KOCHI: HIV, the virus (human immunodeficiency) that leads to AIDS (acquired immunodeficiency syndrome) still remains a major global public health issue. This virus has claimed 40.4 million lives so far. According to WHO, the world has committed to end AIDS by 2030, however, the rates of infections and deaths aren’t falling rapidly enough. Even though there is no cure for HIV infection, with the advancement of science it has become a manageable chronic health condition, enabling people with AIDS to lead long and healthy life.
To achieve this, there should be timely access to effective HIV prevention, diagnosis, treatment, and care.HIV targets the body’s white blood cells, weakening the immune system. The virus spreads from the body fluids of an infected person, including blood, breast milk, semen, and vaginal fluids, and even from a mother to her baby in utero. It’ll never be spread by hugs or sharing food.
At present, we have various testing platforms for detecting the presence of HIV with varying sensitivity and specificity. It ranges from simple card tests to the most advanced NAT testing. The card test will give a positivie result if there are significant amounts of anti-HIV antibodies.
The next test is ELISA (Enzyme-Linked Immunoassay). This one is capable of detecting antibodies at much lower levels. There are various generations of ELISA tests where we can detect the antigens as well. Chemiluminescent immunoassay (CLIA) is another platform which can detect HIV p24 antigen and the antibodies to HIV-1 and/or HIV-2 in human serum or plasma.Lastly, the most advanced test for detecting HIV is NAT testing or RT PCR-based HIV testing.
Nucleicacid testing (NAT) / RT-PCR is a molecular technique which can detect nucleic acid in HIV even at very low levels by amplifying them. Even modern-day blood banks also adopt this strategy of NAT testing for screening blood donations to reduce the risk of transfusion-transmitted infections (TTIs)
Another test to be mentioned here is the Western blot assay. It is a method in which individual proteins of an HIV are separated according to size by polyacrylamide gel electrophoresis. The viral proteins are then transferred onto nitrocellulose paper and reacted with the patient’s serum. Typically, labs would run the Since alternative tests like NAT or RT PCR have become more trustworthy and provide a speedier diagnosis, the Western blot test is less often recommended.
How to reduce the risk of HIV as transfusion-transmitted infection
1. Careful selection of donors.
2. Direct screening of the blood for evidence of the presence of HIV or markers produced by them.
3. Removal of specific components of blood thought to harbour infectious agents for example, by filtration of blood to remove WBCs (Leucodepleted red cells).
4. Physical/chemical inactivation of the contaminating agent that may be present, using pathogen reduction technology.
5. Surveillance for transfusion-transmissible diseases and implementation of new donor screening tests, when available.
The author is the head of Advanced Center for Transplant Immunology & Molecular Science, Medical Trust Hospital, Kochi