South Sudan, Nov. 28 -- The road to Ariath in South Sudan cuts through seemingly endless scorched plains that bake and crack in the hot sun, and then turn to thick mud when it rains.

Inside a mud-walled home, 11-year-old Aher sits beside a clay pot filled with water: his family's improvised refrigerator that holds his lifesaving insulin. Without it, his blood sugar levels spiral out of control, and his body convulses with seizures.

Aher's parents are farmers, and have lived through countless nights of fear. When Aher was barely 2, he fell gravely ill, vomiting, losing weight, and losing consciousness. His parents went from one clinic to another, selling what little they had to pay the medical bills and transport costs, but his condition...