Introduction
Lyme disease is caused by the spirochaete Borrelia burgdorferi and is spread by ticks.
Epidemiology
- Incidence: 12.00 cases per 100,000 person-years
- Peak incidence: 6-15 years
- Sex ratio: 1:1
| Condition | Relative incidence |
|---|---|
| Lyme disease | 1 |
| Reactive arthritis | 0.42 |
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Clinical features
Early features (within 30 days)
Later features (after 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
- headache
- lethargy
- fever
- arthralgia
Later features (after 30 days)
- cardiovascular
- heart block
- peri/myocarditis
- neurological
- facial nerve palsy
- radicular pain
- meningitis
Investigations
Investigation
- 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
Management of asymptomatic tick bites
Management of suspected/confirmed Lyme disease
- 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)