Measles cases extend beyond Alberta, Ontario, hotspot map shows

The spread of measles both within provinces and between one another is keeping doctors and health officials across much of Canada on their toes.

The pace of the outbreak is accelerating in Alberta and more than 3,400 people have been confirmed with measles there and in Ontario so far this year. Measles hangs in the air and is one of the most contagious known viruses, infectious diseases specialists say.

Joseph Blondeau, head of clinical microbiology at Royal University Hospital in Saskatoon, says the more widespread the measles virus is in the province, the more opportunities there are for an individual who may not yet know they're infected to interact with others at social events and transmit it to others.

Measles can cause fever, cough and redness of the eyes, followed by white spots next to the molars and a rash that usually starts around the hairline and moves down the body.

"It's not just one geographically restricted cluster in the province," said Blondeau, who is also the provincial lead for clinical microbiology at the Saskatchewan Health Authority.

While the outbreaks are concentrated in Alberta and Ontario, maps of hotspots across Canada reflect how precarious the situation is in several other provinces, meaning some doctors are recommending vaccines for travel within the country.

"What worries me all the time is that we need to be careful about new individuals that are at a higher risk for more severe infection because those are the ones that could end up with complications, whether it's pneumonia or infection of the brain."

Two doses of measles, mumps and rubella vaccine offer 97 per cent protection, said Dr. Ayisha Kurji, an associate professor of pediatrics at the University of Saskatchewan. Measles is considered eliminated in Canada, but that status could be lost given the extent of spread, largely among those who are unvaccinated.

"It's a vaccine that we know a lot about."

Manitoba started experiencing a significant increase in measles in the spring and there doesn't seem to be a decline, said Dr. Davinder Singh, medical officer of health for the province's Southern Health-Santé Sud health region.

Notably, Singh said, the southwest area is most impacted, which corresponds with it having the lowest immunization uptake for measles-containing vaccines, he said.

There are also pockets of low immunization across Manitoba. Medical experts are conducting home visits for those who can't travel, offering pop-up clinics when a group of families needs immunization and extending hours into the evening, depending on local needs, Singh said.

Infants aged six months to under 12 months in some provinces where measles is circulating are eligible for what's called a dose zero to protect them sooner than when children routinely receive two doses.

Manitoba residents who are being evacuated due to wildfires are also offered vaccines, Singh said.

Southwestern Ontario has faced hundreds of measles cases since April. Now there's been a consistent downward trend over the past few weeks, said Dr. Rod Lim, director of pediatric emergency medicine at the Children's Hospital at London Health Sciences Centre.

"We remain alert and able to provide care to those that need it," Lim said in an email.

For every person who has measles, Singh said, there are likely several others who had it and haven't been tested.

"Unconfirmed cases kind of hang out there," said Dr. Gerald Evans, a medicine professor at Queen's University and an infectious diseases specialist who practises at Kingston Health Sciences Centre.

Evans said he thinks the issue of underreporting is a bigger problem with the American data, where the ratio of deaths and hospitalizations to cases appears out of sync with the reported number of cases. The total stands at 1,309 as of July 15, according to the U.S. Centers for Disease Control and Prevention's website.

There have been three confirmed deaths from measles in the U.S. in 2025. In June, Ontario reported the death of an infant who was born prematurely and infected with the highly contagious virus while in the womb. The child also had other serious medical complications unrelated to the virus, the province's chief medical officer of health said.

In Atlantic Canada, P.E.I. and Newfoundland and Labrador have no active measles cases, with one in Nova Scotia and 15 in New Brunswick so far this year.

On the Pacific Coast, B.C. has more than 120 cases, while Yukon has not seen any measles in 2025.

The Northwest Territories had a single measles case in the spring. There have been no cases in Nunavut, according to the Public Health Agency of Canada.