• Cause: spirochaete Borrelia burgdorferi transmitted by tick bite.
• Age group: any age.
• Incubation: 4–20 days.
• Rash: erythematous macule at the site of the tick bite increases in size and forms a painless red lesion called erythema migrans.
• Early time course (weeks): the symptoms of fever, headache, myalgia, arthralgia, and lymphadenopathy fluctuate over several weeks.
• Later time course (months): dissemination of infection leads to cranial nerve palsies, meningitis, arthritis, or myocarditis.
• Diagnosis: the clinical features and serology after 2–4wks.
• Treatment: in the young child amoxicillin is used. In the child aged >8yrs use doxycycline. In those with heart or CNS disease use ceftriaxone.