The clinical signs associated with acute Lyme disease in humans include erythema migrans, neurologic and cardiac disease, and arthritis. Symptoms and syndromes are thought to occur in some patients after completion of an initial course of treatment. Chronic Lyme disease is classified in this article as a subjective diagnosis assigned to patients with a variety of clinical syndromes that are attributed to Lyme disease, whether or not this is supported by diagnostic evidence. Advocates of this classification claim that chronic Lyme disease occurs in the absence of Lyme antibodies, and suggest explanations that have not held up to scientific scrutiny. The authors, who include members of the Ad Hoc International Lyme Disease Group, discount studies that attempt to isolate Borrelia burgdorferi (and other Borrelia species that cause Lyme disease in Europe) as evidence for persistent Lyme infection. They argue that even if some organisms remain in the body after therapy, there is no way to directly correlate their presence with clinical Lyme disease. The authors dispute the existence of "chronic Lyme disease" as it is defined. They are concerned about inappropriate antibiotic use and lack of scientifically based diagnostics and assert that prolonged, expensive, and potentially dangerous therapies should not be applied in such cases.

COMMENTARY: In human medicine, great debate continues regarding what constitutes chronic disease and whether treatment should be pursued. Patients are diagnosed using very questionable test results -for example, the urinary antigen test, the results of which have been inconsistent. Some people are diagnosed on the basis of symptoms but actually are seronegative. Physicians who believe in the existence of chronic Lyme disease have formed societies and charitable foundations and have developed their own management guidelines. Scientists who challenge the notion of chronic Lyme disease have been severely criticized.

In veterinary medicine, Lyme disease is recognized as a self-limiting infection causing a polyarthritis characterized by fever, lameness, and joint swelling. Borrelia burgdorferi has also been implicated as a cause of immune-complex disease. The points from this article that veterinary medicine should make note of are the following. Seropositivity demonstrates exposure/infection-it does not definitively indicate disease. If clinical signs do not resolve with an appropriate course of antibiotic therapy; then other underlying causes of illness should be investigated. Persisting titers do not indicate the need for continued antibiotics. The diagnosis and treatment of "chronic Lyme disease" need to be supported by the principles of evidence-based medicine.

A critical appraisal of "chronic Lyme disease." Feder HM Jr, Johnson BJB, O'Connell S, et al. N Engl J Med 357:1422-1430, 2007.