doxycycline is not contraindicated → Then: single dose doxycycline 200 mg
