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.

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.

Conclusions: 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.