Malaria. Hepatitis (B&C), Syphilis, AIDS are considered as transmissible infections associated with blood transfusion. According to law all these tests are to be conducted after blood collection. It is not pragmatic to conduct these tests before blood collection as donors have to come twice, to suffer the needle pricks and may have to wait for quite some time. As a result, transfusion service may lose donors. So, donor selection can be on the basis of history of past ailments. After donation laboratory testing of blood should be undertaken in the blood bank.
Presently, a sensitive screening test for malaria is not available. The most effective way of screening donors is to take the proper case history of malaria and of fever that could be due to malaria. Donor selection criteria should be designed to exclude potentially infectious individuals from donating blood. However, available slide test for malarial parasites is mandatory according to the rules now in force in the country.
To reduce the occurrence of post transfusion hepatitis, it is essential to screen all blood donors for hepatitis B surface antigen, by the most sensitive and specific tests. Results may be made known to the donor with an advice to contact family physician for guidance. Hepatitis C can also be transmitted through blood transfusion. HCV antibody testing has become mandatory from June 2001 in India. Serum samples from all blood units must be selected for Venereal Disease Research Laboratory (VDRL) test before transfusion to detect syphilis. Any unit found positive should be discarded. But if blood is kept in cold room for three days, then there is no chance of contracting syphilis by transfusion of such blood as these germs become ineffective in cold.
For transfusion safety, each and every unit of blood donated should be tested by combined HIV/1 and HIV/2 assay using ELJSA reader. This is just a screening test, and not a confirmatory test. Blood should be discarded if the test gives positive results but the donor should not be informed and should not be identified as HIV positive or AIDS patient. Strict confidentiality should be maintained. In smaller blood banks or in cases of emergency, rapid spot tests can be done to reduce the possibility of HIV/AIDS infection
due to transfusion. But all these tests are not full proof. These are indirect tests to trace the antibody formed caused by the entry of foreign body from outside. Body mechanism takes time to produce antibody to fight against entry of germs from outside. There is atime lag between the entry of germs and formation of antibody known as window period. The tests are ineffective during this window period. Motivators should, therefore, attach due importance not only to the truthful declaration of the donors but also to the pre-donation counselling for self exclusion to ensure safe blood transfusion.
The confirmatory tests for HIV infection include Western Blot test and Immunofluorescence tests. These tests cannot be done in the blood banks due to high cost, time and expertise required.