Lyme disease infection causes symptoms that may include a characteristic "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, meningitis, facial paralysis (Bell's palsy), weakness and numbness in the arms and legs, memory problems, and may rarely affect the heart or eyes.
It takes the body some time to begin producing B. burgdorferi antibodies. B. burgdorferi IgM (immunoglobulin M) antibodies are usually detectable in the blood about two to three weeks after exposure. IgM levels increase to maximum concentrations at about six weeks and then begin to decline. IgG (immunoglobulin G) antibodies are detectable several weeks after exposure, increase to maximum levels at about four to six months, and may remain at high levels for several years.
Two tests are typically used to detect and confirm Lyme disease. The Centers for Disease Control and Prevention (CDC) recommend that an ELISA or IFA test method be used first to measure B. burgdorferi IgM and/or IgG antibodies. Since these tests may be positive with infections caused by other bacteria similar to B. burgdorferi, such as the bacterium that causes syphilis, the CDC recommends that any positive or indeterminate test results then be followed by a second test, called a Western Blot, in order to confirm the findings.
How is the sample collected for testing?A blood sample is taken by needle from a vein in the arm. If there are symptoms of meningitis, a sample of cerebrospinal fluid (CSF) is collected by a doctor from the lower back using a procedure called a lumbar puncture or spinal tap.
Is any test preparation needed to ensure the quality of the sample?No test preparation is needed.
How is it used?Lyme disease tests are used to determine if a person with characteristic symptoms has been infected by Borrelia burgdorferi. If the doctor suspects a recent infection, then she may order both an IgM and IgG antibody blood test. If they are negative but symptoms persist, then the tests may be ordered again a few weeks later.
Acute and convalescent samples may be used to track progression of the disease by looking for changes in the amount of antibody present. If the tests are positive, then a Western blot test is ordered to confirm the findings.
Lyme disease can sometimes be challenging to diagnose. If a person has removed a tick from his 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 bacterium 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 CSF.
Occasionally PCR (polymerase chain reaction) testing is performed on a sample because it is a more sensitive way of detecting an infection with B. burgdorferi. This method is useful in detecting the infection in samples such as fluid collected from a joint. It looks for the genetic material (DNA) of B. burgdorferi in the joint fluid (synovial fluid). This method, however has not been found to be sensitive for detecting the infection in samples of CSF.
When is it ordered?Lyme disease testing is ordered when a person has symptoms suggestive of an infection with B. burgdorferi and lives in or has visited a region where deer ticks or black-legged ticks are common, especially when the person has recently been bitten by a tick.
Some symptoms of Lyme disease may include:
- a characteristic "bulls-eye" rash that spreads from the site of the bite
- fever, chills
If left untreated, Lyme disease may progress to cause:
- intermittent joint pain
- facial paralysis (Bell's palsy)
- weakness and numbness in the arms and legs
- memory problems
- may rarely affect the heart or eyes
IgM and IgG tests are ordered first. Western blot testing is ordered as a follow-up test when the first tests are positive or indeterminate. Acute and convalescent samples may be ordered several weeks apart to look for changes in antibody levels.
When someone does not have typical symptoms or a history of a tick bite and has not been in a region where Lyme disease is prevalent, then the doctor may rule out other causes for the person's symptoms before suspecting and testing for Lyme disease.
What does the test result mean?A healthy adult who has never been exposed to the B. burgdorferi bacterium will not have any antibodies. If someone tests positive for the IgM antibody but not the IgG or Western blot test, then he may have a false positive test result or a very recent infection. If his IgM, IgG, and Western blot tests are positive, then it is likely that he has Lyme disease. If his antibody concentrations rise over time, then it is likely that he has an active B. burgdorferi infection.
If an IgM result is not detectable but the IgG and Western blot test are positive, then it is likely that the person tested either has a later stage infection or had an infection at some time in the past. If all tests are negative, then either the person's symptoms are due to another cause or the antibody levels are too low to detect.
The following table summarizes results that may be seen with Lyme disease antibody tests.
IgM antibody IgG antibody Western blot Positive Positive Positive Likely Lyme disease Negative Positive Positive Late or previous infection Negative Negative Negative No infection present; symptoms may be due to another cause or antibody levels too low to detect
If the result from PCR testing is positive, then it indicates infection with B. burgdorferi. If the PCR test result is negative, then there no infection is present or the levels of DNA are too low to detect.
Is there anything else I should know?Once a person has had Lyme disease, he or she will typically have detectable amounts of B. burgdorferi IgG antibodies in their blood for the rest of their life.
Borrelia burgdorferi 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.
Antibiotics can interfere with the test results, so if you are being treated with antibiotics before being tested for Lyme disease, make sure your doctor knows.
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 DEET. 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 only about 80% 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 doctor, since the rash may be gone before you can get an appointment with him/her.
Other symptoms of Lyme disease include fatigue, chills and fever, headache, muscle and joint pain, and swollen lymph nodes. Check with your doctor 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 or black-legged tick. Not every tick bite will result in an infection. Not every tick is infected with Borrelia burgdorferi 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 doctor if they develop any symptoms or if they have any concerns.
Are deer ticks the only way to get Lyme disease?