If it isn’t treated, over time it causes scarring to the eyelid that makes the eyelashes turn inward and scrape against the eye, causing tremendous pain and, eventually, blindness. The infection can be treated with antibiotics, while surgery can stop the eyelashes rubbing against the eyeball.
It is spread by the bite of infected black flies that breed in fast-flowing rivers, which gave rise to the term ‘river blindness’. It can be treated with medication to help stop the spread of infection.
Long-term infection causes painful symptoms including abnormal enlargement of body parts, and the stigma that follows can have an additional devastating impact on those affected.
People infected with intestinal worms can become malnourished and more susceptible to disease and chronic illness. This can have negative long-term effects on employment, education, fertility and happiness.
Once they are inside the human body, the larvae develop into adult worms, causing pain, diarrhoea and even cancer. The infection mainly occurs in poorer communities that don’t have access to clean drinking water or adequate sanitation, but it can be controlled using medication.