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Blood
Transfusion, Organ Donation and Blood Donation Screening Information
UPDATED!
The most
recent information on West
Nile Virus Screening of Blood Donations
and Transfusion-Associated Transmission is found in this update of the
MMWR Dispatch April 9, 2004.
Also, Detection
of West Nile Virus in Blood Donations---United States, 2003 is found
in the MMWR Dispatch September 18, 2003.
For
General Information about Screening of Blood Donations for WNV,
click here.
Update
on Detection of WNV in Blood Donations -- from MMWR, September
18, 2003
Q.
How many blood donations have been screening for WNV in 2003?
A. According to numbers reported to
CDC by blood collection agencies, approximately 2.5 million blood
donations have been screened for WNV since approximately July
2003.
Q.
How many potentially infectious blood donations have been identified?
A. State health departments have reported 489 WNV-viremic
donors (e.g. donors who were infected with West Nile virus without
any signs of illness at the time they donated blood) to CDC's
ArboNet surveillance system as of September 16, 2003.
Information
from blood collection agencies indicates that 601 viremic donations
have been identified, with additional testing underway for another
209 donations. Since each blood donation is separated into component
parts that may then be given to different recipients, the identification
and removal of these donations from the blood system represents
more than one thousand potential recipient infections have been
prevented.
Q.
Have any cases of blood transfusion-associated WNV infection occurred
in 2003?
A. Yes, two cases of blood transfusion-associated WNV infection
have been detected in the US in 2003, 1 in Texas and 1 in Nebraska.
Both persons were receiving care -- including blood transfusions
-- for other serious health conditions, they developed encephalitis
as a result of WNV infection and are recovering as of 9/16/2003.
These cases indicate that the risk of transfusion-related WNV
transmission has not been completely eliminated.
In
both 2003 cases of transfusion-associated transmission of WNV,
the WNV-contaminated blood donations that infected these persons
had screened negative during initial minipool testing. When the
donations comprising the minipools were tested individually during
a retrospective examination it was found that these two donations
contained very low levels of WNV.
Q.
What do these cases of transfusion-associated WNV infection mean
for the WNV testing of the blood supply?
A. These findings suggest a need to develop more sensitive
screening tests for use in minipool testing, or that individual
donation testing (instead of minipool testing) might be considered
in areas experiencing a high number of WNV infections, depending
on the testing capacity of the Blood Collection Agency. Currently
it is not feasible to test individually all blood donations made
in the United States, however individual donation testing is being
put into place at selected blood banks serving Kansas, Nebraska,
North Dakota Oklahoma and South Dakota. It is also important that
health care providers continue to investigate WNV illness in people
who have received blood transfusions and to report suspected transfusion-associated
cases to state health authorities.
Q.
What has been achieved through the efforts to screen the blood
supply? Has the program been a success?
A. The implementation of donor screening for WNV in 2003 has
reduced the risk of transfusion-associated WNV infection substantially
by removing hundreds of units of potentially infectious blood
products donated by asymptomatic donors. CDC will continue to
work with FDA, blood collection agencies and industry to identify
the best approaches to use in the future to ensure the safety
of the blood supply.
General
Information on Screening of Blood Donations for WNV
Q.
What is being done to reduce the risk of transfusion-related West
Nile virus transmission in 2003?
A.
In 2003, all blood banks are using blood screening tests for West
Nile virus. In addition, blood banks will not take donations from
people who have fever and headache in the week before they donate
blood. The screening tests is in place at all of the nation's
blood banks. State and local public health departments will report
cases of West Nile virus infection in patients who have received
blood transfusions in the 4 weeks before they got sick to the
blood collection agency that collected the donation and to CDC
from 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 agency will destroy potentially infectious
units of blood.
The new screening methods will allow blood banks to destroy potentially
infectious blood before it is given to anyone. To reduce the number
of donations from potentially infected people, blood banks will
refuse to accept blood from people with recent fever and headaches.
In addition, public health departments and blood banks will 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 will destroy
the blood products taken from the donor of the transfused blood.
Prompt reporting of these cases will help facilitate withdrawal
of potentially infected blood components.
CDC,
the Food and Drug Administration (FDA), and the Health Resources
and Services Administration (HRSA), blood collection agencies
and state and local health departments will continue to investigate
West Nile virus infections in people who receive blood transfusions
and transplanted organs to make sure these new screening methods
are working.
For more information on current efforts by the FDA see: http://www.fda.gov/cber/gdlns/wnvguid.htm
Q. Should people avoid donating blood?
A. No. There is no risk of West Nile virus infection for people
who give 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 you are fit to donate on a given day.
Q.
Should people avoid getting blood transfusions or organ transplants?
A. Roughly 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.
Q.
How can blood banks avoid collecting blood from donors who may
have West Nile virus?
A. On May 5, 2003, FDA issued guidance for blood banks that
describes methods to screen out potential blood donors who have
symptoms that suggest West Nile viral illness (i.e., headache,
fever) and to define blood product safety practices with regards
to West Nile virus (http://www.fda.gov/cber/gdlns/wnvguid.htm).
Because
most people who have West Nile virus infections do not have symptoms,
it may be difficult to identify them. To avoid this problem, blood
banks and their industry partners have developed tests to screen
the blood for West Nile virus. As of July 14, 2003, every blood
bank in the US is screening donated blood for WNV.
Q.
If a person had a West Nile virus infection in the past, can they
still donate blood?
A. 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. When they get
rid of the virus, they develop an antibody (a protein that helps
fight infections). Developing an antibody means that you are fighting
the infection. The antibody will keep them from getting a West
Nile virus infection again and will keep the virus out of their
blood.
Potential blood donors with a medical diagnosis of West Nile viral
illness that includes a compatible illness and laboratory results
should not be allowed to donate for at least 28 days from the
start of their symptoms OR until 14 days after they recover, whichever
date 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.
Q. If I recently had a transfusion or transplant, should I be
concerned about getting West Nile virus?
A. 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. A large number of West Nile virus infections due
to mosquito bites occurred among people in the United States during
2002. Some of these people also received blood transfusions and/or
organ transplantations. If a patient who recently received a blood
transfusion or organ transplantation develops an infection, that
does not necessarily mean that the transfusion/transplantation
was the source of infection.
Q.
I have heard reports of donors with WNV infection being found
at blood banks, but they don't show up on the maps CDC provides.
Why?
A. CDC maps include people with WNV illness who are reported
to CDC by state health departments. Because people with fever
and headache in the week before donation are not allowed to donate
blood, the infections found by the blood banks are from donors
without symptoms at the time of donation. As a result, they are
not considered "cases." Occasionally, a donor may develop
symptoms of WNV illness after donation. Then, the person would
be counted as a case by the health department and reported to
CDC.
It
is important to know that screening tests used at blood collection
centers are very new, and a much additional testing will be needed
to confirm whether a blood donation is truly infected with WNV.
Although the blood donation is removed from the blood supply as
soon as the initial screening test shows that it could be infected,
it may take several more weeks to confirm the infection.
Q.
How can a person test positive for WNV infection at a blood bank,
but not be considered a "case" by CDC?
A. 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."
For
more information on human cases, disease surveillance, and a map
of cases, go to http://www.cdc.gov/ncidod/dvbid/westnile/surv&control.htm.
Q.
What kind of test is used to test donated blood?
A. 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 used to screen the blood supply were developed
quickly because they were based on tests previously developed
and used at CDC. The tests being used for the blood supply are
experimental test and they are being carefully evaluated by all
the agencies involved.
If
the experimental test is positive, the blood from this donation
is removed from the blood supply. To further evaluate these new
tests, further testing is done. In some cases, the screening test
result may be a "false positive" because the new test
is still being adjusted, and blood banks are taking a cautious
approach to avoid future WNV transmission by transfusion. For
more information, consult the FDA WNV Web page at http://www.fda.gov/oc/opacom/hottopics/westnile.html.
These
blood-screening tests are different than the 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.
Q.
What happens to the blood collected from donors that test positive
for WNV?
A. As soon as 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,
Q.
Is there enough blood to meet the needs of hospitals?
A. 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 even if a few uninfected
products are removed because of "false positive" tests.
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 you have symptoms consistent
with possible WNV infection (such as fever and headache) you will
be deferred from donating at that time but will be allowed to
donate again when you feel better.
Q.
If someone who is donating blood at the same time that I do tests
positive for WNV, can I catch it from them?
A. No. WNV is generally transmitted through the bite of
an infected mosquito. You cannot get infected with WNV from contact
with an infected person. For more information, see the Transmission
page.
Q.
If a blood bank does not use my blood because it tests positive
for WNV, does this mean I'm going to get sick?
A. 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. For more information,
visit the Transmission page.
Q.
Will the blood bank notify me if my blood tests positive for WNV?
A. 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.
Q.
What do I need to do if my blood tests positive for WNV?
A. 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.
Of
course if you do feel ill you should consult your health care
provider.
Q.
Can I get tested for WNV at my doctor's office with the new blood
test that blood banks are using?
A. No. The tests being used at blood banks are new and
not licensed by the FDA. These tests are being used only at blood
banks. This new type of testing was necessary because WNV tests
that look for antibodies (the proteins that are a response to
infection) cannot detect the actual virus in blood from very recently
infected individuals.
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.
Q.
Are all U.S. blood banks testing the blood they collect for WNV?
A. Yes. Most blood banks in the U.S. have been screening
blood since July 1, 2003 and as of July 14, 2003, CDC was informed
by the American Association of Blood Bankers that screening is
going on in every U.S. civilian blood bank, including Alaska and
Hawaii and Puerto Rico.
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