Observations on the Blood Cytology in Experimental Syphilis

Weekly observations were made on the blood cytology of seven syphilitic and nine normal control rabbits. Each animal was examined seven times prior to and fifteen times after inoculation of the experimental group. Comparisons were made between the mean blood cell values obtained from all counts on the experimental and control groups in the preinoculation and postinoculation periods. The mean blood cell formula of the syphilitic group for the 3(1/2) month period after inoculation was significantly different from the preinoculation mean values observed in the same group in the following respects: higher total white cell count, platelet count, neutrophil count, and monocyte count, and lower lymphocyte count. The mean blood cell formula of the syphilitic group for the 3(1/2) month period after inoculation was significantly different from the mean blood cell formula of the normal control group in the same time interval in the following respects: higher total white cell count, platelet count, neutrophil and monocyte counts, and lower lymphocyte count. From these results it was concluded that during the period of disease activity, the blood cytology of rabbits infected with Tr. pallidum is characterized by an increase in the total white cell count, the platelet, neutrophil, and monocyte counts, and a decrease in the lymphocyte count from normal values. These changes were statistically significant.