Severe malaria parasite count — DTM&H MCQ

Correct answer: A — Urgent quantified parasite density

The correct answer is A, urgent quantified parasite density. In confirmed Plasmodium falciparum with features suggesting severe disease (jaundice, breathlessness), the parasite count is essential to define severity and guide treatment. UK malaria treatment guidelines classify infections with parasitaemia above 2% of red blood cells, or with organ dysfunction such as jaundice or respiratory compromise, as severe or complicated malaria requiring intravenous artesunate rather than oral therapy. Speciation alone is insufficient because it does not stratify risk; the actual burden of parasitised red cells drives prognosis and the decision for intravenous therapy, higher level care and repeat films to monitor clearance. This is a time critical investigation that must accompany, not follow, any decision about admission level or drug route. Why the other options are wrong: C. Widal serology: Tests for typhoid antibodies with poor sensitivity and specificity; irrelevant once falciparum malaria is already confirmed on film. D. Hepatitis A IgG: Jaundice here is far more likely due to malarial haemolysis and hepatic dysfunction than hepatitis A, and this result would not change acute management of confirmed severe malaria. B. Schistosoma serology: Reflects chronic or past exposure, takes weeks to become positive, and plays no role in acute assessment of a febrile jaundiced traveller with malaria already diagnosed. E. Urine antigen for Legionella: Could theoretically cause fever and breathlessness, but the malaria diagnosis is already established; chasing an alternative cause before quantifying and grading confirmed malaria delays correct treatment. Key point: Once falciparum malaria is confirmed, urgent parasite quantification (percentage parasitaemia) is mandatory to grade severity and decide whether intravenous artesunate and higher level care are needed.

Reference: PHE Advisory Committee on Malaria Prevention for UK Travellers (Lalloo DG, Shingadia D, Bell DJ, Beeching NJ, Whitty CJM, Chiodini PL). UK malaria treatment guidelines 2016. Journal of Infection 2016; 72(6):635-649. https://www.sciencedirect.com/science/article/abs/pii/S0163445316000475