Undifferentiated tropical fever workup — DTM&H MCQ

Correct answer: E — Malaria film, blood culture, dengue NS1 and IgM, and urinalysis

The correct answer is E: malaria film, blood culture, dengue NS1 and IgM, and urinalysis. In any patient with undifferentiated fever from a tropical or malaria-endemic area, the priority is to exclude the immediately life-threatening but treatable causes, namely falciparum malaria and bacteraemic illness (typhoid, other Gram-negative sepsis), alongside dengue given its potential for severe haemorrhagic or shock presentations, and a urinalysis to identify a treatable urinary source. Thick and thin malaria films remain the diagnostic gold standard and must be done urgently and repeated if negative, since a single negative film does not exclude malaria. Blood cultures identify treatable bacteraemias such as typhoid, which can mimic malaria clinically but requires different antimicrobial therapy. This combination reflects the minimum syndromic screen recommended for undifferentiated fever surveillance and clinical assessment in returning travellers or endemic-area patients before rarer causes are pursued based on exposure history. Why the other options are wrong: B. Full blood count only: FBC gives nonspecific clues (thrombocytopenia in dengue, leucopenia in typhoid) but cannot itself diagnose or exclude malaria, bacteraemia or dengue, so it is inadequate as the minimum workup. D. Malaria film and CRP: CRP is a nonspecific inflammatory marker that does not identify a causative organism, so bacteraemic and dengue infections would be missed. A. Empirical antimalarial treatment without investigation: treating blindly risks missing typhoid, dengue or urosepsis, delays correct treatment, and contributes to antimalarial resistance and misdiagnosis. C. Blood culture alone: this excludes bacteraemia only and would miss malaria, which is the most rapidly fatal treatable cause if untreated. Key point: undifferentiated tropical fever always needs a bundle covering the major treatable killers, malaria, bacteraemia and dengue, plus urinalysis, not a single test.

Reference: PMC (NIHR/Royal College sourced), 'Fever in the returning traveller', clinical assessment and basic investigation panel including blood smears, blood culture and urinalysis-guided workup, https://pmc.ncbi.nlm.nih.gov/articles/PMC8479414/