Lyme disease IgG – laboratory test

Description

Why test for Borrelia IgG antibodies

IgG antibodies against Borrelia burgdorferi are the immune system’s “memory” of exposure to the bacteria that cause Lyme disease. They appear 4–6 weeks after infection, peak after 4–6 months and persist for years, even after successful treatment. IgG testing alone is therefore most useful for diagnosing late manifestations of Lyme disease (affecting the joints, nervous system or skin), rather than assessing a recent tick bite; in the first few weeks, IgM testing or an IgM + IgG package is more useful. The ELISA/CLIA test is a screening step: a positive or equivocal result requires confirmation by Western blot.

When to consider this test

• recurrent or migratory pain and swelling in large joints (most commonly the knee), months after spending time in woodland,
• chronic neurological symptoms: numbness, nerve root pain, facial nerve palsy or memory problems with a history of a tick bite (the doctor will extend the investigations to include cerebrospinal fluid testing),
• bluish-purple, thin, atrophic skin lesions on the limbs (acrodermatitis chronica atrophicans),
• heart rhythm disturbances or conduction block with no other cause in someone exposed to ticks,
• to supplement a negative IgM result when symptoms have lasted longer than 6–8 weeks.

How to prepare

• You do not need to fast; avoid a large meal just before blood collection.
• Wait at least 4–6 weeks after the bite; before this, IgG results are negative despite infection.
• If you have a typical erythema migrans rash, do not wait for tests; see a doctor: treatment starts immediately, without serological testing.
• Tell your doctor about autoimmune conditions, previous syphilis, glandular fever or other infections: these can cause false-positive results.

How to interpret the result

Lyme disease is diagnosed based on clinical symptoms and two positive tests (ELISA and Western blot). A positive result without symptoms does not mean you have the disease, and a result after treatment is not used to assess whether the infection has been cured.

Other tests to consider alongside this test

For recent symptoms: Lyme disease IgM or the IgM + IgG package; after a positive result: Western blot IgG; for joint pain: CRP, RF, full blood count. Read more: Badania-Medyczne.pl.

Sources: ALAB laboratoria, Lyme disease IgG antibodies (IgG peak after 4–6 months, first diagnostic step, Western blot confirmation, erythema migrans in 25–50% of patients); Chmielewski T., Strengths and limitations of serological diagnosis of infectious diseases, part 5: Lyme disease, Medycyna Praktyczna 2019 (two-step ELISA + Western blot testing, erythema migrans without testing, persistence of antibodies, lack of value in testing ticks). This information does not replace a medical consultation.