Q1. Which Plasmodium species form dormant liver hypnozoites causing relapse? A. P. falciparum only B. P. vivax and P. ovale C. P. malariae only D. All species equally ANSWER: B — P. vivax and P. ovale. Why: only these species leave dormant liver forms, which reactivate weeks to months later. Falciparum does not, so it does not relapse in this way — though it can recrudesce from inadequately treated blood-stage infection. LEARNING POINT: relapse is why these species need a liver-stage drug in addition to blood-stage treatment.

Q2. In dengue, the critical phase typically begins: A. On the first day of fever B. As the fever DEFERVESCES, around days 4–6 C. Two weeks after recovery D. Only in patients given NSAIDs ANSWER: B — as the fever settles. Why: plasma leakage begins around defervescence, which is why apparent improvement is the point of greatest danger. LEARNING POINT: patients discharged when the fever settles are the ones who return in shock.

Q3. A patient returning from a malarious area has fever and rigors. One thick film is negative. The correct action is: A. Exclude malaria and investigate other causes only B. Repeat films over 48 hours before excluding malaria C. Treat empirically without further testing D. Discharge with paracetamol ANSWER: B — repeat the films. Why: parasitaemia fluctuates with the parasite's cycle, so a single film can be falsely negative. Three negatives over 48 hours are conventionally required before abandoning the diagnosis in a suspicious case. LEARNING POINT: one negative film excludes nothing.

Q4. A patient with severe falciparum malaria becomes drowsy. Before attributing this to cerebral malaria, the most important immediate check is: A. Blood glucose B. Chest X-ray C. Serum ferritin D. Urine culture ANSWER: A — blood glucose. Why: hypoglycaemia is common in severe malaria and produces identical drowsiness. It is instantly reversible, and missing it means treating the wrong problem. LEARNING POINT: check glucose repeatedly in severe malaria, particularly if quinine is being used.

Q5. A dengue patient becomes afebrile on day 5 but has abdominal pain, vomiting, a rising haematocrit and falling platelets. The correct action is: A. Discharge — the fever has settled B. Admit for monitored intravenous fluid; this indicates plasma leakage C. Give aspirin for the pain D. Transfuse platelets immediately ANSWER: B — admit and monitor. Why: these are warning signs of the critical phase. A rising haematocrit with falling platelets indicates plasma leakage requiring careful fluid management. C: NSAIDs and aspirin are avoided for bleeding risk. D: platelet transfusion is guided by bleeding, not count. LEARNING POINT: defervescence with warning signs is an admission, not a discharge.

Q6. Before giving primaquine for radical cure of vivax malaria, which test is essential? A. Liver function tests only B. G6PD status C. Chest X-ray D. Serum electrolytes ANSWER: B — G6PD status. Why: primaquine is an oxidant drug and precipitates severe haemolysis in glucose-6-phosphate dehydrogenase deficiency. Testing before prescribing prevents a serious iatrogenic haemolytic episode. LEARNING POINT: this connects to the anaemia chapter, where the same enzyme defect appears from the haematological side.

Q7. A patient with prolonged fever after working in scrub vegetation has a painless black-crusted ulcer on the trunk. The most likely diagnosis is: A. Dengue B. Scrub typhus C. Malaria D. Leptospirosis ANSWER: B — scrub typhus. Why: an ESCHAR at the mite bite site is characteristic. It is painless and frequently in a covered area, so it is missed unless the patient is fully undressed and examined. D: leptospirosis follows water contact and causes conjunctival suffusion and severe myalgia. LEARNING POINT: undress the febrile patient and look — the diagnostic sign is often somewhere nobody has looked.