All of the following methods are used for the diagnosis of HIV infection in a two-month-old child, Except?

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

HIV ELISA is an antibody-based test, which is unsuitable for infants under 18 months.
Infants born to HIV-positive mothers carry maternal IgG antibodies, which cross the placenta.
An ELISA test would detect these maternal antibodies, leading to a false-positive result in an uninfected infant.
Therefore, ELISA is the exception and is not used for definitive diagnosis in this age group.

Option B: DNA-PCR is a recommended and preferred method for early infant HIV diagnosis.
Option C: The p24 antigen assay is a valid virologic test used for diagnosing HIV in infants.
Option D: Viral culture is a valid, though rarely used, method for diagnosing HIV in infants.

Clinical Relevance

Nursing practice connection: Use the key finding related to Early Infant Diagnosis of HIV to guide bedside assessment, documentation, and the next nursing action.
Accurate and early diagnosis of HIV in infants is critical for initiating timely antiretroviral therapy (ART), which significantly improves prognosis and reduces mortality.
Using the wrong test (like ELISA) could lead to misdiagnosis, causing immense psychological stress for the family and potentially leading to unnecessary treatment of an uninfected child.
Nurses play a key role in educating parents about the testing process, explaining why specific tests are used at different ages, and providing support during the diagnostic period.

How to Approach the Question

First, identify the keyword 'Except' in the question. This means you are looking for the option that is NOT a valid method.
Next, note the patient's age: 'two-month-old child'. This is the most critical piece of information for pediatric HIV testing.
Recall the major challenge in diagnosing HIV in infants: the passive transfer of maternal antibodies across the placenta, which can persist for up to 18 months.
Evaluate each option based on what it detects: Does it detect the virus itself (virologic test) or the body's antibody response (serologic test)?
DNA-PCR, p24 antigen, and viral culture all detect the virus or its components. These are appropriate for infants.
HIV ELISA detects antibodies. Since maternal antibodies are present, this test is unreliable and inappropriate.

Concept Tested & Keywords

Concept Tested: Early Infant Diagnosis of HIV
Stem keywords: HIV infection, diagnosis, two-month-old child
Lead-in keywords: Except
Clinical cues: Patient age (two-month-old) is the critical factor influencing the choice of diagnostic test.
Negative lead-in flag: EXCEPT

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 2102-2104

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 249-251

Practise the full JODHPUR AIIMS SNO-2018

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