Borrelia burgdorferi IgG Western Blot

What is Borrelia burgdorferi IgG Western Blot?

Confirms IgG antibodies to Borrelia burgdorferi as step two of two-tier Lyme testing, reflecting past or longer-standing exposure.

This Western blot identifies IgG antibodies against specific Borrelia burgdorferi proteins and serves as the confirmatory second step of CDC-recommended two-tier Lyme disease testing after a positive or equivocal screening ELISA. IgG antibodies generally develop later in infection and can persist for months to years, so this test relates most to longer-standing or past exposure rather than very recent infection. It is commonly ordered together with the IgM Western blot when symptoms have been present for several weeks or more, or when joint, neurological, or cardiac symptoms suggest later-stage disease. A positive result is interpreted alongside symptom timing and history, since antibodies can remain detectable long after an infection has resolved.

Tests often checked alongside this

• Borrelia burgdorferi Ab (Lyme ELISA) — the initial screening test this confirms
• Borrelia burgdorferi IgM Western Blot — considered together, especially for more recent exposure
• Anaplasma phagocytophilum Ab and Babesia microti Ab — possible co-infections from the same tick bite

How this can show up in how you look and feel

• May be associated with joint swelling or pain, particularly in the knees
• May be associated with neurological symptoms such as facial weakness or tingling
• May be associated with fatigue or, less commonly, heart rhythm changes in later-stage disease

What can affect this marker

• Timing of testing relative to the original tick bite or symptom onset
• Prior Lyme disease exposure, which can keep IgG antibodies detectable for years
• Immune status
• Lab-to-lab variability in Western blot band interpretation

What to track over time

• How this result relates to the initial ELISA and IgM Western blot findings
• Whether symptoms are improving, stable, or changing over time
• Whether the pattern of antibody bands is discussed by your healthcare provider in context
• Repeat testing is not typically needed to "confirm" continued positivity, since IgG can remain positive long-term

What to ask your doctor

• How does this IgG result fit with my ELISA and IgM results?
• Does this suggest a past infection, an ongoing one, or both?
• How do my current symptoms relate to this result?
• Is any additional evaluation needed given my symptom pattern?

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