Borrelia hermsii

Borrelia hermsii is a spirochete bacterium representing the endemic causative agent of tick-borne relapsing fever in eastern regions of North America (more specifically, the eastern United States, and British Columbia region of Canada). It is spread by the soft-bodied tick Ornithodoros hermsi. Human infections characteristically occur among campers and people temporarily lodging in wooden accommodations in proximity to rodents. Human disease is usually relatively mild with low fever.

Epidemiology
B. hermsii is endemic to regions of the U.S. with high elevation (whereas B. turicatae is endemic to low-lying regions such as Texas and Florida).