What is the accuracy of Lyme (Lyme disease) antibody testing?

Accuracy of Lyme Antibody Testing

Lyme antibody testing has significant limitations in early disease with only 30-40% sensitivity in stage 1 (early localized) infection, but reaches nearly 100% sensitivity in late-stage disease, making it unreliable for early diagnosis but highly accurate for late manifestations. 1

Two-Tiered Testing Approach

The CDC-recommended standard approach for Lyme disease diagnosis involves a two-tiered testing algorithm:

First-Tier Test:

• Enzyme immunoassay (EIA) or immunofluorescent antibody (IFA) test
• Sensitivity: 85-100% (but lower in early disease)
• Specificity: 79-95%
• Results reported as positive, negative, or equivocal/borderline 1

Second-Tier Test (only if first tier is positive or equivocal):

• Western immunoblot (WB)
• Specificity: >95% across all stages
• Interpretation criteria:
  • IgM Western Blot: ≥2 of 3 specific bands (21-24,39,41 kDa)
  • IgG Western Blot: ≥5 of 10 specific bands (18,21-24,28,30,39,41,45,58,66,93 kDa) 1

Accuracy by Stage of Disease

The accuracy of Lyme antibody testing varies dramatically by disease stage:

1. Stage 1 (Early Localized - Erythema Migrans):

   • Standard two-tiered testing: Only 31% sensitivity 2
   • Patients are often seronegative 3
   • IgM response evolves from approximately third week post-infection 3
   • IgG antibodies develop from approximately sixth week post-infection 3

2. Stage 2 (Early Disseminated - Neuroborreliosis/Carditis):

   • Standard two-tiered testing: 63% sensitivity 2
   • IgG antibodies become predominant 3
   • Intrathecal antibody production in neuroborreliosis 3

3. Stage 3 (Late Persistent - Arthritis/Acrodermatitis):

   • Standard two-tiered testing: 100% sensitivity 2
   • Usually high IgG antibody titers 3
   • IgM antibodies often undetectable 3

Limitations and Pitfalls

Several factors can affect the accuracy of Lyme antibody testing:

• Early antibiotic treatment can blunt or prevent antibody response 1
• Cross-reactivity with other pathogens, especially with the 41-kDa band (flagellin protein) 1
• False positives in low-prevalence areas (positive predictive value <20%) 1
• Delayed antibody response in early infection leading to false negatives 3
• Subjective interpretation of Western blot bands 3
• Heterogeneous diagnostic properties of commercial test kits 3

Improved Testing Approaches

Recent advances have aimed to improve testing accuracy:

• Two-EIA approach: Using whole-cell sonicate EIA followed by C6 EIA shows higher sensitivity for early Lyme disease (61% vs. 48%) with equivalent specificity (99.5%) compared to standard two-tiered testing 3

• IgG VlsE testing: A modified algorithm using only IgG blot with VlsE band improves sensitivity in early disease while maintaining high specificity:

  • Stage 1: 34% sensitivity (vs. 31% with standard testing)
  • Stage 2: 96% sensitivity (vs. 63% with standard testing)
  • Stage 3: 100% sensitivity (equal to standard testing)
  • Eliminates need for IgM testing while maintaining 100% specificity 2

Clinical Implications

• In endemic areas, patients with classic erythema migrans (EM) rash should be diagnosed clinically without laboratory confirmation 1
• Negative serology in early disease does not rule out Lyme disease 3
• Consider follow-up testing in 2-3 weeks if symptoms persist and clinical suspicion remains high 1
• A positive antibody test without corresponding clinical symptoms is insufficient for diagnosis 3

Important Caveats

• Western blot should never be performed except as a reflex test after a positive/equivocal EIA 1
• Alternative, non-validated tests often have high false-positive rates (up to 58% in healthy controls) 3
• PCR testing of synovial fluid may be useful for suspected Lyme arthritis (sensitivity >75%) 1
• Intrathecal antibody testing is helpful in suspected neuroborreliosis 1

Lyme antibody testing remains a valuable diagnostic tool when used appropriately and interpreted in the context of clinical presentation and exposure history, but clinicians must be aware of its significant limitations in early disease.