Urinary schistosomiasis — DTM&H MCQ
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Correct answer: E — Midday urine filtration for Schistosoma haematobium eggs
The correct answer is E, midday urine filtration for Schistosoma haematobium eggs. A child from a Lake Malawi fishing village with terminal haematuria, suprapubic discomfort and peripheral eosinophilia has the classic picture of urogenital schistosomiasis acquired from freshwater exposure to cercariae shed by infected snails. Egg output from the bladder wall varices peaks around midday, so a urine sample collected between roughly 10am and 2pm and passed through a filter (or centrifuged) maximises the chance of detecting characteristic terminal-spined ova on microscopy. Eosinophilia reflects the host immune response to migrating and egg-laying helminths, reinforcing a parasitic rather than bacterial or malignant cause of haematuria in this epidemiological context. Confirming the diagnosis this way guides prompt praziquantel treatment and prevents progression to obstructive uropathy and bladder pathology. Why the other options are wrong: C. Early morning sputum for acid-fast bacilli: this tests for pulmonary tuberculosis, which does not explain terminal haematuria, suprapubic pain or freshwater exposure, and TB does not typically cause marked eosinophilia. A. Thick blood film at midnight: this is used to diagnose nocturnal microfilaraemia (e.g. Wuchereria bancrofti), which causes lymphoedema or hydrocele, not haematuria or bladder symptoms. B. Stool culture for enteric fever: typhoid presents with fever and systemic illness, not localised urinary tract symptoms, and eosinophilia is not a feature of Salmonella Typhi infection. D. Skin snip from the iliac crest: this detects Onchocerca volvulus microfilariae causing onchocerciasis, which presents with skin and eye disease, not urinary symptoms. Key point: terminal haematuria with eosinophilia after freshwater exposure in an endemic African lake points to S. haematobium, confirmed by midday (or terminal-stream) urine filtration for eggs.
Reference: Exeter Clinical Laboratory International, Schistosoma Urine Microscopy: urine collected between 10am and 2pm (or terminal stream over 24 hours) for detection of S. haematobium eggs, https://www.exeterlaboratory.com/microbiology/schistosoma-urine-microscopy/