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Public Health Dispatch: Investigation of Blood Transfusion Recipients with West Nile Virus Infections

An investigation conducted by CDC, the Food and Drug Administration (FDA), the American Red Cross, and state health departments in Georgia and Florida has confirmed transmission of West Nile virus (WNV) from a single organ donor to four organ recipients (1). During treatment for injuries that eventually proved fatal, the organ donor received numerous transfusions of blood products. However, the source of the organ donor's infection remains unknown.

Subsequently, CDC has been informed of four other patients with WNV infection diagnosed after receiving units of blood in the weeks before WNV diagnosis. Because each of these patients resided in areas with high levels of WNV activity, the most likely mode of infection is mosquito exposure. To rule out blood transfusion-associated transmission, investigations are ongoing and efforts are under way to contact donors of blood given to these patients and other recipients of blood from these donors for follow-up and WNV testing. In each instance, precautionary measures have included a withdrawal of any remaining blood products obtained from the donors whose blood was given to these patients.

The investigations of the organ donor and four other transfusion recipient patients involve follow-up of approximately 100 donors. Initial testing by a quantitative polymerase chain reaction (PCR) assay (TaqMan®) of stored blood specimens obtained from the blood donors at the time of donation has been completed for two investigations. In one investigation, both donors tested negative for WNV. In the second investigation, in which specimens for 15 of 17 donors were available, specimens from three donors had evidence of WNV viral RNA, suggesting that these donors might have had WNV infection at the time of donation. In addition, plasma derived from a donation by one of these three donors also had evidence of WNV RNA. These results are preliminary because all of the specimens available for testing in both investigations were initially processed and stored as part of routine blood collection procedures, which could affect test validity. Therefore, additional follow-up testing and epidemiologic investigation of these donors are necessary.

In cases of suspected WNV meningitis or encephalitis in recent (e.g., <4 weeks before onset of illness) recipients of blood or organs, clinicians should contact local public health authorities to initiate an investigation. Serum or tissue samples should be retained for later studies.


  1. CDC. West Nile virus infection in organ donor and transplant recipients---Georgia and Florida, 2002. MMWR 2002;51:790.

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