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As measles spreads across the Americas, outbreaks in Mexico and Canada have also turned deadly
As measles cases in the United States continue to mount, neighboring countries Canada and Mexico are also experiencing significant outbreaks – all of which have been linked to at least one death.
On Thursday, the chief medical officer of health of the Canadian province Ontario announced that an infant who was born prematurely with a measles infection had died.
'The infant contracted the virus before birth from their mother, who had not received the measles, mumps and rubella (MMR) vaccine,' Dr. Kieran Moore said in a statement. 'While measles may have been a contributing factor in both the premature birth and death, the infant also faced other serious medical complications unrelated to the virus.'
At least four people have died from measles in Mexico in 2025, and three people have died in the US: two children in Texas and one adult in New Mexico, all of whom were unvaccinated.
This years' measles outbreaks are the biggest that Canada and Mexico have seen in decades, and the World Health Organization has warned that the 'overall risk of measles in the Americas Region is considered high.' Low vaccination rates are a key driver of this elevated risk assessment, the agency said.
Mexico has reported at least 1,520 measles cases as of late May, according to data from the Pan American Health Organization.
Canada reached measles elimination status in 1998, meaning that there has not been continuous spread of the virus for more than a year. But there have already been more cases reported so far this year than there were in the previous 27 years combined. At least 2,755 measles cases have been reported in Canada so far this year, according to federal data that was last updated on Monday, the vast majority of those which have been in Ontario residents.
And the US has reported at least 1,168 measles cases so far this year, according to federal data published Friday – nearly 80% of which are associated with an outbreak centered in West Texas that has spread to New Mexico, Oklahoma and possibly Canada. It's the second highest number of cases that the US has reported since achieving measles elimination status in 2000.
Significant shares of the measles outbreaks in the US, Canada and Mexico have been concentrated in Mennonite communities that are closely connected to each other – and that have historically had low vaccination rates due largely to minimal interactions with formal health care systems.
However, in a recent webinar, experts from the Pan American Health Organization did not formally link outbreaks in the three countries to each other.
'The outbreak [in Mexico] started in Chihuahua, at the heart of Mennonite communities, who were very close to Texas through the border, but they're also close to other Mennonite communities in Canada,' Dr. Alvaro Whittembury, regional adviser for the Comprehensive Immunization Special Program, said in a presentation on Wednesday. 'It's important to show that although at first the outbreak starts in Mennonite communities … the vast majority of cases are outside of these communities, and they are sustained in the general population.'
Only a small share of confirmed cases in the Americas have identified genetic sequences, experts from the Pan American Health Organization said, and there haven't been enough identical sequences to explicitly link cases across countries.
In April, Mexico issued a warning for people traveling to the US and Canada due to high measles case rates. The US Centers for Disease Control and Prevention has also stepped up its guidance for travelers, advising that anyone traveling internationally should be vaccinated with two doses of the MMR vaccine.
'Anyone who is unvaccinated is at risk and I urge everyone, but especially those who may become pregnant, to ensure they have received two doses of the MMR vaccine, which will protect both a parent and baby,' Moore said in his statement Thursday. 'This vaccine has been safely used for over 50 years and is highly effective. Two doses provide nearly 100 per cent protection.'
