Measles outbreaks across North America are threatening the region’s status of having officially eliminated the virus, officials from the Pan-American Health Organization warned, potentially undoing a hard-fought victory to wipe out community transmission.
The U.N. agency pointed to a 4.5-times increase in reported measles cases this year across North and South America, compared to the same period last year.
More than 97% of cases across the region so far this year have been in the U.S. or Canada. Cases have also been reported in Mexico and Argentina.
“The risk of outbreaks has increased, given the increase in measles cases worldwide, coupled with factors such as low coverage of the first and second doses of measles, mumps, and rubella vaccine,” PAHO, the World Health Organization’s regional office for the Americas, said in a report published last week.
Other factors driving spread that were cited by PAHO include increased movement of people around the Americas and an uptick in dengue, a mosquito-borne viral infection that can mask the spread of measles due to similar symptoms.
What is measles elimination?
The U.S. achieved measles elimination in 2000, after documenting a year of no endemic spread of the virus. WHO officials declared North and South America free of measles in 2016, making the Americas the first region to reach this milestone in the world.
Health officials define “measles elimination” as proof of no endemic spread of the highly contagious virus within an area for at least 12 months. A continuous chain of transmission persisting for at least a year would reverse that goal.
While the Centers for Disease Control and Prevention usually reports hundreds of measles cases every year around the U.S., many are from short-lived outbreaks linked to unvaccinated young children who were recently outside the U.S.
The last large outbreak of the virus in the U.S. was in Illinois last year. It was largely confined to migrant shelters in Chicago.
CDC officials warned in 2019 that the country was at risk of losing measles elimination status, after outbreaks spread for several months around undervaccinated communities in the New York area. However, the U.S. ultimately kept its status.
Outbreaks in Texas and Canada
Authorities have been grappling with a growing measles outbreak linked to unvaccinated communities across northwest Texas. At least 158 cases have been confirmed, state officials said Monday.
A child died last month from the outbreak. The CDC’s death certificates data suggest the most recent reported U.S. death from measles before that was in 2019.
The Trump administration has ramped up its messaging about the outbreak in recent days, including through an op-ed by Health and Human Services Secretary Robert F. Kennedy Jr. and offers of support for Texas officials.
“The CDC is actively supporting Texas state health officials and will be on the ground Tuesday working with the frontline health care providers,” HHS Principal Deputy Chief of Staff Stefanie Spear said in a statement Monday.
In Canada, officials have also been grappling with a months-long outbreak that spread between two of the country’s provinces.
Ontario’s public health department has reported at least 177 cases linked to the outbreak.
