Why do some patients test CDC positive and some test CDC negative with local labs?
Just curious as to why that is.
Does the bacteria hide better in some cases and not so good in other cases?
Posted by joalo (Member # 12752) on :
Up.
Posted by disturbedme (Member # 12346) on :
It depends on many things. Here are some reasons:
Nine Reasons for False Negative Lyme Disease Blood Test Results
From the Lyme Disease Foundation brochure, Frequently Asked Questions About Lyme Disease
1. Antibodies against Borrelia burgdorferi (Bb) are present, but the laboratory is unable to detect them.
2. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient is currently on, or has recently taken, antibiotics. The antibacterial effect of antibiotics can reduce the body's production of antibodies.
3. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient is currently on or has previously taken anti-inflammatory steroidal drugs These can suppress a person's immune system, thus reducing or preventing an antibody response.
4. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient's antibodies may be bound with the bacteria with not enough free antibodies available for testing.
For this reason, some of the worst cases of Lyme disease test negative -- too much bacteria for the immune system to handle.
5. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient could be immunosuppressed for a number of other reasons, and the immune system is not reacting to the bacteria. [this is a good one as well, and I think it's the reason for MY constant negative tests. My immune system is very poor - to the point where I've had a very low white blood cell count and low blood cell counts for over 14 years!!!!]
6. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the bacteria has changed its makeup (antigenic shift) limiting recognition by the patient's immune system.
7. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient's immune response has not been stimulated to produce antibodies, i.e., the blood test is taken too soon after the tick-bite (8-6 weeks).
Please do not interpret this statement as implying that you should wait for a positive test to begin treatment.
8. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the laboratory has raised its cutoff too high.
9. Antibodies against Bb may not be present in detectable levels in a patient with Lyme disease because the patient is reacting to the Lyme bacteria, but is not producing the "right" bands to be considered positive.
. . . * Clinicians do not realize that the CDC has gone on record as saying the commercial Lyme tests are designed for epidemiologic rather than diagnostic purposes, and a diagnosis should be based on clinical presentation rather than serologic results. . . .