Can Borrelia-specific IgG persist for years after infection?

Borrelia-specific IgG is an exposure marker rather than a reliable indicator of whether infection is currently active. This distinction is particularly important when interpreting positive Lyme serology in people with prior compatible illness or treatment.

Clinical evidence

• Long-term persistence after resolved infection is well documented. In a cohort evaluated 10–20 years after treated Lyme disease, B. burgdorferi IgG reactivity remained detectable in 25% of those previously treated for early disease and 62% of those with prior Lyme arthritis.
• CDC and AAN/ACR/IDSA guidance likewise recognizes that antibodies can persist for months to years—and sometimes decades—after successful treatment.
• Conversely, IgG also develops during active infection. Therefore, a positive IgG result is compatible with both current infection and remote, clinically resolved infection; it cannot independently demonstrate ongoing infection, treatment failure, or a need for retreatment.

Interpretation and practical implications

• Serology should be interpreted in the context of a compatible current syndrome, exposure history, timing of symptoms, and competing diagnoses. Repeating antibody tests to determine whether treatment worked is not recommended, because antibody persistence does not track organism viability or clinical resolution.
• For an 83-year-old man, the same fundamental interpretation applies: isolated IgG positivity should not be attributed to active borreliosis without a clinical presentation consistent with a recognized Lyme manifestation and appropriate corroborating evaluation.
• Direct testing is syndrome- and specimen-dependent rather than a universal confirmation of active infection. Even synovial-fluid PCR may remain positive for weeks to months after treatment and therefore does not alone establish persistent viable infection.

Bottom line

• The claim is well supported: Borrelia-specific IgG may persist for years, including 10–20 years after treated Lyme disease, and by itself cannot distinguish past exposure from active infection.