Fever occurs in almost all cases. In contrast to Lyme disease, rashes are uncommon (less than 10% of cases). Symptoms may include severe systemic symptoms of fatigue, myalgia, chills, and nausea. Patients are often more acutely ill and likely to require hospitalization than with Lyme disease. In more severe disease or in elderly or immunocompromised patients, meningoencephalitis, headache, or cognitive impairment can predominate. While the fever of B miyamotoi disease can wax and wane, there is not an acute presentation as in true relapsing fever disease due to B recurrentis or B hermsii.
Laboratory findings include leukopenia, thrombocytopenia and elevated liver biochemical tests. If available, PCR of blood or CSF samples drawn during acute disease is recommended to detect B miyamotoi; negative results do not necessarily rule out B miyamotoi disease because laboratories may vary in expertise. 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 (EIA followed by immunoblot), the EIA may be positive in B miyamotoi disease due to cross-reactivity but the confirmatory immunoblot will be negative. This may be an indication that B miyamotoi, rather than B burgdorferi, is the causative pathogen. Further testing can then be done using a Glp-Q protein-based assay that 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. There is no definitive diagnostic algorithm, and infectious diseases consultation may be helpful in many cases.