Lyme Disease
NICE Guideline [NG95] Lyme disease. Last updated Oct 2018.
Background Information
Causative agent: Borrelia burgdorferi (spirochete)
Vector: various tick species
Risk factors (for tick exposure):
Vector: various tick species
Risk factors (for tick exposure):
- Grassy and wooded areas
- South of England and Scottish Highlands
Early localised Lyme disease - usually happen 7-14 days after tick bite:
Disseminated Lyme disease:
- Flu-like symptoms (non-specific)
- Erythema migrans around tick bite
- Circular slowly expanding red ring with central clearing
- Usually NOT itchy or painful or hot
Disseminated Lyme disease:
- Neuropathy (neuroborreliosis)
- Cranial nerve palsy (bilateral facial nerve palsy is common)
- Radiculopathy
- Peripheral neuropathy
- Arthritis
- Initial migratory arthralgia
- Late monoarthritis / asymmetric oligoarthritis
- Carditis
- AV block
- Myocarditis, pericarditis
Guidelines
Diagnose and treat Lyme disease if:
- Erythema migrans present (no further testing needed), OR
- Clinical suspicion + positive ELISA AND immunoblot test (see below for more detail)
Erythema migrans is a circular, slowly-expanding red ring with central clearing that is usually NOT itchy, hot, painful.
If the lesion is itchy / hot / painful, it is more likely to be a local reaction, instead of erythema migrans.
If the lesion is itchy / hot / painful, it is more likely to be a local reaction, instead of erythema migrans.
If erythema migrans is present → Lyme disease can be diagnosed without further testing.
If Lyme disease suspected based on clinical features (without erythema migrans) → laboratory testing
If Lyme disease suspected based on clinical features (without erythema migrans) → laboratory testing
- 1st line: ELISA (testing for antibodies against Borrelia burgdorferi)
- If +ve → immunoblot test
- If -ve → consider alternative Dx (if ongoing Sx and test done within 4 weeks of onset → repeat 4-6 weeks after)
- 2nd line: immunoblot test
- If+ve → diagnose Lyme disease
- If -ve → consider alternative Dx
ELISA is a screening test with high sensitivity, immunoblot is a confirmatory test with high specificity which can exclude false positives that ELISA might produce
Approach
Choice of treatment:
IV ceftriaxone for 21 days if:
If <9 y/o: amoxicillin instead of doxycycline
- Offer treatment if Lyme disease diagnosed (i.e. erythema migrans / +ve laboratory testing)
- If <18 y/o → discuss with speicalist
Choice of treatment:
- 1st line for most cases: oral doxycycline for 21 days
- 2nd line: oral amoxicillin
IV ceftriaxone for 21 days if:
- Lyme disease affecting CNS, or
- Lyme carditis + haemodynamic instablity
If <9 y/o: amoxicillin instead of doxycycline
Mechanism: systemic inflammatory reaction secondary rapid destruction of spirochetes
Timing: between 1-12 hours after antibiotics are started
Clinical features:
Management:
Timing: between 1-12 hours after antibiotics are started
Clinical features:
- Fever
- Chills
- Muscle pain
- Headache
- Exacerbation of existing rash
Management:
- Self-limiting (usually resolve within 24-48 hours)
- Advice patient to keep taking their antibiotics
- Supportive care
Jarisch-Herxheimer reaction is NOT an allergic reaction. However it is important to be able to differentiate it from an allergic reaction (espeically anaphlyaxis).
