Researchers in Georgia have reported the first probable case of transfusion-transmitted Ehrlichia ewingii, a tick-borne pathogen that typically resides in leukocytes. The case occurred in a 9-year old boy with a history of acute lymphoblastic leukemia and chemotherapy-induced anemia, who presented with fever, malaise, vomiting, diarrhea, and petechial rash. Antibiotic therapy was initiated, but the patient’s clinical status worsened. A transfusion-acquired infection was suspected because the patient had received multiple transfusions prior to experiencing symptoms. Laboratory analysis identified morulae in granulocytes on a peripheral blood smear, and subsequent PCR testing and sequence analysis confirmed that the patient was positive for E. ewingii. Trace-back investigations revealed that the leukoreduced irradiated single-donor platelets received by the patient had come from a donor who had been exposed to ticks. Further serologic testing found that this donor was positive for E. ewingii, with an IgG titer of 1/512. This case suggests that erhlichiosis can be transmitted through transfusion, and that leukoreduction and irradiation of blood products may not entirely eliminate the risk of transmission.
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