A child with fever, headache, malaise, and a red annular lesion with surrounding clearing is seen. What is the diagnostic step?

A child with fever, headache, malaise, and a red annular lesion with surrounding clearing is seen. What is the diagnostic step?

• A. Ask about recent tick bites.
• B. Obtain a skin culture.
• C. Order blood cultures.
• D. Perform serologic testing.

Answer: (A)

Recognize erythema migrans, a red annular lesion with central clearing, as the classic early sign of Lyme disease. In a child with fever and malaise in an area where ticks are common, this rash makes Lyme disease likely, and the diagnosis is clinical even before lab tests turn positive. The most useful initial step is to ask about recent tick bites or outdoor exposure to ticks, because confirming exposure supports the clinical diagnosis and guides prompt treatment. Serologic tests can be falsely negative in the very early stage, and cultures from skin or blood are not helpful for this organism in early Lyme disease. If exposure history and the exam strongly suggest Lyme disease, treatment should be started even before serology would become positive.

Recognize erythema migrans, a red annular lesion with central clearing, as the classic early sign of Lyme disease. In a child with fever and malaise in an area where ticks are common, this rash makes Lyme disease likely, and the diagnosis is clinical even before lab tests turn positive. The most useful initial step is to ask about recent tick bites or outdoor exposure to ticks, because confirming exposure supports the clinical diagnosis and guides prompt treatment. Serologic tests can be falsely negative in the very early stage, and cultures from skin or blood are not helpful for this organism in early Lyme disease. If exposure history and the exam strongly suggest Lyme disease, treatment should be started even before serology would become positive.