Blood: Donations, transfusions and HIV
Blood transfusions are essential treatment for excessive blood loss and for diseases such as haemophilia. If a person receives a blood transfusion with HIV-infected blood, there is a 95 percent risk they will become infected with the virus.4 However the chances of becoming infected with HIV through a blood transfusion varies between countries depending on the level of safety precautions in place, and there is a notable difference between developed and developing countries. In the UK, the risk is now 1 in 5 million. 5
The first tests for HIV in donor blood were not implemented in countries until 1985, four years after the first case of AIDS was reported. Between 1985 and 1992, the United States, France and Romania had the highest number of AIDS diagnosis as a result of HIV infection through transfusion, with more than 8,000 people in the US believed to have acquired HIV through transfusion during this period.6
"HIV infection continues to be a risk associated with blood transfusions"
Haemophilia is a disease characterized by the deficiency of blood clotting factors in the blood. 7 This condition is treated through the frequent transfusion of blood products such as plasma, which contain platelets, and clotting factors, such as factor VIII.8 9 Thousands of haemophiliacs contracted HIV through receiving these life saving blood products during the late 1970s and 1980s a time when blood was pooled to extract the factor VIII and not screened or treated for HIV.10 11 Plasma is a blood product which can be heat treated and since heat treatment was implemented in 1985, plasma is now completely safe where this method is used.12
The World Health Organisation (WHO) outlines a number of recommendations which countries should follow to maintain a safe and constant blood supply. These steps prevent transfusion-transmissible infections (TTI), which include HIV-1, HIV-2, hepatitis B, hepatitis C and syphilis, passing from a blood donor to the recipient of a blood transfusion.13 According to the recommendations countries need:
- A nationally coordinated blood transfusion service
- Voluntary unpaid donors
- To test all donated blood
- To use blood efficiently and appropriately
- To ensure a safe transfusion practice
- To have a quality systems check throughout the blood transfusion process.
The roll-out of widespread safety measures such as donor selection and screening guidelines makes the risk of HIV transmission today virtually non-existent in developed countries.14 However, where guidelines for blood safety have not been implemented or are not followed, HIV infection continues to be a risk associated with blood transfusions.
HIV and blood donors: Who can donate?
A key aspect of ensuring a safe blood supply is the screening and counselling of donors to limit the number of people infected with HIV from donating.
Voluntary, non-remunerated blood donors are those who donate on their own accord without coercion or incentives, such as money. In some countries, such as the UK, 100 percent of donations come from voluntary, non-remunerated donors. The recommendation by WHO to only use this type of donor was first made in 1975 in the form of the World Health Assembly resolution 28.72.15 These donors are sought after because they are more likely to be donating for altruistic reasons rather than for any personal gain.16 Injecting drug users are more at risk of HIV infection and often need money to fund their drug habit. If donating blood is seen as a source of income, individuals such as IDUs are more likely to donate and therefore risk the safety of blood supplies.
When an individual needs a donation and a family member steps forward to donate blood they are referred to as a 'family/replacement' donor. However, like paid donors, this type of donor often leads to higher number of HIV-infected blood donations. In many countries paid donors and family blood donors continue to make up a large percent of blood donations.17 For example, 70 percent of donations in Pakistan are from 'family and replacement' donors with a further 10 percent of donations from paid donors.18 The risk posed by these donors is illustrated by 2008 figures which show that 6.8 percent of IDUs in Pakistan admit to selling blood in return for money and in some provinces HIV prevalence in blood donations is more than 5 percent.19
The process of screening donors involves asking a series of questions about the donors' lifestyle to ensure individuals who participate in risky behavior, such as IDUs, or those who fall into a group which has a high-HIV prevalence, such as men who have sex with men, do not donate blood.20 21
The most recent reported case in the US of HIV being transmitted through transfusion occurred in 2008.22 This followed a six year period whereby there were no reported HIV transmissions through transfusion. HIV transmission occurred in this case, firstly because the routine donor (and therefore often considered the safest type of donor) answered incorrectly to questions about high-risk behaviour during the donor screening questionnaire and secondly, due to being recently infected the donor was in the window period (approximately 12 days when tests are unlikely to detect HIV) which resulted in the infected blood being used.
The importance of donors answering honestly to eligibility questionnaires is emphasised by this case. It was highlighted by the CDC that although the risk of HIV transmission through blood transfusion is extremely unlikely in the United States, it should not be ruled out as a possible route for HIV transmission.23
The debate: Men who have sex with men (MSM) donating blood
The ban on MSM from donating blood is currently enforced in many countries, such as the UK and the United States. The United States' ban was enacted in 1983 before testing of donor blood for HIV began, as more MSM were infected with HIV than other donor groups.
The United States policy bans any man who has had sex with a man since 1977 (which includes single encounters) from donating for life. However, the policy for heterosexuals is markedly different. For example, a heterosexual is deferred for only 12 months if they have sex with a man who has sex with men (if you are female), an injecting drug user, or a sex worker.24
"the ban is outdated and unscientific"
Banning MSM from giving blood has been a controversial issue for some time. Many argue that the ban is outdated and unscientific as many MSM are in long term relationships and practice safe sex but are banned for life, whereas heterosexuals who engage in risky behaviour are only banned for a year.25 26 27 28 29 Organisations such as the American Red Cross support a deferral rather than a lifetime ban for MSM.30 It is believed that a donor should be evaluated on the risk they pose by the behaviour they engage in, rather than the group they fall into.31 On these grounds it is argued that eligibility questions should be reviewed. The availability of nucleic acid tests (NAT), which reduces the window period and makes testing much more accurate, helped to support the argument for a change in the ban against MSM donating. These tests have been found to almost eliminate the possibility that HIV infected blood will pass through the testing stage, even in countries with high prevalence.32
In support of upholding the current policy, the Centre for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) identify that in the US, HIV prevalence in those MSM who are likely to donate is 15 times higher than the general population.33 34 FDA modelling illustrates the increase in risk by introducing a deferral period for MSM, like those used for individuals such as sex workers. A 12 month deferral will result in 1,600 more HIV infected units being donated, detection of which will rely on screening.35
Following a review in June 2010 the Advisory committee on Blood Safety and Availability decided to uphold the ban against MSM donating. They claimed that further scientific research was needed on this topic.36
How is blood tested for HIV?
Testing 'algorithms' are a sequence of specific tests, or assays, which are organised to create a certain HIV testing strategy.37 These must take into consideration the resources, infrastructure and staff expertise available in different countries so the specified algorithms are always followed, to ensure consistency in the testing of blood.38
Initial HIV testing uses antibody tests to detect antibodies to HIV in the blood. As the virus becomes established the body makes increasing amounts of antibodies. However, it can take between 3 weeks and 3 months after initial infection before an individual produces antibodies and HIV is detectable. This gap is known as the window period and blood donations infected with HIV screened with antibody tests at this time may not be detected.39
However, other tests exist to further reduce this window period, such as p24 antigen tests, which screen for proteins attached to the HIV infected cell and nucleic acid testing (NAT), which screen for the genetic material of HIV.40 These tests reduce the window period down to about 12 days. It is because these 12 days remain that donor screening and counselling is still important to further reduce the chance of a person infected with HIV giving blood.
The NAT test is particularly important where prevalence is high as the number of window period donations are more likely. However, HIV prevalence is often highest in poorer countries and unfortunately NAT tests are expensive and therefore these countries usually only have antibody tests. The chance that an HIV-infected donation will not be detected is therefore greater in these countries.
In 2009 blood screened for HIV in Greater Accra, Ghana amounted to 33,294 units of blood, of which 3.68 percent was found to be HIV positive. 41 Ghana tests 100 percent of its blood donations, however this is done using only antibody tests. Therefore the window period remains a significant interval, which suggests some units may continue to pass through screening undetected.
In October 2005, South Africa introduced NAT testing and as a result there were no cases of HIV transmission by blood transfusion reported to the haemovigilance programme, a transfusion surveillance system.42 43
During the testing process a screening policy, good laboratory practice and a quality assurance system should be in place to avoid any HIV positive samples passing undetected. 44 45 The WHO asserts this is reliant on the formulation and implementation of a national blood policy by a country's government.46
Do all countries test for HIV?
More than 85 million blood donations took place in 2007 across 162 countries, of which 41 lacked the resources to screen for transfusion-transmissible infections (TTIs).47 UNAIDS figures show only half of Pakistan's annual 1.5 million bags of transfused blood are screened48 and it is believed that 19 percent of new HIV infections in Pakistan are due to unsafe blood.49 50 Worryingly it is often countries with a high HIV prevalence that have inadequate screening programmes in place. In Tanzania, HIV prevalence is 5.7 percent and yet blood screening is extremely limited.51 For example, 2007 data shows only 125,000 of the 350,000 units of blood donated or 35.7 percent were screened for HIV and other TTIs.52
The situation in China during the early years of the epidemic highlights the need not only for voluntary, non-remunerated donors but also safe procedures for blood collection, testing and transfusion.53 Farmers from Henan province donated blood during the 1990s to collection sites where, to save money, the donors blood was pooled, the plasma extracted and then the remaining blood injected back into the donor.54 55 More than 100,000 farmers were infected with HIV in this way and unknowingly continued to donate infected blood, which was passed on through blood transfusion.
The importance of safe, sustainable blood supplies
Blood shortages can increase the risk of HIV transmission through blood transfusion as health authorities may become less stringent about the source of donated blood.56 57 This is especially problematic when screening is not in place and when HIV prevalence is high.
Acquiring 100% voluntary, non-remunerated donors is a challenge for many countries. For a country to maintain a sustainable blood supply only 1 to 3 percent of a country's population need to donate blood. However, 2007 figures show the donation rate in 73 countries, out of 162 surveyed, is less than 1 percent of the population.58
Blood donation rates are considerably less in developing countries when compared to transitional countries, which have a donation rate 3 times higher, and developed countries, which have a donation rate 13 times higher.59 For example, sub-Saharan Africa is home to 14 percent of the world's population, yet total blood donations are estimated to be 6.3 percent of the total global blood donations.60 61
Sometimes cultural factors may inhibit the success of blood programmes. For example in China, cultural beliefs are often the cause of blood shortages. In traditional Chinese culture the loss of blood is not only detrimental to your health but also a disloyal act against your ancestors.62 However, on the other hand it is also believed that receiving an unnecessary blood transfusion benefits your health and in many rural parts this practice is used as a 'health booster'.63 64 Inappropriate clinical use of blood, such as this, not only contributes to blood shortages, but in countries which do not test blood appropriately, can increase the risk of HIV infection.
Those most in need of safe blood and therefore most vulnerable from blood shortages and unscreened blood are pregnant women, children and haemophiliacs.65 66 A lack of safe blood in southern Africa accounts for an estimated 15 percent of anemia related child deaths67 68 and 44 percent of maternal deaths are due to hemorrhaging during pregnancy in sub-Saharan Africa.69 70
Attempts globally to meet the Millennium Development Goals 4 (to reduce child mortality), 5 (Improve maternal health) and 6 (to combat HIV/AIDS, malaria and other diseases)71 will not be achieved without persistent efforts by individual countries to develop safe and sustainable blood supplies.
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