An Air France flight was diverted to Montreal after a passenger who should not have boarded was found to be subject to U.S. entry restrictions related to Ebola risk. American authorities have put travel restrictions in place to reduce the potential spread of Ebola, and this passenger was not permitted to enter the United States. The individual was removed from the flight before it continued to its destination of Detroit.
From the source
A spokesperson for the agency says the passenger 'should not have boarded' the plane bound for Detroit due to U.S. entry restrictions put in place to reduce Ebola risk.