World Cup surveillance goes on alert for measles

As the 2026 World Cup kicks off across 16 U.S. cities, health agencies are preparing for outbreaks in tightly packed crowds, with measles topping the list. Experts say daily situation reports, wastewater testing, and intensified checks at airports and hospital

The first thing health officials are watching isn’t the final score. It’s what travels when thousands of people pour into stadiums, bars, and tourist sites—day after day, across North America.

For the 2026 World Cup. officials are putting surveillance teams on high alert for infectious germs that can spread fast in crowds. A heat wave may be the most obvious threat during summer games. but experts say outbreaks are the risk they can’t afford to guess wrong about. They plan to scrutinize wastewater, hospital visits, and even public signals such as social media for early warning signs.

Measles is among the top concerns. The Pan American Health Organization. PAHO. issued a warning this week. pointing to a nearly six-week stretch of packed stadiums. bars. and tourist sites in 16 cities. Officials are watching for infections ranging from the stomach bug norovirus to mosquito-borne dengue fever.

“This is truly a marathon,” said Palak Raval-Nelson, Philadelphia’s health commissioner.

The work is landing on health agencies already under strain. The mass gatherings come at a tense moment for budget-strapped health agencies in the U.S. as the Centers for Disease Control and Prevention has been hit hard by Trump administration staffing cuts. The CDC was already dealing with a growing Ebola outbreak in central Africa and a cruise ship hantavirus outbreak. while its expected World Cup disease surveillance dashboard was “in final development” days before games began. according to the Department of Health and Human Services.

“Our public health professionals are pretty stretched,” said global health specialist Rebecca Katz of Georgetown University, who is leading an unusual new hub to help.

At the Health Security Operations Center. a joint effort between Georgetown and MedStar Health. workers analyze data from around the country so they can alert health authorities—potentially including emergency rooms—if trouble starts to brew. The center is issuing daily “situation reports” about disease trends around World Cup host cities and team base camps to several hundred local and federal public health groups. emergency management and hospital officials. and others who have signed up.

“It’s important that we don’t become alarmist,” said MedStar emergency medicine specialist Dr. Shane Kappler. “We’re trying to be the insurance policy.”

More than 2,000 people in the U.S. have come down with measles this year, nearly as many as during all of last year, according to the CDC. Patients can spread measles before the rash appears and they realize they’re sick. The concern is sharper because, until recently, the U.S. seldom saw measles except from international travel by unvaccinated people.

“With frequent U.S. outbreaks, actually a lot of our international partners are worried about measles being exported to them after the games,” said Georgetown’s Katz.

Measles isn’t confined to the U.S. PAHO says it is spreading in Canada and has exceeded 11,000 cases in Mexico. The organization is urging soccer fans to be sure they’re vaccinated, with a health campaign warning that a single measles patient can spread the virus to up to 18 unprotected people.

So why do so many officials and experts keep mentioning Ebola in the same breath as measles?. Brown University’s Dr. Craig Spencer. who survived Ebola while working in the West Africa outbreak over a decade ago. said he has repeatedly been asked about the risk during the World Cup—but called it far from the top threat.

“For me, Ebola is not the No. 1 or No. 2 or even No. 3 threat.” Spencer added: “I am concerned about importation of measles, I am much more concerned about the importation of other infectious threats that may not seem as scary to us as Ebola.”

Many health experts agree the risk of Ebola spreading in the U.S. is very low. They point to government travel screenings and restrictions on people recently in outbreak-affected areas. They also note that Ebola spreads by contact with bodily fluids from someone showing symptoms. not through the air like measles or respiratory viruses.

“One fortunate thing about this virus is you’re most contagious when you’re really quite ill. It’s not like COVID, where you could be sitting next to someone who doesn’t even know they’re infected and perhaps contract the virus,” said Jennifer Nuzzo, director of Brown’s Pandemic Center.

There’s also precedent for germs finding their way into big sporting events. Canadian scientists linked a community measles outbreak to the 2010 Olympics in Vancouver, and clusters of norovirus had to be contained during the Olympics this year in Milan and in 2018 in South Korea.

To detect signs of trouble, experts look at how certain infections shed genetic material. Sophisticated testing of wastewater can spot it before clinicians see patients. Measles, for example, can appear in wastewater days before an emergency room sees its first patients.

This week’s surveillance reports from Katz’s center noted that wastewater testing recently found diarrhea-causing rotavirus, hepatitis A and norovirus in some parts of the U.S.—a warning signal as soccer crowds arrive.

In Dallas, officials ramped up wastewater screening, including at the international airport. Dr. Phil Huang. director of Dallas County Health and Human Services. said the approach casts a wide net rather than targeting specific illnesses. His team is also enhancing the usual mosquito testing. checking not just for West Nile virus that regularly spreads in the U.S. but for viruses more common in other countries like dengue and chikungunya.

Philadelphia’s Raval-Nelson said the city has been preparing for months, including mock emergency drills and communications with counterparts around the country.

“I don’t want to send a message that there’s one key thing,” she said. “We have the frameworks in place to carry out what we need to.”

The push is clear: the stakes are tied less to one headline virus and more to how quickly public health can spot the first hint of spread—then act before a “marathon” of crowds turns into a chain reaction.

2026 World Cup measles PAHO Centers for Disease Control and Prevention CDC Ebola wastewater testing public health surveillance rotavirus hepatitis A norovirus dengue chikungunya West Nile virus Health Security Operations Center Georgetown University MedStar Health