Borrelia hermsii

Borrelia hermsii is a spirochete bacterium representing the endemic causative agent of tick-borne relapsing fever in eastern regions of North America. 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.
Borrelia hermsii express a surface protein called FhbA. This protein evades the immune system by binding to FH and FHL-1, which are regulators of the complement system. This prevents the immune system from attacking bacteria. The FhbA is a surface-exposed lipoprotein that encodes for a single-genetic locus. It has a high affinity for binding to FH and recombinant FH. It has an important role in bacterial survival and therefore can be used for diagnosis- FhbA genes are mingled with majority of relapsing fever clade.