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Microbiology · Parasitology
Sample itemA patient treated with chloroquine for Plasmodium vivax malaria recovers, but fever with parasitaemia recurs eight months later without any travel. What is the explanation?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
C. Relapse from dormant hypnozoites in the liver
Plasmodium vivax and ovale form hypnozoites in hepatocytes that can reactivate months later. Chloroquine acts on erythrocytic stages only, so radical cure needs a tissue schizonticide such as primaquine.
Option by option
A. Development of resistance by the sporozoites
Resistance is a property of blood stage parasites and does not explain a late recurrence of this type.
B. Recrudescence from persisting erythrocytic parasites
Recrudescence arises from surviving blood forms after inadequate treatment, usually within weeks and typically in falciparum malaria.
C. Relapse from dormant hypnozoites in the liver (correct)
Correct. Liver hypnozoites reactivate, and are eradicated by primaquine.
D. Fresh infection through a transfusion
No exposure through transfusion or travel is described, so a fresh infection is not the most likely cause.
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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