The recent outbreak of Ebola in Uganda and the Democratic Republic of the Congo are pushing U.S. officials to act. More than 200 people have died, according to the World Health Organization, as the Bundibugyo strain driving the infections is rare and has no known treatment or vaccines. 

Already, U.S. officials have imposed a 30-day travel ban for most foreign nationals who have recently visited the two African countries as well as South Sudan because of its proximity. U.S. citizens and nationals returning from those countries can return immediately but need to route through specific airports for enhanced Ebola screening and also agree to 21 days of post-arrival monitoring. 

Not even the athletes participating in the world’s biggest sporting event are free from scrutiny. The executive director of the White House Task Force on the FIFA World Cup 2026, Andrew Giuliani, said last month the U.S. asked the DRC’s national team to quarantine in Belgium for 21 days before arriving in the U.S. The tournament begins on June 11. 

“They need to maintain that bubble or they risk not being able to travel to the United States,” he said in an interview with ESPN. “We cannot be any clearer.”

While the U.S. prepares aggressively for Ebola, measles “currently poses a substantially greater public health threat than Ebola,” Dr. Steven Goldberg, the chief medical officer of molecular diagnostic laboratory HealthTrack, told Fortune.

Though it is less fatal than Ebola, measles can cause pneumonia and swelling of the brain, as well as death in some cases, and immunocompromised people and children are especially at risk.

Measles’ unique risk

Given the mass of international visitors set to visit the U.S. this summer, public health officials will also be monitoring other infectious diseases, including COVID and influenza. But measles may pose a unique risk.

Measles have been getting more common in the U.S. for years. And with just over 2,000 cases reported this year, the U.S. is already close to exceeding last year’s total of 2,207, according to a tracker by the Johns Hopkins Bloomberg School of Health. 

In addition, measles can spread through the air, while Ebola spreads through interaction with bodily fluids of the infected.

The nature of the World Cup also amplifies the risk. Whereas other major sporting events, such as the Super Bowl and the Olympics, are usually held in a single city or a handful clustered nearby, the World Cup is taking place in 16 cities across the U.S., Mexico, and Canada, with fans likely traveling between different cities and countries to support their teams as the tournament progresses. A total of 48 nations, more than ever before, are also participating in the tournament.

“Stadiums, fan zones, airports, hotels, and public transit create ideal conditions for airborne transmission,” Goldberg told Fortune. “A single infected individual in a public area can lead to multiple exposures, and the virus persists in the air for up to 2 hours after the infected person has left.”

The U.S. officially eradicated the measles in the year 2000. But in recent years, there have been outbreaks in states like Texas, Utah, and Arizona, tracking closely with pockets of unvaccinated or undervaccinated individuals, which can lead to a drop in herd immunity. There were more than 2,200 infections and three deaths attributed to measles in 2025. 

People coming to the U.S. from countries where measles is still endemic could add to the risk, said Goldberg. Iraq, the Democratic Republic of the Congo, and Ivory Coast fall into that category and are participating in the World Cup this year.

While the strict measures being put in place in the U.S may be able to constrain the spread of Ebola, measles will be harder to contain.

“Measles exploits gaps in vaccination coverage that are widening due to vaccine hesitancy and pandemic-related disruptions,” said Goldberg.

Some of the best advice for avoiding infection include staying up to date on vaccinations and masking in crowded areas, like stadiums.

Still, it’s yet to be seen whether cases of disease will overshadow goals and big wins as the most memorable part of the World Cup.