LABORATORY FINDINGS IN COWS AFTER EXPERIMENTAL-INFECTION WITH EHRLICHIA-PHAGOCYTOPHILA

The goal of this study was to assess various hematological variables i n 10 cows after experimental infection with Ehrlichia phagocytophila. Blood samples were collected at regular intervals for examination of l eukocytes for Ehrlichia organisms and for determination of hematologic al and biochemical variables, In addition, PCR amplification was perfo rmed throughout the disease period on blood and milk samples for the d etection off. phagocytophila organisms, The time of seroconversion and the duration of serum titers indicating positivity were determined by indirect immunofluorescence. For all cows, E. phagocytophila organism s were first detected microscopically in leukocytes 5 to 8 days postin fection and could be demonstrated for a period of 6 to 14 days. For al l cows, the appearance of E. phagocytophila organisms in leukocytes co incided with transient erythropenia, leukopenia, and thrombocytopenia and a decrease in hematocrit and hemoglobin concentration, For five la ctating cows, E. phagocytophila organisms were identified in leukocyte s of milk samples during the acute phase of the disease, which, we bel ieve, has not previously been reported. E. phagocytophila DNA was dete cted in blood samples by nested PCR from 1 to 2 days before to 2 to 12 days after the organisms were identified microscopically. In milk sam ples, E. phagocytophila DNA was detected for an average of 11 days.