The IgG Borrelia miyamotoi test detects antibodies against Borrelia miyamotoi, a tick-borne bacterium closely related to Lyme disease pathogens but classified as a relapsing fever Borrelia species. Unlike Borrelia burgdorferi sensu lato (which causes classical Lyme disease), B. miyamotoi is associated with hard-tick relapsing fever (HTRF) and can cause recurring fever episodes, flu-like symptoms, and in some cases, neurological complications.
What IgG B. miyamotoi Means
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IgG antibodies usually develop weeks after infection and may remain detectable for months or years, even after symptoms resolve.
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A positive IgG result suggests past exposure or immune memory to B. miyamotoi.
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Because IgM reflects more recent infection, IgG testing provides insight into later or ongoing immune responses.
Clinical Importance
Testing for IgG Borrelia miyamotoi is particularly useful in patients with:
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Relapsing fever symptoms such as recurrent fever, chills, sweats, or fatigue
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Neurological complaints, including headache, meningitis-like symptoms, or confusion
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A history of tick exposure in areas where Lyme disease and relapsing fever Borrelia overlap (Europe, Asia, North America)
Patient Takeaway
A positive IgG B. miyamotoi result means your immune system has previously recognized this relapsing fever Borrelia. This does not always indicate an active infection, since IgG antibodies can persist after past exposure.
Your healthcare provider will interpret the result in combination with your symptoms, exposure history, and other Borrelia test results to determine next steps.
If your result is reported as equivocal (borderline), antibody levels are near the cutoff and the finding is uncertain. In this case, repeat or confirmatory testing may be recommended.
IgG B. miyamotoi
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