Long Island Lyme Disease Testing
Updated: Sep 30, 2020
“Dear Dr. Dempsey,
Our family just returned from a 10-day trip to the north fork of Long Island. We were staying at a beach house in the Peconic that we stay at every summer for almost two weeks. After we left yesterday, my friend went to the house with her family and this morning they found a deer tick on the rocking chair on the back porch. The owners did not spray and the lawn care folks did tell us the day before we left that there were ticks in the brush leading to the beach. My kids were playing on the back lawn, and porch the entire time we were there. They are 3 and 6. No one has signs of Lyme disease as of yet, and we checked the kids constantly. We all do have a few mosquito bites but none have rings around them. But sometimes, as I learned at the GLA event where I first heard you speak, there are no rings. Should we all go have our blood tested just to be sure no one was bit? Or is there something else we can do?”
A: Should you have a blood test to determine if you have been exposed to lyme disease acutely? The short answer is no, especially if there is no evidence of having a tick attachment. The problem is that lyme testing is wrought with inconsistencies and inaccuracies. The common lyme test ordered by most doctors is an Elisa test which is really just a screening test to determine whether there are antibodies to lyme disease. The assumption is that if you have antibodies and the Elisa is positive, then you have had exposure and then a western blot test will be run to see which antibodies (or bands) you have. Having antibodies doesn't necessarily mean that this is an active infection and not having antibodies doesn't necessarily mean you are in the clear either. It can take 4-6 weeks after a tick bite to build up antibodies in the blood to the bacteria that causes Lyme, Borrelia burgdorferi (Bb). There are multiple strains of Bb but the current commercially available test only detects one strain, so if you were exposed to a different strain, the test could be "falsely" negative. Ticks also transmit many different infections. A negative lyme test can't tell you that you are negative for all tick-borne infections and it can't even tell you without a doubt that you are negative for Bb.
So, what can you do if you have been in an area with a large tick population but didn't get a known tick bite? You need to be vigilant about any new rashes and any new symptoms. A fever in the summertime is a red flag that might warrant testing for tick-borne infections. Be on the lookout for non-specific symptoms such as fatigue and malaise, muscle aches, joint pain, back or neck pain, and change in mood. If you see your doctor with concern regarding Lyme disease, make sure that they test all possible tick-borne infections, not just Lyme.
What should you do in the future?
You need to be extra vigilant wherever you go. While some areas of the country (and world) are known to be endemic for Lyme disease, the truth is that tick-borne and even insect-borne infections, in general, are found everywhere. Use precautions such as insecticide-coated clothing, insect repellents whenever there is potential contact with insects and frequent skin checks at least at the end of each day.
While you shouldn't let your worries over Lyme disease rule your life, you should take it seriously enough to make some changes in your behaviors with any outdoor activity.
What are the best ways to remove a tick?
The best way to remove a tick is to do it carefully with a fine tweezer as close to the skin as possible. The tick should be pulled upwards with even pressure. The main thing you want to prevent is breaking the tick apart and leaving the mouth parts still attached. If that happens, you will need to gently lift the mouth-part out of the skin. Sometimes this can be difficult to do and the mouth-part might remain in the skin. The skin should be cleaned afterward with alcohol and be sure to wash your hands. Once the tick is removed, it should be placed in a plastic bag or medicine bottle to save for testing. There are various labs all over the country that will test the tick to determine the species of the tick but also to see what infections it is carrying. Understanding that information can be helpful in determining if any treatment should be started.
LYME DISEASE TESTING
This is an important prospective multi-center study looking at the use of the C6 peptide ELISA, also known as C6 EIA test to distinguish between Lyme arthritis and septic arthritis in children. These two forms of arthritis require different treatment and it is critical to make a quick and accurate diagnosis.
C6 ELISA LYME DISEASE TEST
The C6 EIA test has shown promise over the older ELISA test that is part of the two-tier Lyme testing recommended by the CDC dating back to 1995. There are serious limitations to the two-tier test, including a nearly 50% false-negative rate. The C6 EIA test done alone appears to be more sensitive, picking up about 64% of positive cases. Unfortunately, that still results in a 36% false-negative rate, which is concerning. The main benefit of using the C6 EIA assay is the faster turnaround time, leading to faster and more appropriate treatment strategies.
While this study shows promise in the ability to accurately identify Lyme arthritis with the use of the C6 EIA test, it is not clear what the false negative rate was in this study. Their numbers show that they were able to diagnose 23.2% of children with Lyme arthritis, 1.2% with septic arthritis but 75.6% were identified as having inflammatory arthritis, which means that the diagnosis is unclear. What if a subset of those diagnosed with inflammatory arthritis truly have Lyme arthritis that was missed with the use of the C6 EIA test?
Based on the published false negative rate of this test, we can assume that a fair percentage of those with inflammatory arthritis probably had Lyme arthritis. Interestingly, the authors of the study reflected on one of the limitations of the study being misclassification of children with septic arthritis due to the lack of certain tests or results but they didn’t mention that one of the limitations is the potential misclassification of inflammatory arthritis in the majority of those they tested.
One key point that should be mentioned is that the study design included a confirmatory immunoblot test for C6 EAI positive or equivocal results. This would be equivalent to a two-tier test. There are two issues with their approach.
First, no immunoblot testing was done on any of the C6 EIA negative results. Since we know a large number of patients will be missed by this approach, it is discouraging to think of all those patients who might still be suffering with Lyme disease that was undetected with the screening C6 EAI test.
Second, in the study design they automatically disregarded immunoblot results in patients with symptoms greater than 30 days, who only IgM positive bands considering this to be a false positive. This was based on a report published in the Journal of Pediatrics in 2016 titled “False Positive Lyme Disease IgM Immunoblots in Children,” which has its own set of flaws, including a lack of understanding of the IgM Immunoblot test and what it represents. IgM is considered an acute antibody and it is understood that during an acute infection, IgM levels will go up first and then IgG, which is a chronic antibody, will kick in and IgM levels will go down.
In many patients, with immune-dysregulation, they can continue to have IgM levels persisting for longer, even 10-20 years according to another set of studies. Unfortunately, many of these patients are ignored and under-treated.
WHY WE NEED BETTER TESTING FOR LYME DISEASE
There is no question that we need better testing for Lyme disease. The C6 EIA has some benefits but is clearly not sufficient. The Immunoblot test relies on the presence of antibodies and may not be helpful in picking up present or past infection, especially in immunodeficient patients. There is hope for the future as there are many labs scrambling to come up with a gold standard test with high sensitivity and specificity for Lyme disease. In the meantime, we need to rely on these imprecise measurements and to do so we must use our clinical judgment.
As doctors, we treat patients, not numbers on paper and with patients who have complex, chronic diseases, including Lyme and tick-borne infections, this is essential.