Serial measurements of hematologic counts during the active phase of humangranulocytic ehrlichiosis

To describe the changes that occur in blood count parameters during the nat ural course of human granulocytic ehrlichiosis, we designed a retrospective cross-sectional case study of 144 patients with human granulocytic ehrlich iosis and matched controls who had a different acute febrile illness. Patie nts from New York State and the upper Midwest were evaluated from June 1990 through December 1998. Routine complete blood counts and manual differenti al leukocyte counts of peripheral blood were performed on blood samples tha t were collected during the active illness, and values were recorded until the day of treatment with an active antibiotic drug. Thrombocytopenia was o bserved more frequently than was leukopenia, and the risk of having ehrlich iosis varied inversely with the granulocyte count and the platelet count. P atients with ehrlichiosis displayed relative and absolute lymphopenia and h ad a significant increase in band neutrophil counts during the first week o f illness. Knowledge of characteristic complete blood count patterns that o ccur during active ehrlichiosis may help clinicians to identify patients wh o should be evaluated specifically for ehrlichiosis and who should receive empiric antibiotic treatment with doxycycline.