Can retesting confirm active Lyme disease?

Retesting for Active Lyme Disease

Retesting for Lyme disease is not recommended to determine if the infection is still active, as antibodies persist for months to years after successful treatment and do not indicate active infection. 1

Understanding Lyme Disease Testing and Interpretation

Lyme disease testing follows a specific two-tier approach recommended by the Centers for Disease Control and Prevention (CDC):

1. First tier: Enzyme-linked immunoassay (EIA/ELISA) or immunofluorescence assay (IFA)
2. Second tier: Western immunoblot if the first tier is positive or equivocal 1

Key testing principles:

• For illness ≤30 days: Test for both IgM and IgG antibodies
• For illness >30 days: Test for IgG antibodies only 1

Why Retesting Is Not Useful for Determining Active Infection

Antibody persistence is the main reason retesting is not helpful:

• Antibodies persist for months to years after successful treatment
• Positive serology alone does not indicate active infection 1
• Recent research confirms that viable B. burgdorferi do not persist after conventional antimicrobial treatment 2

Post-Treatment Evaluation

If symptoms persist after treatment, consider:

1. Post-Treatment Lyme Disease Symptoms (PTLDS):

   • Occurs in approximately 10.9% of patients with culture-confirmed early Lyme disease
   • Only about 4.7% have documented PTLDS at long-term follow-up 3
   • Most patients (64.3%) experience only a single symptom 3

2. Alternative diagnoses:

   • Coinfections (Babesia microti, Anaplasma phagocytophilum)
   • Other conditions with similar symptoms 1

Common Pitfalls to Avoid

1. Misinterpreting persistent antibodies: A positive test after treatment does not mean active infection 1

2. Extended antibiotic courses: Not supported by research and may lead to unnecessary side effects 1

3. Relying on PCR or culture alone: Not recommended due to limited sensitivity 1

4. Testing without appropriate pretest probability: Can lead to false positives, especially in low-risk populations 1

5. Variability in test results: Different first-tier tests can yield different results for the same patient 4

When Additional Evaluation Is Warranted

Consider further evaluation (not necessarily retesting for Lyme) if:

• High-grade fever persisting >48 hours despite appropriate therapy
• Unexplained leukopenia, thrombocytopenia, or anemia
• More severe initial symptoms than expected 1

In these cases, testing for coinfections rather than retesting for Lyme disease may be more appropriate.