Testing for Lyme has always been an often controversial subject fraught with difficulties for both Doctor and patient. Following will be information I’ve read through and collected on my own. This process is extremely wordy, scientific and technical-eyes will glaze over and boredom will ensue-but hang in there! This is my interpretation of it all. I am in no way a scientist, or an expert. I am merely a person with Lyme disease doing my best. Below are the links where I found some of my information.
The CDC (Center for Disease Control and Prevention) has in place what is called a “Two-tier Testing Decision Tree”. This means that if you present with the common symptoms of Lyme, then you will be given 1 of 2 tests; the IFA (Immunofluorescence Assay) or the ELISA (Enzyme-linked Immunoassay). If you test negative your Doctor will consider an alternative diagnosis, or-depending on how long you have had symptoms-consider getting a convalescent serum.
If you test positive, you will get the Western Blot. However, you will only get both the IgG and IgM Western Blot if your symptoms have persisted for more than 30 days. If it is 30 days or under you will only receive the IgG Western Blot. The CDC is only interested in diagnosing Lyme based on symptoms and history of possible exposure.
Seems simple enough, right? Unfortunately, the Western Blot is notorious for false-negative results, and the ELISA (the more popular of the 2 initial tests) is known for it’s false-positive results. My goal here is to share with you my understanding of the very confusing process that is testing for Lyme and hopefully help you understand how it all works a little better.
Let’s start with the ELISA test. Aside from the Western Blot, ELISA is one of the more popular tests given in the United States for early Lyme testing. It has been around since 1984, and proves to be the least expensive and simple of all the tests out there-perhaps why it has a history of being popularly used by many Doctor’s as a first step in Lyme diagnosis. The test is quantitative, and is designed to be “sensitive” meaning that if it is used properly, than everyone who has Lyme should test positive. Though if the patient being tested has any other chronic disease (especially a Spirochetal infection like Syphilis) the test will likely give back a positive reading. The ELISA is used to test antibodies in the blood in response to Bb (Borrelia burgdorferi). The test solution will turn a different color if the target substance is found in the blood.
Again, it is a simple test but it leaves a lot to be desired as far as getting a really comprehensive result goes. If you get a positive result from the ELISA test, it must be followed up with a Western Blot test. While more comprehensive, the Western Blot is still lacking in it’s efficiency for Lyme testing and diagnosis.
The Western Blot is split into two smaller tests; the IgG and the IgM (immunoglobin). The IgM tests for the earliest antibodies to appear in response to an infection. The IgG tests for the longest remaining antibodies. Essentially what the Western Blot does, is it maps the different antibodies the immune system produces to the bacteria into bands. It separates the antibodies by the weight of their respective antigens. The weight of each antibody is reported in units called kilo Daltons (kDa). Each band represents a specific antibody response to specific proteins found on the Spirochete.
Now what the CDC has required from the Western Blot test is this: the IgG must report 5 positive band results out of the following 10 bands-18, 21, 28, 30, 39, 41, 45, 58, 66 and 93kDa. The IgM test must have 2 or more of the following 3 bands test positive: 23, 39 and 41 kDa. You only need 1 positive band in either test to confirm exposure-however exposure does not prove a current Lyme infection, hence why the CDC has required that a net of 10 specific and different bands be reported.
In theory, it’s a great idea. But here’s the kicker, the Western Blot does not report on bands 22, 25, 28, 31, 35, 37 and 83kDa-these bands are Bb specific bands. Note how many of the 10 bands the Western Blot reports on that are non-specific cross-reacting bands, meaning that they aren’t Lyme specific. Crazy, huh? Of the bands that are specific to Bb (Lyme), several of them contain OSPA, OSPB and OSPC (Outer surface proteins): these are the 3 most widely recognized Bb anitgens. Only 1 of the bands containing these 3 antigens is reported on the Western Blot- band 23 on the IgM.
When you get your test results back the Band markings will be 1 of the following:
– Not present
+/- Indeterminate (there, but not as intense as Low)
Many labs do not report the +/- findings, but IGeneX does.
The CDC does not yet recognize the IGeneX lab results because they are a private lab, but that does not mean that the results are any less valid. What it does mean, though, is that insurance is unfortunately less likely to cover the cost. IGeneX processes over 20,000 Lyme tests a year, and can adhere to a more specialized structure than the CDC regulations. IGeneX includes band 31 in their testing, and also offers 30-31kDa confirmation-these bands are often positive due to cross-reactivity with other viruses, and IGeneX uses highly specific recombination antigens to validate results. In addition, IgG needs only 2 bands present (instead of 5), and the IgM needs 2 (like the Western Blot).
As comprehensive as these tests can be, they are only good for US testing. They may miss other strains of the Borrealia organism, especially those specifically found in Europe.
The ELISA and the Western Blots are not to be belittled- they are very important steps in the journey to diagnosing Lyme. Once again, though, false results are common place when testing for Lyme because so little is known about the spirochete that is the root of the disease.
My advice to patients trying to navigate their way through this process is that you must ALWAYS get personal copies of all lab results. You are your own advocate. It’s about the results of the bands tested, and a Lyme-literate doctor will know how best to interpret each individual result.
Next week: What the hell is a spirochete?? And why Lyme is so often misdiagnosed.
Melissa Kaplan, “Interpreting the IgG and IgM Western Blot for Lyme Disease”, http://www.anapsid.org/lyme/wb.html
Tom Grier, “Laboratory Tests”, www.lymeneteurope.org/info/laboratory-tests
Center for Disease Control and Prevention, http://www.cdc.gov/lyme/diagnosistesting/labtest/twostep/index.html
Laura Torrentera, “Lyme Disease”, http://www.austincc.edu/microbio/2704x/bb.htm
Scott, “Testing”, http://www.betterhealthguy.com/lyme/testing