Anti-Borrelia burgdorferi IgG Immunoassay (Serum/Plasma)

Why This Test Is Done

Your healthcare provider may order this test if you have symptoms of Lyme disease, such as fever, rash (like a bullseye rash called erythema migrans), joint pain, or neurological issues. It may also be used to confirm a diagnosis after other tests or if symptoms persist after treatment. Sometimes, it’s part of a screening or follow-up process.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm to draw blood. It usually takes a few minutes. If you’re nervous, let your provider know—they can help make it more comfortable. Avoid eating or drinking anything (except water) for a short time before your blood draw if instructed.

What the Test Results Mean

Positive results suggest you may have been exposed to *Borrelia burgdorferi* and your body has mounted an immune response. However, a single positive test doesn’t always confirm Lyme disease—additional testing or clinical evaluation is often needed. Negative results mean no detectable antibodies were found in this sample, but they don’t rule out infection entirely, especially if symptoms are recent.

How the Test Works

This test uses an immunoassay (a lab method that detects specific antibodies) to measure IgG antibodies in your serum or plasma. The test looks for antibodies that your immune system produces after exposure to the Lyme bacterium. It’s not a direct test for the bacterium itself, so it’s used alongside other clues (like symptoms, physical exam, or other tests) to diagnose Lyme disease.