The teen has not been identified and health officials would not say how long he was in isolation.
People are placed in isolation when they are contagious and considered a public health threat.
Wake County Health officials are focusing their efforts on people he came in contact with who have not been immunized.
The virus can be deadly and is highly contiguous.
"The risk is pretty high. If you put ten people in a room who are not vaccinated and you put someone with measles in the room with them, nine of the people will get sick," said Wake County Medical Director Dr. Kimberly McDonald.
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If you or your children are covered with the two vaccinations, officials say there is no risk. If you aren't protected, it could take up to 21 days for someone to start seeing symptoms.
Officials are scrambling to alert thousands of people exposed to the virus.
"It takes a lot of time and a lot of effort, but that's what we're here to do," McDonald said.
The Cary YMCA has sent out a notification to its 5,500 members. The email warns the patient was at the Y last week, and spent most of his time in the weight room and men's locker.
The center was one of nine spots the teen visited before seeking treatment.
CLICK HERE FOR DETAILED LIST OF PLACES EXPOSURE MAY HAVE OCCURRED
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