Transmission of West Nile Virus Through a Hematopoietic Stem Cell Transplant

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Record number: 
Adverse Occurrence type: 
MPHO Type: 
Estimated frequency: 
Rarely described
Time to detection: 
11 days
Alerting signals, symptoms, evidence of occurrence: 
An 8-year-old boy diagnosed with high-risk acute myeloid leukemia underwent a haploidentical-donor HSCT. Eleven days after the HSCT, the patient developed fevers without other symptoms. Results of an infectious disease workup were negative except for low-level cytomegalovirus viremia, and his fever was presumed to be attributable to engraftment syndrome. Twenty one days after the transplant, the patient experienced an acute onset of slurred speech and progressive right-sided weakness. Magnetic resonance imaging (MRI) of his brain revealed signs consistent with possible viral encephalitis. Cerebrospinal fluid (CSF) tested negative for bacterial, viral, and fungal etiologies, including WNV antibody, and the results of viral, fungal, and bacterial cultures were negative. On day 22, neurological examination revealed a comatose state with hypertonicity in his upper extremities and hypotonicity in his lower extremities. Ophthalmological examination revealed liner chorioretinal lesions. On day 42, the results of CSF PCR were positive for WNV (525 WBC, 19 RBC, Glu 60mg/dL, protein 119 mg/dL). The patient received convalescent plasma on a compassionate basis but died after withdrawal of support on day 55.
Demonstration of imputability or root cause: 
Both the patient and the donor had not traveled in the year before the procedure. The donor was screened for infectious diseases 3 weeks before stem cell collection, and at that time, the results were negative for WNV IgM and IgG. Stem cell collection occurred within the standard 30-day period from donor screening. After the diagnosis of WNV encephalitis was made, the donor was retested, and the results were positive for WNV IgM and IgG antibodies, with no evidence of viremia by PCR testing. The timing of onset of fever in the recipient, i.e 11 days after transplant, coincides with the incubation period of WNV. Moreover, the patient had been hospitalized for 12 days before the transplant, which made exposure to mosquitos highly unlikely during that time period (October) but this cannot be excluded.
Imputability grade: 
2 Probable
Suggest new keywords: 
chorioretinitis; convalescent plasma;
Reference attachment: 
Suggest references: 
Kitagawa MG, Ettinger N, Breen D, Erklauer J, Chang E, Herce H, et al. Transmission of West Nile Virus Through a Hematopoietic Stem Cell Transplant. Journal of the Pediatric Infectious Diseases Society. 2018 May 15;7(2):e52-e4. Hiatt B, DesJardin L, Carter T, Gingrich R, Thompson C, de Magalhaes-Silverman M. A fatal case of West Nile virus infection in a bone marrow transplant recipient. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2003 Nov 1;37(9):e129-31.
Expert comments for publication: 
WNV infection has been described in recipients of bone marrow transplantation and has also been associated with transfusion of blood component to a stem cell recipient, but this case describes probable transmission via infectious bone marrow. Convalescent plasma infusion collected from the stem cell donor was also used but this did not alter the fatal outcome in this case.