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This is not intended to infringe upon copyright, but to make
this information available to my readers in a more visually comfortable format.
DONOR SCREENING AND DEFERRAL
The Donation Process
Education
When prospective donors enter a blood bank, they are asked to read educational
materials such as the AABB pamphlet titled “An Important Message to All
Blood Donors.” These materials contain information on the risks of infectious
diseases transmitted by blood transfusion, including the signs and symptoms
of AIDS. Prospective donors are asked to acknowledge in writing that they
have read and understood these materials, have been given the opportunity
to ask questions, and have provided accurate information. The prospective
donors can elect to leave at this point without donating. (Self-deferral can
occur at any point in the donation process when a donor voluntarily chooses
not to complete the process.)
Health History
Prospective donors who do not self-defer, proceed to the next step –
giving a detailed health history. The history is designed to ask questions
that protect the health of both the donor and the recipient. To ensure that
every donor is asked the same questions, the AABB recommends use of a uniform
donor history questionnaire. However, donor centers often create their own
questionnaires using the same general guidelines. In addition to questions
about transfusion-transmissible diseases, prospective donors are asked questions
to determine whether donating blood might endanger their health. If a prospective
donor responds positively to any of these questions, he or she will be “deferred”
or asked not to donate blood. The health history also is used to identify
prospective donors who have been exposed to, or who may have diseases, such
as human immunodeficiency virus (HIV), hepatitis or malaria. These individuals
are further evaluated and those at high risk of disease are deferred.
Physical Examination
The next step in the donation process is an abbreviated physical
examination that includes checking the blood pressure, pulse and temperature.
A few drops of blood are taken from a finger to ensure that anemia is not
present. Abnormalities found in any part of the physical examination may be
a cause for deferral. Donors also must meet the weight requirement of 110
pounds.
The Actual Donation
A prospective donor who passes successfully through these steps
proceeds to the actual whole blood donation process, which takes about 20
minutes. The donor lies down or sits in a reclining chair. The skin covering
the inner part of the elbow joint is cleansed. A new, sterile needle connected
to plastic tubing and a blood bag is inserted into an arm vein. The donor
is asked to squeeze repeatedly his or her hand to help blood flow from the
vein into the blood bag. Typically, one unit of blood, roughly equivalent
to a pint, is collected. After the blood is collected, it is sent to the laboratory
for testing and component preparation. The donor is escorted to an observation
area for light refreshments and a brief rest period.
Adult males have about 12 pints of blood in their circulation and adult females
have about nine pints. The donor's body replenishes the fluid lost from donation
in about 24 hours. The red blood cells that are lost are generally replaced
in a few weeks. Whole blood can be donated once every eight weeks.
The Deferral Process
Individuals disqualified from donating blood are known as “deferred”
donors. A prospective donor may be deferred at any point during the collection
and testing process. Whether or not a person is deferred temporarily or permanently
will depend on the specific reason for disqualification (e.g., a person may
be deferred temporarily because of anemia, a condition that is usually reversible).
If a person is to be deferred, his or her name is entered into a list of deferred
donors maintained by the blood center, often known as the “deferral registry.”
If a deferred donor attempts to give blood before the end of the deferral
period, the donor will not be accepted for donation. Once the reason for the
original deferral no longer exists and the temporary deferral period has lapsed,
the donor may return to the blood bank and be reentered into the system.
TESTING OF DONOR BLOOD FOR INFECTIOUS DISEASE
The AABB and its members are committed to ensuring a safe blood supply for
everyone who may need transfusions. An important step in ensuring safety is
the screening of donated blood for infectious diseases. Today, nine tests
for infectious diseases are conducted on each unit of donated blood. Tests
for hepatitis B and syphilis were in place before 1985. Since then, tests
for human immunodeficiency virus (HIV-1 and HIV-2), human T-lymphotropic virus
(HTLV-I and II) and the hepatitis C virus (HCV) have been added. The following
tests are performed on each unit of blood:
Hepatitis B Surface Antigen (HBsAg)
The hepatitis B virus, which mainly infects the liver, has an inner
core and an outer envelope (the surface). The HBsAg test detects the outer
envelope identifying an individual infected with the hepatitis B virus. Hepatitis
B can cause inflammation of the liver, and in the earliest stage of the disease,
infected people may feel ill or even have yellow discoloration of the skin
or eyes, known as jaundice. Fortunately, most patients recover
completely and test negative for HBsAg within a few months after the illness.
A small percentage of people become chronic carriers of the virus, and in
these cases, the test may remain positive for years. Chronically infected
people can develop severe liver disease as time passes, and need to be followed
carefully by an experienced doctor.
Antibodies to the Hepatitis B Core (Anti-HBc)
The anti-HBc test detects an antibody to the hepatitis B virus
that is produced during and after infection. If an individual has a positive
anti-HBc test, but the HBsAg test is negative, it may mean that the person
once had hepatitis B, but has recovered from the infection. Of the individuals
with a positive test for anti-HBc, many have not been exposed to the hepatitis
B virus. This kind of test result is called a false positive,
and although the individual may be permanently deferred from donating blood,
it is unlikely that the person’s health will be negatively affected.
(Note: This antibody is not produced following vaccination against hepatitis
B. Hepatitis B vaccination, by itself, will rarely cause the HbsAg test to
be positive for a few days after the shots.)
Antibodies to the Hepatitis C Virus (Anti-HCV)
This test is used to screen donors for the hepatitis C virus (HCV).
It works by detecting antibodies manufactured by the body in reaction to portions
of the virus called antigens. HCV causes inflammation of the
liver, and up to 80 percent of those exposed to the virus develop chronic
infection. Eventually, up to 20 percent of people with HCV may develop cirrhosis
of the liver or other severe liver diseases. As in other forms of hepatitis,
individuals may be infected with the virus, but may not realize they are carriers
since they do not have any symptoms. Because of the risk of serious illness,
people with HCV need to be followed closely by a physician with experience
evaluating this infection.
Antibodies to the Human Immunodeficiency Virus,
Types 1 and 2 (Anti-HIV-1, -2)
This test is designed to detect antibodies directed against antigens
of the HIV-1 or HIV-2 viruses. HIV-1 is much more common in the United States,
while HIV-2 is prevalent in Western Africa. Donors are tested for both viruses
because both are transmitted by infected blood, and a few cases of HIV-2 have
been identified in US residents. Both of these viruses can cause acquired
immunodeficiency syndrome, or AIDS.
HIV-1 p24 Antigen
This test screens for antigens of the HIV-1 virus. The extra safety
added by doing this test derives from its ability to detect HIV-1 infection
a week earlier than the antibody test. Thus, the HIV-1 infection can be identified
sooner, and the risk of getting HIV-1 from a blood transfusion has decreased.
HIV-1 p24 antigen testing may be discontinued in the future when we know more
about the performance of a new kind of testing called nucleic acid amplification
testing or NAT (described below). The new tests are believed to identify HIV
infection even sooner than p24 testing, and it may make it unnecessary.
Antibodies to Human T-Lymphotropic Virus, Types
I and II (Anti-HTLV-I, -II)
This test screens for antibodies directed against portions of the
HTLV-I and HTLV-II viruses. Both of these viruses are relatively uncommon
in the United States, but do occur more frequently in certain populations.
HTLV-I is more common in Japan and the Caribbean. The infection can persist
for a lifetime, but rarely causes major illnesses in most people who are infected.
In rare instances, the virus may, after many years of infection, cause nervous
system disease or an unusual type of leukemia. HTLV-II infections are usually
associated with intravenous drug usage, especially among people who share
needles or syringes. Disease associations with HTLV-II have been hard to confirm,
but the virus may cause subtle abnormalities of immunity that lead to frequent
infections, or rare cases of neurological disease.
Syphilis
This test is done to detect evidence of infection with the spirochete
that causes syphilis. Blood centers began testing for this shortly after World
War II, when syphilis rates in the general population were much higher. The
risk of transmitting syphilis through a blood transfusion is exceedingly small
(no cases have been recognized in this country for many years) because the
infection is very rare in blood donors, and because the spirochete is fragile
and unlikely to survive blood storage conditions.
Nucleic Acid Amplification Testing (NAT)
NAT employs new forms of testing technology that directly detect
the genetic material of viruses like HCV and HIV. Because NAT detects the
genetic material of a virus, instead of waiting for the body’s response
— the formation of antibodies, as with many current tests — it offers
the opportunity to reduce the window period during which an infecting agent
is undetectable by traditional tests, thus further improving blood safety.
NAT has yet to be approved by the FDA for donor screening in the U.S. however,
because of the promise that this technology holds for improving the safety
of the blood supply, blood collection organizations are already using NAT
for HIV and HCV under the FDA’s Investigational New Drug (IND) application
process.
Confirmatory Testing
All of the above tests are referred to as screening tests,
and are designed to detect as many infections as possible. Because these tests
are so sensitive, some donors may have a false positive result, even if the
donor were never exposed to the particular infection. In order to sort out
true infections from false positive test results, screening tests that are
reactive may be followed up with more specific tests called confirmatory
tests. Thus, confirmatory tests help determine whether a donor is
truly infected.
If the test result from a donated unit of blood is abnormal for any of these
disease markers, the unit is discarded and the donor is notified. The donor’s
name is then added to a donor deferral list and is prohibited from donating
blood indefinitely.
TRANSFUSION-TRANSMITTED DISEASES: VIRUSES
Human Immunodeficiency Virus (HIV)
Transfusion transmission of HIV, the virus that causes AIDS, has
been almost completely eradicated, since blood banks began interviewing donors
about at-risk behaviors and a blood test became available in early 1985. The
HIV antibody tests, used on every blood donation since then, have undergone
continuous improvement, and in 1996 blood centers added yet another HIV test
called the HIV antigen assay (HIV-1). This new test makes the blood supply
even safer, because it can detect HIV about one week sooner than the antibody
test. Used in combination, these tests reduced the risk of getting HIV from
a single blood transfusion to between 1 in 450,000 and 1 in 660,000. Starting
in 1999 Nucleic acid amplification (NAT) testing has been used to directly
detect the genetic material of the HIV virus in blood, and current estimates
are that fewer than 1 in 1,900,000 blood components is capable of transmitting
HIV. Transfusion medicine specialists are continually researching new technologies
to further reduce the transmission of HIV. Examples of technologies on the
horizon include methods to kill viruses in donated blood (called viral inactivation)
and blood component substitutes.
Hepatitis
Hepatitis was the first documented transfusion-transmitted disease.
Many of the current practices for diminishing risk in transfusion medicine
are based on the experiences of controlling the transmission of hepatitis.
Hepatitis viruses, which infect the liver, fall primarily into two groups:
viruses with a chronic course that can readily be transmitted by blood transfusion
(hepatitis B and C) and viruses that cause only acute disease and are rarely
transmitted by transfusion (hepatitis A and E).
Hepatitis B Virus (HBV)
Transmission of hepatitis B virus (HBV) is rare because of routine
testing of blood for the HBsAg and hepatitis B core antibody, donor screening
and deferral for risk of HBV infection, and the use of only altruistic volunteer
blood donors. HBV is a major cause of acute and chronic hepatitis. Each year
in the US, an estimated 300,000 persons are infected with HBV. More than 10,000
patients require hospitalization, and an average of 350 die from the disease.
There is an estimated pool of 750,000–1,000,000 chronically infected
HBV carriers in the US. Approximately 25 percent of carriers have active hepatitis
that can progress to cirrhosis of the liver. An estimated 4,000 people die
each year from hepatitis B-related cirrhosis, and more than 800 die from hepatitis
B-related liver cancer. The number of HBV infections in the US is falling
because hepatitis B vaccinations of health care professionals and school-age
children has become nearly universal.
Screening blood donors for HBV began in 1969 and became mandatory in 1972.
By the mid-1970s, testing and an all-volunteer blood donor supply reduced
the rate of post-transfusion hepatitis B to between 0.3 and 0.9 percent. From
1982 to 1985, an average of 3.0 percent of hepatitis B cases in the US were
related to blood transfusion. During the period from 1986 to 1988, the percentage
of reported cases related to blood transfusion declined to 1.0 percent, possibly
as a consequence of the donor screening questions that were instituted to
identify persons at increased risk for HIV infection. In 2000, the frequency
of post-transfusion hepatitis B developing after a blood transfusion was estimated
at 1 in 137,000 screened units of blood.
Hepatitis C Virus (HCV)
Hepatitis C, formerly known as non-A, non-B hepatitis, was discovered
in the late 1980s, and all blood donations have been screened for it since
1990. Acute hepatitis C virus (HCV) is a relatively mild infection, and most
people are unaware they have become infected; however, HCV becomes chronic
in 80 percent of those infected. In the general population, 1.8 percent of
the population has some evidence of HCV-infection. While the rate of new HCV
infections is falling rapidly due to behavior changes and blood screening,
HCV is an important source of serious chronic liver disease, which often develops
decades after the initial exposure to the virus.
Antibody screening was started in 1990, and the test has undergone significant
improvement since. In 1999, NAT testing was added in the US. After more than
10 years of testing for HCV, the risk of HCV transmission through transfusion
is less than 1 per 1,000,000-screened units of blood.
Hepatitis A Virus (HAV)
Hepatitis A (HAV) infection is rarely transmitted through blood
transfusion; it is usually spread by contaminated food and water. About 23,000
cases are reported annually in the US, but epidemiologists estimate that the
virus infects 150,000 Americans each year. Hepatitis A is very prevalent in
the developing world, including Mexico and parts of the Caribbean. Because
HAV antibodies are present in approximately 20 percent of the population,
many with no history of hepatitis, it is assumed that many people experience
unrecognized infection. There have been occasional reports in the US of transfusion-transmitted
HAV, but little can be done to prevent this rare occurrence. A vaccine recently
developed for HAV has replaced immune globulin as a pre-exposure prophylactic
measure for people at a high risk for acquiring this infection, although the
latter remains useful after exposure.
Human T Lymphotropic Virus I, -II (HTLV-I, -II)
HTLV-I and -II are viruses that are not related to HIV. HTLV-I
is found mainly in Southwestern Japan and Caribbean islands. The virus can
cause blood or nervous system diseases in a small number of infected people
(less than 5 percent lifetime risk). HTLV-II is endemic in the Americas (including
the US), and also may infrequently cause nervous system disease or slightly
increased susceptibility to infections. Both of these viruses, although rare,
were found in the US blood donor population in the 1980s. Few people have
gotten HTLV as a result of transfusion, but because of the small transfusion
risk that existed in the 1980s, tests to detect HTLV-I antibodies were developed
and quickly implemented; these tests also detected many, but not all, HTLV-II
infections. Tests specifically designed to detect both viruses are now available
and are used by blood centers to screen every donation.
Cytomegalovirus (CMV)
Cytomegalovirus (CMV) is a virus belonging to the herpes
group that is rarely transmitted by blood transfusion. According to
the Centers for Disease Control and Prevention (CDC), about 50 to 85
percent of adults in the United States are infected with CMV by the
age of 40. CMV infection is usually mild, but it may be serious
or fatal in those who are immunocompromised. Particularly at risk are
low-birth weight infants and bone marrow and organ transplant patients.
If a patient is at high risk of getting CMV diseases, blood that tests
negative for CMV can be transfused. Alternatively, blood that has been
filtered to decrease the number of white blood cells — the cells
that carry CMV — will protect patients from getting a CMV infection
from transfusion.
TRANSFUSION-TRANSMITTED DISEASES: Parasitic
Infections
Malaria
Between 1958 and 1998, the CDC recorded 103 cases of transfusion-transmitted
malaria. These cases were most likely caused by donations from people who
felt well and were not aware that they were carrying malaria. Although exceedingly
rare, malaria can cause serious consequences, including fatalities. There
is no practical test available to screen donors so AABB requires blood centers
to temporarily defer blood donations from people who have visited malarial
areas in the past year or who emigrated from a malarial area within the past
three years.
Babesiosis
Babesiosis is a parasitic infection carried by the white-footed
mouse and transmitted by tick bites. It appears primarily in the northeastern
US, in coastal areas that are home to the white-footed mouse. Cases also have
been identified in the Upper Midwest and Pacific Northwest. About 30 transfusion-associated
cases have been reported in the US. While babesiosis is often quite mild,
some patients, including those without a spleen, the elderly, or the immunocompromised,
may be at risk of serious illness. There are no useful tests available for
screening blood donors, although testing strategies are being developed and
discussed. The AABB requires that all donors be asked if they have a history
of babesiosis. Those individuals with a history of the disease are permanently
deferred from donating blood.
Chagas’ Disease
A Brazilian doctor, Carlos Chagas, discovered Chagas’ disease
almost 100 years ago. This disease is caused by a parasite that infects as
many as 18 million people worldwide. Once infection is established, it is
lifelong. Each year, several thousand South and Central Americans die of heart
and digestive problems caused by the disease. Up to 20% of infected people
never exhibit symptoms. This infection is rare in the US, but because of recent
global population shifts, individuals from countries where this disease is
common now reside in the US. To date, there have been only five cases of transfusion-transmitted
Chagas’ disease reported in North America. The AABB requires that blood
centers permanently prohibit blood donation from anyone who has had Chagas’
disease, and tests are being developed and screening strategies discussed.
Lyme Disease
Although transfusion-related cases have not been reported, public
health agencies and the AABB are monitoring this disease because of the remote
chance that it could affect transfusion safety. Lyme disease is associated
with the bite of certain species of the deer tick, and can cause an illness
that affects many systems within the body. Donors with a history of Lyme disease
can donate, provided they have undergone a full course of antibiotic treatment
and no longer have any symptoms.
CREUTZFELDT-JAKOB DISEASE (CJD)
CJD is a rare degenerative and fatal nervous system disorder. It is
diagnosed in about one person per million per year in the US and worldwide.
There are three forms of CJD that can affect humans: sporadic CJD has
no known risk factors and accounts for 85 percent of CJD cases; hereditary
CJD occurs only in individuals with a family history of the disease
and/or tests positive for specific genetic mutations; and acquired CJD
is transmitted by exposure to brain or nervous system tissue. Acquired
CJD accounts for less than 1 percent of CJD cases and can occur in individuals
who have received injections of human pituitary gland growth hormone,
or who have had their brain’s outer lining (dura mater) repaired
with dura mater from someone else who had CJD.
Individuals who will develop CJD can remain without symptoms for decades
and then progress rapidly to dementia, severe loss of coordination and
death. Scientists believe abnormal brain proteins that have undergone
a peculiar shape change can cause other brain proteins to do the same
and cause CJD.
Currently, there is no screening test for the disease, and while blood
transfusions have never been shown to transmit any form of the disease,
as a precaution the Food and Drug Administration (FDA) prohibits blood
donation by individuals who may be at risk. These include potential
donors who have received injections of human-derived pituitary hormone,
those with a family history of CJD, or those who have had surgeries
that involved transplanted dura mater.
Variant Creutzfeldt-Jakob
disease (vCJD)
Similar to CJD, vCJD, commonly known as the human form of
“mad cow” disease, is a similar, rare degenerative and fatal
nervous system disorder. There is reason to believe that vCJD occurs
when humans eat beef contaminated with bovine spongiform encephalopathy
(BSE or “mad cow”). This new form of CJD has appeared only
in residents of the United Kingdom, France, and a single individual
in Hong Kong. There have been no cases of vCJD infection in humans or
of BSE in cattle in the US. Currently, there is no screening test in
humans for the disease.
Even though there is no evidence that vCJD has ever been transmitted
through a blood transfusion, the FDA, requires donor deferral policies
for anyone who potentially could have been exposed to the disease, by
eating contaminated beef products in areas of the world where BSE has
been found. These policies are changing as we learn more about vCJD
and BSE.
[SphynxCat's Note: vCJD has been reported
in deer and elk in various parts of the USA. Since this article was
written, there MAY be test methods available, but they may only be post-mortem
- after death - since the brain tissue needs to be analyzed.]
These current FDA recommendations will be put in place over
the next year (2003?).
The FDA recommends that the following donors
be deferred indefinitely due to vCJD risk:
Phase I
- Donors who spent a total of three months or more in the United
Kingdom (UK) from the beginning of 1980 through the end of 1996;
- Donors who have spent a total of five years or more in France
from 1980 to the present;
- Current or former US military personnel, civilian military employees
and their dependents who resided at US military bases in Northern
Europe (Germany, UK, Belgium, and the Netherlands) for a total of
six months or more from 1980 through 1990, or elsewhere in Europe
(Greece, Turkey, Spain, Portugal, and Italy) from 1980 through 1996.
Phase II
- Donors who have received any blood or blood component transfusions
in the UK between 1980 and the present;
- Whole blood, but not source plasma, donors, who have lived cumulatively
for five years or more in Europe from 1980 to the present, (which
includes the aforementioned deferral periods applied to the UK and
France). Unless deemed unsuitable for other reasons, these donors,
although deferred from whole blood collection, remain eligible to
serve as source plasma donors;
- Donors who have injected bovine insulin since 1980, unless it
is possible to obtain confirmation that the product was not manufactured
after 1980 from cattle in the UK.
Other organizations have slightly different
policies summarized here:
Department of Defense (DoD)
The DoD implemented its set of new donor deferral rules in October.
All active-duty military personnel, civil service employees, and
these two groups’ family members will be deferred indefinitely
due to vCJD risk if they are:
- Donors who traveled or resided in the UK for a cumulative total
of three months or more at any time from 1980 through the end of
1996;
- Donors who have received a blood transfusion in the UK at any
time from 1980 to the present;
- Donors who have traveled to or resided anywhere in Europe for
a cumulative total of six months or more at any time from 1980 through
the end of 1996;
- Donors who traveled to or resided anywhere in Europe for a cumulative
total of five years or more at any time from Jan. 1, 1997, to the
present.
American Red Cross (ARC)
The ARC implemented its set of new donor deferral rules in October
2001. All ARC donors will be deferred indefinitely due to vCJD risk
if they are:
- Donors who have lived in the UK for a cumulative total of three
months since 1980;
- Donors who have lived in any European country or a combination
of countries (including the UK) for a cumulative total of six months
since 1980;
- Donors who have received blood transfusions in the UK since 1980.
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