The IgG Bartonella test measures antibodies against Bartonella species, a group of bacteria transmitted by ticks, fleas, or scratches from infected animals (especially cats). Bartonella henselae and Bartonella quintana are the most common human pathogens. Infection can lead to cat scratch disease, trench fever, or tick-borne bartonellosis, which may cause persistent systemic or neurological symptoms.
What IgG Bartonella Means
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IgG antibodies generally appear weeks after infection and can remain detectable for months or years.
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A positive IgG result usually indicates past exposure or immune memory rather than an active infection.
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Because IgM antibodies reflect recent or acute infection, IgG testing is more useful for identifying later or chronic immune responses.
Clinical Importance
Testing for IgG Bartonella can be useful in patients with:
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Persistent fatigue, fever, or swollen lymph nodes
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Neurological complaints such as headaches, neuropathy, or cognitive issues
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Joint or muscle pain that overlaps with other tick-borne illnesses
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A history of tick bites, cat exposure, or flea bites in areas where Bartonella is present
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Suspected co-infections, since Bartonella is often found alongside Lyme disease and Babesia
Patient Takeaway
A positive IgG Bartonella result means your immune system has previously recognized Bartonella, suggesting prior exposure or infection. However, IgG alone does not confirm whether the infection is still active, as antibodies may persist long after initial illness.
Your healthcare provider will interpret the result alongside your symptoms, medical history, and other diagnostic tests (such as IgM, PCR, or culture-based methods).
If the result is equivocal (borderline), antibody levels are close to the cutoff and not clearly positive or negative. In these cases, repeat or confirmatory testing is usually recommended.
IgG Bartonella
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