The U.S. is on pace to break the record for the most measles cases in a year since the disease was eradicated two decades ago. Health officials are reporting 555 cases so far this year. And officials have identified a patient zero for one of the major outbreaks. Last November a man flew from Israel to Brooklyn, which was in midst of a measles epidemic. From there, he traveled to Michigan, visiting ultra-Orthodox Jewish communities and unknowingly bringing the virus with him. He stayed in private homes, stopped by multiple synagogues and ultimately infected 39 people in the Detroit area.