Transfusion‐transmitted anaplasmosis from a leukoreduced platelet pool

BACKGROUND Human granulocytic anaplasmosis is an emerging tick‐borne illness. Anaplasma phagocytophilum resides intracellularly, can cause asymptomatic infection, and can survive blood component refrigeration conditions for at least 18 days. To date, eight cases of transfusion‐transmitted anaplasmosis (TTA) have been reported: seven attributed to red blood cell (RBC) units, five of which were prestorage leukoreduced using RBC leukoreduction filters, and one involving a process leukoreduced apheresis platelet (PLT) unit. Here, we report a case of TTA from a whole blood–derived PLT pool. STUDY DESIGN AND METHODS Donation segments from the 7 units of RBCs and two PLT pools transfused were examined. Fast protocol multiplex real‐time A. phagocytophilum polymerase chain reaction (PCR) and serologic testing for immunoglobulin (Ig)M and IgG antibodies to A. phagocytophilum by enzyme immunoassay were performed. RESULTS Transmission was confirmed by positive A. phagocytophilum PCR and serology in one of 16 donors and by positive PCR and seroconversion in the recipient. CONCLUSION This is the first confirmed case of TTA from a whole blood–derived PLT pool prepared from PLT concentrates leukoreduced by in‐line filtration of PLT‐rich plasma.