The 2026 World Cup poses a significant risk for infectious disease spread as millions of fans from around the globe converge on 16 host cities across the United States, Canada and Mexico for five weeks of matches, packing into stadiums, airports, hotels, bars and public transport systems. While events of this scale rarely cause major outbreaks, the sheer volume of international travel and mixing creates conditions that can amplify transmission and test public health systems.
Respiratory infections present the greatest danger
By far the most probable threats to World Cup attendees are respiratory infections spread by coughing, sneezing and breathing in crowded spaces. Measles, one of the most contagious infectious diseases known, is surging across the United States, Canada and Mexico. As of 4 June 2026, the US Centers for Disease Control and Prevention (CDC) had confirmed 2,030 measles cases in the US this year, nearing the total for all of 2025 and significantly higher than in previous years. Approximately 92% of those cases have been in unvaccinated individuals or people with an unknown vaccination status, the CDC reports. A single infectious traveller passing through Denver International Airport in 2025 triggered an outbreak of at least 10 cases — a stark illustration of the risk an infected fan in the stands, at an airport or in a bar could pose.
The 2025–2026 flu season reached a 30-year high in severity, according to US health authorities, and COVID-19 continues to cause an estimated 290,000 to 450,000 hospitalisations per year in the US. Mass gatherings amplify the risk of transmission for all three viruses. In the background, avian influenza H5N1 — bird flu circulating in dairy cows and poultry — has caused 70 human infections in the US since 2024, primarily linked to occupational exposure. As of 27 May 2026, 71 cases had been identified, with two associated deaths. The CDC assesses the public health risk as low, and no person-to-person spread has been detected. However, scientists are watching closely for mutations that could change that.
Ebola and mosquito-borne diseases remain on the radar
Though far less likely, more dramatic threats are also being monitored. In May 2026, the World Health Organization declared a Public Health Emergency of International Concern over an Ebola outbreak in the Democratic Republic of Congo and Uganda caused by the rare Bundibugyo strain. This strain kills roughly one in three people it infects; past outbreaks have had case fatality rates ranging from 30% to 50%. No approved vaccines, rapid diagnostic tests or specific treatments exist for this strain, although early supportive care is crucial. As of 2 June 2026, the DRC had reported 378 confirmed cases and 63 confirmed deaths, with the outbreak originating in Ituri Province. Uganda has confirmed two imported cases, including one death. As of 18 May, the DRC had reported 516 suspected cases, including 131 suspected deaths, across seven health zones in Ituri and North Kivu provinces.
Despite the emergency declaration, the risk of Ebola reaching a World Cup stadium is considered very low. The virus spreads only through direct contact with bodily fluids such as blood or saliva, not through the air, and infected people are not contagious until they show symptoms. The US has banned entry for non-US citizens and green card holders who have been in the affected countries within the past 21 days and is screening all passengers travelling from affected areas. Mexico and Canada also have travel restrictions in place.
Mosquito-borne diseases add another layer of risk, particularly for matches in southern US and Mexican host cities during peak summer mosquito season. Dengue set a US record in 2024, with nearly 3,800 cases — a 359% jump over the prior 14-year average. Most cases occurred in travellers returning from the Caribbean and Central America, but locally acquired cases have cropped up, mainly in Los Angeles. Mosquitoes capable of transmitting dengue are found throughout large areas of the southeastern and southwestern US and continue to spread.
Yellow fever, absent from the US, remains a threat to fans travelling from parts of sub-Saharan Africa and South America, where the disease is native. In 2024, 61 human cases of yellow fever were confirmed in the Americas, with 30 fatalities, across Bolivia, Brazil, Colombia, Guyana and Peru. A 2024 outbreak outside the Amazonian jungle hinted that spread to urban areas is possible. Oropouche virus, a once-obscure mosquito-borne illness, exploded across Latin America in 2024 in the largest epidemic ever recorded, with over 8,000 confirmed cases in Brazil alone. The virus has spread beyond the Amazon basin, with cases reported in Cuba for the first time outside the endemic region. Although infection is usually mild, it can cause dangerous complications such as brain inflammation and bleeding disorders, and it can harm a developing fetus. No vaccines or treatments exist. Travel-associated cases have been identified in the US and Europe, but local transmission in the US has not been detected. Travelers carrying these infections may need medical care, but familiarity with them among US physicians tends to be low.
Sexually transmitted infections represent a category of risk that is attracting less media attention. About one in five international travellers engages in casual sex, according to one study, and nearly half of those encounters are unprotected. Mpox, a viral infection that spreads through close physical contact, continues to circulate in the US; as of 1 September 2024, the US had recorded 1,968 mpox cases of clade II. Travel-associated cases of clade I mpox, which has been associated with more serious disease, have been identified but sustained transmission has not occurred. Syphilis is experiencing a global resurgence. In the US, cases have tripled since 2010, reaching their highest numbers since the 1950s. Factors contributing to the rise include declining condom use, the facilitation of casual sex by digital platforms, and practices such as chemsex. Congenital syphilis rates are also rising.
Public health systems brace for heightened demand
Public health authorities across the US, Canada and Mexico have scaled up monitoring efforts to keep World Cup travellers safe. A coalition of academic institutions, companies, nonprofits and public health organisations led by Georgetown University and non-profit healthcare provider MedStar Health has launched the Health Security Operations Center (HSOC). The HSOC will keep close tabs on disease transmission during the event, aiming to fill a public health intelligence gap — particularly in light of reduced CDC coordination systems caused by federal cuts. However, some experts have raised concerns about US resilience to public health threats at the World Cup due to significant cuts to public health infrastructure since 2025, including to the CDC. Key federal leadership roles in biosecurity and pandemic preparedness remain vacant, affecting coordination during major international events.
Fans can take several steps to protect themselves. They should ensure routine vaccinations — especially for measles, flu and COVID-19 — are up to date; practise safe sex; use mosquito repellent; and stay home or wear a mask if they feel sick.
