The ELISA is a broad screening test. It measures whether your blood contains antibodies that react to Borrelia burgdorferi antigens. It is designed to be sensitive — meaning it catches most true positives — but it is not specific, meaning it produces many false positives from other infections, autoimmune conditions, and cross-reactive bacteria.

Critical limitation: The ELISA also misses patients whose immune systems can't mount a strong antibody response — a common problem in chronic Lyme. If the ELISA is negative, many labs stop there, and the Western Blot is never ordered.

If the ELISA is positive or equivocal, a Western Blot is performed. This test separates the proteins (antigens) of Borrelia by molecular weight, producing a pattern of bands measured in kilodaltons (kDa). Your immune system's antibodies either do or don't react to each band — and those reactions are the map to interpreting your result.

Two antibody classes are tested: IgM (early immune response, typically present 2–4 weeks post-exposure) and IgG (later immune response, typically present 4–6 weeks post-exposure and in chronic infection). Understanding which class reacted — and to which bands — is where clinical interpretation begins.

These bands are unique or nearly unique to Borrelia burgdorferi. Any single one of these positive is clinically significant — even if the CDC criteria call the result "negative." In particular, bands 31 and 34 are so specific they were removed from the CDC criteria specifically to prevent false positives in people who had received the (now discontinued) Lyme vaccine — which means the CDC criteria actively exclude two of the most diagnostic bands.

Band 41 is the flagellin protein — the motor that Borrelia (and many other bacteria) use to move. It's typically the first band to appear after infection, and it's often the strongest band on the blot. However, it cross-reacts with dozens of other bacteria including oral spirochetes present in normal dental biofilm. This means:

These bands have some cross-reactivity with other conditions but add meaningful weight when combined with highly specific bands or strong clinical symptoms. Multiple moderate bands alongside band 41 and a compelling history warrants serious clinical consideration.

IgM antibodies typically appear 2–4 weeks post-infection; IgG takes 4–6 weeks. Testing in the window before antibodies develop will produce a false negative even in acute Lyme. A test ordered within the first week of symptoms is almost guaranteed to miss active infection.

In some patients with long-standing Lyme, antibody levels may have peaked years ago and declined below detectable thresholds — even as active infection persists. The immune system's "memory" fades, but the bacteria doesn't. This is especially common in patients who were partially treated with short antibiotic courses.

When the immune system is significantly compromised — by co-infections, chronic inflammation, mold toxicity, or deficient signaling gases — it may not generate sufficient antibodies for detection. This is not a negative result. It's an immune system that can't respond adequately. The infection is present; the response is absent.

Borrelia is exceptionally good at evading immune detection. It can alter its outer surface proteins, downregulate antibody-triggering antigens, and retreat into intracellular compartments and biofilm structures that shelter it from immune surveillance. Some patients with confirmed Lyme (via PCR or culture) never develop detectable antibodies through any phase of infection.

Highly specific bands (18, 23–25, 31, 34, 39, 83–93) carry far more diagnostic weight than band 41 alone. One highly specific band positive is more meaningful than five moderate bands positive.

They are population surveillance tools, not clinical diagnostic criteria. Many Lyme-literate practitioners use different interpretation frameworks — and they're right to do so.

It's often the first band to appear, but by itself it cannot confirm Lyme due to cross-reactivity with other bacteria. It's a starting point, not an answer.

It's most useful when Western Blot is inconclusive or negative but clinical suspicion is high. A CD57 below 60 alongside a compelling symptom picture is powerful evidence — even without a "positive" Western Blot.

Deficient Nitric Oxide and Hydrogen Sulfide suppress NK cell function and antibody production — meaning a negative Western Blot may reflect terrain dysfunction, not the absence of infection. Restoring gas pressure sometimes makes the invisible visible.

Some patients with confirmed Lyme disease (via PCR or culture) never develop detectable antibodies. A negative Western Blot does not close the case when clinical presentation is compelling.

Your lab results exist within the context of your symptoms, exposure history, and clinical presentation. Never interpret labs in isolation — and never let a provider make a clinical decision from a number alone.