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An emerging spirochetal disease caused by B miyamotoi subspecies, which are taxonomically closely related to Borrelia recurrentis and Borrelia hermsii, the pathogens of relapsing fever
Similarities between BMD and Lyme disease
Differences between BMD and Lyme disease
BMD: Peak months of risk to humans is later in summer to early fall because B miyamotoi can be vertically transmitted to larval Ixodes ticks
Lyme disease: Peak months of risk to humans is early summer because Borrelia burgdorferi is transmitted by the nymph or adult tick
Prevalence of B miyamotoi in the northern United States is 5% or less, compared to up to 30% for B burgdorferi
An additional contrast is that BMD may occur shortly after attachment of an infected tick, while Lyme disease risk is highest after 36–48 hours of attachment and feeding on a human host
Rodents and birds are reservoirs for B miyamotoi
Avoidance of tick exposure is best prevention
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Fever occurs in almost all cases
Fatigue, myalgia, chills, and nausea
Meningoencephalitis, headache or cognitive impairment can predominate in more severe disease or in elderly patients
Rashes are uncommon (< 10% of cases)
Differential diagnosis
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Leukopenia
Thrombocytopenia
Elevated liver biochemical tests
Polymerase chain reaction (PCR) of blood or cerebrospinal fluid (CSF) samples
When drawn during acute disease, may be helpful to detect B miyamotoi
Negative results do not necessarily rule out BMD
If PCR is not available, spirochetes may sometimes be visualized on a blood smear using Wright or Giemsa-stain or by darkfield microscopy of CSF
If using the recommended two step testing algorithm for B burgdorferi (enzyme immunoassay [EIA] followed by immunoblot), the EIA may be positive in BMD due to cross-reactivity but the confirmatory immunoblot will be negative
Glp-Q protein-based assay can distinguish between B burgdorferi and B miyamotoi
Paired acute and convalescent sera may be most useful for confirming the diagnosis in hindsight
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