Parasitology: Casoni test: 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: Casoni test

Sample item

An old intradermal test in a patient with a cystic liver lesion produces an immediate wheal in response to fluid from a sheep parasite. Which infection did it support?

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

The answer and the reasoning

A. Hydatid disease

The Casoni test is an intradermal hypersensitivity test using hydatid fluid for Echinococcus granulosus infection, now replaced by serology and imaging because of poor specificity. Amoebic abscess, fascioliasis and kala-azar are not diagnosed this way.

Option by option

  • A. Hydatid disease (correct)

    Correct. The Casoni test uses hydatid antigen.

  • B. Visceral leishmaniasis

    Kala-azar is diagnosed by rK39 and amastigotes.

  • C. Fascioliasis

    Fascioliasis is diagnosed by eggs and serology.

  • D. Amoebic liver abscess

    Amoebic abscess is diagnosed by imaging and serology.

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, Hydatid disease. The Casoni test is an intradermal hypersensitivity test using hydatid fluid for Echinococcus granulosus infection, now replaced by serology and imaging because of poor specificity.

Why is "Visceral leishmaniasis" not the answer?

Kala-azar is diagnosed by rK39 and amastigotes.

Why is "Fascioliasis" not the answer?

Fascioliasis is diagnosed by eggs and serology.

Why is "Amoebic liver abscess" not the answer?

Amoebic abscess is diagnosed by imaging and serology.

What concept does this question test?

It tests Parasitology: Casoni test in Microbiology. Amoebic abscess, fascioliasis and kala-azar are not diagnosed this way.

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: Casoni test?

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.