A 6-year-old child from a tribal area in Chhattisgarh is brought to the Primary Health Centre (PHC) with a 2-month history of poor weight gain, persistent diarrhoea, and recurrent respiratory infections. The PHC doctor suspects severe acute malnutrition (SAM) with immunodeficiency. Which investigation is the most appropriate next step to assess immune status and guide nutritional rehabilitation?

Explanation

## Investigation of Choice for Immune Assessment in Malnourished Child ### Clinical Context: SAM with Recurrent Infections **Key Point:** Severe acute malnutrition (SAM) impairs cell-mediated immunity. The combination of poor weight gain, chronic diarrhoea, and recurrent respiratory infections raises suspicion for underlying immunodeficiency (including HIV), which must be ruled out before initiating nutritional rehabilitation. **High-Yield:** CD4+ T-cell count and HIV serology are the investigations of choice because: 1. **Immunodeficiency screening** — SAM + recurrent infections + chronic diarrhoea is a classic triad for HIV in children 2. **Public health imperative** — Early detection of HIV enables access to ART and prevents onward transmission 3. **Prognostic significance** — CD4 count guides timing and intensity of nutritional rehabilitation 4. **NACO guidelines** — National AIDS Control Organisation recommends HIV testing in all children with SAM and recurrent infections 5. **Differential diagnosis** — Rules out HIV before attributing immunosuppression solely to malnutrition ### Why CD4+ and HIV Serology? | Investigation | Rationale | Timing | Yield in SAM + Recurrent Infections | |---------------|-----------|--------|--------------------------------------| | **CD4+ count & HIV serology** | Identifies immunodeficiency; guides ART initiation | First-line | High (especially in endemic areas) | | **Serum protein & albumin** | Assess nutritional status; supportive only | Baseline | Moderate (all malnourished children) | | **Hb & PCV** | Assess anaemia; common in SAM | Baseline | Moderate (nutritional anaemia) | | **Stool culture** | Identify pathogenic diarrhoea | Only if bloody stools | Low (non-specific) | **Clinical Pearl:** A child with SAM who fails to respond to standard nutritional rehabilitation should always be tested for HIV. Early diagnosis changes management and prognosis. **Mnemonic:** **SAM-HI** = **S**evere **A**cute **M**alnutrition + **H**IV **I**mmunity assessment