Drs. Stricker and McNeil quote my editorial incorrectly. It is important to distinguish chronic Lyme arthritis, in which a knee remains inflamed for months or several years despite antibiotic therapy, from chronic post–Lyme disease syndrome or so-called chronic Lyme disease, in which patients develop musculoskeletal, neurocognitive, or fatigue symptoms (similar to chronic fatigue syndrome or fibromyalgia) during or soon after Lyme disease despite standard antibiotic treatment for Borrelia burgdorferi infection.

We have postulated that genetically susceptible patients with B. burgdorferi–infected knees may develop autoimmunity within the proinflammatory milieu of the joint because of molecular mimicry between an immunodominant epitope of outer-surface protein A and a host protein (1). A candidate molecular mimic was a sequence on the light chain of human lymphocyte function-associated antigen-1 (LFA-1 _L332-340), but we have come to think that this is not a relevant autoantigen in this disease (2). We have never postulated that autoimmunity or LFA-1 has any role in the pathogenesis of chronic post–Lyme disease syndrome.

In contrast with the statement of Drs. Stricker and McNeil, the weight of evidence is against the idea that chronic post–Lyme disease syndrome or "chronic Lyme disease" results from active infection with B. burgdorferi. Although the spirochete has been seen in intracellular locations in several tissue culture experiments, the organism has been seen only extracellularly in affected tissues from patients with Lyme disease (3). In a mouse model of Lyme disease, a few attenuated, noninfectious spirochetes were found in ticks that fed on the mice 3 months after 1-month courses of antibiotic therapy, but no mice had positive results 6 months after treatment (4).

Most important, long-term persistence of the spirochete has not been substantiated in any large series of patients treated with currently recommended antibiotic regimens. In a double-blind, placebo-controlled trial that sought to determine whether patients with persistent symptoms after Lyme disease would benefit from additional 3-month courses of antibiotic therapy (5), no patient had positive cultures or positive results by polymerase chain reaction before treatment, and no differences were noted in outcome between the antibiotic and placebo groups.

As with chronic fatigue syndrome or fibromyalgia, symptomatic treatment may be helpful for some patients with "chronic Lyme disease." In addition, a team approach by health care professionals or cognitive behavioral therapy has been shown to be of value for some patients with chronic fatigue syndrome or fibromyalgia. There is no substitute for sympathetic listening and explanation.