Parasitology: Plasmodium knowlesi: practice question

A Microbiology 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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Microbiology · Parasitology: Plasmodium knowlesi

Sample item

A 35-year-old forest worker returns from Borneo with daily fever spikes. A smear shows band forms resembling Plasmodium malariae but with 12% parasitaemia, and the platelet count is low. Within 48 hours his condition worsens with jaundice and renal impairment. Which species is most likely?

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

The answer and the reasoning

C. Plasmodium knowlesi

P. knowlesi is a zoonotic malaria of macaques in South-East Asia. It has a 24-hour asexual cycle (quotidian fever), morphologically resembles P. malariae on smear, and can cause high parasitaemia and severe disease. Severe cases are treated like severe falciparum malaria with intravenous artesunate.

Option by option

  • A. Plasmodium vivax

    P. vivax is not typically associated with such high parasitaemia, and has Schuffner dots and enlarged red cells.

  • B. Plasmodium malariae

    P. malariae has a 72-hour cycle and usually causes low parasitaemia.

  • C. Plasmodium knowlesi (correct)

    A 24-hour cycle, a P. malariae-like appearance and high parasitaemia indicate P. knowlesi.

  • D. Plasmodium ovale

    P. ovale causes mild disease with oval red cells and a 48-hour cycle.

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 Microbiology question

What is the answer to this Microbiology question?

The best answer is C, Plasmodium knowlesi. P.

Why is "Plasmodium vivax" not the answer?

P. vivax is not typically associated with such high parasitaemia, and has Schuffner dots and enlarged red cells.

Why is "Plasmodium malariae" not the answer?

P. malariae has a 72-hour cycle and usually causes low parasitaemia.

Why is "Plasmodium ovale" not the answer?

P. ovale causes mild disease with oval red cells and a 48-hour cycle.

What concept does this question test?

It tests Parasitology: Plasmodium knowlesi in Microbiology. knowlesi is a zoonotic malaria of macaques in South-East Asia. It has a 24-hour asexual cycle (quotidian fever), morphologically resembles P. malariae on smear, and can cause high parasitaemia and severe disease. Severe cases are treated like severe falciparum malaria with intravenous artesunate.

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 Parasitology: Plasmodium knowlesi?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology 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.