Antimicrobials: Mazzotti reaction: practice question

A Pharmacology 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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Pharmacology · Antimicrobials: Mazzotti reaction

Sample item

A man with itchy skin, nodules and microfilariae in skin snips is mistakenly given diethylcarbamazine. Within hours he has fever, intense itching, rash and hypotension. Which reaction has occurred?

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

The answer and the reasoning

D. Mazzotti reaction

Rapid killing of Onchocerca microfilariae by diethylcarbamazine releases antigens and triggers the Mazzotti reaction. Ivermectin is the preferred drug for onchocerciasis, and DEC is avoided in endemic areas of the disease.

Option by option

  • A. Red man syndrome

    Red man syndrome follows rapid infusion of vancomycin.

  • B. Serum sickness

    Serum sickness is an immune-complex reaction appearing after one to two weeks.

  • C. Jarisch-Herxheimer reaction

    Jarisch-Herxheimer reaction follows treatment of spirochaetal infections such as syphilis.

  • D. Mazzotti reaction (correct)

    Correct. Mazzotti reaction follows death of microfilariae after DEC in onchocerciasis.

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 Pharmacology question

What is the answer to this Pharmacology question?

The best answer is D, Mazzotti reaction. Rapid killing of Onchocerca microfilariae by diethylcarbamazine releases antigens and triggers the Mazzotti reaction.

Why is "Red man syndrome" not the answer?

Red man syndrome follows rapid infusion of vancomycin.

Why is "Serum sickness" not the answer?

Serum sickness is an immune-complex reaction appearing after one to two weeks.

Why is "Jarisch-Herxheimer reaction" not the answer?

Jarisch-Herxheimer reaction follows treatment of spirochaetal infections such as syphilis.

What concept does this question test?

It tests Antimicrobials: Mazzotti reaction in Pharmacology. Ivermectin is the preferred drug for onchocerciasis, and DEC is avoided in endemic areas of the disease.

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 Antimicrobials: Mazzotti reaction?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology 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.