Lyme disease - emergency medicine revision
Overview
Lyme disease is a multisystem infection caused by Borrelia spirochetes transmitted by Ixodes ticks. In the UK the common species are Borrelia burgdorferi, B. afzelii and B. garinii.
Clinical presentations range from a pathognomonic skin lesion (erythema migrans) to early disseminated disease (neurological, cardiac, articular, ocular) and late manifestations such as intermittent inflammatory arthritis and chronic skin changes.
Management in the ED focuses on recognising characteristic features, understanding test limitations, starting empiric therapy when indicated, and identifying red flags that require admission and specialist input (NICE NG95; UKHSA).
Epidemiology and prevention
- Cases occur across the UK with geographic variation and rising reported incidence; laboratory‑confirmed counts underestimate true incidence because many cases (notably erythema migrans) are treated clinically.
- Routine antibiotic prophylaxis after an asymptomatic tick bite is not recommended in the UK; emphasis is on correct tick removal, patient education and safety‑netting (UKHSA).
- Do not use commercial tick‑testing results to guide clinical management. Contact local public health or RIPL for specialist advice when needed.
Pathogenesis
- Borrelia are motile spirochetes that multiply in skin at the bite site and may disseminate via blood or lymphatics.
- Different Borrelia species have differing tissue tropisms (for example, B. garinii is associated with neurological disease and B. afzelii with cutaneous disease).