New Measles Case Count on Decline in Ontario, Public Health Data Indicates

An electron microscope image of a measles virus particle, provided by the U.S. Centers for Disease Control and Prevention. Cynthia Goldsmith/Centers for Disease Control and Prevention via AP

Ontario continues to see a reduction in measles cases after months of escalating numbers, the latest data shows.

Public Health Ontario (PHO) reported 12 new cases in the province as of July 2, a decrease from the 33 cases reported last week and the 96 cases from the week before that.

Four more people were infected in the Southwestern Public Health zone which covers Oxford County, Elgin County, and the City of St. Thomas. It has been the province’s hardest hit area for several months.

Three more cases of the highly contagious disease have emerged in the Huron Perth Public Health zone, which encompasses London, Stratford, and the surrounding area.

There were two cases each in the Grand Erie district of Brant, Haldimand, and Norfolk counties and in the Algoma district which includes Elliot Lake and Sault Ste. Marie stretching north to Wawa, a region that had been showing the biggest increase in cases for a few weeks.

One case was also recorded in the Windsor-Essex region.

Public health officials noted the downward trend but also pointed out that new cases continue to arise on a weekly basis. A reporting delay also means it’s possible that infections from previous weeks remain unreported.

Numbers often drop during an outbreak “as the proportion of susceptible people in communities become immune, through vaccination or infection,” PHO said.

Ontario Leads Nation in Case Count

Ontario continues to lead the nation in reported measles cases this year with 2,223 cases confirmed as of July 2.

Canada has documented 3,216 confirmed cases and 310 probable cases of measles in 2025 as of June 21, according to Health Canada figures. After Ontario, Alberta has had the second highest incidence of measles with 1,065 cases, followed by Manitoba with 116.

Nearly 74 percent of all cases in Ontario have been among those 19 or younger, according to PHO stats. An additional 20.5 percent of cases were recorded among those aged 20 to 39 and slightly more than 5 percent were found in adults 40 or older.

Risks of Measles

Measles is an extremely contagious disease that poses the risk of severe health complications. It is easily transmitted to those who have not received the measles vaccine or have never contracted the disease, with symptoms manifesting within seven to 21 days of being infected.

Symptoms of measles can include fever, cough, runny nose, and red, watery eyes. The condition usually presents with a rash characterized by red spots and blotchy patches, that initially appear on the face and then spread to the body, arms, and legs.

Measles can cause serious health complications including blindness, severe breathing problems, pneumonia, and encephalitis, an infection causing brain swelling and potentially brain damage, according to the World Health Organization (WHO).

Children younger than 5, adults older than 30, and pregnant women are most susceptible to complications, the WHO said. If a woman contracts measles during pregnancy, this can result in her baby being born prematurely with a low birth weight.

The Canadian Press contributed to this report.