A clinical approach to Lyme disease.

Lyme disease (also known as Lyme borreliosis) is an emerging, newly described infectious disease with diverse clinical manifestations. The disease is caused by the spirochetal agent Borrelia burgdorferi, which is transmitted to humans by the bite of certain species of Ixodes ticks harboring the organism. The most readily identifiable clinical feature is the distinctive skin lesion, erythema migrans. If recently infected patients go untreated, approximately 15% will develop neurologic conditions (most commonly facial nerve palsy), 8% will develop myocarditis (typically with heart block), and 60% will develop migratory mono- or pauci-articular arthritis. Diagnosis depends on clinical suspicion, recognition of the characteristic signs and symptoms, and appropriate testing for antibody to B. burgdorferi. Serology for Lyme disease, although in need of better standardization, is most useful in diagnosing patients with manifestations of Lyme disease other than erythema migrans. All manifestations of Lyme disease are potentially treatable with either a beta-lactam antibiotic (for instance penicillin, amoxicillin, or ceftriaxone) or a tetracycline preparation. However, the optimal antimicrobial regimen, including choice of drug, drug dose, route of administration, and length of therapy, is unknown. Other important areas for future research include Ixodes biology and control, improved laboratory tests for diagnosis and for assessing response to therapy, and vaccine development.