You may have noticed that each time you give blood samples are taken as well: these samples are used to complete some safety tests that are mandatory on every single blood donation whether this is your first donation or just one of the many you have given over the years. These tests play a very important role in ensuring a safe blood supply to patients, as they test for your blood group as well as infections that can be passed from donor to patient via a blood transfusion.
The tests that are conducted most often are the following:
Syphilis is caused by an organism called Treponema pallidum. Syphilis is usually a sexually transmitted disease which if untreated, can be serious. This disease is fully treatable with penicillin.
The tests we use look for antibodies, which can often be found in a person's blood long after the infection has gone. A positive test for syphilis usually relates to an infection in the past, but if the test is positive we are not able to use your blood.
Hepatitis B Virus (HBV):
This virus infects the liver; it can cause inflammation of the liver (hepatitis) and liver damage. Hepatitis B is very common in some parts of the world where it is often transmitted from mother to child at birth or in infancy. Most donors we identify have an association with those places and appear to have been infected since childhood or early life.
Our test looks for a substance called hepatitis B surface antigen, which is part of the 'coat' of the virus. If we find this substance in a donor's blood then further tests are performed to confirm the result. Most of the donors we identify are long - term carriers of the virus who feel completely well. Acute hepatitis B infection is uncommon in blood donors. Occasionally we get a positive result because the donor has recently had an immunization against hepatitis B and not because infection is present.
Human Immunodeficiency Virus (HIV):
This virus causes Acquired Immune Deficiency Syndrome (AIDS). Once an individual becomes infected with HIV then the virus remains in the body and eventually causes destruction of the immune system. It is mainly transmitted sexually, or from mother to baby, or by intravenous drug use. A person who has HIV does not necessarily have AIDS.
Our test looks for antibodies to the virus, but unlike many other infections the presence of the antibody shows that the virus is present, and not that the infection is in the past.
Hepatitis C Virus (HCV):
This virus infects the liver and can cause inflammation and liver damage. It is commonly transmitted by intravenous drug use. We have two kinds of test; a test for antibodies and a test for the virus. The test for virus is an extra safety test and can tell us whether a donor with antibodies is infected or not. Most of the donors we identify are long-term carriers of the virus who feel completely well.
Human T-Lymphotropic Virus (HTLV):
This virus infects white cells called T-lymphocytes, and can cause a neurological disorder called Tropical Spastic Paraparesis (or HTLV Associated Myelopathy) and Adult T cell Leukemia. It is relatively common in some populations and is thought to be transmitted mainly from mother to child at birth and by breast-feeding.
The test is for antibodies and a positive test means the individual is infected with the virus. Comparatively few infected individuals become ill and most carriers feel completely well.
These tests are not performed on every donation. Whether or not they are done depends on the donor's individual circumstances, in particular with reference to travel. Supplementary tests are also done to provide specifically tested blood for particular types of patient.
Malaria is caused by a parasitic infection transmitted by the bites of Anopheles mosquitoes. The infection causes fever and is a major cause of death in some parts of the world. The test is for antibodies to the malaria parasite. A positive result does not necessarily mean that the individual has active malaria, merely that they have had malaria at some time in the past. The antibodies can disappear over time, so donors with a positive malaria antibody test are not necessarily unable to give blood in the future.
This is a parasite called Trypanosoma cruzi. The parasite is found in certain parts of Central and South America and is transmitted to humans by biting insects or from mother to baby at the time of birth. Long-term carriers of the parasite are at risk of illness (also called Chagas Disease), due to destruction of the muscles in the heart and intestines.
Not all carriers become ill.
Our tests look for antibodies, to the infection. A donor's place of birth and travel history determines whether the test is required.
This is a very common virus which causes a mild 'flu-like' illness. Individuals in good health make a full recovery and are usually unaware of having been ill. We test for antibodies and a positive test indicates that the individual has had CMV infection and may still be carrying the virus. Having antibodies to CMV is of no significance to the health of the donor.
For those patients with a poor immune system, (bone marrow recipients or small babies) the presence of CMV in the blood given to them can cause a life-threatening illness. However, CMV positive blood is safe to give to other patients not at risk, so donors are not informed of a positive result.
Until recently if you had had skinpiercing of any kind, you had to wait 12 months before giving blood. We have now introduced an extra supplementary test that means that we can now take donations 6 months after skin-piercing.
The test looks for evidence of past hepatitis B infection. Donors with positive test results will probably have to stop donating. If you fall into this group we will give you more detailed specific advice depending on your individual results.
All laboratory tests can produce 'false alarms', the technical term for this is a 'false reaction'. This is a positive result (usually a weak reaction) in the screening test, which, on confirmatory testing is shown to be negative. False reactions are a recognized complication of all biological tests and are perfectly normal. They are of no significance for the health of the donor.