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 have developed 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 4 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. During a lumbar puncture, a needle is inserted into the spinal column to remove the fluid.
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.
A history of Lyme disease, symptoms, diagnosis, treatment, and prevention. National Institute of Allergy and Infectious Diseases website. Available at: http://www.niaid.nih.gov/topics/lymeDisease/Pages/history.aspx. Updated March 29, 2011. Accessed September 26, 2012.
Diagnosis and testing. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/lyme/diagnosistesting/index.html. Updated July 26, 2012. Accessed September 26, 2012.
Lyme disease. EBSCO DynaMed Plus website. Available at:http://www.dynamed.com/topics/dmp~AN~T114365/Lyme-disease. Updated August 15, 2016. Accessed October 6, 2016.
Lyme disease diagnosis. Lyme Disease website. Available at: https://www.lymedisease.org/lyme-basics/lyme-disease/diagnosis. Accessed September 26, 2012.
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Last reviewed November 2018 by David L. Horn, MD Last Updated: 12/20/2014