A measles outbreak has been declared in Pennsylvania. Earlier this week, the Erie County Health Department confirmed two additional cases of measles.

Here are key things to know about measles and the outbreaks in the U.S. What Is Measles? Measles is a highly contagious, airborne disease able to infect up to 90% of people who ar ...

Half of states in the US are now reporting measles cases, with the national total surpassing 800 cases so far this year, ...