A 28-year-old woman presents with a one-week history of a slightly raised erythematous lesion on her chest. She has been experiencing fatigue and joint pain since taking a walk through the woods in eastern Massachusetts earlier this month. She is 33-weeks pregnant and is otherwise well. An enzyme-linked immunosorbent assay (ELISA) test comes back negative for Lyme antibodies.
Image credit: @badness.
A diagnosis of early Lyme disease can be made based on this patient’s clinical findings and history of exposure in an endemic area. Erythema migrans can present before adaptive immune response occurs. Serologic testing is not required (and will often come back negative) in patients with localized Lyme disease. Although doxycycline is generally the preferred treatment, it should be avoided in pregnant women and children. Early Lyme disease can also be treated with a course of amoxicillin or cefuroxime for two to three weeks.
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