B. burgdorferi IgG, IgM by ELISA
The B. burgdorferi IgG, IgM ELISA detects antibodies to the spirochaete causing Lyme disease and serves as the first tier of the two-tier serological algorithm. IgM appears within weeks of infection; IgG follows and persists. Serology is insensitive in the first 1–2 weeks and must be confirmed by Western blot when positive or equivocal, interpreted with clinical features and tick exposure.
2
Biomarkers
Blood (serum)
Sample
5–7 business days
Turnaround
No
Fasting
What is the Borrelia ELISA test?
The B. burgdorferi IgG, IgM by ELISA test detects antibodies to the spirochaete that causes Lyme disease, the most common vector-borne infection in temperate regions of North America and Europe. Serology is the mainstay of laboratory diagnosis when the characteristic erythema migrans rash is absent or in later disseminated stages, but it is an indirect marker of immune response rather than direct detection of the organism. Practitioners order this ELISA as the first tier of the two-tier testing algorithm recommended by major infectious disease societies, where positive or equivocal results are reflexed to Western blot for confirmation. The test is not useful in the first week or two of infection, when antibodies have not yet appeared, and a negative result in early localised disease does not exclude Lyme borreliosis. Interpretation requires integration with clinical features, geographic exposure, and an understanding of the test's performance characteristics across disease stages.
What does the Borrelia ELISA test measure?
IgG antibodies to B. burgdorferi typically appear several weeks after infection and persist for months to years. They reflect the adaptive humoral response to spirochaete surface proteins, predominantly outer surface protein C and the 41 kDa flagellar antigen in early infection, with later expansion to include other antigens. IgG seropositivity indicates exposure and immune memory but does not distinguish active infection from past resolved disease.
IgG serology supports the diagnosis of Lyme disease in patients with compatible clinical features and epidemiological exposure, particularly in late disseminated or chronic presentations where the rash is absent. Positive IgG alone does not confirm active infection and must be interpreted with clinical context, travel history, and other laboratory findings. Serological testing is insensitive in the first few weeks of illness.
IgM antibodies appear earlier than IgG, often within the first few weeks of infection, and may decline after several months. They predominantly target the 23 kDa and 41 kDa flagellar antigens. Isolated IgM positivity without IgG, especially outside the first month of symptoms, has a high false-positive rate and should be confirmed by Western blot or repeated with convalescent serology.
IgM is useful in early Lyme disease (within the first month of symptoms) but has limited specificity. Isolated IgM positivity in patients with chronic symptoms (more than one month) is often a false positive and should not be used to diagnose late Lyme disease without confirmatory testing. IgM must always be interpreted alongside IgG, clinical presentation, and exposure history.
Why is the Borrelia ELISA test ordered?
- Patients with erythema migrans rash in whom serological confirmation is desired, though clinical diagnosis alone is sufficient in endemic areas
- Investigation of suspected early disseminated Lyme disease presenting with multiple erythema migrans lesions, facial palsy, lymphocytic meningitis, or carditis with a history of tick exposure
- Evaluation of suspected late disseminated disease with oligoarticular arthritis, particularly affecting the knee, or neurological manifestations months after potential exposure
- Work-up of unexplained neurological or rheumatological symptoms in patients with epidemiological risk, interpreted alongside imaging, cerebrospinal fluid analysis, and other serology
- Screening in asymptomatic patients is not recommended, as seropositivity reflects exposure and does not indicate active disease or need for treatment
- Follow-up serology after treatment is generally not indicated, as antibodies persist and do not correlate with cure or treatment response
Sample collection and turnaround
Sample type
Blood (serum)
Fasting required
No
Collection method
Venipuncture at patient service centre
Turnaround
5–7 business days
Collection notes
Phlebotomy required; serum separated and sent to Immunosciences Lab, Inc. for ELISA. Timing relative to symptom onset is critical — test at least 2–3 weeks after rash onset or tick bite for adequate sensitivity. Note travel and tick exposure history on the requisition to aid interpretation.
Specimen requirements
Minimum 1 mL serum in a serum separator tube. Separate from cells within 2 hours and refrigerate or freeze if shipping is delayed. Note date of symptom onset to guide interpretation.
What can affect Borrelia ELISA results?
Antibodies are absent or below detection in the first 1–2 weeks of infection, so early serology is insensitive; repeat testing 2–4 weeks later is recommended if clinical suspicion remains high.
ELISA can cross-react with antibodies to syphilis, leptospirosis, relapsing fever Borrelia, and some viral infections, leading to false positives; confirmatory Western blot reduces this issue.
The discontinued LYMErix vaccine induced antibodies to outer surface protein A, which could cause positive serology; this is rarely relevant now but may be encountered in older literature or patients.
Conditions such as systemic lupus erythematosus, rheumatoid arthritis, and Epstein-Barr virus infection can produce non-specific antibody reactivity and false-positive ELISA results.
Patients on immunosuppressive therapy or with primary immunodeficiency may mount a blunted antibody response, reducing test sensitivity despite active infection.
European Lyme disease is caused by multiple genospecies (B. afzelii, B. garinii, B. burgdorferi sensu stricto), and some assays are optimised for North American strains; confirm assay antigen composition for the patient's exposure region.
What do Borrelia ELISA results mean?
Elevated
Positive IgG or IgM index values indicate antibody response to B. burgdorferi. IgM positivity in the first month with compatible clinical features supports early Lyme disease; IgG positivity with or without IgM supports disseminated or late disease. Positive or equivocal ELISA results should be confirmed by Western blot (IgM blot if symptomatic <30 days, IgG blot if ≥30 days or chronic symptoms). Isolated IgM positivity in chronic presentations is often a false positive.
Normal
A negative result makes Lyme disease unlikely in patients symptomatic for more than a month but does not exclude it in the first few weeks of infection. If clinical suspicion remains high and symptoms are recent, repeat serology in 2–4 weeks. Negative serology argues strongly against late disseminated Lyme disease.
Reduced
Not applicable — antibody levels are reported as positive, negative, or equivocal rather than quantitative reductions.
Note: ELISA is the screening test in a two-tier algorithm; it should not be used in isolation. Do not order serology for asymptomatic screening or to monitor treatment response, as antibodies persist after cure. False positives occur with cross-reactive conditions, and false negatives occur in very early infection. Clinical and epidemiological context is paramount.
Frequently asked questions
IgM antibodies appear earlier, usually within 1–3 weeks of infection, and are useful in early disease. IgG appears later, after several weeks, and persists for months to years. Isolated IgM positivity without IgG in chronic symptoms is often a false positive.
How to access the Borrelia ELISA test
The Borrelia ELISA reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.
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Published: October 7, 2026
Last reviewed: October 7, 2026
- Wormser GP, et al. The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. (2006)
- Centers for Disease Control and Prevention. Recommendations for test performance and interpretation from the Second National Conference on Serologic Diagnosis of Lyme Disease. MMWR. (1995)
- Lantos PM, et al. Clinical practice guidelines by the Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR): 2020 guidelines for the prevention, diagnosis and treatment of Lyme disease. Clin Infect Dis. (2021)
- Steere AC, et al. Lyme borreliosis. Nat Rev Dis Primers. (2016)
This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.