Parasitology: filariasis: 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: filariasis

Sample item

A man from an endemic area has recurrent fever, painful lymphadenitis and later scrotal swelling. When should a blood sample be taken to detect microfilariae of Wuchereria bancrofti, and which drug is used?

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

The answer and the reasoning

A. At night, around midnight, with diethylcarbamazine

Microfilariae of Wuchereria bancrofti show nocturnal periodicity, appearing in peripheral blood mainly at night, so thick smears are taken around 10 pm to 2 am. Diethylcarbamazine (with albendazole in mass drug administration) kills microfilariae, and the vector is Culex quinquefasciatus. Antigen tests (ICT) can be used at any time.

Option by option

  • A. At night, around midnight, with diethylcarbamazine (correct)

    Correct. Samples are taken at night, and diethylcarbamazine is the standard agent.

  • B. Early morning on an empty stomach, with metronidazole

    Metronidazole has no activity against filarial worms.

  • C. At any time as periodicity is absent, with ivermectin alone

    This species is nocturnally periodic; ivermectin alone is not the standard in India.

  • D. At noon, with albendazole alone

    Daytime samples miss the nocturnally periodic microfilariae.

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 A, At night, around midnight, with diethylcarbamazine. Microfilariae of Wuchereria bancrofti show nocturnal periodicity, appearing in peripheral blood mainly at night, so thick smears are taken around 10 pm to 2 am.

Why is "Early morning on an empty stomach, with metronidazole" not the answer?

Metronidazole has no activity against filarial worms.

Why is "At any time as periodicity is absent, with ivermectin alone" not the answer?

This species is nocturnally periodic; ivermectin alone is not the standard in India.

Why is "At noon, with albendazole alone" not the answer?

Daytime samples miss the nocturnally periodic microfilariae.

What concept does this question test?

It tests Parasitology: filariasis in Microbiology. Diethylcarbamazine (with albendazole in mass drug administration) kills microfilariae, and the vector is Culex quinquefasciatus. Antigen tests (ICT) can be used at any time.

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 Parasitology: filariasis?

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.