P. malariae blood-stage treatment — DTM&H MCQ

Correct answer: C — Oral chloroquine

Oral chloroquine (C) is correct because Plasmodium malariae remains uniformly chloroquine sensitive worldwide, and this parasite causes a quartan fever pattern (fever every fourth day) with a benign, non-severe course, exactly as described. Current UK malaria treatment guidance states that non-falciparum malaria (P. vivax, P. ovale, P. malariae) can be treated with either an oral ACT or chloroquine, and since P. malariae never develops chloroquine resistance and has no hepatic hypnozoite stage, a straightforward 3-day oral chloroquine course is definitive treatment with no need for radical cure. The absence of severe features (no organ dysfunction, high parasitaemia, or impaired consciousness) confirms that parenteral therapy is unnecessary here. Why the other options are wrong: D. Intravenous artesunate: reserved for severe or complicated malaria, almost always due to P. falciparum; this patient has no severe features and a non-falciparum species, so IV therapy is not indicated. E. Miltefosine: this is an antileishmanial agent used for visceral and cutaneous leishmaniasis, not an antimalarial, and has no role here. B. Albendazole: an anthelmintic used for helminth infections (for example, hydatid disease, soil-transmitted helminths); it has no activity against Plasmodium species. A. Primaquine radical cure: primaquine eradicates dormant hepatic hypnozoites, a feature unique to P. vivax and P. ovale; P. malariae has no hypnozoite stage, so radical cure is unnecessary and would expose the patient to needless G6PD-related haemolysis risk. Key point: P. malariae causes quartan fever, lacks a hypnozoite liver stage, and remains chloroquine sensitive, so uncomplicated infection is treated with oral chloroquine alone, without primaquine.

Reference: Lalloo DG, Shingadia D, Bell DJ, et al. UK malaria treatment guidelines 2016. Journal of Infection 2016;72(6):635-649. Recommendation 19: Either an oral ACT or chloroquine can be used for the treatment of non-falciparum malaria. https://www.journalofinfection.com/article/S0163-4453(16)00047-5/fulltext