West Nile virus infection transmitted by granulocyte transfusion

To the editor:

Eleven cases of transfusion-transmitted West Nile virus (WNV) infection and associated illness have been reported from 9 blood donors since the introduction of minipool nucleic acid testing (MP-NAT) in 2003.^1-3  This number of breakthrough infections is against a background of more than 2800 cases of WNV infection identified in blood donors in the United States through 2010. No cases of transfusion-transmitted WNV have been reported following the transition to individual-donation NAT (ID-NAT) in locations experiencing WNV activity. However, even with the use of ID-NAT,^4,5  transfusion transmission is theoretically possible from blood units having low viral loads.¹  We report the first case of WNV infection acquired via apheresis granulocyte (granulocyte) transfusion.

A 25-year-old white woman with a history of precursor B-lymphoblastic leukemia was admitted on July 9, 2010, for postchemotherapy fever and found to be neutropenic. Escherichia coli–positive blood cultures were identified and antibiotic therapy initiated. Neutropenia persisted and Candida endocarditis developed. Antifungal therapy was initiated and daily granulocyte transfusions began on August 7. Infectious disease testing results obtained on August 10 revealed that the August 9 granulocyte collection was positive for WNV. On August 25, the patient developed sudden onset of confusion with extremity weakness. A lumbar puncture revealed no malignant cells. CSF was WNV-NAT– and IgM-positive. Intravenous immunoglobulin, hydration, and nutritional support were administered and the patient discharged. The patient was readmitted and died on November 6 from complications of sepsis secondary to febrile neutropenia.

The multi-time donor is a 45-year-old man who received dexamethasone before donation. He was asymptomatic at donation, but subsequently became ill on August 22 with fever, chills, severe fatigue, headache, joint and bone pain, tremor, rash, and difficulty thinking. He was hospitalized on August 26 for treatment of WNV meningitis. His symptoms were consistent with those reported in WNV-infected donors.⁶  He cleared his WNV infection and seroconverted at follow-up (Table 1).

Granulocytes must be transfused as soon as possible after collection and thus transfused before completion of infectious-disease testing.⁷  The collecting facility performed WNV ID-NAT from August 3 through October 11 because of WNV activity in the area, consistent with recommendations in the United States.³  The WNV infecting unit had a high viral load sufficient for detection by MP-NAT. Even though ID-NAT results are available sooner than those from MP-NAT, they were not available before the need for transfusion. The time required for generation of test results by any licensed screening test, including WNV NAT, prevents their availability before the need for transfusion of highly time-sensitive components. This case illustrates the need to evaluate the benefits of granulocyte transfusion for critically ill, neutropenic patients in the face of the rare possibility of WNV transmission during epidemic periods. Health care providers should be aware that granulocytes may transmit WNV, and thus health care providers should consider WNV as a potential cause of neurologic complications after granulocyte transfusion.