It's a small world after all: The measles outbreak that has spread from Disneyland probably began with a foreign visitor to the California park or an American who became infected overseas, according to Centers for Disease Control and Prevention officials. The chief of the CDC's National Center for Immunization and Respiratory Diseases says the outbreak, which involves a measles strain similar to ones seen in Indonesia, Qatar, Azerbaijan, and Dubai, "is a wake-up call to make sure that we keep measles from regaining a foothold in our country," NBC reports.