Yellow fever — DTM&H MCQ

Correct answer: D — Yellow fever

Yellow fever (D) is correct because this vignette describes the classic toxic phase: an unvaccinated traveller in a forested (sylvatic) area of Brazil who develops fever followed by jaundice, albuminuria and haematemesis. UKHSA notes that after the initial febrile illness, a proportion of patients go on to develop jaundice, abdominal pain, renal failure and haemorrhage, which is exactly this triad. The forest setting points to the jungle (sylvatic) transmission cycle via Haemagogus mosquitoes, and lack of vaccination is the key risk factor, since a single dose of live-attenuated vaccine gives lifelong protection. Albuminuria combined with jaundice and haematemesis is a recognised discriminating feature that helps separate yellow fever from simple viral hepatitis. Why the other options are wrong: E. Malaria: causes fever and can cause jaundice in severe falciparum disease, but it does not typically produce marked albuminuria or haematemesis as a defining feature, and there is no mention of cyclical fever or blood film findings pointing to this. A. Leptospirosis: can cause jaundice and renal impairment (Weil's disease) but is acquired through contact with water contaminated by animal urine, not simply forest exposure, and haematemesis is not a characteristic feature. B. Hepatitis A: causes jaundice but is transmitted faeco-orally, has no link to forest exposure or mosquito bites, and does not cause albuminuria or haemorrhagic features such as haematemesis. C. Dengue fever: causes fever and can progress to haemorrhagic manifestations, but jaundice and significant albuminuria are not typical, and severe dengue is more associated with plasma leakage, thrombocytopenia and shock rather than this hepatorenal-haemorrhagic picture. Key point: unvaccinated traveller with fever progressing to jaundice, albuminuria and haemorrhage after exposure in a forested area of South America is the classic toxic-phase presentation of yellow fever.

Reference: UKHSA/GOV.UK, 'Yellow fever: guidance, data and analysis', https://www.gov.uk/guidance/yellow-fever-guidance-data-and-analysis