Diagnosis of Lyme Disease
The diagnosis of Lyme disease is usually based on the presence of symptoms and signs of the disease. If you have removed an attached tick from your body, tell your doctor. For 30 days after being bitten, you should watch closely for the characteristic “bulls-eye” rash at the site of the bite, or a fever. If you think you develop these or any other symptoms, see your doctor immediately. You are much less likely to develop Lyme disease if the tick had been attached to you for less than 24 hours. Treatment with appropriate antibiotics after a tick bite, while not endorsed by all experts, may also reduce your risk.
Presently, there are no tests that are completely accurate in diagnosing Lyme disease. However, your doctor may order one or more of the following tests to support the diagnosis of Lyme disease:
Antibodies are the body’s defense against an infection. If you have been infected with the Lyme disease bacteria, your body will release specific antibodies to fight it. It takes about four weeks or more for these antibodies to become detectable. Examples include:
- Antibody titer (ELISA or IFA)—This test measures the level of Lyme disease antibodies in the blood. If this test is equivocal or positive, you will need to have a Western Blot to confirm the results
- Western blot —This test detects the presence of the antibody to specific Lyme disease proteins in the blood.
Both of these tests can have false negative results (the test is negative even though you are infected) or false positive results (the test is positive even though you are not infected).
Some reasons why false negatives may occur include:
- The test is performed too soon after infection.
- Too few antibodies are made.
- The test is performed incorrectly.
Some reasons why false positives may occur include:
- The test is performed incorrectly.
- Your immune system produces unrelated antibodies that appear in the test as if they were produced in response to Lyme disease.
Direct Detection Tests
These tests look directly for the bacteria, or pieces of it, in the blood and other fluids of the body, such as urine and spinal fluid. Two main types are:
Antigen detection tests—These look for a unique protein from the Lyme disease bacteria that may be in body fluids. This test is useful for detecting Lyme disease in certain situations, such as:
- If you are taking antibiotics
- During a later flare-up of symptoms
- Polymerase chain reaction (PCR)—This test identifies specific DNA from the Lyme bacteria and is able to detect very small amounts of bacterial DNA
This test is done by actually growing the Lyme bacteria from fluid taken from an open sore or other source of body fluids. If the bacteria grow, the test is considered positive. Cultures often take many weeks to grow the bacteria and are rarely used today.
Analysis of Spinal Fluid
This test is done when your symptoms indicate that Lyme disease is affecting the nervous system. Spinal fluid is tested for bacteria using one of the tests listed above. The spinal fluid is removed by ]]>spinal tap]]> (inserting a needle into the spinal column).
Single Photon Emission Computed Tomography (SPECT)
This test is rarely used, but may be done in certain cases with symptoms that involve the nervous system. It is a kind of brain scan that looks for brain wave patterns that may indicate Lyme disease infection.
Frequently asked questions. American Lyme Disease Foundation website. Available at: http://www.aldf.com/faq.shtml . Accessed October 5, 2008.
Lyme disease. Lyme Disease Foundation website. Available at: http://www.lyme.org/otherdis/ld.html . Accessed October 5, 2008.
Lyme disease. National Institute of Allergy and Infectious Diseases website. Available at: http://www3.niaid.nih.gov/topics/lymeDisease/ . Accessed October 5, 2008.
Marques AR, Martin DS, Philipp MT. Evaluation of the C6 peptide enzyme-linked immunosorbent assay for individuals vaccinated with the recombinant OspA vaccine. J Clin Microbiol. 2003;40:2591.
Philipp MT, Marques AR, Fawcett PT, et al. C6 test as an indicator of therapy outcome for patients with localized or disseminated lyme borreliosis. J Clin Microbiol. 2003;41:4955.
Last reviewed August 2008 by ]]>David L. Horn, MD, FACP]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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