Lassa fever — DTM&H MCQ

Correct answer: B — Lassa fever

The correct answer is B, Lassa fever. Lassa fever is endemic in Nigeria, and Edo State (home to the Irrua Specialist Teaching Hospital, the country's main Lassa referral centre) is a recognised hotspot, so a funeral exposure there is a classic epidemiological clue. The combination of fever, pharyngitis, retrosternal chest pain and facial oedema is a highly specific clinical pattern for Lassa fever; indeed, fever, pharyngitis and retrosternal pain together have been shown to be strong predictors of Lassa fever detection, and facial oedema is a recognised feature not typically seen in the other viral haemorrhagic fevers. The markedly elevated AST (5200 IU/L) reflects the characteristic severe hepatocellular damage of Lassa virus infection, with AST rise (more than ALT) being a well documented poor prognostic marker. This constellation, exposure history plus pharyngitis plus retrosternal pain plus facial oedema plus grossly deranged AST, is essentially pathognomonic for Lassa fever among the listed haemorrhagic fever viruses. Why the other options are wrong: C. Ebola virus disease: Ebola typically causes more prominent gastrointestinal symptoms (profuse vomiting and diarrhoea) and overt haemorrhagic manifestations, but pharyngitis and facial oedema are not characteristic features, and Nigeria's outbreaks have been sporadic and travel linked rather than endemic in Edo State. A. Yellow fever: Yellow fever classically causes jaundice, a brief remission ('period of calm') followed by haemorrhagic relapse, and is associated with severe hepatitis, but pharyngitis, retrosternal chest pain and facial oedema are not typical, and it is vaccine preventable with high coverage reducing incidence in endemic areas. D. Marburg virus disease: Marburg presents similarly to Ebola with a maculopapular rash and gastrointestinal bleeding, but it is not endemic in West Africa (linked to bats in East/Central Africa) and lacks the pharyngitis/facial oedema pattern. E. Crimean-Congo haemorrhagic fever: This is tick-borne or from contact with infected livestock blood, geographically concentrated outside West Africa, and does not present with facial oedema or pharyngitis as key features. Key point: Fever with pharyngitis, retrosternal chest pain, facial oedema and markedly raised AST in someone from Nigeria's Lassa fever belt (including Edo State) is the classic presentation of Lassa fever.

Reference: UKHSA (GOV.UK) Viral Haemorrhagic Fever Algorithm and Guidance for clinicians; supporting clinical data: McCormick JB et al., cited in Ajayi NA et al., 'Lassa Fever 2016 Outbreak in Plateau State, Nigeria', Frontiers in Public Health 2018