Lyme Disease Testing Panel: Standard Two-Tiered Approach
The specific Lyme disease panel consists of a two-tiered serologic testing algorithm: first-tier enzyme immunoassay (EIA/ELISA) or immunofluorescence assay (IFA) measuring both IgM and IgG antibodies, followed by reflex Western immunoblot (also measuring both IgM and IgG) only if the first test is positive or equivocal. 1, 2
The Standard Testing Algorithm
First-Tier Test
- EIA/ELISA or IFA measuring total antibody response (both IgM and IgG simultaneously) to Borrelia burgdorferi antigens 1
- Most laboratories use whole-cell sonicate preparation of B. burgdorferi as the antigen 1
- Newer FDA-cleared EIAs use specific antigens like VlsE protein or C6 peptide, which offer higher specificity with similar sensitivity 1
- This first tier is designed for high sensitivity to minimize false negatives 1
Second-Tier Test (Reflex Only)
- Western immunoblot performed only if first-tier is positive or equivocal 1
- Separate IgM and IgG immunoblots are run 1
- This second tier provides high specificity (>98%) to reduce false-positives from the first-tier test 1
Beyond Basic IgM and IgG: What the Panel Actually Measures
The Western immunoblot goes beyond simple IgM/IgG detection by identifying specific protein bands that represent antibodies to individual B. burgdorferi antigens 1:
IgM Western Blot Interpretation
- Requires at least 2 of 3 specific bands: 23 kDa (OspC), 39 kDa, and 41 kDa (flagellin) 1
IgG Western Blot Interpretation
- Requires at least 5 of 10 specific bands: 18,21,28,30,39,41,45,58,66, and 93 kDa 1
- Patients with disseminated or late-stage disease demonstrate expanded IgG banding patterns 1
Newer Antigen-Specific Tests
- VlsE (C6 peptide) testing is increasingly used as it detects a protein primarily expressed in vivo 1
- C6 peptide ELISA can serve as either first-tier or confirmatory testing 3
- These recombinant antigen tests reduce cross-reactivity while maintaining sensitivity 1
Test Performance by Disease Stage
Early Localized Disease (Erythema Migrans)
- Sensitivity is only 30-40% in acute phase samples 2, 3
- Improves to 61% in convalescent phase (3-4 weeks later) 2, 3
- Clinical diagnosis without laboratory testing is recommended for patients with erythema migrans in endemic areas 2, 1
Early Disseminated and Late Disease
- Sensitivity reaches 70-100% for disseminated disease 1, 2
- Specificity exceeds 95% when two-tiered testing is used correctly 1, 2
- Nearly all patients with neurologic, cardiac, or joint involvement have positive serology 3
Critical Testing Pitfalls to Avoid
Never Order Western Blot First
- Western immunoblot should never be ordered without first performing EIA/IFA 2
- Ordering Western blot alone dramatically increases false-positive rates 2
- The two-tiered approach only works when tests are performed sequentially 1
Geographic Exposure is Essential
- Even highly specific tests produce false-positives when pretest probability is low 2
- In non-endemic areas without travel history, positive predictive value drops to only 10% 2
- Only 0.7% of patients in non-endemic areas with compatible symptoms actually have Lyme disease 2
Avoid Non-Validated Tests
- Do not use urine antigen tests or CD57 tests—these lack validation 2
- PCR is not standardized for routine diagnosis and should only be attempted by reference laboratories 1
- Culture requires specialized media and is impractical for routine diagnosis 1
Post-Treatment Testing is Not Indicated
- Never retest patients after treatment to assess cure 2, 4
- Antibodies persist for months to years after successful treatment 1, 4
- Seroreactivity alone cannot distinguish active from past infection 1, 4
- Clinical response, not serologic findings, determines treatment success 4
Alternative Testing Scenarios
IgA Testing (Not Standard)
- IgA antibodies to B. burgdorferi are detected in approximately 39% of early Lyme disease patients 5
- May correlate with disseminated disease in some patients 5
- Not part of standard diagnostic algorithms and not routinely recommended 5