An 11-month-old child presents with sudden onset weakness of both lower limbs. Acute flaccid paralysis is reported and the child is admitted. For adequate virological classification, when and how many stool specimens must be collected?
- A Three samples collected over 7 days starting from day 21 of paralysis
- B One sample collected immediately on admission
- C Two samples collected at least 24 hours apart, each within 14 days of onset of paralysis ✓
- D Two samples collected 48 hours apart, any time within 60 days of onset
Correct answer: C. Two samples collected at least 24 hours apart, each within 14 days of onset of paralysis
Explanation
AFP surveillance standards require two good-quality stool specimens, taken at least 24 hours apart, each within 14 days of onset of paralysis, transported cold to a WHO-accredited laboratory. Adequate samples allow virus isolation and intratypic differentiation between wild, Sabin-like and vaccine-derived strains. The 60-day mark relates to residual paralysis assessment for follow-up examination, not stool collection, and delayed sampling sharply reduces isolation yield.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.