Lyme disease has three stages: early localized, early disseminated, and late. The early localized stage of the infection manifests with a nontoxic, nonspecific febrile illness (low-grade fever, myalgias, or fatigue) and the classic ECM lesion, described as a red patch with central pallor (also called a target lesion). A single ECM lesion or multiple lesions may be present at the site of inoculation. This may be the only symptom a patient experiences, and it is diagnostic (necessitating treatment even without serologic proof of the disease).
The joints may be involved in early localized disease with arthralgia, often described as a migratory joint pain caused by bursitis, tendonitis, synovitis, or myositis. The spirochete is able to invade human fibroblasts and remain dormant for months to years. In a small percentage of infected patients, untreated Lyme disease may lead to the development of further organ-system involvement.
Early disseminated disease typically occurs within weeks to months after the initial infection. It manifests as multiple ECM lesions beyond the site of inoculation, with accompanying extracutaneous manifestations. The neurologic system may be affected, with patients describing headaches heralding CNS penetration and possible meningitis. Bell palsy may occur, with facial nerve involvement leading to unilateral facial droop affecting the lower and upper portions of the face.
Cardiac manifestations typically occur within the early disseminated stage of the infection. Approximately 8%-10% of patients with Lyme disease have cardiac involvement. The presenting symptoms may include light-headedness, palpitations, or syncope, and they are typically caused by a conduction defect ranging from first-degree block to complete atrioventricular dissociation.
With treatment of the underlying infection, most conduction defects are reversible processes. In addition to conduction defects, other cardiac manifestations include myopericarditis, ventricular dysfunction, cardiomegaly, and pericardial effusion with possible tamponade.
Finally, ocular manifestation in early disseminated disease is typically limited to conjunctivitis, described by patients as red, itchy eyes. Rarely, ocular involvement may present as ophthalmitis with unilateral blindness in later stages.
Latent disease typically presents months to years later, with arthritis (frank arthritis with painful swelling and redness, typically involving the large joints) or CNS complications. In this stage of the disease, any portion of the CNS and peripheral nervous system may be affected; the manifestations range from chronic encephalopathy to peripheral neuropathies or radiculopathy.
The disease is most often diagnosed by history, physical examination, and clinical suspicion. Serologic studies by enzyme-linked immunosorbent assay or Western blot are typically performed, but negative results do not rule out infection. The timing of the sample is crucial to obtaining a reliable result. Early in the infection, serologic studies are often negative. Seropositivity may not develop for several weeks. In addition, patients inoculated in the past may have persistent seropositivity for years after inoculation; therefore, neither a positive result nor a negative result can definitively establish or rule out the presence or absence of an active infection.
Other useful laboratory studies may include a complete blood cell count, serum chemistries, erythrocyte sedimentation rate, blood cultures, and specific testing for such organisms as babesiosis and ehrlichiosis. Further studies, as indicated on presentation, may include cerebrospinal studies or joint fluid aspiration.
Although there are no definitive radiologic studies, some studies may be warranted to rule out other causes of pain or neurologic symptoms. An ECG should be obtained as part of the basic workup for any patient in whom the diagnosis of Lyme disease is being entertained. Irrespective of whether the patient's history or physical examination findings support cardiac involvement, any evidence of conduction system disease must be ruled out.
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