Toronto Public Health officials say the risk is low, but they are warning people who flew on a number of flights recently that they may have been exposed to the measles.
The agency has issued a news release saying it's investigating three confirmed cases of the measles.
It says one of the people caught the disease in another country, while the other two cases involved Toronto residents who were exposed to a person with measles who lives outside the Greater Toronto Area.
Westjet confirms one of its crew members has been diagnosed with the measles.
Health officials say members of the public may have been exposed to measles if they were on certain Westjet or Emirates Airline flights earlier this month.
They're advising people to check immunization records and watch for symptoms of measles if they were on any of the following flights:
- Emirates Airline flight EK517, which left Delhi, India on March 19 and arrived in Dubai, United Arab Emirates.
- Emirates Airline flight EK241, which departed Dubai, March 20 bound for Toronto.
- WestJet flight WS450, departed Abbotsford, B.C. on March 22 and arrived in Calgary.
- WestJet flight WS610, departed Calgary on March 22 bound for Ottawa.
- WestJet flight WS369, departed Ottawa on March 22 for Toronto.
- WestJet flight which departed Toronto on March 23 and arrived in Montreal.
- Westjet flight WS581, which departed Montreal on March 24 and arrived in Toronto.
- WestJet flight WS2668, which left Toronto for the Turks and Caicos Islands on March 24.
- WestJet flight WS2669, which left Turks and Caicos Islands for Toronto on March 24.