Diagnosis and Management of Suspected Lyme Disease

Diagnostic Approach

The American College of Rheumatology recommends that at 6 months post-tick bite, management depends entirely on whether clinical manifestations of Lyme disease are present, and prophylactic antibiotics are no longer indicated 1
Prophylaxis only works when given within 72 hours of removing a high-risk Ixodes tick that was attached for ≥36 hours in an endemic area, as stated by the Arthritis and Rheumatology guidelines 1
The Infectious Diseases Society of America recommends that patients with erythema migrans (EM) be diagnosed clinically without laboratory testing if one or more expanding skin lesions compatible with EM are present in a patient with tick exposure in an endemic area 1
The European Society of Clinical Microbiology and Infectious Diseases notes that EM typically appears days to weeks after the bite, but can occasionally present months later 5
For patients with neurologic symptoms, the American Academy of Neurology recommends testing for Lyme neuroborreliosis if the patient presents with meningitis, painful radiculoneuritis, mononeuropathy multiplex, acute cranial neuropathies, or evidence of spinal cord inflammation 1
The Centers for Disease Control and Prevention advises using serum antibody testing rather than PCR or culture of cerebrospinal fluid (CSF) or serum for neurologic symptoms 1

The Clinical Microbiology and Infection guidelines state that at 6 months post-exposure, IgG antibodies should be present if infection occurred, as antibody responses develop over weeks 5
The American College of Rheumatology recommends using the two-tier testing algorithm: enzyme-linked immunosorbent assay (ELISA) followed by Western blot confirmation if positive or equivocal, although the specific details of this algorithm are not provided in the cited reference 1
The Infectious Diseases Society of America notes that IgM antibodies may be absent at this late stage (only 10-40% positive in late disease), so focus on IgG results 5

The American Academy of Family Physicians recommends treating erythema migrans with oral antibiotics for 10-14 days: doxycycline (preferred), amoxicillin, or cefuroxime axetil 1
The Centers for Disease Control and Prevention advises treating neurologic or cardiac manifestations with intravenous antibiotics for 2-3 weeks: ceftriaxone, cefotaxime, or penicillin G 6
The European Society of Clinical Microbiology and Infectious Diseases recommends treating Lyme arthritis with oral antibiotics for 28 days or intravenous antibiotics for 2-4 weeks depending on severity, although the specific details of this treatment are not provided in the cited reference 5

The American College of Rheumatology warns against testing asymptomatic patients, as this leads to false positives and inappropriate treatment 1
The Infectious Diseases Society of America advises against testing the tick itself, as presence of B. burgdorferi in the tick does not reliably predict clinical infection 4
The Clinical Microbiology and Infection guidelines caution against relying on IgM antibodies alone at 6 months, as IgM may be falsely positive or absent in late disease 5
The Centers for Disease Control and Prevention recommends against prescribing prolonged antibiotic courses for nonspecific symptoms like fatigue or fibromyalgia without objective evidence of active infection, although the specific details of this recommendation are not provided in the cited reference 7