How Lyme Disease Is Diagnosed

Your doctor or healthcare provider may have difficulty diagnosing Lyme disease because many of its symptoms are similar to those of other disorders and illnesses. The only distinctive sign unique to Lyme disease (the erythema migrans, or "bull's-eye," rash) is absent in at least a quarter of the people who become infected. Although a tick bite is an important clue for diagnosis, many people can't recall having been recently bitten by a tick. This isn't surprising because the deer tick is tiny, and a tick bite is usually painless.

Lyme disease diagnosis
Illustration by Joshua Seong. © Verywell, 2018. 

Self-Checks

Though you can't diagnose or rule out Lyme disease on your own, you can look for the tell-tale symptoms and make sure you understand when you need to see your doctor. You should always inspect yourself, your children, and your pets for ticks after they've been outdoors as well. Be sure to check warm, moist areas such as in between the buttocks, in the groin, in the belly button, on the backs of knees, and on the scalp. Keep in mind that ticks can range from the size of a poppy seed to less than a quarter of an inch, depending on where they are in their life cycle.

You should see your doctor under these circumstances:

  • If you have the distinctive erythema migrans rash that comes with many cases of Lyme disease, even if you're not sure you've been bitten by a tick. This red rash will likely expand and may start to look like a bull's eye.
  • If you have flu-like symptoms that aren't going away, and especially if you live in or have recently been to a region of the United States where Lyme disease is more prevalent (this includes the Northeast, Mid-Atlantic, and north-central states).
  • If you know you had a tick attached for more than 48 hours and you have a rash and/or flu-like symptoms.

Be sure to let your doctor know if you have been bitten by a tick or if you've been exposed to ticks, even if you're not aware of being bitten.

Clinical Judgment

Again, only healthcare providers can diagnose Lyme disease. In making the diagnosis of Lyme disease, your healthcare provider will consider several factors:

  • Detailed medical history
  • Physical examination
  • Symptoms
  • Time of year (tick bites are most likely to occur in the summer months)
  • Habits/location (for example, whether or not you spend time outdoors in an area where Lyme disease is more common)
  • Known history of a tick bite

In some cases, laboratory testing is used to support a suspected diagnosis. In addition, your healthcare provider will investigate other diseases that might cause your symptoms.

Labs and Tests

There are three stages of Lyme disease, including:

  1. Early localized stage
  2. Early disseminated stage
  3. Late stage

The characteristics of the disease at these stages, as well as any ongoing treatment, can make testing for it challenging.

In addition, the Lyme disease bacterium is difficult to detect in laboratory tests of body tissues or fluids. Therefore, most healthcare providers look for evidence of antibodies against B. burgdorferi in your blood to confirm the bacterium’s role as the cause of symptoms.

Some people with nervous system symptoms may also get a spinal tap, which allows a healthcare provider to detect brain and spinal cord inflammation and look for antibodies or genetic material of B. burgdorferi in spinal fluid.

Antibody Tests

Healthcare providers cannot always firmly establish whether Lyme disease bacteria are causing symptoms. In the first few weeks following infection, antibody tests are not reliable because your immune system has not produced enough antibodies to be detected. Antibiotics that are given early during infection may also prevent your antibodies from reaching detectable levels, even though Lyme disease bacteria are causing your symptoms.

The antibody test most often used is called an EIA (enzyme immunoassay) test, which is approved by the Food and Drug Administration (FDA). If your EIA is positive, your healthcare provider should confirm it with a second, more specific test called a Western blot. Both test results must be positive to support a diagnosis of Lyme disease. But again, negative results don't mean that you don't have Lyme disease, particularly in the early stage. A positive EIA test doesn't necessarily mean you have Lyme disease either as false-positives do happen.

Tick Testing

Even if a tick is tested and found to be harboring the Lyme Borrelia burgdorferi bacteria, it may not have necessarily transmitted the bacteria to anyone it has bitten. Therefore, testing a tick will not be an accurate indication of whether someone it has bitten has acquired Lyme disease.

Because testing the tick is not a good indicator of Lyme disease transmission, most hospital or state-run medical labs will not test ticks for Lyme bacteria. However, there are dozens of private labs that will test ticks for bacteria with prices ranging from $75 to hundreds of dollars.

New Tests Under Development

Healthcare providers need tests to distinguish between people who have recovered from the previous infection and those who continue to suffer from active infection. To improve the accuracy of Lyme disease diagnosis, National Institutes of Health (NIH)-supported researchers are re-evaluating existing tests and developing a number of new tests that promise to be more reliable than those currently available.

NIH scientists are developing tests that use the highly sensitive genetic engineering technique known as polymerase chain reaction (PCR) as well as microarray technology to detect extremely small quantities of the genetic material of the Lyme disease bacterium or its products in body tissues and fluids. A bacterial protein, outer surface protein (Osp) C, is proving useful for early detection of specific antibodies in people with Lyme disease. Since the genome of B. burgdorferi has been sequenced, new avenues are available for improving understanding of the disease and its diagnosis.

Differential Diagnoses

Lyme disease is sometimes called "The Great Imitator" because it so often mimics many other illnesses, according to LymeDisease.org, a non-profit that advocates for health care for people with Lyme disease as well as other tick-borne infections. Conversely, other types of arthritis or other autoimmune diseases can be misdiagnosed as Lyme disease.

Symptoms of Lyme disease can mimic conditions such as:

Your healthcare provider will consider all of these possibilities when making a diagnosis.

Early vs. Later Diagnosis

Lyme disease has been diagnosed long enough, and the infectious bacteria that causes it is easy enough to identify, that most patients with early Lyme disease are able to find a doctor who can accurately diagnose it. Even those patients who are originally told by a doctor that their symptoms are all in their head are often able to find another doctor to help them get the accurate diagnosis.

But in some cases, patients find great difficulty in getting a Lyme disease diagnosis. And that's because there is a controversy that surrounds such a diagnosis for patients who don't suffer symptoms until long after they were possibly bitten by a tick. While some people exhibit symptoms, including the classic "bull's eye" rash, early after a tick bite, it's possible that symptoms won't show up for months or years after being infected.

Furthermore, some patients are treated early with antibiotics, but those antibiotics don't completely destroy the Lyme Borrelia bacteria, or other symptoms occur even when no sign of any lingering infection remains.

"Chronic" Lyme Disease Diagnosis Controversy

Although no one denies that some people treated appropriately for Lyme disease go on to have persistent symptoms, there is a huge controversy over what it's called, what causes it, and how it's best treated. It has been called "chronic Lyme disease"; the Centers for Disease Control and Prevention (CDC) calls it post-treatment Lyme disease syndrome (PTLDS).

Using the term "chronic" suggests that an infection and inflammation are still present, but for PTLDS, there is little evidence that this is the case. The debate is less about whether patients are still suffering physical symptoms and more about if it's caused by persistent infection and whether people with PTLDS should be treated with antibiotics—a treatment that may not only be ill-advised but could create bigger problems for these patients.

In fact, the CDC is joined by other well-known and well-respected medical organizations and authorities in the United States in clarifying that available evidence does not support the idea that "chronic Lyme disease" is caused by persistent infection with the Lyme bacterium; this is why they prefer the name "post-treatment Lyme disease syndrome." These groups include the Infectious Diseases Society of America (IDSA), the American Academy of Neurology, and the NIH.

Further, healthcare professionals who treat PTLDS with long-term antibiotics may be putting their patients at unnecessary risk and increasing rates of antibiotic-resistant bacteria. 

Pursuing the Chronic Diagnosis

If you believe you do have PTLDS, or chronic Lyme disease, find a doctor who understands the current science behind Lyme disease and post-treatment Lyme disease syndrome, even if they won't call it chronic Lyme. 

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