- How
is Lyme Disease Diagnosed?
There is no
test that can determine if a patient is infected with the LD
bacterium and then demonstrate that the patient has become bacterium-free.
Therefore, LD is clinical diagnosis, based on signs and symptoms,
with the patients travel history to endemic areas and test results
being additional pieces of information in the complete picture.
No test can "rule-out" Lyme disease.
WHAT LABORATORY
TESTS AID IN THE DIAGNOSIS?
INDIRECT TESTS
(Antibody Tests)
Antibodies
are the immune system's response to "fight off" infection.
Tests strive to be both sensitive (detecting any LD antibodies)
and specific (detecting just LD antibodies).
Test Interpretation
- False Negative
tests occur due to defects in test sensitivity; too low an antibody
level to detect (e.g. they are bound to the bacteria, with too
few free-floating; the patient taking antibiotics or other drugs;
naturally low antibody production); the bacterium has changed,
limiting recognition by the immune system; or bacterial strain
variations.
- False positive
tests occur due to test failure or cross-reacting antibodies
(e.g. syphilis, periodontal disease, ANA or RF).
Types of Tests
- Titer (ELISA,
EIA, IFA) - These tests measure the level of Bb antibodies
in fluid. Laboratories use different detection criteria, cut-off
points, types of measurements, and reagents.
- Western blot
- This test produces bands indicating the immune system's reactivity
to Bb. Laboratories differ in their interpretation and
reporting of these bands.
- C6 Lyme Peptide
ELISA - identifies antibodies to a consistent surface protein
that is present on every known strain of the Lyme disease bacteria,
Borrelia burgdorferi (Bb). The C6LPE is more sensitive for diagnosing
all stages of Lyme disease, including those patients with late
stage Lyme disease.
DIRECT DETECTION
TESTS
- Antigen detection
- These tests detect a unique Bb protein in fluid (e.g.
urine) of patients. This may be useful for detecting LD in patients
taking antibiotics or during symptom flare-up.
- Polymerase
chain reaction (PCR) - This test multiplies the number of Bb
DNA to a detectable measurable level.
- Culturing
- Growing the bacterium in culture is difficult and can take
months.
- Staining
- Staining of tissue is time consuming and has low yield. The
problem is that in Lyme disease there are too few of the Lyme
spirochete in the body, and could result in the biopsy having
no bacteria.
Next: How is Lyme Disease Treated?
Back:
What are the Symptoms of Lyme Disease?
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