Cerebral malaria — DTM&H MCQ

Correct answer: D — Cerebral malaria

Cerebral malaria (D) is correct because the WHO clinical case definition requires unarousable coma in a patient with P. falciparum parasitaemia once other causes of encephalopathy, particularly hypoglycaemia, post-ictal state and bacterial meningitis, have been excluded, exactly as described in this child. In endemic sub-Saharan Africa, falciparum malaria is by far the commonest cause of non-traumatic coma with seizures in children, reflecting sequestration of parasitised erythrocytes in cerebral microvasculature causing diffuse encephalopathy. The stem deliberately supplies a normal glucose (excluding hypoglycaemic coma, a recognised confounder and complication of severe malaria and of quinine treatment) and absent meningism (making bacterial meningitis unlikely), leaving cerebral malaria as the unifying diagnosis for coma plus positive blood film. Persistence of coma beyond the immediate post-ictal period in a parasitaemic, febrile African child is the classic examination vignette for cerebral malaria. Why the other options are wrong: E. Japanese encephalitis: this is a mosquito-borne flavivirus confined to Asia and the Western Pacific, not transmitted in Mozambique, and would not explain a positive P. falciparum film. C. Severe dengue: dengue causes plasma leakage, haemorrhage and shock rather than a primary encephalopathic coma syndrome, and again does not account for falciparum parasitaemia on the film. B. Bacterial meningitis: this is explicitly excluded by the stem's statement of no meningism, and while it is an important differential for febrile coma it is not supported by the parasitological finding here. A. Rabies encephalitis: this follows an animal bite with a much longer incubation and a distinct clinical course (hydrophobia, agitation, later paralysis), not an acute convulsion with parasitaemia and normal glucose. Key point: unarousable coma with P. falciparum parasitaemia, once hypoglycaemia and meningitis are excluded, defines cerebral malaria.

Reference: UK Malaria Treatment Guidelines (Lalloo DG et al, on behalf of PHE and British Infection Association), Journal of Infection 2016 (updated), Diagnosis and management of severe falciparum malaria, https://www.journalofinfection.com/article/S0163-4453(16)00047-5/fulltext