Yellow fever — DTM&H MCQ

Correct answer: C — Yellow fever

The correct answer is C, Yellow fever. This is the classic biphasic (saddleback) presentation: an initial acute febrile phase with jaundice and epigastric pain, followed by a brief remission, then a toxic phase with haemorrhage (haematemesis), oliguria (renal failure), and confusion (hepatic encephalopathy). This pattern of remission followed by hepatorenal decompensation is pathognomonic for yellow fever and reflects direct hepatotropic and renal viral injury with consumptive coagulopathy. The unvaccinated status and Nigerian setting (a yellow fever endemic country) further support arboviral transmission by Aedes mosquitoes as the mechanism, and current UK travel health guidance identifies Nigeria as a yellow fever risk country requiring vaccination. Why the other options are wrong: D. Hepatitis A: Causes jaundice and malaise but does not produce a biphasic remission-relapse pattern, nor does it typically cause haemorrhage, oliguria, or acute renal failure; fulminant hepatic failure is rare in young adults. E. Leptospirosis: Can cause jaundice and renal impairment (Weil's disease) but the classic course is a single septicaemic phase followed by an immune phase with meningism, not a distinct haemorrhagic hepatorenal crisis after remission, and haematemesis is uncommon. B. Dengue haemorrhagic fever: Causes fever, haemorrhage, and plasma leakage, but jaundice is not a prominent feature and the defervescence is followed by a critical plasma-leak phase (shock), not primarily hepatorenal failure with jaundice. A. Acute hepatitis B: Has an insidious onset over weeks, not sudden fever, and does not classically present with a febrile remission-relapse pattern or acute haemorrhagic renal failure. Key point: A biphasic illness, remission then relapse with jaundice, haemorrhage, and renal failure, in an unvaccinated traveller from an endemic African country is the hallmark of yellow fever.

Reference: NaTHNaC/TravelHealthPro, Yellow Fever factsheet and country risk guidance, travelhealthpro.org.uk