Onchocerciasis vector — DTM&H MCQ

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

ModerateHelminthic infectionsOnchocerciasis vectorDTM&H

A river-valley community in West Africa has clusters of pruritic dermatitis and visual impairment. Larvae breed in fast-flowing oxygenated water. What is the vector or intermediate host most relevant to this infection?

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

Reveal the answer and explanation

Correct answer: E — Simulium blackfly

Simulium blackfly is the single best answer because Onchocerca volvulus is transmitted by Simulium blackflies that breed in fast-flowing rivers. Anopheles mosquito is plausible in a related presentation, but it is less appropriate because it does not fit the key discriminator in this vignette. The teaching point is that river blindness reflects the ecology of the vector as well as parasite pathogenicity.

Reference: Manson's Tropical Diseases; WHO neglected tropical diseases guidance; CDC DPDx