Yellow fever — DTM&H MCQ

Correct answer: A — Yellow fever

The correct answer is A, Yellow fever. This unvaccinated traveller from a forested (sylvatic) area of Angola, a yellow fever endemic zone, shows the classic biphasic course: an initial period of infection with fever, myalgia and conjunctival injection, a brief remission, then the toxic phase with jaundice, haemorrhage (haematemesis) and renal involvement (proteinuria). This pattern of hepatorenal and haemorrhagic disease following a period of remission is pathognomonic for yellow fever's intoxication phase and reflects direct hepatocellular necrosis and renal injury by the flavivirus. Angola requires proof of yellow fever vaccination for entry precisely because of ongoing sylvatic and urban transmission risk, and the man's unvaccinated status is the key risk factor that permits this diagnosis. Why the other options are wrong: B. Leptospirosis: causes fever, conjunctival suffusion, jaundice and renal impairment (Weil disease), but lacks the classic biphasic remission-then-intoxication pattern and haematemesis is not a defining feature; exposure history would usually involve fresh water or rodent contact rather than forest travel alone. D. Rift Valley fever: causes fever and occasionally haemorrhagic complications or hepatitis, but is linked to livestock or mosquito exposure in specific outbreak areas, and the classic biphasic jaundice-haemorrhage-renal triad is not its hallmark presentation. E. Hepatitis A: causes jaundice but is faeco-orally transmitted, has a much longer incubation, and does not cause haematemesis, proteinuria or the acute febrile prodrome with conjunctival injection described here. C. Dengue without warning signs: by definition excludes bleeding, organ impairment and the severe features described; the presence of haematemesis and proteinuria would reclassify this as severe dengue, not this option. Key point: A biphasic illness in an unvaccinated traveller from a yellow fever endemic area, with remission followed by jaundice, haemorrhage and renal involvement, is the classic toxic phase of yellow fever.

Reference: NaTHNaC TravelHealthPro, Angola country page (yellow fever vaccination requirement under International Health Regulations): https://travelhealthpro.org.uk/country/7/angola