Western blot for Lyme disease

Alternative names
Lyme disease serology; ELISA for Lyme disease; Lyme disease antibody

These tests are used to confirm the diagnosis of Lyme disease.

How the test is performed

Blood is drawn from a vein on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For an infant or young child, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

For the screening test, an ELISA is done as follows: the spirochete Borrelia burgdorferi, the causative organism of Lyme disease, is grown in culture and fixed to a microscope slide. The slide is then incubated with a sample of your serum (the portion of blood that contains antibodies). A fluorescent-labeled antiglobulin is placed on the slide and viewed under ultraviolet light. If human antibody to Lyme disease is present, it will bind to the fluorescent antiglobulin and be visible under the ultraviolet light.

A more specific test is a Western blot, where the specific antigen bands for Lyme disease are analyzed. This test is the true confirmation of Lyme disease.

How to prepare for the test
There is no special preparation for the test.

For infants and children:
The preparation you can provide for this test depends on your child’s age and experience. For specific information regarding how you can prepare your child, see the following topics:

  • Infant test or procedure preparation (birth to 1 year)  
  • Toddler test or procedure preparation (1 to 3 years)  
  • Preschooler test or procedure preparation (3 to 6 years)  
  • Schoolage test or procedure preparation (6 to 12 years)  
  • Adolescent test or procedure preparation (12 to 18 years)

How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed
The test is performed to help confirm the diagnosis of Lyme disease.

Normal Values
Nonreactive or a very low serum titer (antibody count) are normal.

What abnormal results mean
A titer of 1:128 is borderline and further testing should be done. A positive serology by ELISA can help confirm the diagnosis of Lyme disease, but it is not definitive because other diseases and high rheumatoid factors can cause false positives. A Western blot can confirm the diagnosis of Lyme disease.

What the risks are

The risks associated with having blood drawn are:

  • Excessive bleeding  
  • Fainting or feeling light-headed  
  • Hematoma (blood accumulating under the skin)  
  • Infection (a slight risk any time the skin is broken)  
  • Multiple punctures to locate veins

Special considerations
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Johns Hopkins patient information

Last revised: December 5, 2012
by David A. Scott, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.