How long can the Lyme enzyme immunoassay (EIA) stay positive after treatment for Lyme disease?

Duration of Lyme Enzyme Immunoassay Positivity After Treatment

Antibodies to B. burgdorferi often persist for months to years after successful treatment of Lyme disease, and should not be used as a marker of active infection. 1

Persistence of Serologic Markers

• Antibodies against B. burgdorferi typically persist for months to years after successfully treated or untreated infection, making seroreactivity alone unsuitable as a marker of active disease 1
• In patients treated for early Lyme disease, antibody levels decline over time but can remain detectable for more than a year after treatment 2
• Studies show that in children followed for up to 20 months after treatment, 18% still had IgM antibodies and 6% had IgG antibodies by ELISA 2

Factors Affecting Antibody Persistence

• The peak antibody response typically occurs 8-12 days into treatment, with approximately 80% of patients showing positive results at this time 3
• Antibody persistence varies based on:
  • Disease stage at time of treatment (early vs. late) 1
  • Type of antibody (IgM vs. IgG) 2
  • Individual immune response 3
• Approximately 20% of patients with documented early Lyme disease may remain seronegative throughout follow-up despite clinical infection 3

Clinical Implications

• Neither positive serologic test results nor a history of previous Lyme disease ensures that a person has protective immunity; repeated infection with B. burgdorferi has been reported 1
• The presence of persistent antibodies should not be confused with persistent infection 4
• Serologic testing should not be used to determine treatment success or failure 4
• Clinical response should be the primary determinant of treatment success, not serologic findings 4, 5

Distinguishing Persistent Antibodies from Active Infection

• Objective clinical manifestations are uncommon after appropriate treatment of Lyme disease 1
• Subjective symptoms (arthralgia, myalgia, fatigue) may persist for weeks to months after treatment due to slow resolution of the inflammatory process, not persistent infection 1
• In patients treated for early Lyme disease, subjective symptoms were present in 35% at day 20,24% at 3 months, and 17% at 12 months 1
• PCR positivity after treatment should not be interpreted as evidence of ongoing infection without corresponding clinical symptoms and other supporting evidence 4

Common Pitfalls in Interpretation

• Misinterpreting persistent antibodies as evidence of treatment failure or ongoing infection 1, 4
• Using serologic testing to monitor treatment response 4
• Failing to recognize that positive Lyme disease test results may have poor positive predictive value in low-prevalence regions (fewer than 20% of positive tests represent clinically likely Lyme disease in such settings) 6
• Prescribing prolonged or repeated courses of antibiotics based solely on persistent seropositivity without objective evidence of active infection 7