What Is a Lyme Disease Test?

One of the challenges of Lyme disease, a bacterial infection transmitted by tick bite, is ensuring proper diagnosis. The symptoms can mimic the flu, and not everyone develops the “bullseye rash” that is usually a sign.

Alongside evaluation of symptoms, several tests may be needed. Blood tests include enzyme-linked immunoassay (ELISA) and the Western blot blood test. Assessment of cerebrospinal fluid (CSF) using spinal tap and other specimens may be done if symptoms warrant.

Types of Tests

When Lyme disease is suspected, the first steps are an assessment of symptoms and the likelihood of tick bite. If a person displays characteristic symptoms (especially the bullseye rash), lives in an area where there are bacteria-spreading black-legged ticks and there’s a risk of exposure, testing will be called for.

Tests for Lyme disease involve assessment of either blood samples or CSF, which is the fluid that surrounds the brain and spine. These include:

• ELISA test: This blood test is used to detect antibodies your body has produced to fight specific pathogens.
• Western blot test: This test is used to confirm the initial positive or inconclusive results of an ELISA test. It also screens for antibodies in the blood, looking for both the IgM antibodies, which arise as an initial response, and IgG antibodies, which are signs of longer-term infection.

The polymerase chain reaction (PCR) test can be used on CSF if antibodies against the organism causing Lyme disease were detected. This test looks for bacterial DNA. It is done only to determine if a symptom is related to Lyme disease. It may be used on CSF if meningitis/encephalitis is suspected, on other specimens, or on synovial fluid, but generally not on blood or urine.

Purpose of Tests

Given the range of tests that can potentially be used to detect Lyme disease, it’s important to understand their differences, and what each can and can’t do. While all can be helpful for diagnosis of this condition, each has its own specific advantages and disadvantages.

What symptoms prompt a healthcare provider to call for diagnostic testing in the first place? The early symptoms—beginning three to 30 days after tick exposure—include:

• Bullseye rash (a red ring with a clear center)
• Fever
• Chills
• Pains in the hands and feet
• Swollen lymph nodes
• Stiff neck
• Severe headache
• Persistent fatigue
• Muscle/joint aches

In addition, several other factors are taken into account, and can prompt tests even in absence of symptoms:

• You’ve recently had or currently have a tick attached.
• You’ve spent time in heavily wooded areas native to ticks.
• You are or were in areas where ticks are native, such as the Northeast, mid-Atlantic, and Midwest regions of the United States.

Generally speaking, tests of antibody levels, most often ELISA and Western blot, are considered the “gold standard” of diagnosis. Other tests, including PCR, look for DNA evidence of the bacteria, so they may also prove useful.

Notably, the accuracy of these tests varies based on disease progression; what works during an earlier stage may not be as effective down the line, and vice versa. Here’s a quick breakdown:

• Early stage: Within a month of exposure to Lyme disease, during its “localized” phase, testing isn’t generally necessary if Lyme-specific symptoms, such as the rash, are present. Since it takes a couple of weeks for the body to develop antibodies, tests like ELISA are less likely to be accurate in this phase. Retesting or PCR testing may be needed.
• Stage 2: During the “early disseminated” stage of Lyme disease, the infection has begun spreading to other bodily systems. At this point, the Centers for Disease Control and Prevention (CDC) recommends a two-stage testing process. An initial positive or inconclusive ELISA test may need to be repeated and/or confirmed using Western blot.
• Stage 3: The antibodies produced to fight off Lyme disease persist in the body long after infection, so two-tiered testing could still detect an advanced form of Lyme disease. At this stage, the infection often has spread to the central nervous system, so CSF antibody or PCR tests can also help.

Despite their broad application, there are a couple of things to keep in mind when it comes to antibody tests like ELISA:

• Within four weeks of infection, antibody tests may be much less accurate.
• Antibody tests can’t tell you if you’ve been cured.
• False positives can arise due to other diseases, such as autoimmune disorders, lupus, or rheumatoid arthritis.  
• If a person has been ill longer than 30 days, a positive IgM antibody result should be disregarded and require additional confirmation.

Risks and Contraindications

For blood tests, the primary complications are bruising and discomfort at the site of needle entry. More invasive and impactful are CSF tests, which require lumbar puncture. Though the overall risk of the procedure is minimal, there are some occasional complications, including:

• Pain at the site of injection
• Headaches
• Nausea
• Low blood pressure
• Elevated heart rate
• Inflammation
• Bleeding

It's unsafe to have a lumbar puncture if there is inflammation at the intended site of injection, an increased risk of uncontrolled bleeding, or if pressure within the skull (intracranial pressure) is too high.

Before the Test

Preparing for both blood tests and lumbar puncture means understanding timing, what to wear, and what else you might need to have along. Here’s a quick rundown of what you need to know:   

• Timing: A blood draw takes about five minutes. A lumbar puncture for CSF takes about 45 minutes for the procedure, then lying flat for an hour or two.
• Location: Samples of blood and CSF can be taken at a clinic or in the hospital. Those getting lumbar puncture are prone on a bed, examination table, or operating table.
• What to wear: Loose-fitting, comfortable clothes are fine for blood draws. Those who need lumbar puncture will be asked to change into a gown.
• Food and drink: Generally speaking, there are no dietary restrictions before these tests. Since some types of blood tests that might be drawn at the same time may require fasting beforehand, it’s worth checking with your healthcare provider.
• Cost and health insurance: Insurance plans can vary when it comes to testing and treatment for Lyme disease, with some companies being much more restrictive. Talk to your insurer to find out what is covered.
• What to bring: While you should leave valuables at home, it’s a good idea to have your ID, a list of medications you’re taking, as well as a notebook for note-taking. For lumbar puncture CSF tests, it’s a good idea to have someone else drive you home.

During the Test

Pre-Test

Blood tests are very easily tolerated and require little in the way of preparation; however, much more is involved when getting ready for a CSF test. What happens before the lumbar puncture procedure? Several important steps:

• You’ll be asked to empty your bowels and/or bladder.
• You’ll undergo physical evaluation, focusing on blood clotting ability.
• Your intracranial pressure will be checked.
• You’ll discuss medications you’re taking with your healthcare provider.

Throughout the Test

Collecting a specimen for a blood test takes about five minutes. Basically, a healthcare professional will find an appropriate vein, usually in the upper arm. While making a fist, you’ll feel a pinch as a needle is inserted and blood is drawn into a test tube.   

CSF tests are a little more involved. Preparation and recovery in the hospital or clinic are more extensive. Here’s what typically happens:

• To allow the vertebrae to separate as much as possible, you’ll be asked to sit or lie down on your side and arch your back.
• The skin is cleaned, and then a larger needle is inserted, drawing out CSF.
• There will be a pinch as the needle enters the skin.
• After 10 to 15 milliliters (mL) are drawn, the needle is removed and the site bandaged. This process takes about five minutes.

Post-Test

Those who have blood samples taken are able to go home as soon as they’re ready afterward. For CSF tests, however, a little more recovery is involved, as patients need between one and four hours of recovery time in the clinic or hospital. You can go only when the healthcare provider is sure it’s safe for you to leave.

After the Test

Following Lyme disease tests, it’s most important that you are vigilant about how you’re feeling and are on the lookout for any unfortunate side effects. Typically, these tests are well tolerated and cause no problems, but some care is needed regardless.

Managing Side Effects

Following a blood draw, you may have some residual pain and need to ensure the injection site is not infected. Infection can cause redness and swelling in the area, as well as fever; if you experience any of this, be sure to call your healthcare provider.

If you have CSF testing using lumbar puncture, you should expect to feel fatigued and seek rest for about 24 hours afterward. In addition, many experience a collection of symptoms called “post-lumbar puncture headache,” which lead to:

• Headache
• Nausea
• Rapid heart rate
• Low blood pressure

While this typically resolves within a couple of hours of the procedure, it may take up to five days. If the symptoms persist longer than that—or if there’s any sign of infection in the puncture site—make sure to call your healthcare provider.

Interpreting Results

It can take up to two weeks to get the results of Lyme disease tests. Much depends on where you're having the work done. Each test measures specific attributes. Here’s a quick primer on the kinds of results you might encounter:

• The ELISA test detects the presence of antibodies in the blood, essentially categorizing normal from abnormal results. Measures are broken down into numbers, with results greater than or equal to 1.0 indicating potential infection. This test may be less effective in the early going—since antibodies may not have formed—but is very sensitive.
• Western blot results list levels of IgM and IgG antibodies. These results come in the form of bands. For recent exposure (within four weeks), two out of a possible three IgM bands indicate positive results. For remote exposure (greater than four weeks) five out of 10 IgG bands indicate positive results. In most cases, Western blot will confirm a case caught using the ELISA test.
• PCR tests detect bacterial DNA rather than antibodies, offering positive or negative results. It’s typically used to detect early cases or those that are very advanced. Since this DNA can linger for months after the infection has cleared, false positives can occur.
• The CSF test is reserved for more advanced cases of Lyme disease, especially when spread to the central nervous system is suspected. The presence of antibodies is quantified as negative if the result is less than 1.0, possible and needing retest if the value is 1.0 to 1.2, and positive if this is found to be above 1.21.

Typically, you’ll have an appointment or phone conversation with your healthcare provider to discuss your results. In these consultations, it’s essential that you’re open with your practitioner and that you learn as much as you can about your condition from them.

Follow-Up

As noted, not every test is conclusive, and positive results may not always mean you have Lyme disease. However, negative ELISA results are strong indicators that you don’t have Lyme disease, as the test is very sensitive.

In addition, these tests can lead to false positives or require additional testing for confirmation. Here’s what you need to keep in mind:

• Positive or inconclusive ELISA results call for additional testing, as other infections or disorders can lead to false positives. Negative ELISA results typically mean you’re in the clear.
• With Western blot, positive IgM values are not considered if the infection has been going on for longer than 30 days. False positives can also occur with this test, which is why it’s usually paired with ELISA.
• When CSF testing yields a positive result, additional tests are required to confirm that result.

So what happens if a case is confirmed? Most often, courses of antibiotics will be prescribed to take on your case. In more advanced cases, of course, more intensive treatment is necessary.

Other Considerations

When discussing your results with your healthcare provider, don’t be shy; engage in the dialogue, and try to learn as much as you can about your condition. What should you ask? Some good questions include:

• Does this positive result mean I have Lyme disease?
• Will I need more testing?
• Can I get Lyme disease if I’ve never seen the tick bite?
• Will I always have these symptoms?
• What symptoms should I look out for?
• How quickly will the antibiotics work, and how do I take them properly?
• How soon will medications take effect? How quickly will I feel better?

The more you know—and the better you engage with the process of diagnosis and testing—the better off you’ll be. Make sure to use your consultations with the healthcare provider wisely; these professionals are excellent resources of information, and they’re working for you.

A Word From Verywell

Lyme disease can take many forms; if treated quickly, it generally resolves quickly. However, untreated or advanced cases can become quite serious and may become chronic. Multiple rounds of accurate and effective testing, then, are essential in the fight against the condition.

If you’re feeling anxious about your results, remember that Lyme disease, though debilitating, can be effectively managed. The chances are great that you will see a full recovery.

If you’ve been diagnosed, what’s essential is that you carefully follow treatment guidelines. With some effort and good help, you can surely get the best of this disease.