One morning last autumn, four-year-old Joey Wilcox did not feel right when he woke up. The boy had lost feeling on the left side of his face. It was the first sign of a much more serious condition. Three days later, Joey was in a hospital, unable to move his arms or legs or sit up. Tests failed to identify a cause. Doctors feared he might lose the ability to breathe. “It’s devastating,” his father, Jeremy Wilcox of Virginia, told the Associated Press. “Your healthy child can catch a cold, and then become paralyzed.” Joey survived, but still suffers some of the effects. He was one of 228 confirmed victims of acute flaccid myelitis, known as AFM, in the United States last year. AFM is a rare, mysterious and sometimes deadly paralyzing disorder. The number of cases seems to rise and then fall every other year. The condition is beginning to worry public health officials because it is striking more and more children.