Janet Anna, Marketing Manager, Quidel Corporation
Richard Egan, PhD, Director of R&D, Quidel Corporation
February 20, 2019
There are many challenges to diagnosing Lyme. Ticks are small and hard to see, the bacteria are evasive and difficult to detect, and the symptoms are often generic, mimicking other more prevalent, or well publicized, illnesses. Long waits for test results and a lack of information about how lab tests work – and how well they work – don’t help.
CLIA-waived Sofia 2 Lyme FIA with a finger-stick whole blood sample is designed to be run at the point of care, reducing time to results for some patients and helping patients get on the path to recovery right away, without delay.
Lyme disease is on the rise, and on the move. The U.S. CDC has reported that vector-borne illnesses – of which Lyme disease comprises over 60% – more than doubled between 2004 and 2016, and that counties with high incidence of confirmed Lyme disease cases had grown substantially., These findings are backed up by research and analyses from Quest Diagnostics and FAIR Health, as well. Despite being the most common vector-borne illness in the United States, Lyme disease and the diagnosis of Lyme disease remain misunderstood, even in areas of high endemicity. This whitepaper seeks to provide information around a new diagnostic tool to help patients suspected of Lyme infection receive a more timely diagnosis and care.
Lyme disease is notoriously difficult to diagnose. In part, this is because of the pathogenesis of the disease. First, humans contract Lyme disease from the bite of an infected tick. Often, the offending critter is a young nymph tick, tiny and difficult to see. However, a bite alone is not sufficient to guarantee transmission of the disease – the tick must be attached for at least 36 hours before the disease can be transmitted (although some research suggests transmission might occur with just 12 hours of attachment). Once contracted, the invading bacteria, Borrelia burgdorferi, embeds itself in human tissues and remains in the bloodstream only in low levels. While some tests claim to detect Borrelia burgdorferi in other bodily fluids, such as spinal fluid or urine, the CDC does not recommend such tests, and the FDA has not cleared any non-serological Lyme diagnostic assays.
The CDC recommends a two-tiered approach using serology-based testing for the detection of IgM and IgG antibodies to the Borrelia burgdorferi bacteria. This algorithm consists of a sensitive immunoassay – most often ELISA, but sometimes an immunofluorescent assay (IFA) – to rule in the possibility of a Lyme infection. A positive tier-one result will then be reflexed to a second-tier Western Blot, a specific assay meant to confirm positive tier-one results. A case of suspected Lyme disease is confirmed only if both the first-tier immunoassay and second-tier Western Blot return positive results.
Antibodies persist in the blood stream for months or years, making serology a very useful tool in the diagnosis of Lyme disease. The detection of antibodies to diagnose Lyme disease has its challenges, as well. One key challenge with serologic testing is the potential for cross-reactivity with other pathogens. Two pathogens known to be highly cross-reactive with Lyme antibody tests are Treponema pallidum, the causative agent of Syphilis, a spirochetal bacterium like Borrelia burgdorferi, and Epstein-Barr Virus, the causative agent for Mononucleosis, a virus that causes symptoms similar to early Lyme infection.
For these and other reasons, a sensitive test is needed to detect antibodies to the evasive bacteria (tier- one immunoassay) while a specific test is needed to confirm positive results (tier-two Western Blot). This is also why Lyme serology tests should only be performed on patients in whom a Lyme infection is reasonably suspected – a symptomatic patient with known or probable exposure to a Lyme-carrying tick.
Further contributing to the mystery around Lyme disease diagnosis is a lack of knowledge around the testing methods utilized by the laboratory performing the assay. Because testing has traditionally not been performed in-office, it can be a challenge to the provider in understanding which specific assay is being utilized by their selected lab. Providers interested in accurately diagnosing and treating their suspected Lyme patients must consider the following three questions regarding the lab they’ve chosen to conduct their Lyme testing and the Lyme tests themselves:
1 – Does this lab adhere to the CDC recommendations and two-tiered algorithm for Lyme serology?
2 – Have these tests been evaluated and cleared by the FDA?
3 – What is the accuracy of these tests?
While it is easy, and tempting, to assume that all testing conducted in the United States has been cleared by the FDA and adheres to the CDC’s recommendations, this is not the case. Regarding in vitro diagnostic assays, the FDA regulates only those assays marketed and sold by one party to another. You can find information about FDA-cleared assays on the FDA’s website, including FDA submissions with detailed explanations of methodology, clinical trial design, and clinical performance.
Assays developed by one party for their own use and not made available to other parties are known as Laboratory Developed tests (LDTs) and are not regulated by the FDA. Information about these tests – such as their methodology and accuracy – may not be made publicly available or may be difficult to find. Regarding LDTs, the FDA has said “patients and providers cannot uniformly rely on all tests offered for clinical use as some are not subject to active premarket oversight to ensure they provide accurate measurements and valid claims.” In an article published in Morbidity and Mortality Weekly in 2014, CDC researchers noted “In 2005, CDC and the Food and Drug Administration (FDA) issued a warning regarding the use of Lyme disease tests whose accuracy and clinical usefulness have not been adequately established” and “FDA clearance/approval of a test…provides assurance that the test itself has adequate analytical and clinical validation and is safe and effective.”
Furthermore, not all lab tests adhere to CDC recommendations. In addition to offering PCR or culture, methodologies not recommended by the CDC, some labs have defined Lyme diagnostic criteria that do not follow the CDC recommendations.
Not all commercially available Lyme tests are created equal. Not all commercially available Lyme tests adhere to CDC testing and interpretation guidelines, not all commercially available Lyme assays have been evaluated and cleared by the FDA, and not all commercially available Lyme assays have performance data that is publicly available
The last challenge in Lyme disease diagnosis discussed here is the time to result. From the time a provider orders a Lyme test to when the result is received can take days or a week or more. This is due to a few factors. First, a serology test requires a venous blood draw. This may be done immediately, or the patient may need to go to a lab. Next, the blood must be processed to collect the serum or plasma, a process which can take close to an hour. Once the sample is prepared, it is stored until the lab is ready to test. Some labs prefer to batch their Lyme testing because the instruments and workflows used to test for Lyme make it more efficient to test in batches rather than test each sample individually as it arrives at the lab.
The wait to get a Lyme result can be a source of great anxiety for patients. Much has been written about the importance of early treatment for a patient’s recovery from the disease. What’s more, if the result is negative (researchers at the CDC have found tier-one EIA tests deliver negative Lyme results more than 88% of the time), it can feel like days or weeks of wasted time while the patient continues to suffer.
Tier-One Lyme Testing – A New Option
Sofia 2 Lyme FIA is a tier one Lyme assay intended for use as an aid in diagnosis of Lyme disease. It detects IgM and IgG antibodies to the Borrelia burgdorferi bacteria, and it provides differential IgM and IgG results on a single test cassette. It has demonstrated clinical performance on par with other FDA-cleared, in-market Lyme assays. Sofia 2 Lyme FIA uses a finger-stick whole blood sample and has a simple workflow that requires only about a minute of hands-on time. It is CLIA-waived, which means Sofia 2 Lyme FIA can be run in most physician’s offices right at the point of care. Sofia 2 Lyme FIA is the only tier-one Lyme assay that can deliver results in the same amount of time as a rapid flu test – just 15 minutes or less.
Why does a point of care Lyme test matter? For 88% of patients whose first-tier Lyme results will be negative, waiting days or weeks for those results only delays your investigation and patient care. For a patient who fears they may have Lyme, a tier-one result in just 15 minutes could save them days or weeks of worry. A result in just 15 minutes or less means you can move forward with next steps right away, without delay.
Lyme disease is on the rise, and on the move. The nature of the disease also makes Lyme difficult to diagnose. The CDC recommends a two-tiered serology for the detection of IgM and IgG antibodies to the Borrelia burgdorferi bacteria. Not all commercially available Lyme tests have been evaluated and cleared by the FDA or adhere to CDC testing and interpretation guidelines. Contributing to the challenge of diagnosing Lyme is a lack of knowledge that occurs when testing is performed far from both patient and provider. For patients, the wait to get a Lyme result can be a source of great anxiety.
Sofia 2 Lyme FIA is a CLIA-waived tier-one Lyme test that uses a fingerstick whole blood sample and is run at the point of care. Sofia 2 Lyme FIA is simple to run and provides results fast, allowing providers to deliver negative results and consider alternative diagnoses immediately, or to know whether further testing with Western Blot is needed. Sofia 2 Lyme FIA lets patient and provider move on with next steps right away, without delay.