Thrombocytopenia is temporally correlated with spirochetemia. (A) 129Sv/C57BL6 mice were inoculated intraperitoneally with decreasing numbers of B hermsii DAH, as indicated. Spirochetemia (i-v) was measured by visually counting the number of spirochetes in the infected blood under dark-field microscopy, whereas platelet counts (vi-x) were determined by flow cytometry. The broken line indicates the detection limit for spirochetemia. (B) Mice inoculated intraperitoneally with 10⁶B hermsii DAH, spirochetemia, and thrombocytopenia were monitored as described.²⁸  Peaks of spirochetemia (labeled S1, S2, S3, and S4; top panel) were temporally associated with episodes of thrombocytopenia (labeled T1, T2, T3, and T4; bottom panel).