Chronic Lyme Disease: A Working Case Definition

Although Lyme disease is the most common tickborne illness in the USA and Eurasia, the pathophysiology and clinical course of chronic Lyme disease (CLD) have not been formally defined. The purpose of this paper is to present a working case definition of CLD based on analysis of more than 700 peer-reviewed publications. According to this definition, CLD is a multisystem illness with diverse musculoskeletal, neuropsychiatric and/or cardiovascular manifestations that result from ongoing infection with pathogenic members of the Borrelia spirochete complex often associated with other tickborne disease (TBD) pathogens. To qualify for the diagnosis of CLD, patients must have Lyme-compatible symptoms and signs that are either consistently or variably present for six or more months. Two subcategories of CLD include untreated chronic Lyme disease (CLD-U) and chronic Lyme disease following a limited course of antibiotic treatment (CLD-T). The symptom patterns and optimal therapy of CLD require further study.