Blood Transfusion is still the lifeline for millions of people around the world because there is no alternative to that. Annually, millions of people require blood transfusion for various reasons. Therefore, the safety of blood products remains the primary responsibility of every transfusion center. The basic principles of blood safety are safe blood donors, a responsible blood transfusion service that can ensure appropriate and safe processing and testing of blood, and appropriate use of blood. This is the aim of celebrating World Blood Donor Day every year on 14th June to increased awareness towards the need for safe blood and blood products. Also, to thank voluntary (unpaid) blood donors for their contribution to health systems in the world and create wider public awareness of the need for regular blood donation. Amidst this, we feel it is extremely essential to spread the word about blood infections – something that may hamper safe donation and transfusion.
What is Transfusion Transmitted Infection (TTI)?
A single unit of blood donation is separated into three or more components which means screening blood for transfusion-transmitted infection (TTI) is important to obtain safe blood. The screening of blood is being done worldwide, still, TTI’s are reported though their numbers have decreased significantly. The prevalence of TTI’s in blood donations in high-income countries is considerably lower than in low- and middle-income countries. This is because of multiple factors.
The proportion of replacement and professional donations is high
Specificity and sensitivity of screening tests
Collection of blood during the window period
Why Go Through The Testing Procedure?
The importance of mandatory testing for infectious organisms transmissible by transfusion is because some carriers of the disease are often asymptomatic, some viral infections have long incubation periods and sometimes skin microflora contaminates the blood, as blood is a good culture media.
TTI is an infection transmitted through the parenteral administration of blood and blood products. It is caused by an agent present in the donor’s blood which is not detected by screening methods employed by the blood bank. The transfusion-transmitted infective agents are Viral. (like Hepatitis B, Hepatitis C, HIV 1&2), Bacterial (like Treponema pallidum, Pseudomonas, Enterobacter, staphylococcus, etc.), Protozoal (like Malarial Parasite, Toxoplasma, etc.), Prions (Creutzfeldt-Jakob/variant CJD), and seasonal (Like Dengue/West Nile/SARS/Plague, etc.)
Screening For Blood Donations
WHO recommends that all blood donations should be screened for infections prior to use. Screening for HIV, hepatitis B, hepatitis C, and syphilis is mandatory. The screening for other organisms likely to be transmitted by transfusion is usually done according to prevalence in a particular geographic area or population because of which the drug control department, MoHFW, GOI mandates testing for malaria because it is an endemic disease in India.
The Evolution of Testing Methodologies
The testing methods have improved drastically over the period of time reducing the window period for the detection of infection. There are different methods for every infection-causing agents like Immunodiffusion, Latex agglutination, Chromatographic Immunoassays, Enzyme Immunoassays (ELISA), Radio Immunoassays, particle agglutination, specialized rapid tests for viral agents; Venereal disease research laboratory (VDRL) test and Rapid plasma regain (RPR) test for syphilis: specialized rapid tests for malaria. These conventionally used methods for blood screening target the human body’s response to a virus so the interval between the donor’s exposure to a virus and detectable amount of antibodies/antigens is missed by these methods, thus creating a need for a more sensitive and specific method to detect the presence of virus directly. Nowadays fully automated FDA-certified methods are available for nucleic acid technology testing for blood screening. The nucleic acid technology testing is more sensitive and specific. It is based on the amplification of targeted RNA and DNA thus reducing the window period drastically. However, NAT is technically very demanding and involves higher costs.
The transfusion of safe blood is proven only to treat a condition otherwise leading to significant morbidity/mortality that cannot be prevented or managed effectively by other means. The benefit of transfusion should outweigh the risks.
Zero risk transfusion is no transfusion.
“Give blood and keep the world-beating”
“Be a blood donor, be a hero – a real one.”
This post first appeared on The Health Site
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