Malaria: relapse versus recrudescence: 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 · Malaria: relapse versus recrudescence

Sample item

A 28-year-old man had Plasmodium vivax malaria treated with a complete course of chloroquine and recovered fully. Five months later he has fever again, and a smear shows P. vivax. He has not travelled and no mosquito exposure is suspected. What is the most likely explanation and the appropriate addition?

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

The answer and the reasoning

C. Relapse from dormant liver hypnozoites, treated with primaquine after checking G6PD status

P. vivax and P. ovale form hypnozoites in hepatocytes that can reactivate months after the blood stage is cleared, causing relapse. Chloroquine does not kill hypnozoites, so a radical cure needs primaquine, given after G6PD deficiency is excluded because of the risk of haemolysis. Recrudescence occurs within weeks, from incompletely cleared blood forms.

Option by option

  • A. Reinfection by a new mosquito bite, needing no further drug beyond chloroquine

    Reinfection requires a new mosquito exposure, which is not suggested, and chloroquine would not prevent later relapses.

  • B. Transfusion-acquired infection, treated by screening blood donors

    No transfusion is described, and donor screening is a prevention measure, not a treatment.

  • C. Relapse from dormant liver hypnozoites, treated with primaquine after checking G6PD status (correct)

    A late recurrence after adequate blood-stage therapy points to hypnozoites, which primaquine eradicates.

  • D. Recrudescence of chloroquine-resistant blood forms, treated by switching only the schizonticidal drug

    Recrudescence usually appears within weeks of treatment and would not explain a 5-month gap.

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.

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Questions about this PSM question

What is the answer to this PSM question?

The best answer is C, Relapse from dormant liver hypnozoites, treated with primaquine after checking G6PD status. P.

Why is "Reinfection by a new mosquito bite, needing no further drug beyond ch…" not the answer?

Reinfection requires a new mosquito exposure, which is not suggested, and chloroquine would not prevent later relapses.

Why is "Transfusion-acquired infection, treated by screening blood donors" not the answer?

No transfusion is described, and donor screening is a prevention measure, not a treatment.

Why is "Recrudescence of chloroquine-resistant blood forms, treated by switch…" not the answer?

Recrudescence usually appears within weeks of treatment and would not explain a 5-month gap.

What concept does this question test?

It tests Malaria: relapse versus recrudescence in PSM. vivax and P. ovale form hypnozoites in hepatocytes that can reactivate months after the blood stage is cleared, causing relapse. Chloroquine does not kill hypnozoites, so a radical cure needs primaquine, given after G6PD deficiency is excluded because of the risk of haemolysis. Recrudescence occurs within weeks, from incompletely cleared blood forms.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Malaria: relapse versus recrudescence?

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.