How far can measles travel?
According to The Record a woman in Waterloo was diagnosed with the first case of measles in the region since 1996. It is believed that the woman contracted the disease while in Florida, where she was in proximity to another infected individual from England (where vaccination rates are low enough that measles is endemic in the population). Neither individuals had been vaccinated against measles. If that was not bad enough, it appears she spent about three and half hours in Conestoga Mall (a local shopping mall) while infectious. It is expected that this will lead to more cases.
As I stated in my posting about Herd Immunity, highly infections diseases can travel the world pretty quickly. As long as the disease exists somewhere, you are just a few flights away from an infected individual.