Lyme Disease Blood Test (Two-Tiered Serology)

What is this test? This is a blood test that looks for antibodies your immune system produces in response to Borrelia burgdorferi, the bacterium that causes Lyme disease and is spread through the bite of an infected blacklegged tick. Your doctor may order it if you have symptoms such as an expanding skin rash, fever, chills, fatigue, headache, muscle aches, or joint pain, especially after time spent in wooded or grassy areas where ticks are common.

The Borrelia burgdorferi IgG and IgM panel is a blood test that detects antibodies (IgM and IgG) produced by your immune system in response to infection with Borrelia burgdorferi, the bacterium that causes Lyme disease. Lyme disease is typically transmitted through the bite of infected blacklegged ticks (Ixodes scapularis/Ixodes pacificus). This test uses an immunoassay technique to identify whether your blood contains these specific antibodies.

How does the testing process work? A healthcare professional will clean your skin, draw a small sample of blood from a vein in your arm, and send it to a laboratory for analysis. The lab first screens the sample with an enzyme immunoassay (EIA). If that screening result is positive or borderline, the sample automatically moves on to a second, more specific test to confirm the finding. The blood draw is minimally invasive, takes only a few minutes, and results are usually available within several days.

A healthcare professional will draw a blood sample from a vein in your arm. This sample is then sent to a laboratory where it is analyzed using immunoassay techniques. The test looks for two types of antibodies: IgM (immunoglobulin M), which are the first antibodies your body produces in response to a new infection, and IgG (immunoglobulin G), which develop later and provide long-term immunity. Results are typically available within a few days to a week, depending on the laboratory.

What do the results mean? A positive result means antibodies against the Lyme disease bacteria were detected, which suggests current or past infection, although antibodies can stay in your blood for months or years after successful treatment. A negative result usually means you are not infected, but if the blood was drawn too soon after a tick bite, antibodies may not yet be detectable, so your doctor may recommend repeat testing. Your provider will interpret the results together with your symptoms and any known tick exposure.

A positive IgM result usually indicates an early infection, as IgM antibodies typically appear within 1-2 weeks after being bitten by an infected tick. A positive IgG result may indicate a later stage of infection or a past infection. However, it can take several weeks for antibodies to develop to detectable levels, so early testing after a tick bite may be negative even if you have been infected. Your healthcare provider will interpret your results alongside your symptoms, medical history, and potential exposure to ticks.

Two-Tiered Testing Approach: Lyme disease is diagnosed using a two-step process recommended by public health authorities. The first test is a sensitive screening assay (EIA or ELISA) that detects antibodies to Borrelia burgdorferi. If this result is positive or equivocal, the same blood sample is tested with a second, highly specific confirmatory assay, such as a Western blot or a second EIA, to reduce the chance of a false-positive result. Infection is considered likely only when both steps are positive, while a negative first test generally rules out infection unless symptoms began very recently.

Lyme disease testing often follows a two-tiered approach recommended by the CDC. First, an initial immunoassay (like this test) is performed. If this initial test is positive or equivocal, a separate confirmatory test (usually a Western blot) is done to verify the result. This two-step process helps ensure accurate diagnosis and reduces the chance of false-positive results.