Lyme disease is caused by the spirochaete Borrelia burgdorferi and is spread by ticks.


  • Incidence: 12.00 cases per 100,000 person-years
  • Peak incidence: 6-15 years
  • Sex ratio: 1:1
Condition Relative
Lyme disease1
Reactive arthritis0.42
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Clinical features

Early features (within 30 days)
  • erythema migrans
    • 'bulls-eye' rash is typically at the site of the tick bite
    • typically develops 1-4 weeks after the initial bite but may present sooner
    • usually painless, more than 5 cm in diameter and slowlly increases in size
    • present in around 80% of patients.
  • systemic features

Later features (after 30 days)


  • NICE recommend that Lyme disease can be diagnosed clinically if erythema migrans is present
    • erythema migrans is therefore an indication to start antibiotics
  • enzyme-linked immunosorbent assay (ELISA) antibodies to Borrelia burgdorferi are the first-line test
    • if negative and Lyme disease is still suspected in people tested within 4 weeks from symptom onset, repeat the ELISA 4-6 weeks after the first ELISA test. If still suspected in people who have had symptoms for 12 weeks or more then an immunoblot test should be done
    • if positive or equivocal then an immunoblot test for Lyme disease should be done


Management of asymptomatic tick bites
  • tick bites can be a relatively common presentation to GP practices, and can cause significant anxiety
  • if the tick is still present, the best way to remove it is using fine-tipped tweezers, grasping the tick as close to the skin as possible and pulling upwards firmly. The area should be washed following.
  • NICE guidance does not recommend routine antibiotic treatment to patients who've suffered a tick bite

Management of suspected/confirmed Lyme disease
  • doxycycline if early disease. Amoxicillin is an alternative if doxycycline is contraindicated (e.g. pregnancy)
    • people with erythema migrans should be commenced on antibiotic without the need for further tests
  • ceftriaxone if disseminated disease
  • Jarisch-Herxheimer reaction is sometimes seen after initiating therapy: fever, rash, tachycardia after first dose of antibiotic (more commonly seen in syphilis, another spirochaetal disease)