Which parasite is classically associated with river blindness and pruritic skin nodules due to microfilariae in the skin?

• A. Wuchereria bancrofti
• B. Loa loa
• C. Brugia malayi
• D. Onchocerca volvulus

Answer: (D)

Onchocerca volvulus is the parasite that fits river blindness and itchy skin nodules caused by microfilariae in the skin. Adult worms live in subcutaneous nodules and release microfilariae that migrate through the skin, producing intense pruritus and dermatitis; when these microfilariae reach the eye, they can damage the cornea and lead to progressive vision loss. Transmission occurs via the bites of Simulium blackflies that breed around fast-flowing rivers, which is why the disease is concentrated near rivers. The other parasites produce different disease patterns—Wuchereria bancrofti and Brugia malayi cause lymphatic filariasis with edema, and Loa loa causes eye-related migration symptoms but not the classic river-blindness pattern—so this parasite best matches the described condition.