Contributed Commentary by Marc Pollmann
June 28, 2019 | We're seeing it in the news everywhere: tickborne illnesses are on the rise in the US, according to the CDC. It's even brought together US politicians; a new bipartisan effort has introduced the Ticks: Identify, Control, and Knockout (TICK) Act, designed to fund and improve research, diagnostics, and treatment for tickborne diseases.
There are myriad reasons why ticks are increasingly coming in contact with humans and animals. One is climate change; as the planet warms, livable habitat for disease-causing ticks expands. On top of this slow and steady expansion of habitat over decades, 2019 predictions for a wetter-than-normal summer may boost tick numbers even higher.
In addition, researchers have uncovered new tickborne illnesses and disease-causing germs that have added to the type and volume of reported illnesses.
Unfortunately, most tickborne illnesses such as Lyme disease, the more recently discovered Powassan virus, and other related tickborne illnesses are difficult to identify, diagnose, and treat. In fact, accurately diagnosing tickborne illnesses has become one of the most complex factors in managing tickborne disease.
Many factors play into correct diagnosis, including the fact that early symptoms of tickborne disease can vary widely. But changes in diagnostics, clinician resources and education, and analysis may be helping us turn a corner toward more effective tickborne illness management.
Changing How We Diagnose
The way tickborne diseases manifest within the body can be subtle, meaning that some antibody tests don't have the required sensitivity to make an accurate diagnosis and may vary in results based on disease stage. Depending on the knowledge of the clinician and the variations of symptoms, these factors can all lead to inaccurate diagnoses.
In some cases, patients may be diagnosed inaccurately based on the presence of persistent IgM antibodies and patient-reported symptoms, despite a lack of disease. On the other hand, a clinician may misdiagnose a patient as disease-free if the initial ELISA test is negative, simply due to timing of the test, conflicting data or unclear patient symptoms.
Potential co-infections can also impact diagnosis, simply given the added complexity. In light of all this, clinicians need to be aware of the limitations of serological tests and take that information into consideration when looking at test results. With tickborne diseases moving into regions that had limited exposure in the past, it's more important than ever that clinicians become familiar with the intricacies of tickborne illness diagnosis. But the good news is, more education is available now than ever before.
Staying On Top Of Tools And Tech
The 2019 Tick Forecast is a great way to determine areas within the US that are more likely to see patients with suspected tickborne illnesses. It's also valuable in terms of understanding which tick species and related illnesses are more probable locally.
In addition, new educational webinars are available for both clinicians and laboratories to better understand the latest in diagnostics tools—providing valuable background on the benefits, limitations and differences among categories of tests.
Understanding the tools is critical, as most labs today use different tests for tickborne disease screening and confirmation, meaning that clinicians can’t always learn best practices from each other. This, in and of itself, can be problematic because the lack of standardization across serological assays can greatly impact both the test results and the interpretation of results.
It's still up to clinicians and health care teams to understand which tests are being used within their facilities but being able to access educational information that aligns symptomatic data with the abilities of various tests is helping create some clarity.
Understanding VlsE
Tickborne disease scientists still recommend a two-tiered process for testing and confirmation. But because antibody detection has advanced significantly, even in recent years, new tests that leverage VlsE should be prioritized. In addition, using the latest screening and confirmation tests from the same diagnostics testing company can improve results and provide more robust interpretation support for clinicians.
To show the efficacy of using VlsE, Lyme disease research was completed using a sensitive screening test (ELISA or IIFT) which also detects antibodies against the Borrelia major antigen VlsE. Next, positive or borderline tests were followed up with immunoblot for confirmation. Researchers found that printing an additional antigen band with VlsE onto the strip greatly increased the test sensitivity and provided a more accurate diagnosis, even in early stages of Lyme disease.
This finding can help clinicians narrow in on a diagnosis by condensing the time window in which an antibody test is effective. This approach can also help clinicians more easily exclude infection (and save time) if the immunoblot indicates a negative result for IgG and IgM (after a positive screening test).
With a combination of education, insights, and the latest diagnostic technology, we may finally be turning a corner on tickborne illness management. Clinicians struggling with consistently false or unclear results have better resources today than they did just five years ago. Newer tests can reduce uncertainty and provide a clearer picture of both the antibodies and antibody-antigen interactions that indicate infection, but clinicians need to pair this with a better understanding of the benefits and limitations of any system.
And for patients, more knowledgeable, better equipped health care partners offers an opportunity for patients with lingering symptoms to get retested now, to determine a more accurate diagnosis.
Dr. Marc Pollmann is a biologist at EUROIMMUN, a PerkinElmer company, with a specialty in small arachnids. He is an expert on tickborne infectious diseases. He can be reached at m.pollmann@euroimmun.de.