River Blindness

What’s The Entry Point For The Worms That Cause River Blindness

This time our mini bite’s topic is What’s The Entry Point For The Worms That Cause River Blindness and as a pathologist we need to understand it what is the actual reason behind the Entry Point For The Worms That Cause River Blindness.

Entry Point For The Worms That Cause River Blindness

Still on the topic of parasitic worms – and today’s is a teeny tiny worm called Onchocerca volvulus. Actually, it’s more properly termed a filarial nematode, and its vector is black flies (yuck, I knew there was a good reason I can’t stand black flies!).

Infection with Onchocerca volvulus, or onchocerciasis, is also known as river blindness because the black flies’ favourite habitat is near fast-moving water. It is the second most common preventable cause of blindness in sub-Saharan Africa. It’s also common in other parts of Africa, and in South America and Yemen.

The little worms get into the skin and mate in the dermis (ew). Females release tons of microfilariae that accumulate in the skin and in the eye. The eye lesions start in the cornea, with punctate keratitis (caused by inflammation around dying microfilariae) and corneal opacities.

Eventually, the choroid and retina are involved, and blindness ensues.


About Onchocerca volvulus

Onchocerca volvulus is a nematode that causes onchocerciasis and is the second leading cause of blindness from infection worldwide after trachoma. It is one of the 20 neglected tropical diseases listed by the World Health Organization, with elimination expected from certain countries by 2020.



  • Kristine Krafts, MD
  • Robbins Pathology 10th page 398-400.



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