The infectious diseases that experts worry could spread during the World Cup

When millions of soccer fans descend on North America this month for the 2026 FIFA World Cup, they will bring more than team jerseys and national pride.

They will also bring the microbes that travel with people.

Public health officials have spent years preparing for the tournament, which is expected to draw visitors from more than 100 countries to the United States, Canada, and Mexico. Although diseases such as Ebola and hantavirus have been in the headlines, public health experts say the diseases most likely to show up in clinics, emergency departments or urgent care centers are likely to be less exotic.

Instead, their top concerns include measles, dengue, respiratory viruses, and sexually transmitted infections that are already circulating. These diseases are likely to spread more easily as fans crowd into airports, hotels, stadiums, and festivals.

“Measles is what I’m most worried about,” said Krutika Kuppalli, an infectious diseases physician and associate professor at UT Southwestern Medical Center in Dallas.

Texas will host 16 World Cup matches in 2026 — more than any other state — with nine matches in the Dallas-Arlington area and seven in Houston. Dallas will host more matches than any other World Cup venue, including a semifinal. The first U.S. match is Friday, in Los Angeles, when the U.S. faces off against Paraguay.

Measles is the most contagious vaccine-preventable viral infection in the world. It can linger in the air for up to two hours after an infected person leaves a room and can spread rapidly among people who lack immunity. A traveler infected with measles could expose hundreds of people in airports, hotels, public transportation systems, restaurants, and stadiums before realizing they are sick.

The concern comes amid a resurgence of measles in parts of the Americas and elsewhere around the world. Health officials have attributed many recent outbreaks in the U.S. and elsewhere to declining vaccination rates and disruptions to routine immunization programs during and after the coronavirus pandemic.

“Measles is in many parts of the world, not just the United States, and all it takes is a small pocket to spread like wildfire,” said Katelyn Jetelina, a California epidemiologist who writes a weekly newsletter about public health and infectious diseases.

The U.S. has already recorded nearly 2,000 measles cases this year, continuing a resurgence that has alarmed public health officials.

South Carolina’s massive outbreak of 997 cases, mostly among unvaccinated children, was the largest outbreak since measles was eliminated from the U.S. more than a quarter century ago.

Puerto Rico has recently experienced major dengue activity, and local transmission has periodically been detected in several U.S. states.

The mosquitoes capable of spreading dengue — Aedes aegypti and Aedes albopictus — are already established in many parts of the country.

Public health experts worry that some visitors carrying the virus could arrive in communities where the right mosquitoes are already present, creating opportunities for local transmission. Matches will be played during peak mosquito season in many host cities, including Miami, Houston, Dallas, and Los Angeles.

Kuppalli said vector-borne diseases are a particular concern in Texas, where clinicians may need to consider not only dengue, but chikungunya, oropouche (also known as sloth fever) and even malaria in travelers arriving from regions where those diseases are circulating.

“I think all of those vector-borne diseases would be fair game,” Kuppalli said.

Although COVID-19 no longer dominates public life the way it once did, public health and infectious-disease experts say they will be closely monitoring respiratory illnesses during the tournament.

Current levels of COVID-19 remain low in the U.S., but experts point out that there has been a summer wave every year since 2019.

Experts say they will be on the lookout not only for COVID-19, but also influenza, RSV and other respiratory pathogens.

Sexually transmitted infections are a recurring concern during major sporting events and mass gatherings because large numbers of visitors, nightlife activity and temporary social networks can increase opportunities for sexual contact.

Experts do not view STIs as an acute outbreak threat in the same way as measles or dengue, but they remain part of public health planning efforts.

The public risk for Ebola remains low because the virus spreads through direct contact with bodily fluids. The 2014 World Cup in Brazil coincided with the West Africa Ebola outbreak in 2014-2016, the largest Ebola outbreak in history. And there was no outbreak during that World Cup.

Kuppalli said one concern is that heightened attention to Ebola could lead clinicians to overfocus on a patient’s country or continent of origin rather than taking a careful travel and exposure history. Someone with fever who has traveled from Africa, she said, should not automatically be assumed to pose an Ebola risk. Clinicians need to ask where the person has been, when they were there, what symptoms they have and what exposures they may have had.

The CDC has expanded disease surveillance efforts in host states and is working with local health departments, hospitals, and emergency medical services to improve preparedness and response capabilities, officials said. The agency has also provided technical assistance to some host cities and is supporting training and coordination related to infectious-disease threats.

Federal officials say they are paying particular attention to diseases that could be imported through international travel, including measles and dengue.

With more World Cup matches than any other state, Texas is taking an unusually proactive approach to infectious-disease preparedness.

Kuppalli and other infectious-disease specialists have partnered with the state health department to establish a round-the-clock consultation hotline that will connect the state’s clinicians with experts in travel-related and emerging infections. The service will be available to healthcare providers across Texas and to medical staff working with World Cup teams seeking guidance on suspected infections tied to the tournament.

Kuppalli, one of the hotline’s medical directors, said the hotline will be staffed by 15 to 20 adult and pediatric infectious-disease specialists within the University of Texas health system. The hotline is designed to give real-time guidance to clinicians who may not regularly evaluate rare or travel-associated infections.

That kind of support may be especially important in Texas, where patients may show up not only at major academic medical centers but also at community hospitals, emergency departments and urgent care clinics spread across a large state.

To help monitor for any concerns from afar, one of the more unusual preparedness efforts is not being run by a government agency at all.

Georgetown University in Washington, D.C., and MedStar Health, one of the largest healthcare providers in the Washington metropolitan region, have established a Health Security Operations Center that will function as an independent hub for monitoring infectious-disease threats during the tournament.

The center, which became operational June 1, is pulling together information about emerging health threats from wastewater surveillance, hospitalization data, international disease alerts and reports from host cities, according to Rebecca Katz, who heads the operation. She is director of Georgetown’s Center for Global Health Science and Security.

Public health experts say wastewater surveillance can sometimes detect pathogens days before health officials see corresponding increases in diagnoses at clinics, emergency departments or hospitals.

The center plans to issue daily public situation reports throughout the World Cup and provide alerts if significant health risks are detected. It also plans to monitor disease activity in host cities and in countries sending large numbers of travelers to the tournament.

For June 9, the report notes growing measles outbreaks in the U.S., Canada and Mexico. The location of these surging outbreaks overlaps with the base camp and match locations of multiple teams, the report said. Pennsylvania is dealing with a large measles outbreak centered in Lancaster County, about 75 miles west of Philadelphia, one of the World Cup’s U.S. host cities. Côte d’Ivoire, or Ivory Coast, has its base camp in nearby Chester.