Western Blot Lyme Testing Restrictions: What Changed and Why It Matters
For years, clinicians relied on Western blot testing to clarify cases where Lyme disease was strongly suspected but screening tests were negative. When access to this test was restricted, it exposed a larger problem: diagnosis depends not only on tests — but on how those tests are used and who can order them.
These challenges are part of broader issues in Lyme disease test accuracy, where timing and immune response affect results in ways that laboratory policy cannot fully account for.
When Access to Western Blot Testing Was Restricted
In 2014, LabCorp implemented a policy that prevented physicians from ordering Western blot testing unless the initial screening test — ELISA or IFA — was positive or equivocal. If the screening test was negative, even when clinical suspicion remained high, the Western blot was automatically denied.
For clinicians treating patients in endemic areas with strong clinical presentations, this created a significant barrier to diagnosis — particularly in early Lyme disease, when screening tests are least reliable.
Why Physicians Ordered Western Blot Independently
Clinicians commonly ordered Western blot testing even when screening tests were negative because the limitations of screening tests in early Lyme disease were well established.
The sensitivity of the whole-cell ELISA to the B31 strain typically falls between 33–49% for patients presenting with an erythema migrans rash. The FDA-approved C6 peptide test showed 37% sensitivity in well-defined cases and 66.5% sensitivity in patients with an EM rash. These findings demonstrate that screening tests miss a substantial number of early Lyme cases.
Western blot provided additional diagnostic insight that screening tests could not. An IgM Western blot can persist for at least two years in individuals with established Lyme disease infection — and may persist for months to years even after antibiotic treatment. An IgG Western blot can be positive in individuals with a negative screening test. For experienced clinicians, Western blot was often an essential diagnostic tool, not an optional one.
Why Testing Access Was Restricted
The restrictions reflected broader concerns within the diagnostic community. Western blot requires visual interpretation, which can vary between laboratories. CDC two-tier testing criteria were originally designed for population surveillance rather than individual clinical diagnosis. Automated immunoassays provide faster and more consistent results. Additionally, Western blot may remain negative in the first weeks of illness regardless of clinical presentation.
These concerns supported standardization — but did not resolve the real-world diagnostic limitations that clinicians faced in practice.
The Impact on Patient Care
Restrictions created immediate clinical challenges including delayed diagnosis, increased costs as patients were directed to alternative laboratories, and reduced access for patients with high clinical suspicion but negative screening results.
This reflects a central tension in Lyme disease care: policies designed for consistency may not fit complex clinical presentations. These delays are part of the broader pattern described in delayed Lyme disease diagnosis, where early testing fails to capture evolving disease.
What Changed: Current Access
Access to Western blot testing has since been restored. Physicians can now order Western blot testing regardless of screening results — a change that reflects recognition that clinical decision-making requires flexibility beyond protocol-driven testing sequences.
Modified Two-Tier Testing has also been introduced, using two enzyme immunoassays instead of the traditional ELISA followed by Western blot. Despite these changes, Western blot remains valuable for its detailed antigen-specific band pattern information that immunoassays do not provide.
Why Testing Alone Is Not Enough
All antibody-based tests share a fundamental limitation: they depend on the immune response. They may not reliably detect early infection before antibodies develop, infection in immunosuppressed patients, or disease in patients whose immune response has been altered by prior antibiotic treatment.
This means testing supports the diagnosis — but does not define it. Clinical judgment remains essential, particularly when symptoms evolve, exposure history is compelling, or testing is inconclusive despite a presentation that clearly suggests Lyme disease.
Frequently Asked Questions
Can Western blot testing be ordered now?
Yes. Physicians can now order Western blot testing regardless of screening test results. The 2014 restriction that required a positive or equivocal ELISA before Western blot could be ordered has been reversed.
Why was access to Western blot restricted?
Due to concerns about interpretive variability between laboratories, pressure to standardize testing protocols, and alignment with CDC two-tier surveillance criteria that were not originally designed for individual clinical diagnosis.
Is Western blot more accurate than ELISA for Lyme disease?
The tests provide different information. ELISA screens for antibody reactivity while Western blot identifies specific band patterns. Both have limitations in early infection — but Western blot can detect IgG or IgM bands that ELISA misses in some patients.
What is Modified Two-Tier Testing?
A newer approach using two enzyme immunoassays instead of ELISA followed by Western blot. It provides faster results but does not offer the same antigen-specific band pattern information that Western blot provides.
Which Lyme test should be used?
This depends on clinical judgment. No single test replaces careful evaluation of symptoms, exposure history, and clinical presentation. A negative test does not exclude Lyme disease — particularly in the first weeks of infection.
Clinical Takeaway
The restriction on Western blot testing highlighted a fundamental truth about Lyme disease diagnosis: access to testing matters, but testing limitations matter more. Early Lyme disease — the stage when treatment is most effective — is also when testing is least reliable. Restoring access improved diagnostic flexibility without resolving the underlying challenge.
Lyme disease remains a clinical diagnosis supported by laboratory findings, not defined by them. When symptoms and exposure suggest infection, care should not be delayed while waiting for tests to confirm what the immune system has not yet revealed.
A negative screening test in a patient with a compelling clinical presentation and endemic area exposure is not permission to stop looking — it is an indication to look more carefully.
Related Articles
- Lyme Disease Test Accuracy and Limitations
- Delayed Lyme Disease Diagnosis
- Beyond CDC Testing Guidelines
- Don’t Wait for a Positive Test
- Lyme Disease Misdiagnosis
References
- LabCorp newsletter for clients. Lyme disease testing now employs a two-tier antibody standard. Available at: labcorp.com. Last accessed August 16, 2014.
- Aguero-Rosenfeld ME, Nowakowski J, Bittker S, Cooper D, Nadelman RB, Wormser GP. Evolution of the serologic response to Borrelia burgdorferi in treated patients with culture-confirmed erythema migrans. J Clin Microbiol. 1996;34(1):1–9.
- Trevejo RT, Krause PJ, Sikand VK, et al. Evaluation of two-test serodiagnostic method for early Lyme disease in clinical practice. J Infect Dis. 1999;179(4):931–938.
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- Wormser GP, Schriefer M, Aguero-Rosenfeld ME, et al. Single-tier testing with the C6 peptide ELISA kit compared with two-tier testing for Lyme disease. Diagn Microbiol Infect Dis. 2013;75(1):9–15.
- Steere AC, Hardin JA, Ruddy S, Mummaw JG, Malawista SE. Lyme arthritis: correlation of serum and cryoglobulin IgM with activity, and serum IgG with remission. Arthritis Rheum. 1979;22(5):471–483.
- Massarotti EM, Luger SW, Rahn DW, et al. Treatment of early Lyme disease. Am J Med. 1992;92(4):396–403.
- Craft JE, Grodzicki RL, Shrestha M, Fischer DK, Garcia-Blanco M, Steere AC. The antibody response in Lyme disease. Yale J Biol Med. 1984;57(4):561–565.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
