In a previous publication we (1) showed that the serum of rats solidly hyperimmunized to Borrelia novyi contained lytic bodies for the Texas relapsing fever spirochete. The serum of rats similarly hyperimmunized to strains of the Texas spirochete was shown to be lytic for Borrelia novyi. Since this cytolytic property was not observed in these sera for other strains of relapsing fever spirochetes, Borrelia kochi, Borrelia duttoni, and Borrelia obermeieri, we concluded that the Texas relapsing fever spirochete is closely related to, if not identical with, Borrelia novyi.
Brumpt (2) has recently shown that a strict specificity exists between the vector of relapsing fever in Texas, O. turicata, and the spirochete causing the disease. He found that this particular tick did not transmit other known strains of relapsing fever spirochetes, and, for that matter, that there was a similar degree of specificity between other vectors and spirochetes as they occur in different localities.