Decoding HIV Testing: A Comprehensive Overview of Various Test Types

In the realm of healthcare, laboratory diagnosis stands as the primary method for determining the HIV status of an individual's blood, blood products, organs, and tissues. This comprehensive guide explores the three main types of HIV tests, antibody tests, antigen/antibody tests, and nucleic acid tests (NAT) - highlighting their methodologies, timelines, and significance in accurate HIV detection. Antibody tests, Antigen/antibody tests are serological tests.

Fig. 1: Tests used for HIV diagnosis in people above 18 months of age

• Antibody tests search for HIV antibodies in blood or oral fluid, taking 23 to 90 days to detect HIV post-exposure. Rapid tests and the FDA-approved HIV self-test fall into this category. Generally, tests using blood from a vein detect HIV sooner than those using a finger stick or oral fluid.

·        Antigen/antibody tests seek both HIV antibodies and antigens. Antibodies are produced in response to virus exposure, while antigens activate the immune system. An antigen called p24 is produced in early HIV infection. Recommended for labs, these tests can usually detect HIV 18 to 45 days after exposure when performed with blood from a vein. There is also a rapid antigen/antibody test available that is done with a finger stick. Antigen/antibody tests done with blood from a finger stick can take 18 to 90 days after exposure. Rapid tests with a finger stick take 18 to 90 days post-exposure.

Enzyme-linked immunosorbent assays (ELISAs), rapid tests, and western blots (WBs) are the standard methods for detecting HIV antibodies. For accurate HIV diagnosis, these tests follow a specific sequence or algorithm. Moreover, Chemiluminescence Immunoassays (CIA), Immunofluorescent Assays, and Line Immunoassays provide additional options for targeted HIV antibody detection. Commercial assays are also accessible for P24 antigen detection.

• Nucleic acid amplification tests (NAAT) examine the actual virus in the blood. This test is recommended for individuals with recent or potential exposures exhibiting early HIV symptoms that have tested negative with an antibody or antigen/antibody test. A NAAT can typically detect HIV 10 to 33 days after exposure.

In the initial HIV test, either an antigen/antibody test or an antibody test is commonly employed. If a rapid or self-test yields a positive result, individuals should consult a healthcare provider for follow-up testing. Similarly, if a lab test is positive, the lab typically conducts follow-up testing on the same blood sample to confirm the result. While HIV tests are generally accurate, follow-up tests are crucial to confirming results and ensuring comprehensive healthcare.

Fig. 2: Acute HIV infection

While HIV tests are generally accurate, understanding the nuances of each type is crucial for effective diagnosis. This guide empowers individuals to navigate the complexities of HIV testing, promoting informed healthcare decisions and contributing to the global effort against HIV/AIDS.

Transasia’s offerings – Advanced Diagnostic Solutions for HIV detection

Discover Transasia Bio-Medicals Ltd.'s comprehensive range of diagnostic kits tailored for HIV diagnosis. Our lineup features ErbaQik HIV 1+2 and ErbaLisa HIV Gen 3 and Gen 4, comprising both rapid and ELISA screening kits. Noteworthy is ErbaLisa HIV Gen 4, offering early diagnosis by simultaneously detecting p24 Antigen and Antibodies to HIV 1 and HIV 2. Our 'Point of Care Testing Solution' includes ErbaQik HIV 1 +2, a rapid test ideal for mass screening in high-risk populations during blood camps. These kits boast unparalleled sensitivity and specificity, ensuring precise and timely HIV diagnosis.

NOTE: Mandatory testing is recommended in India, only for the screening of donated units of blood, blood products, and donors of semen, organs, or tissues in order to prevent the transmission of HIV to the recipient. The national HIV testing policy reiterates the following: No individual should be made to undergo a mandatory testing for HIV. No mandatory HIV testing should be imposed as a precondition for employment or for providing healthcare services and facilities. Any HIV testing must be accompanied by pre-test and post-test counselling services and informed consent. Confidentiality of result should be maintained.

References:

1. HIV testing | Centres for Disease Control and prevention.
2. National guidelines for HIV testing, NACO.
3. National HIV Curriculum