"It is caused by at least 15 spirochete species belonging to the genus Borrelia, and can be vectored to humans by either lice or ticks."
columbia-lyme.org/patients/tbd_relapsing.htmlIt has been connected to certain types of Borrelia species, such as Borrelia hermsii:
www.ncbi.nlm.nih.gov/pubmed/19624916And Borrelia recurrentis and B. duttonii:
www.ncbi.nlm.nih.gov/pubmed/16790790