: A Comprehensive Review.

is an emerging tick-borne pathogen in the Northern Hemisphere and is the causative agent of disease (BMD). is vectored by the same hard-bodied ticks as Lyme disease , yet phylogenetically groups with relapsing fever and thus, has been uniquely labeled a hard tick-borne relapsing fever . Burgeoning research has uncovered new aspects of in human patients, nature, and the lab. Of particular interest are novel findings on disease pathology, prevalence, diagnostic methods, ecological maintenance, transmission, and genetic characteristics. Herein, we review recent literature on , discuss how findings adapt to current doctrines, and briefly consider what remains unknown about .