CUBN and tick-borne relapsing fever: Further examples of IGS sequence homology were found between spirochetes that cause louse-borne relapsing fever and those that cause tick-borne relapsing fever, in samples from 2 patients from Tanzania with tick-borne relapsing fever (Bd4 and Bd14) and also from 2 blood donors from Tanzania (Tz blood donor 6 and Tz blood donor 19); the isolates clustered among B. recurrentis type II.