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Measles is a highly contagious viral infection that spreads through the air when an infected person breathes, coughs or sneezes.

Measles can result in complications such as pneumonia, ear infections, brain infections, other infections and infrequently, death can occur.

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How is it spread?

Measles is a virus that spreads easily through the air. It is transmitted in tiny droplets when an infected person coughs, sneezes or breathes. It can survive in the air for up to two hours. Measles can be spread from four days before the rash appears until four days after the onset of the rash.

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What do you do if you are exposed to measles?

If you are born before 1970, have had measles in the past, or have received two doses of measles-containing vaccine you are considered protected against measles infection.

If you have been exposed and are not protected, a vaccine can prevent measles from developing if given within 72 hours (3 days) of exposure. These individuals should contact their health care provider, or the Middlesex-London Health Unit, at the phone number listed below as soon as possible. 

Pregnant women who are not protected, individuals who have problems with their immune system and are not protected, and infants under six (6) months of age can be treated with another medication up to six (6) days after exposure. These individuals should contact their health care provider, and the Middlesex-London Health Unit, at the phone number listed below as soon as possible.

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Signs and Symptoms:

  • Fever, cough and runny nose
  • Red, irritated eyes and light sensitivity
  • Small white, grey or blue spots in the mouth
  • Red, blotchy rash, which is the last symptom to appear. The rash appears on the face and then spreads down over the body, and will begin to fade after about a week.

Symptoms can start anywhere from 7 to 21 days after a person has been exposed to the virus. Symptoms usually develop around 10 days after exposure and the rash usually develops 14 days after exposure.

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What to do if you develop symptoms:

  • Stay home and do not allow others to visit for at least four (4) days after the rash starts.
  • Contact a healthcare provider as soon as possible and describe your symptoms over the phone. Because measles is so contagious, follow their instructions so that they can arrange to see you without exposing others to the virus.
  • On arrival, immediately ask for a mask when you enter the office/clinic, and to be placed in a private room. If this is not possible, wait in your car until you are seen by the healthcare provider.

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How is measles treated?

There is no treatment for this viral illness. Supportive measures can be taken to relieve sore throat, cough and fever. Care should be taken not to expose others to infection by staying home and not allowing others to visit for at least four (4) days after the start of the rash. Immunization prior to exposure is the best defense against infection.

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How can measles be prevented?



Two doses of measles vaccine are given to children after their first birthday to provide optimal protection. Measles vaccine is given in combination with other vaccines.

  • 1st dose MMR (measles, mumps, rubella) vaccine: for children 12 months of age
  • 2nd dose MMRV (measles, mumps, rubella, varicella): between four to six years of age, preferably prior to school entry. Second dose was historically given at 18 months.


  • Some adults may have received only one dose of the vaccine in the past. A second dose of MMR is recommended for anyone born in 1970 or later.
  • Measles vaccine should not be given to pregnant women or people with immune system problems.

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Vaccine Information

The measles, mumps and rubella (MMR) vaccine is publicly funded and available at your health care provider's office or through the London Travel Clinic.

Information is also available on the following websites:

If you're uncertain about your vaccination status and whether you are up to date, please contact your healthcare provider to verify. Or you can access your vaccination records via Immunization Connect Ontario (ICON).

Travel Health Advice 

Click here for information on travel health guidance.

Healthcare Providers

Access additional information intended for healthcare providers here.

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Date of creation: March 15, 2014
Last modified on: March 14, 2024