A transfusion transmitted infection (TTI) is a

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

, or other potential

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

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 ''Simian foamy virus'' (''SFV'') is a species of the genus ''Spumavirus'' that belongs to the family of ''Retroviridae''. It has been identified in a wide variety of primates, including prosimians, New World and Old World monkeys, as well as ap ...

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 The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause AIDS, acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the ...

(HIV) leads to the best known of the transfusion transmitted diseases,

acquired immune deficiency syndrome Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual ma ...

(AIDS). Blood that is processed into medications by

fractionation Fractionation is a separation process in which a certain quantity of a mixture (of gases, solids, liquids, enzymes, or isotopes, or a suspension) is divided during a phase transition, into a number of smaller quantities (fractions) in which the ...

is treated in a multi-step process called pathogen inactivation that is analogous to

pasteurization Pasteurization or pasteurisation is a process of food preservation in which packaged and non-packaged foods (such as milk and fruit juices) are treated with mild heat, usually to less than , to eliminate pathogens and extend shelf life. The ...

: it destroys most viruses and bacteria in the blood. Donors are still screened and tested.

Viruses

Many of these viruses are controlled through laboratory screening tests. These fall into three basic varieties: antibody tests,

nucleic acid tests A nucleic acid test (NAT) is a technique used to detect a particular nucleic acid sequence and thus usually to detect and identify a particular species or subspecies of organism, often a virus or bacterium that acts as a pathogen in blood, tiss ...

(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 Human sexual activity, human sexual practice or human sexual behaviour is the manner in which humans experience and express their Human sexuality, sexuality. People engage in a variety of sexual acts, ranging from activities done alone (e.g. ...

or by contact with blood, usually either drug use, accidental needle injuries among health care workers, unsterilized

tattoo A tattoo is a form of body modification made by inserting tattoo ink, dyes, and/or pigments, either indelible or temporary, into the dermis layer of the skin to form a design. Tattoo artists create these designs using several Process of tatt ...

and

body piercing Body piercing, which is 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, or where an implant could be inserted. The word ''piercing'' can refer to ...

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 usually includes: * Sex in exchange for money or drugs. *

Men who have sex with men Men who have sex with men (MSM) are male persons who engage in sexual activity with members of the same sex. The term was created in the 1990s by epidemiology, epidemiologists to study the spread of disease among all men who have sex with men, r ...

, the most

controversial Controversy is a state of prolonged public dispute or debate, usually concerning a matter of conflicting opinion or point of view. The word was coined from the Latin ''controversia'', as a composite of ''controversus'' – "turned in an opposite ...

criterion. * A recent history of

sexually transmitted disease Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs) and the older term venereal diseases, are infections that are spread by sexual activity, especially vaginal intercourse, anal sex, and oral ...

. * 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.

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

The virus that causes

AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual m ...

is the best known of the transfusion-transmitted infections because of high-profile cases such as

Ryan White Ryan Wayne White (December 6, 1971 – April 8, 1990) was an American teenager from Kokomo, Indiana, who became a national poster child for HIV/AIDS in the United States after his school barred him from attending classes following a diagn ...

, a

haemophiliac Haemophilia, or hemophilia (), is a mostly inherited genetic disorder that impairs the body's ability to make blood clots, a process needed to stop bleeding. This results in people bleeding for a longer time after an injury, easy bruising, ...

who was infected through

factor VIII Factor VIII (FVIII) is an essential blood-clotting protein, also known as anti-hemophilic factor (AHF). In humans, factor VIII is encoded by the ''F8'' gene. Defects in this gene result in hemophilia A, a recessive X-linked coagulation disorder. ...

, 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

. The standard test for HIV is an

enzyme immunoassay An enzyme immunoassay is any of several immunoassay methods that use an enzyme bound to an antigen or antibody. These may include: * Enzyme-linked immunosorbent assay The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analyti ...

test that reacts with

antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

to the virus. This test has a

window period In medicine, the window period for a test designed to detect a specific disease (particularly infectious disease) is the time between first infection and when the test can reliably detect that infection. In antibody-based testing, the 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 HIV tests are used to detect the presence of the human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS), in serum, saliva, or urine. Such tests may detect antibodies, antigens, or RNA. AIDS diag ...

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 is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

where

subtypes of HIV The subtypes of HIV include two major types, HIV type 1 (HIV-1) and HIV type 2 (HIV-2). HIV-1 is related to viruses found in chimpanzees and gorillas living in western Africa, while HIV-2 viruses are related to viruses found in the sooty mangabey, ...

that are not reliably detected on some tests are found, specifically HIV group O. People who have been in

prison A prison, also known as a jail, gaol (dated, standard English, Australian, and historically in Canada), penitentiary (American English and Canadian English), detention center (or detention centre outside the US), correction center, correc ...

for extended periods are also excluded for HIV risk.

Hepatitis A Hepatitis A is an infectious disease of the liver caused by ''Hepatovirus A'' (HAV); it is a type of viral hepatitis. Many cases have few or no symptoms, especially in the young. The time between infection and symptoms, in those who develop them ...

* 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 Hepatitis B is an infectious disease caused by the ''Hepatitis B virus'' (HBV) that affects the liver; it is a type of viral hepatitis. It can cause both acute and chronic infection. Many people have no symptoms during an initial infection. Fo ...

* 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.

Hepatitis C Hepatitis C is an infectious disease caused by the hepatitis C virus (HCV) that primarily affects the liver; it is a type of viral hepatitis. During the initial infection people often have mild or no symptoms. Occasionally a fever, dark urine, a ...

* Often silent infection * Most likely significant TTI in developed countries

Alanine transaminase Alanine transaminase (ALT) is a transaminase enzyme (). It is also called alanine aminotransferase (ALT or ALAT) and was formerly called serum glutamate-pyruvate transaminase or serum glutamic-pyruvic transaminase (SGPT) and was first character ...
(ALT)

* Used as a surrogate for other Hepatitis testing, losing favor now that HCV tests have improved

Human T-Lymphotropic Virus The human T-lymphotropic virus, human T-cell lymphotropic virus, or human T-cell leukemia-lymphoma virus (HTLV) family of viruses are a group of human retroviruses that are known to cause a type of cancer called adult T-cell leukemia/lymphoma and ...
(HTLV I/II)

* "HTLV III"

Cytomegalovirus ''Cytomegalovirus'' (''CMV'') (from ''cyto-'' 'cell' via Greek - 'container' + 'big, megalo-' + -''virus'' via Latin 'poison') is a genus of viruses in the order ''Herpesvirales'', in the family ''Herpesviridae'', in the subfamily ''Betaherpe ...
(CMV)

* Not relevant unless recipient's immune system is compromised (i.e. infants).

West Nile virus West Nile virus (WNV) is a single-stranded RNA virus that causes West Nile fever. It is a member of the family ''Flaviviridae'', from the genus ''Flavivirus'', which also contains the Zika virus, dengue virus, and yellow fever virus. The virus ...

* is

Japanese encephalitis Japanese encephalitis (JE) is an infection of the brain caused by the Japanese encephalitis virus (JEV). While most infections result in little or no symptoms, occasional inflammation of the brain occurs. In these cases, symptoms may include he ...

a possible TTI? * Pool vs. individual testing.

Simian foamy virus ''Simian foamy virus'' (''SFV'') is a species of the genus ''Spumavirus'' that belongs to the family of ''Retroviridae''. It has been identified in a wide variety of primates, including prosimians, New World and Old World monkeys, as well as ap ...
(SFV)

* Not known to cause disease, recent studies

SARS Severe acute respiratory syndrome (SARS) is a viral respiratory disease of zoonotic origin caused by the severe acute respiratory syndrome coronavirus (SARS-CoV or SARS-CoV-1), the first identified strain of the SARS coronavirus species, ''sever ...

* Donors screened * No demonstrated transmission, hypothetical risk * No resurgence of disease

Parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...
and specific
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

Malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...
(''Plasmodia spp.'')

* Tests exist, but they're not very good. * Endemic in many areas of the world. * Only relevant for

red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

transfusions.

Babesiosis Babesiosis or piroplasmosis is a malaria-like parasitic disease caused by infection with a eukaryotic parasite in the order Piroplasmida, typically a ''Babesia'' or ''Theileria'', in the phylum Apicomplexa. Human babesiosis transmission via ti ...

Babesia microti is transmitted by ixodes ticks and causes babesiosis. Transfusion-associated babesiosis has been documented.

Chagas disease Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects in the subfamily ''Triatominae'', known as "kissing bugs". The symptoms change over the cou ...

* New test in use

Leishmaniasis Leishmaniasis is a wide array of clinical manifestations caused by parasites of the trypanosome genus ''Leishmania''. It is generally spread through the bite of phlebotomine sandflies, ''Phlebotomus'' and ''Lutzomyia'', and occurs most freq ...

* Donors screened, problem for donors who have been to Iraq.

Syphilis Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, an ...

* Does not survive at refrigerated temperatures * Used as test for high-risk sexual behavior

Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the ''Borrelia'' bacterium, which is spread by ticks in the genus ''Ixodes''. The most common sign of infection is an expanding red rash, known as erythema migran ...

* No cases have been reported, but the CDC urges caution due to a theoretical risk.

Other bacteria

Skin flora

Bacteremia and platelets

* Testing * Part of the reason that platelet shelf life is so short

Variant Creutzfeldt–Jakob disease Variant Creutzfeldt–Jakob disease (vCJD), commonly referred to as "mad cow disease" or "human mad cow disease" to distinguish it from its BSE counterpart, is a fatal type of brain disease within the transmissible spongiform encephalopathy fa ...
(vCJD)

* "Mad Cow" * UK imported plasma for transfusion

References

External links

AABB list of TTIs. {{Transfusion medicine Transfusion medicine