8 Straight Up Revolting Things In Nature

We all know that one person who is just a total parasite. They might eat all your food, borrow money without paying it back or use your sofa as their own personal hotel room. This worm is a little bit like that, apart from instead of finishing your Corn Flakes, it causes debilitating blindness.

Onchocerca volvulus is a nematode that causes onchocerciasis or "river blindness" and it is a particular problem in developing parts of Africa.

The worm is spread by the bite of a black fly. Once the parasite is inside its host, the larvae spread throughout the subcutaneous tissue and into the eyes. The larvae in the eye will cause repeated scarring and, eventually, blindness.

The slightly less damaging, but infinitely more disgusting Loa loa nematode worm (pictured), will actually live in the eyeball as an adult creating the rather charming effect above.

Both of these parasites can live for nearly 20 years, that's a long time to play host to an unwelcome guest.