Onchocerciasis — SCE Infectious Diseases MCQ

Instant feedback + full explanation. One question, done properly.

ModerateParasitologyOnchocerciasisSCE Infectious Diseases

A 30-year-old man from sub-Saharan Africa presents with a painless firm subcutaneous nodule on his iliac crest. He has been experiencing intense pruritus with a papular rash, and ophthalmological examination reveals punctate keratitis. Skin snip shows microfilariae. What is the diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — Onchocerciasis (river blindness; Onchocerca volvulus)

Subcutaneous nodules (onchocercomata containing adult worms), intense pruritus with papular dermatitis, ocular involvement (punctate keratitis, sclerosing keratitis, chorioretinitis), and microfilariae on skin snip are diagnostic of Onchocerciasis (Onchocerca volvulus). Transmitted by Simulium blackflies near fast-flowing rivers. Treatment is Ivermectin 150 µg/kg as a single dose, repeated every 6–12 months. Doxycycline 100 mg BD for 4–6 weeks (anti-Wolbachia) is increasingly used as a macrofilaricidal strategy to kill adult worms.

Reference: WHO 2022 – Onchocerciasis; UKHSA 2023 – Imported filariasis