The effect of doxycycline on blood counts in patients infected with human granulocytic ehrlichiosis (HGE)

We reviewed records from 77 patients with IFA or PCR-confirmed HGE to study changes in blood counts during the period of acute illness as well as the influence of doxycycline towards restoring abnormal values. Mean values for WBC and Pit (x 10⁹/l), Hgb (g/dl), as well as the absolute concentration and relative (%) distribution of neutiophils and lymphocytes were calculated for each day before and after doxycycline therapy had begun. Pre-treatment days were labeled as negative days. The Mann-Whitney-test was used to compare independent variables, and p-values < 0.05 were considered significant. Doxycycline therapy was started 5.8 (SD 3.9) days (range 1-17) after onset of clinical symptoms. There was a progressive reduction in WBC (5.1 to 3.9; p = 0.089) and Pit (158 to 83 ;p = 0.21) between pre-treatmentday -5 and treatment day 1, while Hgb remained stable (12.8 -14.3; p = 0 70). By treatment day 5 the WBC and Plt counts had risen to 7.0 (p = 0.063) and 122 (p = 0.246), respectively, but Hgb values remained stationary (12.4 - 12.3). Between treatment days 1 and 4 neutrophil band forms decreased from 0.63 (22%) to 0.45 (9%; p = 0.374), while total neutrophils and lymphocytes increased from 1.93 (75%) to 3.06 (45%, p = 0.038) and 1.11 (20%) to 3.21 (55%, p = 0.007), respectively. All 77 patients had normal WBC and Pit values at treatment day 7 and normal Hbg values by treatment day 14.. WBC counts recovered more quickly than Plt counts. Marked relative lymphocytosis and disappearance of band forms were noted after 7 days of therapy. Doxycycline treatment leads to rapid resolution of pancytopenia observed in patients with acute HGE.