Lyme disease

Question 1

Definition

Answer 1

Bacterial infection caused by group of bacteria: Borrielia burgdorferi = transmitted to humans following a bite from an infected tick.
Animals serve as the primary reservoir for Borrelia

Question 2

Epidemiology

Answer 2

• Outdoor activities: occupational or recreational exposure to woodlands and fields
• Increased duration of tick attachment: Transmission from ticks to humans occurs from 36 hours

Question 3

Pathophysiology

Answer 3

Stage 1: Early localised disease (Usually <30 days of tick bite)
- Occurs soon after bite + identified presence of RED-RING, EXPANDING RASH = ERYTHEMA MIGRANS
Stage 2: Early disseminated disease > 30 days
- Bacteria spreads via haematogenous dissemination to attach to host integrins -> pro-inflammatory response in particular tissues
Stage 3: Late disease (Up to 7 years after infection)
- Characterised by ACRODERMATITIS CHRONICA ATROPHICANS
and arthritis
- Suspected secondary to inflammatory and protein changes that occur within the skin and joints

Question 4

Early localised disease signs and symptoms

Answer 4

Expanding ‘bull’s eye’ rash
= Erythema migrans
= Occurs at site of tick bite

Question 5

Early disseminated disease signs and symptoms

Answer 5

• Multiple bulls eye rashes
• Weakness of the muscles and face = Facial nerve palsy (CN VII)
• Lymphadenopathy
• Myalgia
• Heart block

Question 6

Late disease signs and symptoms

Answer 6

• Arthritis = usually oligoarthritis with evidence of synovitis
• Unilateral violet discolouration of the extensor surfaces

Question 7

Non-specific symptoms

Answer 7

Fever,
Lymphadenopathy,
Headaches

Question 8

Diagnosis

Answer 8

Majority of patients on experience the first stage of the disease
Clinical diagnosis for Px who present with erythema migrans
Consider:
- FIRST LINE for sus px w/o bull eye lesions = Enzyme-linked immunosorbent assay (ELISA) antibodies to borrelia burgdorferi
= If ELISA +ve = perform immunoblot test for Lyme disease
= If immunoblot +ve = diagnose Lyme disease
= If ELISA is negative : repeat ELISA after 4-6 weeks if Lyme disease is still suspected

Question 9

Treatment

Answer 9

FIRST LINE = Abx
- DOXYCYCLINE: Twice daily for 21 days
- If FL CI = give amoxicillin
Second line =
- 2nd course Abx = if symptoms persist
= Further treatment following two courses of Abx not recommended

Question 10

Complications

Answer 10

Jarish-Hexheimer reaction
- fever
- rash
- tachy
Neurological symptoms:
- facial nerve paralysis
- meningitis
- peripheral neuropathy
Cardiovascular:
- 1st heart block
- Myocarditis
Acrodermatitis chronica atrophicans: violet discolouration of the extensor surfaces
Lyme arthritis