Parasitology: crusted scabies: 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: crusted scabies

Sample item

A 70-year-old nursing home resident on long-term oral corticosteroids has thick, scaly plaques on the hands and elbows with little itching. Several staff and residents have developed intense nocturnal itching. Which management is most appropriate?

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

The answer and the reasoning

C. Topical permethrin plus oral ivermectin, with treatment of contacts and isolation

Crusted (Norwegian) scabies occurs in immunosuppressed patients and holds thousands of Sarcoptes scabiei mites, making it highly contagious. Treatment requires repeated topical permethrin with oral ivermectin, keratolytics, isolation and simultaneous treatment of contacts and environment. A single topical application is usually insufficient.

Option by option

  • A. Topical corticosteroid for the plaques

    Steroids would worsen the infestation in this immunosuppressed host.

  • B. Oral antihistamines and emollients

    Symptomatic treatment does not kill mites and permits continued spread.

  • C. Topical permethrin plus oral ivermectin, with treatment of contacts and isolation (correct)

    Combination therapy with contact treatment is needed to clear a heavy mite burden and stop an outbreak.

  • D. A single application of topical permethrin alone

    A single application of a scabicide does not penetrate thick crusts or reach contacts.

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, Topical permethrin plus oral ivermectin, with treatment of contacts and isolation. Crusted (Norwegian) scabies occurs in immunosuppressed patients and holds thousands of Sarcoptes scabiei mites, making it highly contagious.

Why is "Topical corticosteroid for the plaques" not the answer?

Steroids would worsen the infestation in this immunosuppressed host.

Why is "Oral antihistamines and emollients" not the answer?

Symptomatic treatment does not kill mites and permits continued spread.

Why is "A single application of topical permethrin alone" not the answer?

A single application of a scabicide does not penetrate thick crusts or reach contacts.

What concept does this question test?

It tests Parasitology: crusted scabies in Microbiology. Treatment requires repeated topical permethrin with oral ivermectin, keratolytics, isolation and simultaneous treatment of contacts and environment. A single topical application is usually insufficient.

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: crusted scabies?

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.