Lyme Disease Tests
When you show symptoms of Lyme disease, especially when you live in or have recently visited an area where black-legged ticks are common and suspect that you have been bitten by a tick
A blood sample is taken by needle from a vein. If there are signs and symptoms suggesting that the central nervous system is affected (meningitis), a sample of cerebrospinal fluid (CSF) is collected by a healthcare practitioner from the lower back using a procedure called a lumbar puncture or spinal tap.
Lyme disease is an infection caused by the bacteria Borrelia burgdorferi and Borrelia mayonii. Lyme disease tests measure Borrelia antibodies in the blood, or in the cerebrospinal fluid (CSF) if there are signs and symptoms of central nervous system disease.
These antibodies are produced by the body's immune system in response to Borrelia infection, also called Lyme disease. It is spread by the bites of infected deer ticks or black-legged ticks. The disease is most common in the spring and summer in the regions where these ticks live, such as the northeastern, mid-Atlantic, and midwestern United States.
Lyme disease infection causes symptoms that may include a characteristic erythema migrans (EM) or "bulls-eye" rash that spreads from the site of the bite, fever, chills, headache, and fatigue. If left untreated, Lyme disease may progress to cause intermittent joint pain and swelling, meningitis, facial paralysis (Bell's palsy), weakness and numbness in the arms and legs, memory problems, and may rarely affect the heart or eyes. For more on Lyme disease, read the condition article: Lyme Disease.
It takes the body's immune system some time to begin producing Borrelia antibodies. Lab tests can detect two different classes of antibodies. IgM antibodies are usually detectable about two to three weeks after onset of infection and IgG antibodies are detectable several weeks after onset of infection. (See the How is the test used? section for more details on the tests.)
How is the test used?
Lyme disease tests are used to determine if your signs and symptoms are due to an infection caused by the bacteria Borrelia burgdorferi or Borrelia mayonii. The tests detect antibodies produced by the immune system in response to the infection.
Lab tests are used to detect two different classes of antibody:
- Borrelia IgM (immunoglobulin M) antibodies can usually be detected in the blood about two to three weeks after infection. IgM levels increase and then peak at about six weeks and then begin to decline.
- IgG (immunoglobulin G) antibodies cannot be detected until several weeks after infection. Levels peak at about four to six months later and may remain at high levels for several years.
The Centers for Disease Control and Prevention (CDC) recommends that two different methods be used to detect these antibodies and to confirm a diagnosis of Lyme disease.
- The initial test may use methods such as an enzyme immunoassay (EIA) or immunofluorescence (IFA) method to measure Borrelia IgM and/or IgG antibodies. The initial test is intended to be very sensitive so that it will detect as many cases of Lyme disease as possible. However, it may be positive with infections caused by other bacteria similar to Borrelia, such as a different tick-borne disease or syphilis, or in other conditions such as an autoimmune disorder (e.g., lupus).
- The CDC recommends that any positive or indeterminate results from an initial test be followed by a second test, called a Western blot that detects specific antibodies to multiple antigens, to confirm the findings.
The following chart illustrates the recommended steps:
Lyme disease can sometimes be challenging to diagnose. If a person has removed a tick from his or her skin, had a known tick bite, and lives in or has visited an area of the country where Lyme disease is most prevalent, then the timing of the potential infection can be closely estimated. However, the tick is about the size of the head of a pin and the bite may not be noticed. Not everyone will develop the characteristic rash, and the symptoms that a person does have may be nonspecific and flu-like in the early stages, with joint pain that develops into chronic arthritis and/or with neurological symptoms that appear months later.
A blood test for antibodies to the bacteria is the preferred test for the diagnosis of Lyme disease. However, if a person has central nervous system symptoms, such as meningitis, then IgM, IgG, and western blot testing may sometimes be performed on cerebrospinal fluid (CSF).
In special cases, polymerase chain reaction (PCR) testing may be performed on a sample because it is a more sensitive way of detecting an infection with Borrelia. However, this is not an FDA cleared or approved test method and it is not widely available. The CDC does not currently recommend PCR testing for the diagnosis of Lyme disease.
When is it ordered?
Lyme disease testing is ordered when you have signs and symptoms suggesting an infection with Borrelia and you live in or visited a region where deer ticks are common, especially when you were recently bitten by a tick.
Some early signs and symptoms of Lyme disease may include:
- A characteristic "bulls-eye" rash that spreads from the site of the bite
- Fever, chills
- Muscle and joint aches
- Swollen lymph nodes
If left untreated, Lyme disease may progress to cause:
- Muscle and joint pain that comes and goes
- Stiff neck and severe headaches (meningitis)
- Facial weakness and paralysis (Bell's palsy)
- Weakness and pain in the arms and legs
- Arthritis with joint pain and swelling that comes and goes, especially in larger joints like the knees
- Spells of dizziness or being short of breath
- Shooting pains, numbness or tingling in the hands or feet
- Memory loss, difficulty concentrating, and changes in sleep patterns
- Less commonly, eye inflammation or heart problems such as irregular heartbeat
Testing may be repeated a few weeks later when initial testing is negative but suspicion of Lyme disease remains high.
What does the test result mean?
A positive result on both initial and confirmatory tests means that your signs and symptoms are likely caused by Lyme disease.
A negative IgM result but positive results for IgG and Western blot tests means it is likely that you have a later stage infection or had an infection at some time in the past.
Negative results on all tests mean your symptoms are due to another cause or the antibody levels are too low to detect at that time; retesting in 2 to 3 weeks may be needed to confirm or rule out infection.
Negative results on IgM and Western blot but positive IgG results mean that you have recovered from Lyme disease or the results are due to antibodies produced in response to a different condition (cross-reacting) and your symptoms are due to another cause.
The following table summarizes results that may be seen with Lyme disease antibody tests.
IgM Antibody IgG Antibody Western Blot Likely Interpretation Positive Positive Positive Likely Lyme disease if consistent with other signs and symptoms Positive Negative Negative Early infection or false-positive IgM test due to cross reactive antibodies Negative Positive Positive Late or previous infection Negative Negative (usually not performed if IgM and IgG are negative) No infection present; symptoms may be due to another cause or antibody levels are too low to detect Negative Positive Negative Prior infection or false-positive IgG test due to cross-reactive antibodies
Is there anything else I should know?
Once someone has had Lyme disease, the person will typically have detectable amounts of Borrelia IgG antibodies in their blood for the rest of their life.
Borrelia belongs to a class of bacteria called spirochetes. Other spirochete diseases, such as syphilis and leptospirosis, can cause false-positive results, as can other conditions such as HIV infection, mononucleosis, and a variety of autoimmune disorders.
When you do not have typical signs and symptoms or a history of a tick bite and have not been in a region where Lyme disease is prevalent, then your healthcare provider may rule out other causes for your symptoms before suspecting and testing for Lyme disease.
Where can I read more about the treatment of Lyme disease?
Can I do anything to protect myself from becoming infected?
Yes. If you are in the woods or garden in tick-infested areas, avoid contact with the soil, leaves, and vegetation. Wear closed shoes, light-colored clothing, and use insect repellant containing 20-30% DEET or permethrin. Check your clothing and exposed skin frequently and remove ticks promptly. Animals such as dogs, cats, horses, and cows can also carry the deer tick. Check your pet often, particularly the head, neck, ears, and between the toes. Use a tick repellent prescribed by your veterinarian.
How can I recognize the signs if I don't show the rash?
The rash appears in up to 75% of those infected. This rash may be the classic "bull's eye," but may also be blotchy or red and may be confused with poison ivy, spider bites, or ringworm. It may appear between a few days and a few weeks after being bitten and can disappear quickly. If possible, take a picture of the rash to show your healthcare provider since the rash may be gone before you can get an appointment.
Other symptoms of Lyme disease include fatigue, chills and fever, headache, muscle and joint pain, and swollen lymph nodes. Check with your healthcare provider if you have any of these symptoms and cannot explain how you got them.
Should I be tested for Lyme disease if I don't have any symptoms?
Testing people who do not have symptoms is not recommended; the tests tend to have a higher incidence of false positives when this is done. This is true even when someone has been bitten by a deer tick, also known as the black legged tick. Not every tick bite will result in an infection. Not every tick is infected with Borrelia and even with those that are, it typically takes between 24 and 72 hours from the time a tick attaches to a person for the bacterium to be transmitted. If a tick is promptly removed, then the risk of getting Lyme disease is decreased. Those who have been bitten should talk to their healthcare provider if they develop any symptoms or if they have any concerns.
What is Post-Treatment Lyme Disease Syndrome?
In a small percentage of people treated for Lyme disease with the recommended 2-4 week course of antibiotics, symptoms including fatigue and joint and muscle pain linger, sometimes for more than 6 months. This has been given the name Post-Treatment Lyme Disease Syndrome (PTLDS). Research is ongoing to better understand the cause of this syndrome. People should be aware that if their symptoms continue after treatment, they should contact their healthcare provider to discuss ways in which to manage these symptoms.
Can ticks be tested for Lyme disease?
Yes, some state and local public health departments offer testing of ticks as well as identification of the types that transmit Lyme disease. You can check with your health department to see if it offers these. However, testing ticks may not always be useful for a few reasons. Even though a tick is positive for Lyme disease, it does not mean it passed it on to you. If it is negative, it may give false reassurance because you could have been bitten by a different tick that is infected. And if you are infected, you may develop symptoms before you get the tick results. You should not wait for those results if you are ill and should consult your healthcare provider.