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Diseases transmittable by blood - the other side of donation
| What are the most important diseases, transmittable by blood for which donor blood is tested? At the beginning of the 1940s, the reputation of blood transfusion was frequently in question due to infections that eventually led to inflammation of the liver. These were suspected to be caused by a virus. It soon turned out that liver disease occurred more frequently in patients who had received blood from remunerated donors or prisoners. For this reason, the decision was made to no longer call on these donor groups – a significant step towards safer blood. The next major step was made at the end of the 1960s, when the research team of Dr. Baruch S. Blumberg in Philadelphia, identified a special antigen in the blood of patients with ‘serum hepatitis’. Soon after this discovery, donor blood could be tested for the presence of the antigen, called HBsAg (hepatitis B surface antigen). However, liver infections had not yet been eradicated. Later on, other forms of hepatitis were discovered, which can nowadays be identified as well. At the start of the 1980s, the world was confronted with AIDS and HIV-contaminated blood products. The AIDS virus later proved to be very unstable outside the body and could, consequently, be easily inactivated. New technologies were developed with the specific aim to inactivate or remove viruses without affecting the biological activity of the vulnerable plasma proteins.
Hepatitis AIDS Syphilis Leukaemia Hepatitis Hepatitis is an inflammation of the liver, which may be accompanied by jaundice. There are many viruses that can cause hepatitis. These viruses are designated by consecutive letters of the alphabet: hepatitis A, hepatitis B, etc. Hepatitis A has been known for centuries and is caused by the hepatitis A virus (HAV), which is transmitted orally, for example by food or water contaminated with faeces. The virus was quite common in the Netherlands in the first half of the twentieth century, when hygienic conditions left a lot to be desired due to the aftermath of World Wars. After World War II, the number of cases decreased and is now minimal. Current cases of hepatitis A generally occur in patients who travel to countries in the tropics and make no use of protective measures. For this reason, HAV is also known as the cause of ‘travellers hepatitis’ (see the Immunoglobulins section in Plasma fractionation). The two most important hepatitis viruses that may be transmitted by blood are the hepatitis B virus (HBV) and the hepatitis C virus (HCV). As early as in the 1940s, it was discovered that one in 60 to 70 recipients of donor blood developed an inflammation of the liver of unknown origin. At the end of the 1960s, it was discovered that HBV (see illustration 28) caused jaundice. Epidemiologically, this virus clearly differed from the already identified HAV. Since the discovery of HBV, donor blood has been tested for this virus. However, some recipients of donor blood still developed inflammation of the liver. Since neither HAV nor HBV could be the cause, the responsible virus was called the ‘hepatitis non-A, non-B-virus’. In 1988, the pathogen was discovered and named the hepatitis C virus (HCV). In 1991, the first test to reveal HCV in donor blood was developed. Both HBV and HCV are transmitted primarily via contact between the blood of two persons, which means that it may also be transmitted from a mother to her unborn child. In addition, HBV can be transmitted by sexual contact. However, the sexual transmission of HCV is less common. Carriers of HBV or HCV are not necessarily ill. People with HCV mostly carry the virus their whole life, while HBV is removed in approximately 90% of those infected with this virus. Eventually, the liver of chronic carriers of these viruses can be permanently damaged. In recent years, other hepatitis viruses have been discovered, and have all been given consecutive letters of the alphabet. However to date, the relevance of these viruses for blood transfusion is negligible. Top AIDS Another important virus that can be transmitted by blood is the human immunodeficiency virus (HIV), which causes AIDS (Acquired Immune Deficiency Syndrome). Discovered in 1981, AIDS affects the immune system so powerfully that in the course of time the patient can no longer combat infections, including those caused by common opportunistic pathogens. The AIDS virus, HIV, was first isolated in May 1983. Nowadays, AIDS symptoms and viral replication can be treated with a combination of anti-viral drugs, but the virus cannot be eradicated, hence life long treatment is required. There are two types of HIV, namely HIV-1 (discovered in 1983) and HIV-2 (discovered in 1985). Each type is subdivided into various subtypes, based upon homology in genetic material. These subtypes, also called ‘clades’, are designated with a letter from the alphabet. The three primary HIV clades (B, C and E) are responsible for the three main epidemics in different areas of the world. The spread of the HIV clade 0 is very small and is limited to only one area in Africa. HIV-1 is rapidly spreading from various parts of the world (Africa, Europe, North and South America, Asia and Australia), while HIV-2 is slowly spreading in West Africa and also in India. These two types of viruses differ with regard to their manifestation, their manner of transmission, their activity and the area of prevalence. In 1985, the first test to reveal anti-HIV antibodies in blood became available. Since then, all donors are tested for these antibodies. If antibodies against HIV are found in the blood, it confirms that the individual in question has come into contact with HIV and is most likely infected. For this reason, his or her blood is regarded as infected and he or she is, of course, not permitted to donate blood. Fortunately, infection with HIV due to blood transfusion or administration of blood products was very limited in the Netherlands and there now remains only a very small risk. This is due to the adequate measures, implemented rapidly in response to scientific knowledge of HIV. This was unfortunately not the case in many other countries. Top Syphilis Donor blood is also tested for Treponema pallidum, a bacteria that belongs to the Spirochete group and causes syphilis. Treponema pallidum is almost exclusively transmitted by sexual contact, and therefore syphilis is regarded as a venereal disease. However, Treponema pallidum can also be transmitted by ‘fresh blood products’, such as red blood cells. However, the chance of this is small since Treponema pallidum survives very shortly at a temperature between 2°C and 6°C, which is the temperature at which blood cells are stored. Syphilis can be treated with antibiotics, after which the patient is no longer infectious. However post-recovery blood tests for syphilis can be unreliable and for this reason, sufferers from syphilis can no longer be blood donors. Top Leukaemia We also test donor blood for HTLV, which is an abbreviation of human T-cell leukaemia virus. There are two types of HTLV. Since 1993, we have tested donor blood for the presence of HTLV-I and, since January 1997, for HTLV-II. In principle, cellular blood products, including red blood cells, may transmit these viruses. People infected with HTLV will carry the virus throughout their life. A very small percentage (less than 1%) of these carriers actually become ill. These viruses can penetrate the leukocytes and cause these cells to divide indefinitely, leading to a rare form of leukaemia. Sometimes, several decades after infection, a spinal cord disease develops, accompanied by symptoms of paralysis. The HTLV virus is rare in the Netherlands. There is a greater risk of infection in Japan, tropical Africa, Central and South America and the Caribbean (Surinam and the Antilles). Top |