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West Nile Virus

Blood Transfusion Questions & Answers
September 01, 2002

This is an official CDC Health Update

Seven Questions and Answers:

Q-1. Is West Nile virus transmitted by blood transfusion?

A-1. To date, there are no documented instances where West Nile virus was transmitted through transfusion. However, the virus may be transiently present in the blood of those infected, so it is possible that this could occur.

Q-2. What is being done about this possibility?

A-2. On August 17 FDA issued an alert to blood banks and organizations to be vigilant in excluding individuals who may have early symptoms of West Nile virus from donating blood. In addition, the Food and Drug Administration and the Centers for Disease Control and Prevention have asked that blood banks and others report any cases where a blood recipient develops West Nile virus for investigation of whether transfusion could have been involved. Such an investigation is now being conducted by CDC to determine whether blood transfusion or donor organs may have been a source for the possible West Nile virus cases in the current transplant recipients.

Q-3. What else can be done to protect people against this possible threat?

A-3. In this case, even though a blood source is unproven at this time, as a precaution, to protect others, blood banks are recalling any remaining units of blood products from all donors whose blood was administered to the transplant donor. There is currently no validated blood test to screen donated blood. If it is shown that people without symptoms can transmit West Nile virus through donating blood, public health partners will work with others to help facilitate availability of such a test.

Q-4. Should people avoid donating blood or getting blood transfusions?

A-4. Blood is lifesaving and is currently in short supply. Donating blood is safe and we encourage blood donation now and in the future. For patients who need a blood transfusion, the benefits far outweigh any risks.

Q-5. How can blood banks avoid collecting blood from donors who may have West Nile virus?

A-5. Most people who have West Nile virus do not show symptoms making it difficult to defer them from donation. However, some individuals develop minor symptoms of fever and headache. Blood banks need to be vigilant to defer all of those who may have minor illnesses especially in areas where West Nile virus is most active.

Q-6. If a person has had West Nile virus, can they still donate blood?

A-6. With West Nile virus infection, the viremia usually is transient and people recover very quickly. Blood centers will take precautions to be sure that donors who have been diagnosed with West Nile virus have fully recovered before donating.

Q-7. If I recently had a transfusion, should I be concerned about getting West Nile virus?

A-7. There have been no cases where transmission by blood transfusion has been documented. Although, by natural routes, infection would probably be expected in 2-14 days, it is unknown what incubation period would be expected if transmission were transmitted by transfusion. If you have symptoms of West Nile virus or other concerns you should contact your physician.