Cytomegalovirus (CMV)

A very common virus which causes a mild ‘flu-like’ illness. Individuals in good health make a full recovery and are usually unaware of the infection. We may test for antibodies against the virus. A positive test indicates that the individual has had CMV infection and may still have the virus. Having antibodies to CMV is of no significance to the health of the donor. However, for some patients with a poor immune system (particularly small babies), CMV can cause a life-threatening illness. CMV-positive blood is safe for most patients, and donors are not informed of a positive result.

Trypanosoma cruzi (T.cruzi)

Trypanosoma cruzi is a parasite (often abbreviated to T.cruzi), found in certain parts of Central and South America. It is transmitted to humans by biting insects or from mother to baby at the time of birth, or by blood transfusion. Over many years, the parasite can cause damage to the muscles in the heart and intestines, leading to an illness called Chagas disease. Not all infected people become ill. Our tests look for antibodies to the infection. A donor’s place of birth and travel history determine whether the test is required.


Caused by parasites which are transmitted by the bites of mosquitoes. The infection causes fever and is a major cause of death in some parts of the world. We test for antibodies to the malaria parasites. A confirmed positive result does not necessarily mean that the individual has active malaria, merely that they have had malaria at some time.


Caused by a bacterium called Treponema pallidum. This family of bacteria can also cause tropical diseases called Yaws and Pinta. Syphilis is usually a sexually transmitted infection which, if untreated, can cause serious disease. Yaws and Pinta cause skin and joint problems. All three diseases are fully treatable with antibiotics. The tests we use look for specific antibodies to the bacterium. These antibodies remain in a person’s blood many years after the infection has gone. A positive test for syphilis often relates to an infection in the past, but we are not able to use blood as long as the test is positive.

Hepatitis B virus (HBV)

One of several viruses that can cause inflammation of the liver (hepatitis), and sometimes liver damage. Hepatitis B is very common in many 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 these areas of the world and appear to have been infected since childhood or in early life. We do two tests for the virus; one looks for a marker called hepatitis B surface antigen, which is part of the ‘coat’ of the virus; and the second looks for the virus itself, targeting the virus nucleic acid. If we find surface antigen and/or the virus nucleic acid in a donor’s blood then further tests are performed to confirm the result. Many of the donors we identify have been infected with the virus for years and are completely well. Sometimes we find a donor with new (acute) hepatitis B infection. Most adults who get hepatitis B have a short illness and overcome the infection. Occasionally we get a positive result in our hepatitis B test because the donor has recently had an immunisation against hepatitis B and not because infection is present. In some circumstances, such as skin piercing, where there is extra risk of getting hepatitis B due to reusable needles, we carry out extra tests to see if you have ever had hepatitis B infection.

Human immunodeficiency virus (HIV)

If untreated, affects the immune system with the development of Acquired Immune Deficiency Syndrome (AIDS). The HIV virus is transmitted sexually, can be passed from mother to baby, and by intravenous drug use. Once an individual becomes infected with HIV, the virus remains in the body. A person who has HIV does not necessarily have AIDS. We perform two tests for the virus; one is a combination test that looks for both a protein in the virus coat and antibody to the virus; and a second that looks for the virus itself, targeting the virus nucleic acid. If either or both of the tests are reactive, further tests are done to confirm the result. Unlike many other infections the antibodies produced do not protect against the virus.

Hepatitis C virus (HCV)

Like hepatitis B, infects the liver and can cause inflammation and liver damage. The virus is commonly transmitted by needles, and thus may be associated with injecting drug use. Like HIV, HCV can persist in the body even when antibodies are present. We perform two tests for the virus, one that looks for antibody to the virus, and a second that looks for the virus itself, targeting the virus nucleic acid. If either or both of the tests are reactive, further tests are done to confirm the result. Like HIV, the antibodies produced do not protect against the virus. Many of the donors we identify have had the virus for years and feel completely well.

Hepatitis E Virus (HEV)

Both animals and humans can be infected. HEV infection usually causes no symptoms, if it does cause symptoms they are generally mild. Normally the virus infection will clear by itself. However, it is known that patients whose immune system is suppressed (eg chemotherapy or transplant patients) can have a more serious illness if they contract Hepatitis E. You will be informed if the virus is found in your donation.

Donors cannot donate until at least 6 months have passed since recovery from Hepatitis E infection.  Alternatively, if a blood test taken when a donor feels fully recovered shows clearance of the virus nuclei acid and the development of immune antibodies then they can donate again before this 6 month period.

Human T-lymphotropic virus (HTLV)

A virus which infects white cells called T-lymphocytes. Like HIV, the HTLV virus remains in the body once an individual is infected, even though antibodies develop. Most people who are infected with the virus are perfectly well and never have any illness. Occasionally, it can cause a neurological disorder called Tropical Spastic Paraparesis (or HTLV Associated Myelopathy) or a blood disease called Adult T-cell Leukaemia. These diseases are very rare.

The infection is found most commonly in people from Japan, the West Indies and parts of the Middle East. The virus is commonly transmitted from mother to child by breast feeding, but is also passed on by sexual contact or by intravenous drug use. We screen for antibodies against HTLV, and if the test is reactive further tests are performed to confirm the result.