Lyme Disease Western Blot: What Your Result Means
Result guide · Infectious Disease
Content last reviewed 2026-09-12 · Educational information — not medical advice
Quick answer
The Lyme Western Blot is the confirmatory second step of Lyme disease testing. It detects antibodies against specific Borrelia proteins, adding specificity after a screening test. It is interpreted using strict criteria, not just any band.
What is Lyme Disease Western Blot?
Lyme disease testing uses a two-step approach: an initial screen, and if that is positive or equivocal, a Western Blot to confirm. The blot detects antibodies to individual bacterial proteins and shows them as bands. Because healthy people can have some bands, the result is interpreted with standardized criteria — a certain number of specific bands must be present to call it positive.
Typical reference interval: Reported as positive, negative, or equivocal based on the number and type of bands. The interpretation follows public-health criteria and should be read by someone familiar with them. Timing matters: early infection may not yet produce enough antibodies.. Laboratories differ — the interval printed on YOUR report always governs.
If your Lyme Disease Western Blot is high
Common reasons Lyme Disease Western Blot runs above the reference interval:
- Current or past Lyme infection — a positive blot confirms the immune system has responded to Borrelia
- Two-step confirmation — the blot is only run after a positive or equivocal screen — the pair is the real result
- Persistent antibodies after treatment — antibodies can remain for years after successful treatment
If your Lyme Disease Western Blot is low
Common reasons Lyme Disease Western Blot runs below the reference interval:
- No confirmed Lyme infection — a negative blot after a positive screen often means the screen was a false positive
- Testing too early — in the first weeks after a bite, antibodies may not have formed yet
- Antibiotic treatment before testing — early treatment can blunt the antibody response and affect results
Symptoms worth knowing
The classic early sign is an expanding rash, often with fever and aches; later disease can bring joint pain, nerve symptoms, and heart-rhythm issues. The blot supports the diagnosis but is always interpreted with symptoms and exposure history.
What usually happens next
Get your Lyme Disease Western Blot checked
These lab tests measure Lyme Disease Western Blot directly. Ordering online takes a few minutes and results arrive securely.
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Frequently asked questions about Lyme Disease Western Blot results
Why do I need a Western Blot if my Lyme screen was positive?
Because screening tests are designed to catch every possible case, which means they sometimes react in people without Lyme. The Western Blot confirms by looking for specific antibody patterns — the two-step approach greatly reduces false positives.
Can the Western Blot stay positive after treatment?
Yes — like many antibody tests, it can remain positive for years after successful treatment. That is why a positive blot alone does not prove active infection; symptoms and timing guide interpretation.
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