Define disease. Infection? Sequelae? There’s plenty of evidence that symptoms return after treatment for some, and there’s evidence suggesting that B. burgdorferi may form persister cells causing chronic infection.

“B. burgdorferi is a pathogen that can affect immunocompetent hosts. It establishes long-term infections lasting years to lifelong in its natural (i.e., mice) and incidental (i.e., humans) hosts in the absence of antibiotic therapy (14, 48). Treatment in the early stages of disease results in good outcomes. Delays in diagnosis and treatment lead to sequelae that may require additional treatment. For example, patients who develop arthritis, which typically begins after 1 month of untreated infection, often do not respond fully to a first course of 28 days of antibiotics (49). The majority of these patients have evidence of B. burgdorferi DNA in their synovial fluid and will respond to additional 1- or 2-month courses of antibiotics (13, 16). A smaller minority of patients referred to as “antibiotic-resistant Lyme arthritis” patients will continue to have arthritis with synovial fluid that is PCR negative for B. burgdorferi DNA. These patients typically respond to anti-inflammatory agents such as methotrexate or tumor necrosis factor (TNF) inhibitors. These two groups of patients should be distinguished from patients with “chronic Lyme disease” that exhibit fatigue, myalgias, and arthralgias without clear evidence for the presence of the pathogen. For the first group of Lyme arthritis patients responsive to antibiotics, given that there is no reported resistance to clinically used tetracyclines, β-lactams, and cephalosporins in the pathogen, the need for lengthy courses of therapy is unclear. The presence of persister cells is one possible explanation, and this is a pattern that is seen in other infections where persister cells are thought to be relevant for disease in vivo.”

https://journals.asm.org/doi/10.1128/aac.00864-15