Recurrent Erythema Migrans
Untreated patients can develop recurrent EM as a result of hematogenous spread of the spirochete. Recurrent EM can also occur in patients who received appropriate treatment per guidelines, prompting debate over whether these recurrences represent relapsed disease or reinfection. A recent prospective study used 3 different genetic tests to characterize the B burgdorferi isolates from 17 adults with ≥ 2 episodes of culture-confirmed EM; all patients received appropriate antibiotic therapy consistent with guidelines with each episode of Lyme disease. In evaluating 22 paired, consecutive episodes of EM, the same B burgdorferi genotype was not identified in any patient, indicating that the subsequent EM lesion was caused by a new infection as opposed to relapsed disease. Even if each patient was infected with 2 different genotypes during the initial infection (of which only 1 was cultured), the probability that chance alone accounted for these findings is 1 in 5 million. Moreover, previous studies have suggested that relapses of EM following ineffective therapy occur within days or weeks[5,6]; in contrast, all recurrences in this study occurred ≥ 1 year apart.
Medscape Pediatrics © 2013
Cite this: Recurrent Lyme Disease: Old or New Infection? - Medscape - Oct 21, 2013.