Clinical Scenario:
A 5-month-old infant is brought to the pediatric clinic because his mother is living with HIV. The infant has never undergone HIV testing. A rapid antibody test is performed and is reactive.
What is the most appropriate next step?
A. Repeat rapid antibody testing
B. Start lifelong ART immediately
C. Perform virological testing
D. Wait until 18 months of age
E. Perform a CD4 count
Correct answer & Explanation:
Correct answer: C. Perform virological testing
Explanation
In an infant younger than 18 months, a reactive antibody test cannot establish HIV infection, because maternal HIV antibodies can persist in the infant and cause a reactive antibody test even when the infant is not infected.
Therefore, virological testing (NAT) is required to diagnose HIV infection in infants under 18 months. WHO recommends virological testing for early infant diagnosis rather than relying on antibody-based testing.
This distinction is important:
- ≥18 months: HIV antibody-based testing using the recommended testing strategy can establish diagnosis.
- <18 months: use virological testing (NAT) for diagnosis.
A CD4 count does not diagnose HIV infection, and waiting until 18 months would unnecessarily delay diagnosis and treatment.
Reference:
World Health Organization. Consolidated guidelines on differentiated HIV testing services. 2024.
World Health Organization. WHO recommendations on HIV diagnosis in infants and children.
