Information about Measles

Measles is a disease that is caused by a virus. It is very contagious. Over 90 per cent of people who are not immune to measles will become infected after being exposed to someone with measles.

People who are not up-to-date with their measles vaccination are at highest risk of infection. Make sure you and your children are up-to-date. This is especially important before travelling outside of Canada. Learn about vaccination for measles.


Symptoms of measles can appear seven to 21 days after being exposed to the measles virus. Symptoms of measles include:

  • Fever
  • Cough
  • Runny nose
  • Red / watery eyes
  • Small blue-white spots on the inside of the mouth / throat (known as Koplik spots). These spots are not always present.
  • Blotchy red rash. This rash appears about three to seven days after the other symptoms develop.

If you develop symptoms

It is important to monitor for these symptoms in yourself and children, especially after returning home from travelling outside of Canada. If you develop symptoms:

  • Stay home and avoid contact with others, especially with those who are most at risk
  • Do not go to work, school or child care for at least four days after your rash starts. The onset of a rash is day zero. This is because you could spread measles to others.
  • Contact your health care provider. Make sure to call ahead before going to a clinic. This is so the health care staff can take appropriate precautions to prepare for your visit. This may include seeing you when there are less patients in the office and providing a mask for you to wear when you arrive.

How measles spreads

Measles spreads very easily. People who have measles can spread it from four days before a rash appears to four days after they get a rash. People can get sick with measles by:

  • Breathing the air in a location where someone with measles has recently been, even up to two hours after that person has left the room
  • Coming into contact with an infected person's cough or sneeze
  • Touching an infected surface, and then touching their eyes, nose or mouth. The measles virus can live on infected surfaces for at least two hours.

Who is most at risk

Some people are at higher risk of developing severe disease. These include:

  • Infants under 12 months of age
  • Immunocompromised individuals
  • Pregnant individuals. People who get measles while pregnant may suffer from a miscarriage, go into premature labour or give birth to an infant with low birth weight.
  • Anyone who has not had their age appropriate vaccines

More information

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