General Information on Screening of Blood Donations for WNV

by CDC

(Page 2 of 3)

What is being done to reduce the risk of transfusion-related West Nile virus transmission?

All blood banks in the United States have been screening blood donors and donations for West Nile virus since 2003.

State and local public health departments report cases of West Nile virus infection in patients who have received blood transfusions during the 4 weeks before they got sick to the blood collection agency that collected the donation. Health departments also report this information to CDC through ArboNET, the national database where information about cases of West Nile virus is kept. In addition, cases of West Nile virus infection in people who donated blood in the 2 weeks preceding illness onset should also be reported to CDC and blood collection agencies where the sick person donated blood. The blood collection agencies destroy potentially infectious units of blood.

How does the blood screening test protect people from WNV?

The blood screening methods allow blood banks to destroy potentially infectious blood before it is given to anyone.

In addition, public health departments and blood banks cooperate to identify and destroy blood products (if necessary) from donors who develop a West Nile viral illness after they give blood. If someone becomes ill after a transfusion, blood banks destroy the blood products taken from the donor of the transfused blood. Prompt reporting of these cases helps facilitate withdrawal of potentially infected blood components.

Should people avoid donating blood?

No. There is no risk of of being infected by West Nile virus through giving blood. Blood saves lives and is always needed, especially during the summer months. Because donating blood is safe, we encourage blood donation now and in the future. We also encourage all donors to truthfully answer the questions asked by the blood bank to make sure they are fit to donate on a given day.

Should people avoid getting blood transfusions or organ transplants?

No. About 4.5 million people receive blood or blood products annually. The benefits of receiving needed transfusions or transplants outweigh the potential risk for West Nile virus infection. However, doctors and their patients who need blood transfusions or organ transplants should be aware of the risk for West Nile virus infection.

If a person had a West Nile virus infection in the past, can they still donate blood?

Yes. West Nile virus infections do not last very long. The virus is in the blood for a very short time. People fight the virus and usually get rid of it in a few days. To get rid of the virus, they develop antibodies against it. Antibodies keep people from getting a West Nile virus infection again.

People who have been diagnosed with West Nile virus confirmed by positive laboratory testing should not be allowed to donate blood for 120 days from the start of their symptoms or their laboratory diagnosis, whichever is later. If there are no symptoms to suggest a West Nile virus illness, a positive West Nile virus antibody test result alone should not be grounds for refusing a blood donation.

If I recently had a transfusion or transplant, should I be concerned about getting West Nile virus?

You should be aware of the potential risk for West Nile virus infection and the need to monitor your health. If you have symptoms of West Nile virus or other concerns you should contact your physician. If a patient who recently received a blood transfusion or organ transplantation develops a West Nile virus infection, that does not necessarily mean that the transfusion/transplantation was the source of infection.

How can a person test positive for WNV infection at a blood bank, but not be considered a "case" by CDC?

A WNV "case" is a person who has become ill and been confirmed to have WNV infection. This infection might be either West Nile Fever, a mild illness with fever, or West Nile encephalitis or meningitis, more severe illnesses. Blood donors who do not become ill and do not develop symptoms are counted in a separate category because they are not considered "cases."

What happens to the blood collected from donors that test positive for WNV?

When a unit of blood is identified as possibly infected with WNV by initial screening, it is removed from the blood supply. If the confirmation process reveals that the unit is NOT actually infected, the remaining blood products may be used.

About the Author

www.cdc.gov
The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.