For most people who contract Lyme disease—a bacterial infection borne by ticks—a course of antibiotics does the trick. But for some, especially those who live in areas like the Northeast U.S., where Lyme disease is particularly common, the infection comes back. That raises questions about whether the disease is recurring—a single infection leading to multiple bouts with symptoms—or if reinfection is occurring, meaning the patient is unlucky enough to have been bit again.
Now a new study, published Wednesday in the New England Journal of Medicine, appears to lay the question to rest: Such patients are reinfected, and Lyme disease does not appear to recur after successful courses of antibiotics.
The study looked at 17 patients who had multiple bouts of Lyme disease, analyzing the strain of bacterium that infected each one on each occasion (there are at least 19 different strains of the responsible bacterium, according to the study). The researchers found no example where two subsequent infections were caused by the same strain, meaning the disease was caused the second time by reinfection in all cases—there were no recurrences.
According to an editorial by Dr. Allen Steere of Harvard Medical School, the stakes are substantial because some patient-advocacy groups and physicians have been suggesting that a diagnosis of “chronic Lyme disease” be applied to such patients. And some argue that such a diagnosis should carry with it a different course of treatment: long-term use of antibiotics, an approach that is known to cause increases in antibiotic resistance.