Lyme Ab (IgG) is a blood test used to detect immunoglobulin G antibodies against Borrelia burgdorferi, the bacterium responsible for Lyme disease. Lyme disease is a tick-borne infection transmitted primarily by black-legged ticks (Ixodes species) and is common in parts of North America, Europe, and Asia.
IgG antibodies are part of the body's adaptive immune response and typically develop several weeks after infection, often appearing after the early stage of Lyme disease. Unlike IgM antibodies, which may appear within the first few weeks of infection, IgG antibodies generally indicate longer-term immune exposure. Once produced, IgG antibodies can persist in the bloodstream for years, even after the infection has been treated.
For this reason, the Lyme Ab (IgG) test is commonly used to help identify later-stage or previous Lyme disease infections, especially in individuals who have experienced symptoms for more than a month.
Lyme disease progresses through several stages:
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Early localized infection: often characterized by the classic erythema migrans (“bull’s-eye” rash), fever, fatigue, headache, and muscle aches.
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Early disseminated infection: may involve multiple rashes, neurological symptoms (such as facial palsy), and heart rhythm abnormalities.
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Late Lyme disease: can cause arthritis, chronic joint inflammation, and neurological complications.
Elevated Lyme IgG antibodies may be associated with symptoms such as:
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Joint pain or swelling (especially in the knees)
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Persistent fatigue
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Nerve pain or tingling
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Memory or concentration problems
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Facial nerve palsy
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Chronic headaches or neurological symptoms
Because IgG antibodies can remain positive long after infection, clinicians typically interpret results in combination with symptoms, exposure history, and other laboratory tests. Confirmatory testing, such as a Western blot or other immunoblot assays, is often used to verify positive screening results.
Early diagnosis and treatment of Lyme disease—usually with antibiotics—can help prevent long-term complications. If Lyme disease is suspected, healthcare providers may evaluate both IgM and IgG antibodies, repeat testing if infection was recent, or order additional diagnostic tests depending on symptoms.
LYME AB (IGG)
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