Morgan Birch was puzzled when her four-month-old daughter, Kimie, suddenly fell ill with a fever and rash.

At first, the Alberta mother assumed it was a common side effect of immunisations – or perhaps a case of chicken pox. Ms Birch then consulted her 78-year-old grandmother, who recognised Kimie’s illness immediately.

“That’s measles,” her grandmother said. Ms Birch was stunned, as she thought the disease had been eradicated.

A lab test later confirmed her grandmother’s hypothesis: Kimie had measles, likely contracted after a routine visit to the hospital in the Edmonton area a few weeks earlier.

Kimie is one of more than 3,800 in Canada who have been infected with measles in 2025, most of them children and infants. That figure is nearly three times higher than the number of confirmed US cases, despite Canada’s far smaller population.

Now Canada is the only western country listed among the top 10 with measles outbreaks, according to CDC data, ranking at number eight. Alberta, the province at the epicentre of the current outbreak, has the highest per capita measles spread rate in North America.

The data raises questions on why the virus is spreading more rapidly in Canada than in the US, and whether Canadian health authorities are doing enough to contain it.

In the US, the rise of measles has been partly linked to vaccine-hesitant public figures, like Health Secretary Robert F Kennedy Jr – although he has since endorsed the measles vaccine as safe.

But Canada does not have a prominent RFK Jr-like figure in public health, noted Maxwell Smith, a postdoctoral fellow in public health at Western University in southern Ontario.

“There are other things that need to be interrogated here I think,” Dr Smith said. “Looking at the Canadian context adds another layer of complexity to this.”

Measles overall is on the rise in North America, Europe and the UK. Cases in the US reached a 33-year high this year, while England reported nearly 3,000 confirmed infections in 2024, its highest count since 2012.

Canada’s 2025 figures have surpassed both. The country has not seen this many measles cases since the illness was declared eliminated in 1998. Before this year, the last peak was in 2011, when about 750 cases were reported.

The MMR vaccine is the most effective way to fight off measles, a highly contagious and dangerous virus, which can lead to pneumonia, brain swelling and death. The jabs are 97% effective and also immunise against mumps and rubella.

The hardest-hit provinces have been Ontario and Alberta, followed by Manitoba.

In Ontario, health authorities say the outbreak began in late 2024, when an individual contracted measles at a large Mennonite gathering in New Brunswick and then returned home.

Mennonites are a Christian group with roots in 16th-Century Germany and Holland, who have since settled in other parts of the world, including Canada, Mexico and the US.

Some live modern lifestyles, while conservative groups lead simpler lives, limiting the use of technology and relying on modern medicine only when necessary.

In Ontario, the illness primarily spread among Low German-speaking Mennonite communities in the province’s southwest, where vaccination rates have historically been lower due to some members’ religious or cultural beliefs against immunisation.

Almost all those infected were unvaccinated, according to data from Public Health Ontario.

Catalina Friesen, a healthcare worker at a mobile clinic serving the Mennonite population near Aylmer, Ontario, said she first became aware of the outbreak in February, when a woman and her five-year-old child came in with what appeared to be an ear infection. It later turned out to be a symptom of measles.

“This is the first time I’ve ever seen measles within our community,” Ms Friesen told the BBC.

Cases spread rapidly from that point, reaching a peak of more than 200 a week across Ontario by late April.

While new confirmed cases have since dropped sharply in Ontario, Alberta has emerged as the next hotspot. There, the spread happened so quickly that health officials were unable to pinpoint exactly how or where the outbreak began, said Dr Vivien Suttorp, the medical officer of health in southern Alberta, where cases are the highest.

She, too, said she had not seen an outbreak this bad in her 18 years working in public health.

Ms Friesen noted that Canada has a higher concentration of conservative Low German-speaking Mennonites than the US, which may be a factor behind the higher number of cases.

But Mennonites are not a monolith, she said, and many have embraced vaccinations. What’s changed is the rapid spread of anti-vaccine misinformation both in her community and beyond after the Covid-19 pandemic.

“There’s hearsay that immunisations are bad for you,” Ms Friesen said, or are “dangerous”.

This is amplified by a general distrust in the healthcare system, which she said has historically ostracised members of her community.

“We are sometimes put down or looked down upon because of our background,” she said, adding that she herself has experienced discrimination in hospitals based on assumptions about her beliefs.

Experts say it’s tough to pinpoint why measles have spread wider in Canada than in the US, but many agree that cases in both countries are likely underreported.

“The numbers that we have in Alberta are just the tip of the iceberg,” said Dr Suttorp.

But there is one big reason driving the outbreak: low vaccination rates, said Janna Shapiro, a postdoctoral fellow at the University of Toronto’s Centre for Vaccine Preventable Diseases.

Dr Shapiro said there is “an element of chance” at play, where a virus is introduced to a community by accident and spreads among those who are unprotected.

“The only thing that is going to stop an outbreak is getting those vaccination rates up,” she said. “If the public is not willing to get vaccinated, then it will continue until the virus can’t find anymore receptible hosts.”

In general, studies show that vaccine hesitancy has risen in Canada since the pandemic, and the data reflects that. In southern Alberta, for example, the number of MMR vaccines administered has dropped by nearly half from 2019 to 2024, according to provincial figures.

Covid-19 vaccine mandates were fiercely opposed by some during the pandemic, prompting the so-called “Freedom Convoy” protest in Ottawa where truckers gridlocked the city for two weeks in 2021.

That opposition has since expanded to other vaccines, said Dr Shapiro.

Pandemic-related disruptions also left some children behind on routine immunisations. With measles having been largely eliminated, families likely did not prioritise getting their kids’ vaccinations up to date, Dr Shapiro said.

That is not the case for Ms Birch, who began routine immunisations for her baby Kimie as soon as she was eligible. But Kimie was still too young for the measles vaccine, which is typically given at 12 months in Alberta.

Dr Suttorp said Alberta has since lowered that age cap in response to the recent outbreak, and there has been an uptick in people taking the vaccine.

Health units across the country have also tried to encourage people to get vaccinated through public bulletins and radio advertisements. But the response is notably more muted than that during the Covid-19 pandemic, health officials say.

Kimie has since slowly recovered, Ms Birch said, though she continues to be monitored for potential long-term effects of the virus.

The Alberta mother said she was saddened and horrified when she learned her daughter had measles, but also “frustrated and annoyed” at those choosing not to vaccinate their children.

She called on people to heed public health guidelines and “protect the ones that can’t protect themselves”.

“My four-month-old shouldn’t have gotten measles in 2025,” Ms Birch said.