EXPERIMENTAL BORRELIA-BURGDORFERI INFECTIONS IN THE WHITE-FOOTED MOUSE, DEER MOUSE, AND FULVOUS HARVEST MOUSE DETECTED BY NEEDLE ASPIRATIONOF SPIROCHETES

Three methods were tested for recovering Borrelia burgdorferi from liv e mice onto BSK II culture medium. Four laboratory-reared Peromyscus l eucopus were inoculated intraperitoneally with the JD-1 isolate of Bor relia burgdorferi. Borrelia burgdorferi spirochetes were recovered fro m 13 of 20 (65%) samples taken by needle aspiration between days 7 and 40 post-inoculation (PI) and from 1 of 16 samples of skin obtained by ear punch biopsy during the same sampling period. Spirochetes were no t recovered from culture media inoculated with mouse blood. The use of needle aspirates for recovering spirochetes was compared among three species of mice: P. leucopus, P. maniculatus, and Reithrodontomys fulv escens. Spirochetes were isolated from 14 of 15 aspiration samples fro m four P. maniculatus, 12 of 20 from three P. leucopus, and 15 of 20 f rom four R. fulvescens taken between days 7 and 48 PI. Spirochetes wer e isolated from only one aspiration sample between days 80 and 95 PI f rom any of the mice tested. Needle aspiration was an efficient method for repeated recovery of B. burgdorferi from live, experimentally infe cted mice. We also document R. fulvescens as an experimental host for B. burgdorferi. Based on their susceptibility to infection, all specie s of mice tested herein may play a role in the epidemiology of Lyme di sease where their distribution is compatable with endemic transmission .