Background: Disseminated Lyme disease can be difficult to diagnose, as it begins with nonspecific signs and symptoms, which, if not treated correctly, can lead to atrioventricular conduction blocks and meningitis. In addition, the diagnosis can be further complicated by potentially false-positive test results.
Case Report: We report a case of early-disseminated Lyme disease presenting with Borrelia meningitis and concomitant Lyme carditis, which was misdiagnosed as mononucleosis.