Parasite
Onchocerca volvulus
River blindness from blackfly bites
on-koh-SER-kuh VOL-vyoo-lus
High-yield clue
Blackfly (Simulium) transmission near rivers, subcutaneous nodules, and microfilariae migrating to the eye causing blindness are the core clues.
Overview
A filarial nematode transmitted by Simulium blackflies that breed in fast rivers, the classic study cause of onchocerciasis (river blindness).
Classification
- Nematode (filarial worm)
- Adults coiled in subcutaneous nodules
- Unsheathed microfilariae in skin
- Transmitted by Simulium blackfly
Lab & identification clues
- Skin snip incubation to release microfilariae
- Unsheathed skin-dwelling microfilariae
- Subcutaneous nodule examination vocabulary
Associations
- Simulium blackfly vector near rivers
- Subcutaneous nodules and intense pruritus
- Ocular microfilariae and river blindness
- Wolbachia-endosymbiont teaching point
Commonly confused with
- Wuchereria bancrofti
- Loa loa
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.