Reinfection, Not Relapse, the Cause of Repeat Lyme Disease

Patients who experience a second episode of erythema migrans after their Lyme disease is successfully treated with antibiotics have reinfection, not relapse, a small study showed. 

Robert Nadelman, MD, of New York Medical College in Valhalla, NY, and colleagues collected data on patients that presented to the Lyme disease clinic at New York Medical College from 1991 to 2011 with erythema migrans, the “bulls-eye” at the site of Lyme disease infection. 

Researchers isolated the records of patients who returned with new erythema migrans after successful treatment (defined as "subsequent resolution of the skin lesion or lesions") of the first case.  From each of the remaining 22 episodes, involving 17 patients, they collected specimens of B. burgdorferi.

“None of the 22 paired consecutive episodes of erythema migrans were associated with the same strain of B. burgdorferi on culture. Our data show that repeat episodes of erythema migrans in appropriately treated patients were due to reinfection and not relapse.”

Researchers acknowledged the possibility that patients were infected with multiple strains upon first infection, but estimated the probability of this explaining the results in each of their 22 pairs of episodes at 0.0000002.

-Michael Potts