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

As the 2026 FIFA World Cup draws millions of fans to stadiums across North America, infectious disease experts are sounding the alarm about potential health risks that come with mass gatherings on this scale. The combination of international travel, crowded venues, and summer heat creates conditions that could accelerate the spread of several concerning pathogens.

The World Cup presents a unique epidemiological challenge. Unlike the Olympics, which concentrates athletes and visitors in a single city, the expanded 48-team tournament spreads across 16 host cities in the U.S., Canada, and Mexico — meaning surveillance systems need to monitor outbreaks across a vast geographic area with varying public health infrastructure.

**Diseases of Concern**

Several infectious diseases are drawing particular attention from health officials:

Measles continues to circulate at elevated levels in the U.S., with cases in 2026 running well above pre-pandemic baselines. International visitors from countries with lower vaccination rates could introduce new chains of transmission in crowded fan zones.

Dengue fever has been expanding its range northward as climate change creates more hospitable conditions for the Aedes mosquito. Several U.S. Gulf Coast states have reported locally acquired cases, and the summer tournament timeline coincides with peak mosquito season.

COVID-19 variants continue to circulate, and while most countries have moved past pandemic-era restrictions, mass gatherings remain ideal environments for respiratory virus transmission. The tournament will also bring visitors from regions with different COVID variant landscapes.

Hantavirus has drawn attention following a recent cruise ship outbreak that killed three people, though the risk to World Cup attendees is considered low. Still, the incident highlights how easily unfamiliar pathogens can emerge in travel settings.

**Lessons from Past Events**

The 2022 Qatar World Cup provided a mixed picture. While a large-scale surveillance system successfully monitored disease spread, the tournament also coincided with seasonal respiratory virus peaks. The 2016 Rio Olympics saw Zika virus concerns dominate pre-event coverage, though the actual outbreak impact was less severe than feared.

Public health officials have been planning for the 2026 tournament for over a year, with the CDC, Public Health Agency of Canada, and Mexico's epidemiological directorate coordinating surveillance protocols.

**Preparation and Vigilance**

Host cities are establishing enhanced disease monitoring systems, including wastewater surveillance near fan zones and stadium venues. Mobile health clinics are being set up near major venues, and multilingual health information campaigns are being prepared for visiting fans.

The biggest challenge may not be any single disease but rather the logistics of coordinating health response across three countries with different healthcare systems, vaccination requirements, and public health capabilities. What happens in one host city can rapidly affect another as fans travel between venues.

**What This Means For You**

If you're attending World Cup matches or fan events, update your vaccinations — especially MMR and COVID boosters — before traveling. Carry hand sanitizer, stay hydrated in summer heat, and pay attention to local health advisories in host cities. If you develop symptoms after attending matches, seek medical attention promptly and mention your World Cup exposure. The tournament will be a celebration, but the best fans are prepared ones.