Tick-Borne Disease: Testing, Timing, and Better Diagnosis

TRANSCRIPT for Podcast Episode with the title Tick-Borne Disease: Testing, Timing, and Better Diagnosis

Voiceover [00:00:02]:

Welcome to the Results are in from Quest Diagnostics. Conversations with diagnostics industry leaders who enable optimized care pathways for patients.

Ann Freeman [00:00:14]:

Welcome to the Results are in by Quest Diagnostics. I'm your host Ann Freeman, Senior Product Manager. Today we're taking a closer look at one of the fastest growing infectious disease concerns in the United States. Tick borne illness.

Ann Freeman [00:00:28]:

Lyme disease remains the most common, but there are over a dozen other pathogens to consider, many of which can co infect patients and complicate diagnosis. Our guest today is my friend Dr. Anne Salm, PhD director and medical Science Liaison Lead for Infectious Disease and Immunology at Quest Diagnostics. In this episode we'll unpack the key considerations for tick borne disease, explain when molecular versus serologic testing is most appropriate, and discuss how the modified two tier test for Lyme disease improves diagnostic accuracy and patient care. Ann, welcome to the show.

Dr. Ann Salm [00:01:03]:

Hi Ann, thank you for welcoming me. It's a pleasure to work with you as always, Ann Squared. Yep, what a great idea getting together for this just before tick season. It's time and it's timely.

Ann Freeman [00:01:17]:

Absolutely. Let's start with an overview. How significant is the public health burden of tick borne disease in the US today?

Dr. Ann Salm [00:01:24]:

Well, the burden of tick borne diseases in the United States in 2026 continues to be substantial and is on the rise, driven by expanding tick populations and geographic range due to factors like climate change. In the U.S. 90% of all diseases caused by getting bitten by something, including mosquitoes, are actually caused by ticks. Lyme disease is by far the most common vector borne disease in the United States, we don't know exactly how many people develop Lyme disease every year. But based on the best evidence we have, the CDC has recorded about 476,000 cases a year.

Ann Freeman [00:02:00]:

What trends are you seeing in incidence and geographic spread?

Dr. Ann Salm [00:02:04]:

Cases of illnesses transmitted by ticks are increasing across the U.S. with reported cases more than doubling since 2004. Experts anticipate this trend to continue in 2026. Nearly 95% of all tick borne disease cases are Lyme, predominantly found in the Northeast and upper Midwest regions. The number of US counties identified as high incidence areas for Lyme disease has increased significantly.

Ann Freeman [00:02:28]:

Gosh. So cases have basically doubled in the

Ann Freeman [00:02:31]:

last 20 or so years.

Ann Freeman [00:02:33]:

What are some reasons for that increase in incidence?

Dr. Ann Salm [00:02:36]:

So the increase in incidences can be due to four factors: climate change, habitat change, host population dynamics, and increased awareness and surveillance. Diving a little bit deeper on these four factors, number one, climate change. So warmer temperatures lead to milder winters and longer active seasons for ticks, allowing them to survive and establish populations in new areas further north than before. Number two, habitat changes. Land use changes such as forest development create ideal edge habitats for primary hosts like white footed mice and white tailed deer, which increases tick populations and their interactions with humans. Number three, host population dynamics. A decrease in the predators of small animal hosts such as mice contributes to a rise in the reservoir populations that carry disease causing bacteria. And then finally, number four, increased awareness and surveillance.

Dr. Ann Salm [00:03:33]:

Improved recognition, reporting and tracking by healthcare providers and public health officials also contribute to the recorded increase in cases. The CDC now estimates that approximately 476,000 people may be diagnosed and treated for Lyme disease each year in the US A figure much higher than the number of officially reported cases through routine surveillance.

Ann Freeman [00:03:54]:

Talk about a good example of how interconnected everything is when a change in mouse habitat can lead to an increase in something like Lyme disease in humans. Just incredible. So let me pivot for a minute and ask a little bit about testing. I've heard timing plays a major role in testing decisions. Can you explain why the type of test, either molecular versus serologic, depends on when exposure or symptom onset occurred?

Dr. Ann Salm [00:04:21]:

Sure. So generally there are two types of lab tests that can be used, and you mentioned this, when we're testing for tick borne infections. Molecular testing tests for the genetic presence of a pathogen and serologic testing for antibodies that the body makes in response to the pathogen. So molecular testing is best utilized within one to 10 days following a tick bite, as that is when the pathogen is circulating in the bloodstream at detectable levels. In the case of Borrelia burdorferi, that's the pathogen that causes Lyme. The bacterium seeks out and burrows into our connective tissues, for example, like our joints, and becomes nearly undetectable in a peripheral blood sample within one to two days post exposure. In the case of Lyme, molecular Lyme testing beyond two days post exposure to a deer tick bite is not useful and can produce a false negative result. Serologic testing is best utilized roughly 10 to 14 days post exposure, as that is the amount of time the human body needs to develop antibodies to infection.

Ann Freeman [00:05:21]:

Okay, so are there any other key considerations for providers when selecting a test methodology or testing for suspected tick borne infection?

Dr. Ann Salm [00:05:31]:

Yeah, key considerations that you'd want to be mindful of when selecting a Lyme test is to assess the patient clinically and take a thorough history and do a physical exam. History should include assessing a patient's risk of exposure to deer ticks. Not to be confused with wood ticks. Wood ticks are much larger and they overlap in geographic distribution to deer ticks. In roughly 60 to 70% of Lyme cases, a bullseye rash termed erythema migrans is observed in patients with suspected Lyme. In cases where the patient has traveled or lives in an area of deer tick endemicity and the rash is present, clinicians may forgo lab testing and move to treating empirically for Lyme. If a patient has traveled or lives in an area of tick endemicity and has experienced a tick bite but no bull's eye rash is apparent, a clinician may choose to perform lab testing for Lyme. Molecular testing would only be useful within one to two days.

Dr. Ann Salm [00:06:26]:

As I mentioned before, there are FDA approved Lyme serology tests that would be most appropriate and guideline recommended within that 10 to 14 day post exposure window and beyond.

Ann Freeman [00:06:37]:

So with Lyme disease being the most common tick borne infection, I know there are two different tests for Lyme antibodies. Could you walk us through the evolution of these two different testing strategies? Specifically how we got from the standard two tier test to the modified two tier test for Lyme disease?

Dr. Ann Salm [00:06:56]:

Yeah, okay, that's a great question. So we're jumping into the different types of serology assays. I mentioned that there's an FDA approved serologic testing for Lyme. Serologic testing that the FDA approved involves two steps or tiers termed Standard two tier or STT. The first tier of this test is a Lyme antibody screen. If the Lyme antibody screen is positive, the second tier of testing is performed. The second tier of testing is performed by Western blot or immunoblot for two types of antibodies to Lyme immunoglobulin G or IgG and immunoglobulin M or IgM. The STTT or Standard two tier has been around for several decades and has been the guideline recommended for Lyme.

Dr. Ann Salm [00:07:41]:

In 2019 the FDA approved a comparable test to the standard two tier called the modified 2 tier, also known as MTTT. This test utilizes the same screen and reflexes to confirm via detection of IgG and M. But the methodology for the second tier uses an immunoassay. This immunoassay is faster, less labor intensive and comparable to the performance of Western blot and immunoblot used in the standard two tier test.

Ann Freeman [00:08:11]:

Okay, so are there any limitations for that older traditional standard two tier approach, particularly when it comes to early disease detection?

Dr. Ann Salm [00:08:21]:

Yeah. So the FDA approved modified two tier and it was shown in the clinical trials in the package insert to detect early lyme in around 15% more patients than the standard two tier. This is important as it is widely recognized that the two areas of research need and diagnostic gaps with regard to Lyme are in early Lyme diagnosis as well as testing for Lyme reinfection.

Ann Freeman [00:08:45]:

Okay, so how does Quest's offering for tick borne disease align with CDC recommendations and what options are available for providers through Quest?

Dr. Ann Salm [00:08:56]:

Wonderful. It's a great question. So there was a joint guideline issued by the CDC, the Infectious Disease Society of America and the American Academy of Neurology. They all recommend either the Standard two tier or the Modified two tier as tests for diagnosing Lyme. Both the Standard two tier and the Modified two tier are available through Quest Diagnostics.

Ann Freeman [00:09:17]:

So with both being available and both still being CDC recommended, are there any specific patient populations or clinical scenarios where the modified two tier test offers the most benefit compared to traditional testing?

Dr. Ann Salm [00:09:30]:

So comparing the standard two tier and modified two tier, while the guidelines consider them comparable, there is evidence that the modified two tier is better at detecting early Lyme. Practically speaking, this means that if a patient is presenting on the earlier side of that 10 to 14 day post exposure window, the modified two tier may be a better choice at detecting antibodies to Lyme.

Ann Freeman [00:09:53]:

Okay, that makes sense. Sure. So beyond Lyme disease, are there any other tick borne illnesses we should be concerned with? And how does a potential co-infection complicate a diagnosis for a doctor?

Dr. Ann Salm [00:10:06]:

Yeah. So besides Lyme, there are other tick borne infections including anaplasmosis, ehrlichiosis and babesiosis as most commonly occurring. This complicates diagnosis as clinicians are less aware of these other tick borne diseases and they don't always test for them. Most troubling is that these other tick borne infections are also on the rise and could impact clinical decision making. Particularly in the case of babesiosis as it's a parasitic infection and it won't respond to the antibiotics used to treat bacterial infections like Lyme. To further complicate that picture, more than one infectious agent can be transmitted by the same tick and hence they can have co-infection with multiple tick borne diseases and it's becoming more common. A study of more than 3,000 patients suffering from post-treatment Lyme disease found that over 50% had co-infections and 30% were reporting three or more simultaneous infections.

Ann Freeman [00:11:03]:

Wow. 50% with co-infections. I had no idea.

Dr. Ann Salm [00:11:07]:

Yeah.

Ann Freeman [00:11:08]:

As we think about these various tick borne diseases and overlapping symptoms, are there any test panels to support that differential diagnosis and early treatment?

Dr. Ann Salm [00:11:19]:

Yeah. So differential diagnosis among these different tick borne diseases can be challenging and early treatment is really important. So let's dig a little deeper into testing options beyond Lyme. If after a thorough patient history and physical exam, a clinician wants to test beyond Lyme, Quest offers molecular and serology panels for detecting Lyme and a few other of the more common tick borne infections like Anaplasma, Ehrlichia and Babesia. One option is the tick borne disease Acute Molecular panel. This molecular panel comes both with and without Lyme, and then we also have a tick borne disease antibody panel. These are just a few panel options when looking at combination testing for tick borne diseases at Quest.

Ann Freeman [00:12:00]:

Fantastic. So finally, what key takeaway would you like our listeners to remember about testing for Lyme and other tick borne diseases?

Dr. Ann Salm [00:12:09]:

Lyme incidence is on the rise. Certainly that's an important take home message and by association, the risk of tick co-infections like anaplasmosis, Ehrlichiosis and babesiosis are also something that clinicians should be aware of. Testing is an important part of that diagnostic journey in folks who've been bitten by deer ticks and are experiencing symptoms suggestive of tick borne disease, particularly in the absence of a bull's eye rash. Quest offers single and multiple pathogen panels for molecular and serologic testing for Lyme and other tick borne diseases. Go to questtestdirectory.com or reach out to your local Quest representative for more information.

Ann Freeman [00:12:45]:

Thank you so much for joining me in this conversation today, Anne. Thank you. That brings us to the end of this episode. I'd like to extend a big thank you to Dr. Ann Salm for joining me today. We learned how accurate test selection and the adoption of modified two tier testing can make a real difference in early diagnosis and patient outcomes. If you enjoyed this conversation and want to stay informed about the latest advancements in blood based diagnostic testing, make sure to subscribe to the show and leave a review.

Ann Freeman [00:13:14]:

You won't want to miss our upcoming episodes where we dive into more groundbreaking research and real world stories that impact patient care. Thanks for tuning in. I'm Ann Freeman and we'll see you next time on the Results Are in by Quest Diagnostics.

Voiceover [00:13:39]:

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