It has been estimated that 5–10% of HIV transmission in Africa is by contaminated blood transfusions.If a person receives a blood transfusion with HIV-infected blood, there is a 95 percent risk they will become infected with the virus
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.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.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.
Though efforts to achieve these measures are sought after,developing countries still struggle towards these goals,majorly because there is heavy reliance on foreign donor agencies inhibiting centralized structures that facilitate national blood policies.
Testing for transfusion transmissible diseases would be more effective in a centralized regional laboratory, where economies of scale would make
testing cheaper.
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.
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.These donors are sought after because they are more likely to be donating for altruistic reasons rather than for any personal gain.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
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 Injection Drug Users, 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.
Testing 'algorithms' are a sequence of specific tests, or assays, which are organised to create a certain HIV testing strategy.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.
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.
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.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.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.
Grave Shortage
Blood supplies in Africa have never been able to meet the demand; this is reflected in the high maternal and child mortality rates in the continent.Hemorrhage and anemia account for a large proportion of maternal deaths; many of these could be prevented by provision of good obstetric services and an adequate blood supply.
Malaria is the major contributor to deaths of children under 5 years and it has been shown that children with malarial anemia (hemoglobin,5 g/dl) are at risk of dying if there is delay in getting blood for transfusion.11–13 The number of cases presenting with HIV/AIDS on antiretroviral treatment in recent years has also placed an
additional burden on the blood supplies.It is questionable whether hospital based family replacement blood banks are ever going to be able to maintain adequate blood supplies to meet these needs.There is also clear evidence that a strictly volunteer donor system does not provide sufficient blood, estimated to range between 15 and 20 units/1000 inhabitants.
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.
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.
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.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.
Sometimes cultural and spiritual factors may inhibit the success of blood programmes,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'.
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.
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) will not be achieved without persistent efforts by individual countries to develop safe and sustainable blood supplies.
Nyambura Mundia.
Reference: WHO
International HIV & AIDS charity.
Africa Science News.
No comments:
Post a Comment