Isolation and characterization of Borrelia burgdorferi from Illinois Ixodes dammini

Ixodes dammini ticks from two northwestern Illinois sites were found to be infected with Borrelia burgdorferi at rates of 19 and 32%. B. burgdorferi isolates, one from each site, had protein and antigenic patterns similar to those of the B-31 strain. An indirect immunofluorescence method proved to be more sensitive than dark-field microscopy in detection of these spirochetes. A modified BSK medium containing rifampin was found to be more efficient for spirochete isolation than unsupplemented BSK medium.