EXPERIMENTAL-INFECTION WITH EHRLICHIA-PHAGOCYTOPHILA IN CATTLE

Twenty Norwegian Red cattle, aged 8-10 months were used. Ten animals w ere inoculated intravenously with 3 ml of a whole blood dimethyl sulph oxide stabilate of a bovine strain of Ebrlichia (Cytoecetes) phagocyto phila. The animals were observed on a daily basis for clinical symptom s and rectal temperatures were recorded daily for 36 days post inocula tion. Blood and serum samples were collected regularly during the obse rvation period. All infected animals developed fever of 2-4 days durat ion within a week. Six out of 10 animals had secondary temperature ris es of 1-2 days duration. Three animals showed swellings in the hind li mbs and a stiff gait. Compared with the control group, there was a 10% decrease in the mean haematocrit and a leukopenia that initially was due to a lymphopenia and later to a neutropenia. A monocytosis occurre d after the subsidence of the primary fever period. A thrombocytopenia occurred during the early phase of infection. Granulocytic inclusions were detected for 18-32 days. All infected animals developed antibodi es greater than or equal to 1:4096 to E. phagocytophila within 14 days post infection.