The Guam Department of Public Health is on measles alert after two cases of the contagious disease were confirmed.
The Supervisor of the Department's immunisation programme says he was contacted on Tuesday to say a 30-year old man had contracted the disease while in the Philippines.
Ron Balajadia says the man has also transmitted measles to another member of his household.
Mr Balajadia says the Department has launched an awareness campaign and nurses are monitoring the island.
He says the disease is hard to control.
"It's very labour intensive but what we've done is not only have we networked with our private providers, our clinics and our hospital but we also sent the message out to the media so that the public can be aware and they can also be our allies in detection of rash-type illnesses and with fever and to also give us a heads up so we can all work on this as a community.."