The parasites that cause river blindness and elephantitis have been afflicting people for centuries. Alexis Huguet/AFP via Getty Images In Greek mythology, King Sisyphus was condemned by the god Zeus to spend eternity rolling a boulder up a hill only to have it roll back down, having to start anew every day. His story captured our attention as researchers studying neglected tropical diseases – a collection of conditions that primarily affect poor people in low-income countries.