B. mayonii is a relatively new species of Lyme-causing pathogen that has only been detected in the Upper Midwest of the United States. It is considered a rare cause of Lyme disease and may frequently go undetected. 

Mayo Laboratories recently observed that spirochetes of the pathogen Borrelia mayonii can occasionally be visualized on routine blood smears, much like spirochetes of the Tick-Borne Relapsing Fever group. B. mayonii spirochetes are found at high levels in peripheral blood, whereas B. burgdorferi spirochetes are not. This understanding may raise awareness and recognition of the Lyme