An ongoing outbreak of measles in Ontario can be linked back to a “large gathering” last fall in New Brunswick’s Mennonite community, according to Ontario’s chief medical officer of health.
In a letter to the province’s health units sent earlier this month, Dr. Kieran Moore said measles cases have been on the rise in southwestern Ontario and over 90 per cent of the cases have been among the unvaccinated.
“Cases could spread in any unvaccinated community or population but are disproportionately affecting some Mennonite, Amish, and other Anabaptist communities due to a combination of under-immunization and exposure to measles in certain areas,” Moore wrote.
Moore said in his letter that there have been 177 cases in the province related to this outbreak as of Feb. 26, most of which were in Grand Erie and Southwestern Public Health units.
“Additionally, exposures and subsequent cases have been reported in Manitoba from family visits in Ontario,” he added.
Measles cases surge in Canada—what you need to know
To further exacerbate the problem, Moore said additional exposures from travel over March break are expected. He advised health-care providers to include measles in their diagnoses, especially in patients with respiratory symptoms and those who travelled to high-risk areas.
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New Brunswick health officials declared an outbreak of measles on Nov. 1, 2024. The province said that during the outbreak, health workers reached 266 people through contact tracing and vaccinated 239 people at 30 clinics. The outbreak, which resulted in a total of 50 cases, was declared over on Jan. 7.
Measles, which is a vaccine-preventable disease, has been spreading throughout the country.
As of March 18, the latest data from the Public Health Agency of Canada (PHAC) shows 369 reported cases in Canada since the beginning of the year.
The measles vaccine is available in Canada as measles-mumps-rubella (MMR) or measles-mumps-rubella-varicella (MMRV) vaccine. It’s estimated to be 85 to 95 per cent effective after a single dose given at 12 or 15 months of age. With a second dose, efficacy rises to nearly 100 per cent, according to PHAC.
For more details on who can get the vaccine and whether you’re up to date on your doses, click here.
— With files from Global News’ Katie Dangerfield
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