2223. Borrelia burgdorferi, IgG antibodies (BlotAnalisis)

The Borrelia burgdorferi IgG antibody blot test is a laboratory test performed after a positive or inconclusive result from the initial test for Lyme disease (Borrelia burgdorferi IgG enzyme-linked immunosorbent assay).

The blot test detects antibodies to specific Borrelia proteins, allowing the differentiation of true infection from false positives (positive results without disease). It is used to confirm the diagnosis of Lyme disease (borreliosis) and provides high diagnostic accuracy.

Lyme disease (tick-borne borreliosis) is an infectious disease transmitted by the bite of a tick infected with Borrelia bacteria. The likelihood of transmission increases the longer the tick remains on the skin. If the infection is not detected promptly, it can lead to serious complications, including damage to the joints (Lyme arthritis), heart (Lyme carditis), nervous system (neuroborreliosis), or skin (acrodermatitis).

When Borrelia enters the body after a tick bite, the immune system begins producing protective antibodies. IgM antibodies are the first to appear, signaling the early stages of infection. After 4-6 weeks, IgG antibodies develop, reflecting the developed immune response to the Borrelia bacteria. IgG levels peak after 1.5-3 months and can persist for years even after successful treatment of Lyme disease.

The Borrelia burgdorferi IgG antibody blot test is used to confirm the diagnosis of Lyme disease when symptoms last longer than 30 days, according to CDC and IDSA guidelines. According to the two-step algorithm, the IgG blot test is ordered only after a positive or inconclusive IgG enzyme-linked immunosorbent assay (ELISA) result.

It is important to remember that the blot test is not used to verify the effectiveness of treatment, as IgG antibodies can persist in the blood for years even after successful recovery.

The Borrelia burgdorferi IgG blot test is most informative if at least 30 days have passed since the tick bite, as this is when IgG becomes the primary laboratory indicator of infection, while IgM testing is less indicative during this period.

The test is recommended for:

• Adults and children with prolonged flu-like symptoms (fever, fatigue, headache, joint pain) without an obvious cause, especially after a tick bite or exposure to areas where ticks carrying Lyme disease are common.
• Those who have received a positive or inconclusive result from an ELISA (enzyme-linked immunosorbent assay) screening test for IgG against Borrelia.
• If specific manifestations of late-stage Lyme disease appear several weeks or months after a tick bite: joint pain (arthritis), skin lesions (acrodermatitis), neurological disorders (numbness, weakness in the limbs, facial paralysis), or heart problems (carditis).

What does the result mean?

A positive result means that specific antibodies have been detected in the blood, which may indicate exposure to the Lyme disease pathogen. However, IgG antibodies can persist for many years even after successful treatment, so a positive result alone does not always indicate an active infection.

A physician makes a final assessment of the results, combining laboratory data with clinical manifestations, the history of the tick bite, and the overall clinical picture.

A negative result usually indicates the absence of infection. However, if the test is taken too early (less than 30 days after the tick bite), the immune system may not have yet had time to produce sufficient antibodies. In this case, if clinical symptoms are present, the doctor may recommend a repeat examination in 2-4 weeks.

• Venous blood

In order to exclude factors that may affect the test results, we recommend to follow the preparation rules: