Parasitology: Babesia: 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: Babesia

Sample item

A 62-year-old splenectomised man from the north-eastern United States has fever, haemolytic anaemia and haemoglobinuria after a summer hiking trip. The blood smear shows intraerythrocytic ring forms and tetrads (Maltese cross) without malarial pigment. What is the likely organism?

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

The answer and the reasoning

C. Babesia microti

Babesia microti is transmitted by Ixodes ticks and infects red cells, causing a malaria-like illness that is severe in asplenic, elderly or immunosuppressed patients. Smears show rings and tetrads but no haemozoin pigment or gametocytes. Treatment is atovaquone with azithromycin, and severe cases may need exchange transfusion.

Option by option

  • A. Anaplasma phagocytophilum

    Anaplasma forms morulae within neutrophils, not within red cells.

  • B. Plasmodium falciparum

    P. falciparum forms crescent gametocytes and pigment and is not tick-borne.

  • C. Babesia microti (correct)

    Tetrads in red cells without pigment are characteristic of Babesia.

  • D. Ehrlichia chaffeensis

    Ehrlichia forms morulae within monocytes, not within red cells.

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.

More Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is C, Babesia microti. Babesia microti is transmitted by Ixodes ticks and infects red cells, causing a malaria-like illness that is severe in asplenic, elderly or immunosuppressed patients.

Why is "Anaplasma phagocytophilum" not the answer?

Anaplasma forms morulae within neutrophils, not within red cells.

Why is "Plasmodium falciparum" not the answer?

P. falciparum forms crescent gametocytes and pigment and is not tick-borne.

Why is "Ehrlichia chaffeensis" not the answer?

Ehrlichia forms morulae within monocytes, not within red cells.

What concept does this question test?

It tests Parasitology: Babesia in Microbiology. Smears show rings and tetrads but no haemozoin pigment or gametocytes. Treatment is atovaquone with azithromycin, and severe cases may need exchange transfusion.

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: Babesia?

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.