It’s the first report of a contagious case of measles in Montreal since July, Public Health says.
Montreal Public Health says hundreds of people may have been exposed to measles during a recent NATO conference in the city.
The agency says one of the participants in the military alliance’s parliamentary assembly, which took place in Montreal last month, received a measles diagnosis after returning to their home country and would have been contagious while they were in the city.
The agency is warning people may have been exposed to the highly contagious disease during sessions at the Palais des congrès on Nov. 23, 24 and 25, as well as during private events and at downtown hotels that were frequented by conference participants, including the infected person.
Public Health says the measles virus can remain in the air for up to two hours after a contagious person has left an enclosed space.
A highly effective vaccine exists against measles, which was declared eliminated in Canada in 1998.
Officials say the infected conference participant was not vaccinated against the disease.