Toronto Public Health says it’s investigating a lab-confirmed case of measles in an adult who recently travelled abroad.
It says members of the public may have been exposed to measles on three international flights on May 30.
It says the affected person was on Ukraine International Airlines flight PS423, Icelandair flight FI529 and Icelandair flight FI603.
Toronto Public Health says measles is a highly contagious disease that spreads easily to those who are susceptible.
Anyone who has not had two doses of a measles vaccine or who has not had measles in the past is at risk of infection.
All people who may have been exposed are advised to check their immunization record, watch for symptoms of measles, such as high fever, cold-like symptoms, sore eyes or sensitivity to light and a red rash lasting four to seven days.