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
Frequently asked questions
What is Onchocerca volvulus?
A filarial nematode transmitted by Simulium blackflies that breed in fast rivers, the classic study cause of onchocerciasis (river blindness).
What are the lab clues for Onchocerca volvulus?
Lab clues for Onchocerca volvulus include Skin snip incubation to release microfilariae, Unsheathed skin-dwelling microfilariae, and Subcutaneous nodule examination vocabulary.
What is Onchocerca volvulus commonly confused with?
Onchocerca volvulus is commonly confused with Wuchereria bancrofti and Loa loa.
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.