Question
NACO strategies for HIV diagnosis
Answer
NACO (National AIDS Control Organisation) strategies for HIV diagnosis in India follow a structured testing algorithm designed to ensure accuracy while being feasible in a resource-varied setting, based on WHO-recommended principles.
Three-test (serial/parallel) strategy: unlike a single-test approach, a reactive result must be confirmed using a sequence of three different rapid tests/ELISAs, each based on different antigen preparations or test principles, to minimize false positives before a definitive positive diagnosis is given to an individual:
- Strategy I — used for blood/organ/tissue donor screening: a single ELISA/rapid test is sufficient to determine safety for transfusion/donation (high sensitivity prioritized, since the consequence of a false negative — transfusion-transmitted HIV — is far worse than a false positive requiring further donor deferral/testing).
- Strategy II — used for surveillance (estimating HIV prevalence in a population, e.g., antenatal/STD clinic surveillance): two tests are used; a sample reactive on both is considered positive for surveillance purposes (individual results are not reported back in unlinked anonymous surveillance).
- Strategy III — used for individual diagnosis of HIV infection: three different tests/kits, using different antigens/principles, are required in sequence — a sample must be reactive on all three (tested serially, only proceeding to the next test if the previous one is reactive) before HIV infection is confirmed and reported to the individual; this stringent approach minimizes the risk of a false-positive diagnosis being given to an individual, which would carry serious psychosocial, medical, and legal consequences.
Testing sites and services: NACO has established a network of Integrated Counselling and Testing Centres (ICTCs) across the country, offering free, confidential HIV testing with pre- and post-test counselling; PPTCT (Prevention of Parent-to-Child Transmission) services specifically target pregnant women for antenatal HIV screening.
Rapid tests and point-of-care testing: increasingly used to expand access, particularly in resource-limited/remote settings, using immunochromatographic/agglutination-based kits that can be read visually without laboratory infrastructure.
Confirmatory principle: reactive results at the point-of-care/field level are always confirmed through the full Strategy III algorithm at a linked/referral laboratory before a definitive diagnosis is communicated, ensuring diagnostic accuracy is never compromised even as testing access is expanded.
Additional NACO components: viral load and CD4 count testing (for treatment monitoring, not diagnosis per se) are provided through ART centres once a confirmed diagnosis is established, integrating diagnosis with the treatment/care cascade.