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Transmission of West Nile Virus by Tissue and Body Fluids

West Nile virus apparently can be transmitted in body fluids; guidelines for breast-feeding and screening of donated blood products and organs may need revision.

There is little or no evidence to show that zoonotic infections can be transmitted through exchange of body fluids. Two recent reports indicate that mother's milk and blood products can transmit West Nile virus (WNV).

One report involves a 40-year-old woman who delivered a normal full-term baby. The mother required 2 units of packed red blood cells postpartum for anemia. From the 10th to the 12th day postpartum, the mother developed headache, fever to 102.8°F, and a peripheral white blood-cell count (WBC) of 2900 cells/mm³. Cerebrospinal fluid (CSF) examination showed an elevated WBC (134 cells/mm³) but normal CSF glucose and protein. The mother breast-fed her infant for 6 days following symptom onset. Although the child remained healthy, its serum tested positive for WNV IgM antibodies at 25 days postpartum. The donor's blood contained WNV RNA. The mother's CSF contained WNV-specific IgM, and her breast milk at 16 days postpartum tested positive for WNV RNA and for WNV-specific IgM and IgG. Culture of the breast milk is underway. It was RNA-negative at 24 days after transfusion, but a 1:400 dilution contained WNV-specific IgM.

The other report describes a 47-year-old man who received a liver transplant, 24 units of blood products at the time of transplant, and 15 units of platelets 1 week later. One unit of platelets came from the same donor reported in the first case. Twenty days after the transplant, the patient was readmitted with fever and encephalopathy. CSF findings included WNV-specific IgM and elevated WBC (with lymphocytic predominance) and protein.

Comment: These case reports strongly suggest that WNV can be transmitted through transfusion of blood products -- and, therefore, probably through organ transplantation -- and by breast-feeding. Until the breast-milk culture results become available, the evidence from the baby falls short of proof; however, the IgM levels in the infant are more consistent with response to infection than with passive transfer. No changes in blood-screening or breast-feeding recommendations are mandated yet, but future changes are likely.

— Stephen G. Baum, MD

Published in Journal Watch Infectious Diseases November 8, 2002

Citation(s):

Possible West Nile virus transmission to an infant through breast-feeding -- Michigan, 2002. MMWR Morb Mortal Wkly Rep 2002 Oct 4; 51:877-8.

• Medline abstract (Free)

Update: Investigations of West Nile virus infections in recipients of organ transplantation and blood transfusion -- Michigan, 2002. MMWR Morb Mortal Wkly Rep 2002 Oct 4; 51:879.

• Medline abstract (Free)