Borrelia miyamotoi Disease (BMD)

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

• Both transmitted by Ixodes ticks

• Commonly found in same regions

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

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

• Lyme disease without rash

• Human granulocytic anaplasmosis

• Babesiosis

• Ehrlichiosis

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

• However, these tests may also be positive for the Borrelia of relapsing fever

Paired acute and convalescent sera may be most useful for confirming the diagnosis in hindsight

Doxycycline 100 mg orally twice daily for 14 days

Ceftriaxone 2 g intravenously once daily for 2–4 weeks may be given for severe or CNS disease