Lyme Disease

🔍 When to Suspect

An expanding, circular "bull's-eye" rash (erythema migrans) appearing 3-30 days after potential tick exposure, often with non-specific flu-like symptoms

From the full topic in The Ocean Library: Lyme Disease

🧭 When to suspect

Lyme disease is a tick-borne infection caused by Borrelia burgdorferi (sensu lato), transmitted by the bite of an infected Ixodes ricinus tick. It can be acquired anywhere in the UK but is most common in the South of England and the Scottish Highlands. Most tick bites do not transmit infection, and prompt, correct tick removal reduces the risk.

The hallmark is erythema migrans (EM) – an expanding red rash, sometimes with central clearing (the classic "bull's-eye"), that is not usually itchy, hot or painful, appears 1–4 weeks after a bite (range 3 days to 3 months) and lasts several weeks. EM is a clinical diagnosis: treat it on sight and do not wait for blood tests.

Around one-third of UK cases have no rash, and many patients recall neither a rash nor a bite. Consider Lyme disease in someone with plausible exposure (grassy or wooded areas, gardening, hiking, forestry, deer management) who presents with non-focal symptoms (fever, fatigue, headache, migratory arthralgia, "brain fog") or focal organ involvement (neurological, cardiac, joint or eye). The two key skills are to recognise and treat EM clinically and to never miss disseminated disease – while avoiding over-diagnosis in those without a supportive history or positive serology.

Stage	Typical timing	Characteristic features
Early localised	Days to weeks	Erythema migrans at the bite site, often with flu-like symptoms
Early disseminated	Weeks to months	Multiple EM lesions; neuroborreliosis (facial palsy, Bannwarth's syndrome); Lyme carditis (heart block); uveitis
Late	Months to years	Lyme arthritis (large joints, especially the knee); acrodermatitis chronica atrophicans; late neuroborreliosis

Source: NICE NG95 · UK Health Security Agency

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