The World Cup is a massive event that will expose how profoundly the infectious disease landscape has changed in recent years. Organizations dealing with static assumptions about disease threats may be caught by surprise.
On June 11, the 2026 World Cup kicks off across the United States, Canada, and Mexico. As the first tournament to feature teams from 48 different countries, it will host millions of spectators, attending 104 events in 16 cities. All in just a 39-day span. Mass gathering events, especially those with massive global travel, are known moments of great risk. In a normal year, a country may have a small handful of these events. This summer, we are about to experience dozens of global mass gatherings in a very compressed time frame.
Most tickets have gone to fans in the three host countries, but there are also significant sales from Spain, England, France, Germany, Brazil, Colombia and Argentina. These are countries with serious and varied infectious disease burdens. For example, all three host nations and the four European nations mentioned have either recently lost measles elimination status or are endemic, indicating continual risk of exposure. Vector-borne diseases are currently surging across the fan nations of South America, including a serious yellow fever outbreak in Colombia. Recent evidence also indicates that clade Ib mpox is spreading locally in Spain and other European countries, posing risk of spread through intimate contact.
While the World Cup is indeed a unique event, there are real risks that remain long after the championship is won and fans go home. Coupled with the fact that global tourism surpassed pre-pandemic levels in 2024 and doesn’t show signs of slowing, the new travel health landscape continues to evolve.
Here is an overview of what has changed, and the many ways that travel, environmental and social change can expose organizations to surprising threats.
Vector-borne diseases: the map is evolving
Perhaps you’ve seen a “risk map” of vector-borne diseases, one that might suggest that these threats are steady, unchanging and confined to a select few areas. It’s hard to overstate how misleading an impression this is. Vector-borne diseases are constantly in flux in endemic countries and are also posing serious threats in locations that have never had to deal with them before.
North America: Active Outbreaks and an Increasingly Hospitable Environment
In the host nations of Mexico and the US, dengue presents a significant challenge. Historically, dengue transmission tends to peak in the summer, precisely during the tournament window. For Mexico, dengue is an active threat. BlueDot’s event-based detection shows that Mexico recorded over half a million cases in 2024. In the US, the disease is a growing concern. Southern US states have proven to be susceptible to transmission of all types of vector-borne diseases. A study in the Florida Keys found that a quarter of tested mosquitos were capable of transmitting dengue. Risks here could be further driven by a warm spring and a significant El Niño.
From Information Overload to Confident Action
The complexity of threats can by dizzying, when the first step to taking confident action is to answer: “what is most important to us?” At BlueDot, we don’t simply report on infectious disease events, we also contextualize their risk to your organization and support you in triaging the most important ones. Our intelligence can be seamlessly embedded within your response platforms and protocols, minimizing your time-to-action while maximizing effectiveness of mitigation measures.
South America: High and Complex Burden
Amongst the major ticket-buying nations, vector-borne diseases remain a major challenge in multiple locations. Brazil recorded a record 6.49 million probable dengue cases in 2024. While cases dropped sharply in 2025 to approximately 1.66 million, this figure is still a historically elevated case burden. Activity has also been occurring in locations where the disease was historically absent within the country. Brazil also reported over 22,000 Zika cases and 247,000 chikungunya cases in 2025, a reminder that while dengue carries the highest disease burden of all vector-borne illnesses, it is far from the only one to be aware of.
Colombia is experiencing its worst yellow fever outbreak in a century. Since September 2024, 168 confirmed cases and 76 deaths have been reported as of early February 2026, concentrated in Tolima department. The case fatality rate — roughly 40% among confirmed cases — reflects the severity of lab-confirmed presentations and likely points to a significant number of milder cases spreading undetected. Argentina’s largest dengue outbreak hit in 2024: over 764,000 suspected cases. Chikungunya is now emerging in the country too, with 2,701 cases reported since July 2025.
Perhaps most concerning is that Brazil is facing notable oropouche transmission, as part of a substantial multi-country outbreak. Oropouche is a lesser-known emerging disease that can cause major complications like meningitis, encephalitis, or hemorrhage in rare cases. The country rose from a low endemic baseline to over 26,000 cases between 2023 and 2025. The state of Espirito Santo alone went from 2 cases to over 12,000. Colombia also has active oropouche cases, and travel between Brazil and other countries has led to exported cases among at least eight European countries.
Europe: A Newly Established Threat
The changing vector-borne picture extends beyond the tropics. Italy recently experienced locally acquired dengue outbreaks in Lodi (2023) and Fano (2024), driven by expanding Aedes albopictus mosquito populations. As both a major tourist destination and a country whose fans travel widely to international tournaments, Italy’s local dengue risk has implications well beyond its borders. A 2025 study in The Lancet Planetary Health found that Europe is transitioning from sporadic arbovirus outbreaks to Aedes-borne endemicity. Climate models show that temperatures now support dengue transmission across much of the Mediterranean throughout the summer.
Our Immunity is Degrading
When we think of immunity, we often think of vaccinations. While this is a major driver of an evolving immunity picture, this battle is being fought on multiple fronts. Declining vaccination rates, the emergence of drug-resistant pathogens and novel strains of serious diseases are all occurring in locations that are converging on World Cup sites.
Measles: A Global Challenge
Measles remains a persistent challenge in all three host nations. Mexico is experiencing the worst measles outbreak in its modern history. Over 13,855 cases and 32 deaths have been confirmed across all 32 states as of mid-March. Jalisco — home to World Cup host city Guadalajara — accounts for over 4,000 of those cases. Canada lost its measles elimination status in November 2025 after more than 5,400 cases — its biggest outbreak in decades. The US has reported nearly 1,500 measles cases across 32 jurisdictions.
Among the primary ticket-buying countries, the picture is hardly more encouraging. All four major ticket-buying countries (England, Spain, France and Germany) have either lost measles elimination status recently, or were already considered to be endemic. The WHO European Region recorded over 127,000 measles cases in 2024 — the highest in more than 25 years.
BlueDot recently reported a significant trend of measles outbreaks in South America. On the continent, vaccination coverage is generally lower than observed in North America, and is rarely above the threshold for herd immunity. Argentina and Brazil, major ticket-buying nations, have second dose coverage between 49% to 69%: a far cry from the 95% required for herd immunity. This is just one example of the global erosion of vaccination rates that has yet to recover from interruptions during the pandemic and ongoing vaccine hesitancy.
Never miss a critical event
Get personalized alerts and in-depth intelligence reports to ensure you are always the first to know about a critical trend in infectious disease. Contact us to learn more.
Measles is a highly transmissible disease, with the global resurgence simply reflecting the speed at which travel can drive outbreaks amidst declining herd immunity. The link between travel and importation is well-documented. In Japan, molecular epidemiology traced recent measles re-emergence to genotypes imported after COVID-era travel restrictions lifted. South Korea experienced an outbreak in one of its hospitals that was seeded by a single imported case. GeoSentinel travel clinic data tells a similar story: 53 measles cases imported into 15 countries between 2019 and 2025. This poses enormous challenges not only for locations hosting events, but for those with travelers returning home afterwards.
Evolving Pathogens
Norovirus
Norovirus genotype GII.17 has re-emerged globally. Over the past 20 years, the dominant strain of the “stomach flu” was GII.4. The dominance of this strain meant that most people had some degree of immunity to it as our immune systems were commonly exposed to it and could recognize and fight it in subsequent infections. This suppressed both the severity of symptoms and its ability to spread.
Our communities are less equipped to handle the newer GII.17 strain. This strain has undergone significant antigenic drift, meaning the virus has mutated so effectively that our immune systems no longer recognize it from previous norovirus infections. It has grown to dominance very quickly. In the US, GII.17 went from less than 8% of genotyped outbreaks to over 75% in just two seasons, based on CDC CaliciNet data. The shift has been confirmed across multiple countries: China, South Korea, and Romania have reported GII.17 displacing previously dominant strains, with Finland also documenting its emergence.
Because norovirus is common and usually resolves quickly, its impact is easy to overlook. However, it is responsible for nearly 700 million known cases annually across the globe. An adult with the virus typically misses 3-5 days of work, but “presenteeism” is common— where symptomatic adults go to their workplaces, driving transmission of severe outbreaks within the workplace and causing significant illness among vulnerable individuals.
Norovirus is the pathogen most directly amplified by travel infrastructure. It produces high attack rates in the exact environments that define international travel: stadiums, resorts, cruise ships, and restaurants. Norovirus was identified in 4-29% of travelers’ diarrhea cases across six countries in a recent surveillance study. At the Qatar 2022 World Cup, surveillance documented GI illness patterns among attendees. It’s worth reminding ourselves that relative to any World Cup before it, the scope of the upcoming event is much greater. The event is breaking multiple records: 16 cities, 48 participating countries, 104 total matches. With greater scale, comes greater risk.
Other resistant pathogens
We are also seeing notable risks from drug-resistant pathogens. CDC Level 1 notice for multidrug-resistant Salmonella Newport linked to travel to Mexico is still active. Cases are being driven not only by travelers, but also consumers of a therapeutic moringa powder that is sold online, causing illnesses in seven US states.
Malaria is also showing increased global spread of drug resistance. Artemisinin-resistant Plasmodium falciparum malaria has recently been detected in travelers returning to three high-income countries: the United Kingdom and Australia from Uganda, and Italy from Sub-Saharan Africa. Patients received standard artesunate or artemisinin-lumefantrine therapy and did not respond. A 2026 mBio study identified novel resistance markers in African parasites — consistent with earlier evidence that artemisinin resistance is arising independently in Africa, where it was once typically imported from Southeast Asia. This is notable against the backdrop of rising malaria deaths among travelers. Driven by restored travel and reduced prophylaxis uptake, Germany, as an example, has reported a significant rise in malaria deaths among travelers returning from malaria-endemic locations in recent years.
Response and Containment: Widely Recognized, Still Scattered
There remain significant challenges in detecting, assessing, and responding to infectious disease threats from distant locations in a manner timely enough to interrupt spread at the games. A tri-national framework paper has called for a Health Coordination Center with rapid notification protocols and enhanced genomic sequencing capacity, yet no such center exists. The recently established NAPAHPI framework described an operational vision for real-time data sharing. However, there is no evidence that such a vision will be in place soon. Hundreds of millions of people cross the US-Mexico and US-Canada borders each year – and that’s before you account for the millions of travelers expected for the World Cup.
Every day, BlueDot is pulling in information on thousands of disease events, assessing their risk and modelling their threat to other locations. It is worth noting that since COVID-19, we’ve observed a significant regression in the visibility, quality, and responsiveness of public infectious disease surveillance data. Multiple initiatives have been hampered by budget challenges or closed entirely. The simple question of “what is out there?” and “what should I prioritize?” has become significantly more difficult for organizations to answer. This is why BlueDot remains as committed as ever to our core mission of helping organizations detect, assess and triage threats to their communities, using a variety of sources.
Key Takeaways
- The World Cup converges every major travel health risk into a single five-week window: The three host countries are experiencing active measles outbreaks. The top fan countries carry the highest vector-borne disease burden in the world.
- The vaccine wall is eroding across the tournament map: Outbreaks are ongoing in host and participating countries, and herd immunity can no longer be assumed in most locations.
- Evolving pathogens are changing the risk calculus: Norovirus GII.17 exploits the exact environment — resorts, airports, mass gatherings — that define summer travel and the World Cup. Malaria treatment failures have been documented in returning travelers from Africa. Multidrug-resistant foodborne pathogens are circulating at major travel destinations. Standard protocols are under pressure.
- Travel networks amplify new pathogen variants: The risks facing travelers in 2026 are not the ones most organizations planned for. Mosquitoes now carry dengue in places they didn’t five years ago. A norovirus genotype with an edge over population immunity is circulating globally. Malaria drugs are failing. And the vaccines that were supposed to provide community protection are proving insufficient as coverage erodes.
Travel patterns vary by origin, destination, and season. Generic assessments miss the dynamic, local picture. The World Cup compresses all of it into one summer, across three countries.
BlueDot works with public and private sector teams to provide connectivity-informed, destination-specific intelligence — helping organizations see threats early and act before disruption hits.
To receive monthly expert analysis on infectious disease surveillance and outbreak intelligence, sign up here for Outbreak Insider. To learn more about how BlueDot can support your organization, contact us.
