Poliomyelitis: AFP surveillance: practice question

A PSM question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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PSM · Poliomyelitis: AFP surveillance

Sample item

A 4-year-old child develops acute flaccid paralysis of the left leg. Under the national AFP surveillance programme, which stool sample collection is correct?

AThree stool specimens one week apart during the first monthBTwo stool specimens at least 24 hours apart, both collected within 14 days of onsetCOne stool specimen within 28 days of onsetDTwo stool specimens one week apart, collected within 60 days of onset

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Two stool specimens at least 24 hours apart, both collected within 14 days of onset

Poliovirus is shed in stool for a limited time, so two adequate specimens are collected at least 24 hours apart within 14 days of paralysis onset and sent in a reverse cold chain. A 60-day follow-up examination assesses residual paralysis, which helps classify the case. Adequate stool collection is a key AFP surveillance quality indicator.

Option by option

A. Three stool specimens one week apart during the first month
A schedule of three weekly samples is not the programme standard and falls beyond the optimal window.
B. Two stool specimens at least 24 hours apart, both collected within 14 days of onset (correct)
Two specimens at least 24 hours apart within 14 days give the best chance of virus isolation.
C. One stool specimen within 28 days of onset
A single late sample reduces the yield, because virus excretion declines after the first two weeks.
D. Two stool specimens one week apart, collected within 60 days of onset
Sixty days is the time of follow-up for residual paralysis and not the window for stool collection.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this PSM question

What is the answer to this PSM question?

The best answer is B, Two stool specimens at least 24 hours apart, both collected within 14 days of onset. Poliovirus is shed in stool for a limited time, so two adequate specimens are collected at least 24 hours apart within 14 days of paralysis onset and sent in a reverse cold chain.

Why is "Three stool specimens one week apart during the first month" not the answer?

A schedule of three weekly samples is not the programme standard and falls beyond the optimal window.

Why is "One stool specimen within 28 days of onset" not the answer?

A single late sample reduces the yield, because virus excretion declines after the first two weeks.

Why is "Two stool specimens one week apart, collected within 60 days of onset" not the answer?

Sixty days is the time of follow-up for residual paralysis and not the window for stool collection.

What concept does this question test?

It tests Poliomyelitis: AFP surveillance in PSM. A 60-day follow-up examination assesses residual paralysis, which helps classify the case. Adequate stool collection is a key AFP surveillance quality indicator.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Poliomyelitis: AFP surveillance?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.