Virology: rabies post-exposure prophylaxis: 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 · Virology: rabies post-exposure prophylaxis

Sample item

A 20-kg unvaccinated child has multiple deep bites on the face from a stray dog. Human rabies immunoglobulin is available. What is the correct dose and administration?

A400 IU, infiltrated into and around the wounds, with any remainder given intramuscularly away from the vaccine siteB200 IU, given entirely into the gluteal muscle away from the woundsC800 IU, infiltrated into the wounds with the remainder given intramuscularlyD400 IU, given entirely by slow intravenous injection

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

The answer and the reasoning

A. 400 IU, infiltrated into and around the wounds, with any remainder given intramuscularly away from the vaccine site

Category III exposure needs wound washing, vaccine and rabies immunoglobulin. Human rabies immunoglobulin is given at 20 IU/kg, here 20 x 20 = 400 IU (equine immunoglobulin is 40 IU/kg, which would be 800 IU). As much as anatomically feasible is infiltrated into and around all wounds, and the remainder is given intramuscularly away from the vaccine site.

Option by option

A. 400 IU, infiltrated into and around the wounds, with any remainder given intramuscularly away from the vaccine site (correct)
Correct. The dose is 20 IU/kg, with maximal local infiltration of wounds.
B. 200 IU, given entirely into the gluteal muscle away from the wounds
This is half the required dose, and giving it only at a distant site fails to neutralise virus where it enters.
C. 800 IU, infiltrated into the wounds with the remainder given intramuscularly
800 IU corresponds to equine immunoglobulin at 40 IU/kg, not the human product at 20 IU/kg.
D. 400 IU, given entirely by slow intravenous injection
Immunoglobulin is not given intravenously, and wound infiltration is what neutralises local virus.

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.

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is A, 400 IU, infiltrated into and around the wounds, with any remainder given intramuscularly away from the vaccine site. Category III exposure needs wound washing, vaccine and rabies immunoglobulin.

Why is "200 IU, given entirely into the gluteal muscle away from the wounds" not the answer?

This is half the required dose, and giving it only at a distant site fails to neutralise virus where it enters.

Why is "800 IU, infiltrated into the wounds with the remainder given intramus…" not the answer?

800 IU corresponds to equine immunoglobulin at 40 IU/kg, not the human product at 20 IU/kg.

Why is "400 IU, given entirely by slow intravenous injection" not the answer?

Immunoglobulin is not given intravenously, and wound infiltration is what neutralises local virus.

What concept does this question test?

It tests Virology: rabies post-exposure prophylaxis in Microbiology. Human rabies immunoglobulin is given at 20 IU/kg, here 20 x 20 = 400 IU (equine immunoglobulin is 40 IU/kg, which would be 800 IU). As much as anatomically feasible is infiltrated into and around all wounds, and the remainder is given intramuscularly away from the vaccine site.

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 Virology: rabies post-exposure prophylaxis?

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.