Measles, a disease many thought was largely a thing of the past, is making a concerning comeback in Ontario. Once considered eliminated in Canada thanks to high vaccination rates, measles cases are rising again due to global outbreaks and declining immunization levels.
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According to Public Health Ontario’s latest report, as of February 26, 2025, Ontario has reported 119 confirmed and 23 probable measles cases, with almost all linked to an ongoing multi-jurisdictional outbreak that began in October 2024. The province last saw an outbreak in 2008, when there was a total of 58 cases.
Measles is a highly contagious virus spreading through the air when an infected person coughs or sneezes. The virus can linger in the air and on surfaces for up to two hours, meaning you can get infected even if the sick person has already left the room.
A person with measles is contagious from about four days before the rash appears to four days afterward. Symptoms typically include:
- High fever
- Cough
- Runny nose
- Red, watery eyes
- A red blotchy rash that spreads from the face down the body
The Ontario report notes that the incubation period—the time from exposure to the onset of symptoms—ranges from 7 to 21 days, with an average of 14 days.
The current Ontario outbreak began when a travel-related case in New Brunswick led to measles spreading in Ontario and later into Manitoba. While New Brunswick declared their outbreak over in January 2025, Ontario continues to experience measles transmission.
As of February 26, 2025, Ontario has reported 177 outbreak-related cases (127 confirmed, 50 probable). These cases have been detected in four public health regions:
- Southwestern Public Health (85 cases)
- Grand Erie Public Health (79 cases)
- Grey Bruce Health Unit (8 cases)
- Chatham-Kent Public Health (5 cases)
Of these cases, 141 were in children and adolescents, while 36 were adults. Disturbingly, 97.9% of the affected children and adolescents were unvaccinated. Eighteen outbreak cases required hospitalization, including one child who needed intensive care.
Who Is at Risk?
While anyone who is not vaccinated can contract measles, some groups are at higher risk of severe complications, including:
- Infants under 1 year old who are too young to be vaccinated
- Pregnant women
- People with weakened immune systems
- Unvaccinated individuals
According to historical data, measles cases in Ontario were rare between 2013 and 2023, with only 101 cases reported over a decade. However, in 2024 alone, there were 64 cases, marking a significant rise.
Do Adults Need a Measles Booster?
The measles vaccine (part of the MMR vaccine, which also protects against mumps and rubella) is highly effective. Public health officials recommend that:
- Children receive two doses: the first at 12-15 months old and the second at 4-6 years old.
- Adults born before 1970 are generally considered immune due to previous exposure.
- Adults born in 1970 or later should have documentation of two doses of measles-containing vaccine. If unsure, a blood test can determine immunity.
For adults who only received one dose as a child, getting a second dose is advised, particularly if they plan to travel internationally or work in healthcare or education. The Ontario report shows that only 4.5% of outbreak cases had received two or more doses of the vaccine, demonstrating the importance of full vaccination.
Ontario isn’t the only place seeing a measles resurgence. The United States has also seen a rise in cases, with Texas currently experiencing a significant outbreak. To date, there have been over 130 cases across Texas and New Mexico, with 18 patients hospitalized and one death. The outbreak has been traced to international travel, a common factor in recent measles cases worldwide.
Health officials warn that with increased global travel, measles can spread rapidly in communities with low vaccination rates. The situation in Texas serves as a stark reminder of why maintaining high immunization coverage is important.
What Can You Do?
- Check Your Immunization Status: Ensure you and your children are up to date on vaccinations.
- Stay Informed: Follow updates from public health officials about outbreaks and travel advisories.
- Know the Symptoms: If you suspect measles, call your healthcare provider before going to a clinic or hospital to avoid exposing others.
- Encourage Vaccination: Talk to friends and family about the importance of vaccines in preventing the spread of measles.
