Lyme disease

Lyme disease is the most common tick-borne illness in the USA and Europe. Pathogens involved include Borrelia burgdorferi in the USA and B. afzelii and B. garinii in Europe. The characteristic rash of erythema migrans occurs in 70–80% of patients. Neurological disease, including facial palsy, meningo-encephalitis, aseptic meningitis and polyradiculopathy, occurs in 10–15%. Cardiac disease, primarily manifest as heart block, is seen in 1–4%. Arthritis is a late complication in about 30% of untreated patients. Patients with erythema migrans can be treated for 10–14 days with doxycycline 100 mg orally twice a day. For those unable to tolerate doxycycline, amoxicillin 500 mg orally three times per day for 14–21 days will be effective as will cefuroxime axetil 500 mg two times per day. For central nervous system disease, oral doxycycline has been shown to be equivalent to parenteral ceftriaxone. Lyme arthritis requires the longest courses of antibiotics (28 days) with a second course of therapy required in a substantial fraction of patients. Initial treatment of Lyme arthritis can be with oral antibiotics but intravenous antibiotics are used if there is a poor initial response. Around 15–20% of patients have some persistence of non-specific symptoms such as fatigue and myalgias, but such post-Lyme disease symptoms have not been shown to respond to additional courses of antibiotic therapy. Prevention measures currently rely on tick avoidance, tick repellents and careful inspection and removal of ticks if present. No vaccine for humans is available.