Measles Outbreaks Turn Deadly Across the Americas, with Rising Cases in U.S., Canada, and Mexico

As measles spreads rapidly across North America, public health officials are sounding the alarm over rising infections — and mounting fatalities — in the United States, Mexico, and Canada.

Infants and Children Among the Victims

In a heartbreaking case out of Ontario, Canada, health officials confirmed this week that a premature infant has died after contracting measles in utero. The baby’s mother had not received the measles, mumps, and rubella (MMR) vaccine, and doctors say the infection may have contributed to the premature birth and death, though other unrelated health complications were also involved.

South of the border, Mexico has reported four measles-related deaths in 2025. The United States has seen three fatalities so far this year: two children in Texas and one adult in New Mexico — all unvaccinated.

A Resurgence Not Seen in Decades

Health authorities are grappling with the largest measles outbreaks in decades. According to the Pan American Health Organization (PAHO), Mexico has recorded over 1,500 cases, while Canada has already surpassed all combined totals from the past 27 years with at least 2,755 cases, the majority in Ontario.

Meanwhile, the U.S. has logged at least 1,168 cases in 2025, according to federal data released Friday. Nearly 80% of these are tied to an outbreak that began in West Texas and has since spread to New Mexico, Oklahoma, and possibly Canada. It’s the second-highest case count in the U.S. since measles was officially declared eliminated in 2000.

Why Is This Happening?

The World Health Organization has declared the measles threat across the Americas as “high,” largely due to low vaccination rates.

Many outbreaks have been centered in Mennonite communities, which often have lower immunization coverage due to limited interaction with mainstream healthcare systems. In Mexico, the outbreak began in Chihuahua, home to a large Mennonite population, and closely connected to similar communities in Texas and Canada.

However, officials from PAHO clarified during a recent briefing that while the outbreaks originated in similar communities, most of the ongoing spread is now happening in the general population.

No Clear Genetic Link — Yet

Despite the cross-border spread, health experts caution that there’s currently no confirmed genetic evidence directly linking outbreaks across the three countries. Only a small portion of cases have had their viral genomes sequenced, making it difficult to track precise transmission chains.

Travel Warnings and Vaccine Urgency

With international travel amplifying the risk of spread, Mexico issued a travel advisory in April for those heading to the U.S. and Canada. The U.S. Centers for Disease Control and Prevention (CDC) has also updated its guidance, urging anyone planning international travel to ensure they’ve received two doses of the MMR vaccine.

Ontario’s chief medical officer, Dr. Kieran Moore, reinforced this message Thursday, particularly for those who may become pregnant:

“Anyone who is unvaccinated is at risk, and I urge everyone — 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. This vaccine has been safely used for over 50 years and is highly effective. Two doses provide nearly 100 percent protection.”