Which is a widely used diagnostic test for AIDS?

Appeared in: KPSC Staff Nurse - 2015

Explanation

ELISA (Enzyme-Linked Immunosorbent Assay) is the standard, widely used initial screening test for HIV infection.
It is highly sensitive (greater than 99.9%) and detects antibodies produced by the body in response to the HIV virus.
Modern (4th generation) ELISA tests can also detect the p24 antigen, a viral protein that appears before antibodies, shortening the 'window period' for detection.
A positive ELISA result is always followed by a more specific confirmatory test to rule out false positives.

Option A: A biopsy is an invasive procedure to obtain a tissue sample. It does not detect the HIV virus itself.
Option B: An X-ray is an imaging study that cannot detect a virus like HIV.
Option C: The Widal test is a serological test specifically designed to detect antibodies against the Salmonella bacteria that cause typhoid fever.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Diagnostic tests for HIV/AIDS as background academic context rather than a clinical decision trigger.
Understanding the HIV testing algorithm is crucial for nurses for patient education, counseling, and interpreting lab results.
Nurses must explain the 'window period' to patients – the time between potential exposure and when a test can accurately detect the virus. A negative test during this period may not be conclusive, and re-testing is often necessary.
In the Indian context, the National AIDS Control Organisation (NACO) guidelines emphasize a three-test strategy for diagnosis, ensuring high accuracy before confirming a positive status.

How to Approach the Question

First, identify the core of the question: it asks for a 'widely used diagnostic test' for AIDS.
Scan the options to see if you recognize any of the tests and their primary uses.
Eliminate options that are clearly incorrect. The Widal test is for typhoid, a well-known fact in medical subjects. This is a strong candidate for elimination.
Consider the nature of the remaining tests. Biopsy and X-ray are general procedures used for many conditions, usually to look at tissues or structures, not to detect a specific virus in the blood. They are used for AIDS-related complications, not the initial diagnosis of HIV.
This leaves ELISA. Recall or deduce that ELISA is a common type of blood test used for screening various conditions, including viral infections like HIV.
Confirm that ELISA fits the description of a 'widely used' screening test, making it the most logical answer.

Concept Tested & Keywords

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E6 Pathology-Textbook of PATHOLOGYHarsh Mohan Part 1 (1-214) p. 158-160

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart C (pp 404-604 of 604) p. 15-17

Practise the full KPSC Staff Nurse - 2015

Attempt every question from this paper in a timed mock, then review the full solution for each one.