Transfusion transmitted infection
Encyclopedia
A Transfusion transmitted infection (TTI) is a virus
, parasite, or other potential pathogen
that can be transmitted in donated blood
through a transfusion
to a recipient. The term is usually limited to known pathogens, but also sometimes includes agents such as Simian foamy virus
which are not known to cause disease.
Preventing the spread of these diseases by blood transfusion is addressed in several ways. In many cases, the blood is tested for the pathogen, sometimes with several different methodologies. Donors of blood are also screened for signs and symptoms of disease and for activities that might put them at risk for infection. If a local supply is not safe, blood may be imported from other areas. Human immunodeficiency virus (HIV) leads to the best known of the transfusion transmitted diseases, acquired immune deficiency syndrome (AIDS).
Blood that is processed into medications by fractionation
is treated in a multi-step process called pathogen inactivation that is analogous to pasteurization
: it destroys most viruses and bacteria in the blood. Donors are still screened and tested.
Many of these viruses are controlled through laboratory screening tests. These fall into three basic varieties: antibody tests
, nucleic acid tests (NAT), and surrogate tests. Antibody tests look for the immune system's
response to the infection. Nucleic acid tests look for the genetic material of the virus itself. The third variety are tests that are not specific to the disease but look for other related conditions.
High risk activities for transfusion transmitted infections vary, and the amount of caution used for screening donors varies based on how dangerous the disease is. Most of the viral diseases are spread by either sexual contact
or by contact with blood, usually either drug use
, accidental needle
injuries among health care workers, unsterilized tattoo
and body piercing
equipment, or through a blood transfusion or transplant. Other vectors exist.
Whether a donor is considered to be at "too high" of a risk for a disease to be allowed to donate is sometimes controversial, especially for sexual contact. High risk sexual activity is defined in many different ways, but usually includes:
HIV
The virus that causes AIDS
is the best known of the transfusion-transmitted infections because of high profile cases such as Ryan White
, a hemophiliac who was infected through factor VIII
, a blood-derived medicine used to treat the disease. Another person who died of medically-acquired HIV/AIDS was Damon Courtenay, who died in 1991 due to a bad batch of factor VIII
.
The standard test for HIV is an enzyme immunoassay test that reacts with antibodies to the virus. This test has a window period
where a person will be infected but not yet have an immune response. Other tests are used to look for donors during this period, specifically the p24 antigen test and nucleic acid testing.
In addition to the general risk criteria for viruses, blood donors are sometimes excluded if they have lived in certain parts of Africa
where subtypes of HIV
that are not reliably detected on some tests are found, specifically HIV group O. People who have been in prison
for extended periods are also excluded for HIV risk.
Hepatitis A
Alanine transaminase
Cytomegalovirus
Malaria
Syphilis
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
, parasite, or other potential pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
that can be transmitted in donated blood
Blood donation
A blood donation occurs when a person voluntarily has blood drawn and used for transfusions or made into medications by a process called fractionation....
through a transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...
to a recipient. The term is usually limited to known pathogens, but also sometimes includes agents such as Simian foamy virus
Simian foamy virus
The simian foamy virus is a spumavirus closely related to the Human Immunodeficiency Virus, HIV, the virus that can lead to AIDS. Its discovery in primates has led to some speculation that HIV may have been spread to the human species in Africa through contact with blood from apes, monkeys, and...
which are not known to cause disease.
Preventing the spread of these diseases by blood transfusion is addressed in several ways. In many cases, the blood is tested for the pathogen, sometimes with several different methodologies. Donors of blood are also screened for signs and symptoms of disease and for activities that might put them at risk for infection. If a local supply is not safe, blood may be imported from other areas. Human immunodeficiency virus (HIV) leads to the best known of the transfusion transmitted diseases, acquired immune deficiency syndrome (AIDS).
Blood that is processed into medications by fractionation
Fractionation
See also: Fractionated spacecraftFractionation is a separation process in which a certain quantity of a mixture is divided up in a number of smaller quantities in which the composition changes according to a gradient. Fractions are collected based on differences in a specific property of the...
is treated in a multi-step process called pathogen inactivation that is analogous to pasteurization
Pasteurization
Pasteurization is a process of heating a food, usually liquid, to a specific temperature for a definite length of time, and then cooling it immediately. This process slows microbial growth in food...
: it destroys most viruses and bacteria in the blood. Donors are still screened and tested.
Viruses
The most common diseases transmitted in blood transfusions are viral infections.Many of these viruses are controlled through laboratory screening tests. These fall into three basic varieties: antibody tests
EIA
EIA may refer to:*Edmonton International Airport*EIA Multiport, a North American NTSC SCART connector*Electronic Industries Alliance , a US trade organization...
, nucleic acid tests (NAT), and surrogate tests. Antibody tests look for the immune system's
Adaptive immune system
The adaptive immune system is composed of highly specialized, systemic cells and processes that eliminate or prevent pathogenic growth. Thought to have arisen in the first jawed vertebrates, the adaptive or "specific" immune system is activated by the “non-specific” and evolutionarily older innate...
response to the infection. Nucleic acid tests look for the genetic material of the virus itself. The third variety are tests that are not specific to the disease but look for other related conditions.
High risk activities for transfusion transmitted infections vary, and the amount of caution used for screening donors varies based on how dangerous the disease is. Most of the viral diseases are spread by either sexual contact
Sex
In biology, sex is a process of combining and mixing genetic traits, often resulting in the specialization of organisms into a male or female variety . Sexual reproduction involves combining specialized cells to form offspring that inherit traits from both parents...
or by contact with blood, usually either drug use
Recreational drug use
Recreational drug use is the use of a drug, usually psychoactive, with the intention of creating or enhancing recreational experience. Such use is controversial, however, often being considered to be also drug abuse, and it is often illegal...
, accidental needle
Hypodermic needle
A hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it...
injuries among health care workers, unsterilized tattoo
Tattoo
A tattoo is made by inserting indelible ink into the dermis layer of the skin to change the pigment. Tattoos on humans are a type of body modification, and tattoos on other animals are most commonly used for identification purposes...
and body piercing
Body piercing
Body piercing, a form of body modification, is the practice of puncturing or cutting a part of the human body, creating an opening in which jewelry may be worn. The word piercing can refer to the act or practice of body piercing, or to an opening in the body created by this act or practice...
equipment, or through a blood transfusion or transplant. Other vectors exist.
Whether a donor is considered to be at "too high" of a risk for a disease to be allowed to donate is sometimes controversial, especially for sexual contact. High risk sexual activity is defined in many different ways, but usually includes:
- Sex in exchangeProstitutionProstitution is the act or practice of providing sexual services to another person in return for payment. The person who receives payment for sexual services is called a prostitute and the person who receives such services is known by a multitude of terms, including a "john". Prostitution is one of...
for money or drugs. - Men who have sex with menMen who have sex with menMen who have sex with men are male persons who engage in sexual activity with members of the same sex, regardless of how they identify themselves; many men choose not to accept sexual identities of homosexual or bisexual...
, the most controversialMSM blood donor controversyThe Men who have sex with men blood donor controversy is a dispute over prohibitions on donations of blood or tissue for transplantation. MSM is a classification of men who engage in sex with other men, regardless of whether they identify themselves as homosexual, bisexual or heterosexual...
criterion. - A recent history of sexually transmitted diseaseSexually transmitted diseaseSexually transmitted disease , also known as a sexually transmitted infection or venereal disease , is an illness that has a significant probability of transmission between humans by means of human sexual behavior, including vaginal intercourse, oral sex, and anal sex...
. - Sex with a person who has had a positive test or was at high risk for a disease that can be spread in blood transfusions.
HIVHIVHuman immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
The virus that causes AIDSAIDS
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...
is the best known of the transfusion-transmitted infections because of high profile cases such as Ryan White
Ryan White
Ryan Wayne White was an American teenager from Kokomo, Indiana, who became a national poster child for HIV/AIDS in the United States, after being expelled from middle school because of his infection. A hemophiliac, he became infected with HIV from a contaminated blood treatment and, when diagnosed...
, a hemophiliac who was infected through factor VIII
Factor VIII
Factor VIII is an essential blood clotting factor also known as anti-hemophilic factor . In humans, Factor VIII is encoded by the F8 gene...
, a blood-derived medicine used to treat the disease. Another person who died of medically-acquired HIV/AIDS was Damon Courtenay, who died in 1991 due to a bad batch of factor VIII
Factor VIII
Factor VIII is an essential blood clotting factor also known as anti-hemophilic factor . In humans, Factor VIII is encoded by the F8 gene...
.
The standard test for HIV is an enzyme immunoassay test that reacts with antibodies to the virus. This test has a window period
Window period
In medicine, the window period for a test designed to detect a specific disease is the time between first infection and when the test can reliably detect that infection...
where a person will be infected but not yet have an immune response. Other tests are used to look for donors during this period, specifically the p24 antigen test and nucleic acid testing.
In addition to the general risk criteria for viruses, blood donors are sometimes excluded if they have lived in certain parts of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
where subtypes of HIV
Subtypes of HIV
One of the obstacles to treatment of the human immunodeficiency virus is its high genetic variability. HIV can be divided into two major types, HIV type 1 and HIV type 2 . HIV-1 is related to viruses found in chimpanzees and gorillas living in western Africa, while HIV-2 viruses are related to...
that are not reliably detected on some tests are found, specifically HIV group O. People who have been in prison
Prison
A prison is a place in which people are physically confined and, usually, deprived of a range of personal freedoms. Imprisonment or incarceration is a legal penalty that may be imposed by the state for the commission of a crime...
for extended periods are also excluded for HIV risk.
Hepatitis AHepatitis AHepatitis A is an acute infectious disease of the liver caused by the hepatitis A virus , an RNA virus, usually spread the fecal-oral route; transmitted person-to-person by ingestion of contaminated food or water or through direct contact with an infectious person...
- Not a major concern, viremic donors are often obviously ill, not a chronic disease.
- Recipients of blood-derived clotting factor concentrates have become ill with Hepatitis A, but there are no documented cases of the disease being transmitted in transfused blood.
Hepatitis B
- The first virus routinely screened in blood donations.
- Delta agent not screened for, since it is a superinfection of Hepatitis B and cannot exist alone.
Alanine transaminaseAlanine transaminaseAlanine transaminase or ALT is a transaminase enzyme . It is also called serum glutamic pyruvic transaminase or alanine aminotransferase ....
(ALT)
- Used as a surrogate for other Hepatitis testing, losing favor now that HCV tests have improved
CytomegalovirusCytomegalovirusCytomegalovirus is a viral genus of the viral group known as Herpesviridae or herpesviruses. It is typically abbreviated as CMV: The species that infects humans is commonly known as human CMV or human herpesvirus-5 , and is the most studied of all cytomegaloviruses...
(CMV)
- Not relevant unless recipient's immune system is compromised (i.e. infants).
SARS
- Donors screened
- No demonstrated transmission, hypothetical risk
- No resurgence of disease
MalariaMalariaMalaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
(Plasmodia spp.)
- Tests exist, but they're not very good.
- Endemic in many areas of the world.
- Only relevant for red blood cellRed blood cellRed blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
transfusions.
SyphilisSyphilisSyphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...
- Does not survive at refrigerated temperatures
- Used as test for high risk sexual behavior
External links
- http://www.aabb.org/Content/About_Blood/Facts_About_Blood_and_Blood_Banking/fabloodtrans.htm AABBAABBThe AABB is a United States-based professional body and standards organization that was founded in 1947 as the American Association of Blood Banks. The organization is now international with members in 80 countries and has taken on a broader scope to include all of transfusion medicine as well as...
list of TTIs.