Enlarge Image Blind spot. The parasitic worm Onchocerca volvulus (inset) can move to the eyes and cause blindness as in these two patients in Guinea-Bissau. Onchocerciasis is considered a neglected tropical disease. Credit: Harry Anenden/WHO; (inset) CDC A small parasitic worm is one of the leading causes of blindness in the world. But now researchers have discovered a molecule in the urine of African patients that could help diagnose those infected with the parasite and help eliminate the devastating disease known as river blindness. The illness, scientifically known as onchocerciasis, is caused by the parasitic worm Onchocerca volvulus. Black...