Fily Kamara, 76, was treated for river blindness decades ago and still has his eyesight, although it is greatly diminished. Courtesy Ed Kashi
Fily Kamara, 76, was treated for river blindness decades ago and still has his eyesight, although it is greatly diminished. Courtesy Ed Kashi

How to prevent two of the world's worst diseases for less than the price of a can of cola