What is the recommended serology test for suspected Lyme disease?

Recommended Serology Test for Suspected Lyme Disease

The standard of care for laboratory diagnosis of suspected Lyme disease (when serologic testing is indicated) is two-tiered testing: first-tier enzyme-linked immunoassay (EIA/ELISA) or immunofluorescence assay (IFA), followed by reflex Western immunoblot only if the first test is positive or equivocal. 1

When to Order Serologic Testing

• Do NOT order serologic testing for patients with erythema migrans (EM) in endemic areas — these patients should be diagnosed clinically without laboratory confirmation, as approximately 70-80% of Lyme disease patients present with EM and can be treated based on clinical findings alone 2, 3

• Order two-tiered testing only for:

  • Patients without EM who have suspected disseminated disease (facial palsy, meningitis, carditis, arthritis) 1
  • Patients with neurologic, cardiac, or joint manifestations requiring laboratory confirmation 4

The Two-Tiered Testing Algorithm

First Tier: EIA/ELISA or IFA

• Use a sensitive screening test (EIA/ELISA or IFA) that measures overall IgM and IgG antibody response to Borrelia burgdorferi antigens 1
• Most laboratories use whole-cell sonicate preparation, though newer FDA-cleared EIAs using VlsE or C6 peptide antigens offer similar sensitivity with higher specificity 1
• If first-tier result is negative: Report as negative and stop testing 1
• If first-tier result is positive or equivocal: Proceed to second-tier Western immunoblot 1

Second Tier: Western Immunoblot

• Perform separate IgM and IgG Western immunoblots based on disease duration 1
• For disease duration <30 days: Interpret both IgM and IgG immunoblots 1
• For disease duration ≥30 days: Interpret only IgG immunoblot (IgM results are not reliable after 30 days) 1
• If immunoblot is positive: Report as positive serologic result 1
• If immunoblot is negative: Report as negative serologic result 1

Test Performance Characteristics

• Sensitivity varies dramatically by disease stage:

  • Early localized disease (EM): Only 30-40% sensitive in acute phase, improving to 61% in convalescent phase (3-4 weeks later) 2, 4
  • Disseminated disease (neuritis, carditis, arthritis): 88-100% sensitive 2, 4

• Specificity is consistently high: >95% across all disease stages when two-tiered testing is performed correctly 1, 2

• The two-tiered approach increases specificity to >98% by reducing false-positives from the first-tier EIA alone 1

Critical Pitfalls to Avoid

• Never order Western immunoblot without first performing EIA/IFA — this dramatically increases false-positive rates and violates testing guidelines 2

• Geographic exposure history is paramount — in low-incidence states without recent travel to endemic areas, positive predictive value drops to only 10%, and only 0.7% of patients in non-endemic areas with arthritis, cranial neuropathies, or meningitis actually have Lyme disease 2

• Do not retest after treatment — antibodies persist for months to years after successful treatment and do not indicate active infection 2, 3

• Avoid urine antigen tests and CD57 tests — these lack validation and should not be used 2

• Consider syphilis cross-reactivity — if positive results occur, perform Treponema pallidum hemagglutination assay to exclude cross-reactivity 1, 3

Special Considerations for Early Disease

• If clinical suspicion remains high despite negative serology in early disease: Order convalescent serology 3-4 weeks later, as sensitivity improves from 40% to 61% during this window 2, 4

• Negative serology does not exclude Lyme disease in the first 2-4 weeks due to the antibody window period 3

• Antibiotic treatment during early infection reduces antibody response — this accounts for reduced clinical sensitivity (50%) of two-tiered testing in some studies where patients were treated early 5