Ontario reports 182 new measles cases, surpassing 1,600 since outbreak began

A dose of the measles, mumps, and rubella (MMR) vaccination awaits the next patient during a vaccine clinic at Southwestern Public Health in St. Thomas, Ont. on Tuesday, March 4, 2025. THE CANADIAN PRESS/ Geoff Robins

TORONTO — Health officials say measles has infected 182 more people in Ontario over the last week, bringing the province’s case count to 1,622 since an outbreak began in October.

Public Health Ontario’s measles report says there have been 119 hospitalizations, including nine intensive care cases.

Of those hospitalized, 95 per cent were unvaccinated, including 89 children.

This is the third consecutive week Ontario is reporting that new cases are in the 200-range, which is on the higher end since experts started keeping track of weekly spread.

Southwestern Public Health Unit’s Dr. Ninh Tran called the province’s case count over the last few weeks “significant.”

His public health unit is still where most of the new cases are concentrated. However, he says most cases are no longer infectious.

“This week has been the highest week, and it is being driven by really good detection and significant transmissions in households,” Tran says.

Southwestern has had 104 new cases reported locally over the past week, he says, which is higher than the province’s data because of differences in reporting periods.

Measles cases in Alberta have reached nearly 400 since mid-March, infecting just over 120 kids under age five.

The highly contagious disease continues to primarily infect unvaccinated children, infants and teenagers, both in Ontario and Alberta.

This report by The Canadian Press was first published May 15, 2025.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

Hannah Alberga, The Canadian Press