What is Measles?

Measles is a respiratory disease caused by a highly contagious virus. It is a virus that is easily spread through the air, from person to person, through breathing, coughing or sneezing. Measles is the leading cause of vaccine-preventable deaths in children worldwide.

There has been increased measles activity in Southwestern Ontario. While measles cases are usually linked to travel outside of Ontario, since measles is highly contagious, a single case can result in local outbreaks, particularly among persons who are not fully protected against measles.

Click here for Potential Public Exposures for a list of places where people may have been exposed to the measles virus in Waterloo Region.

How measles spreads

  • If you come into contact with someone who has measles, you could develop symptoms about 7 to 21 days later.
  • Measles can spread if you have shared the same room or airspace with a person who has measles.
  • A person is contagious from four days before the rash begins until four days after the rash has appeared.
  • Measles can remain in the environment for up to two hours after an infected person has left the area.

Symptoms of measles

  • Measles begins with cold-like symptoms such as a runny nose, cough, sore throat, fever, and red, watery eyes that are sensitive to light.
  • Small white spots sometimes appear in the mouth and back of the throat.
  • 3 to 7 days later, a red blotchy rash appears on the face and spreads to the rest of the body.
  • The rash lasts 4 to 7 days.
  • Serious complications can occur such as:
    • One in ten children will develop an ear infection or bronchopneumonia.
    • One in one thousand children will develop an infection of the brain (encephalitis).
    • One or two out of a thousand children will die as a result of measles.

Measles exposure 

A list of places in Waterloo Region that people may have been exposed to the measles virus is available on the Potential Public Exposures page.

If you think you have been exposed to measles:

  • Stay home if you are ill to avoid passing germs to others.
  • Seek medical attention when exposure is suspected and before any symptoms appear.
  • Those who notice possible symptoms are asked to stay home and call ahead before visiting a clinic.

If you have been exposed to a person with measles and are not fully protected against measles, you are at risk of developing the disease.

See Measles Exposures in Ontario for information about measles exposure locations in Ontario.

If you think you have been exposed to measles, click the button to access the Measles Self-Assessment Tool to guide your next steps.

Click here for Measles Self-Assessment Tool

For further information please call Public Health at 519-575-4400 (Monday to Friday 8:30 a.m. to 4:30 p.m.).

Preventing measles with vaccination 

Getting vaccinated is the best way to protect yourself against measles. 

Routine vaccination recommendations for children

  • Current Ontario recommendations are that children receive two doses of a measles vaccine:
    • First dose on/after their first birthday
    • Second dose at 4 to 6 years old
    • For some infants 6 to 12 months of age, one dose of the a measles vaccine can provide protection if there is a risk of exposure

Routine vaccination recommendations for adults 

  • Health care workers or military personnel:
    • Two doses of the measles vaccine are recommended regardless of year of birth
  • Born in 1970 or later:
    • Should have at least one dose of the measles vaccine
    • A second dose is recommended for international travellers and post-secondary students
  • Born before 1970:
    • Adults born before 1970 are considered to be immune to measles based on probable exposure earlier in life
    • One dose of the measles vaccine is recommended for international travellers and post-secondary students.

Vaccination recommendations for individuals who live, work, travel, worship or spend time in affected regions and communities with measles cases and where the risk of exposure is higher:

This currently includes the Southwestern, Grand Erie and Huron Perth local public health units and will be reassessed as needed.

  • Infants (6 to 11 months):
    • Should receive one dose of measles vaccine. Two additional doses continue to be recommended after the age of one year
  • Children (1 to 4 years):
    • Children who have received their first dose of measles vaccine are encouraged to receive a second dose as soon as possible (at a minimum of four weeks from the first dose).
  • Adults (18+ years) born on or after 1970:
    • A second dose of measles vaccine is recommended

If you do not have vaccination records, you can look them up for school-aged children or check with your health care provider. Measles vaccines are usually recorded as ‘MMR’, ‘MMRV’ or ‘M’ on vaccination records.

Where to get vaccinated

Additional resources