General Information on Screening of Blood Donations : Part 2

by CDC

(Page 3 of 3)

Is there enough blood to meet the needs of hospitals?

Although there is always an increased demand for blood products during summer months, only a relatively few units of blood will be removed from the blood supply.

Blood donations usually decrease in summer. Despite the recently identified problems with receiving infectious blood, it is still safe to donate blood. CDC encourages people who can donate to consider making a donation during summer months to help ensure adequate blood supplies for all who need them.

If someone who is donating blood at the same time that I do tests positive for WNV, can I catch it from them?

No. WNV is generally transmitted through the bite of an infected mosquito. You cannot get infected with WNV from contact with an infected person.

If a blood bank does not use my blood because it tests positive for WNV, does this mean I'm going to get sick?

Probably not. What this means is that you have WNV in your blood, so you have been recently bitten by an infected mosquito. Most infected people do not become ill at all and only a very small number develop West Nile fever or more serious disease. It is thought that you will have immunity from WNV for a long period after becoming infected, possibly for life.

Will the blood bank notify me if my blood tests positive for WNV?

Blood banks will contact donors who may have a WNV infection. A subsequent blood sample will be requested in order to help confirm the infection. We thank you in advance for your cooperation in protecting the national blood supply, and helping to validate the tests that are being used.

What do I need to do if my blood tests positive for WNV?

If you learn from a blood bank that your blood was likely infected with WNV you may be requested to give another blood sample to help confirm the infection.

Most WNV infections do not cause any symptoms, and do not require any medical attention. There is nothing in particular that you need to do because of the infection. It is also likely that you have antibodies to prevent you from getting sick with WNV in the future. If you were infected with WNV, this does tell you that there is a risk of infection in your area, and it is important for the rest of your family to protect themselves from mosquito bites.

Of course if you do feel ill you should consult your health care provider.

What kind of test is used to test donated blood?

During the 2002 WNV epidemic, the blood-banking industry, FDA, and CDC worked together closely to identify WNV transmission to humans through blood transfusion and organ donation. These screening tests identify whether West Nile virus is present in the blood. The tests being used for the blood supply are still being validated by all the agencies involved. If the test is positive, the blood from this donation is removed from the blood supply. To validate these new tests, further testing is done. In some cases, the screening test result may be a "false positive", and blood banks are taking a cautious approach to avoid future WNV transmission by transfusion.

These blood-screening tests are different than the already validated tests that are used to diagnose WNV infections among ill people who are not donors. Among people who are not donors, we use tests that identify antibodies (proteins in the blood that help fight infection) that are produced by the body in response to a WNV infection.

Can I get tested for WNV at my doctor's office with the blood test that blood banks are using?

No. The tests being used at blood banks are new and not licensed by the FDA for routine screening purposes. These tests are being used only at blood banks. If your health care provider suspects you may have WNV illness he/she can send a sample of your blood to a private laboratory or to the state health department for testing for antibodies.

Are all U.S. blood centers testing the blood they collect for WNV?

Yes. Screening is going on in every U.S. civilian blood center, including Alaska and Hawaii and Puerto Rico.

Guidance related to donated organs, and the use of screening and diagnostic tests for West Nile virus was issued January 9, 2004 and is posted on the website of the Organ Procurement and Transplantation Network.

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.