(AP) - With one-fifth of states seeing active measles outbreaks, the U.S. is nearing 900 cases, according to figures posted Friday by the U.S. Centers for Disease Control and Prevention.

The spiking rates of two diseases could be signaling a return of childhood illnesses, according to a new ProPublica report.

The measles rash usually doesn’t appear for more than a week after someone has been exposed. Other symptoms are better early indicators of a potential measles case, health experts say.