Lymphatic Filariasis — SCE Infectious Diseases MCQ

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HardParasitologyLymphatic FilariasisSCE Infectious Diseases

A 32-year-old man from Ghana presents with a large scrotal swelling that has developed over several years. Examination reveals massive bilateral hydroceles. Midnight blood film shows sheathed microfilariae with nuclei not extending to the tip of the tail. What is the causative organism?

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Correct answer: D — Wuchereria bancrofti

Lymphatic filariasis presenting with hydrocele (and potentially elephantiasis of the lower limbs/genitalia), with sheathed microfilariae on midnight blood film (nocturnal periodicity) where nuclei do NOT extend to the tail tip, is diagnostic of Wuchereria bancrofti. Brugia malayi microfilariae have subterminal and terminal nuclei at the tail tip. Loa loa has diurnal periodicity. Treatment is Diethylcarbamazine (DEC) in non-Onchocerca/Loa loa endemic areas, or Ivermectin plus Albendazole in co-endemic areas.

Reference: WHO 2022 – Lymphatic filariasis guidelines; UKHSA 2023 – Filariasis