The first case of imported Borrelia miyamotoi disease concurrent with Lyme disease.

Borrelia miyamotoi disease (BMD) is an emerging infectious disease caused by B. miyamotoi. Although BMD has been reported in the United States, Europe, and Japan, no case of imported BMD has been described in the world. Here, we report a 63-year-old American man living in Japan who presented with malaise, headache, myalgia, and arthralgia. We suspected Lyme disease because of his travel history to Minnesota and presence of erythema migrans. Serologic analysis supported our diagnosis, and doxycycline was administered for 14 days. However, we also suspected coinfection with BMD because of his fever, elevated liver function test results and his travel history. The patient was seropositive for the immunoglobulin M antibody to recombinant glycerophosphodiester phosphodiesterase, and was diagnosed with coinfection with BMD. This case suggests that BMD should be considered in febrile travelers returning from the Northeastern and Midwestern regions of the United States, and that BMD and Lyme disease coinfection should be considered to detect cases of imported BMD.