http://www.kindercare.com/uploadedfiles/documents/measlesletter.pdf) as a condition of being allowed to continue to work in infant rooms.
A major outbreak of measles has broken loose in the United States this winter. The outbreak has been partly traced to contacts made between a patient and other visitors to Disneyland in southern California. At least 121 infections have been counted, spread across 17 states. ABC News/Channel 7 covers the outbreak: http://abcnews.go.com/Health/investigators-unsure-started-measles-cluster-illinois/story?id=28802471.