Experts warn of several “crowd diseases” that may emerge during the 2026 Soccer World Cup, which is being held in the United States, jointly with Mexico and Canada. Among the most notable concerns are Andean hantavirus, influenza and norovirus, which could spread among the more than 6.5 million fans who will attend the event.

Since previous days, public health authorities have been working on preventive initiatives, reported the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota. Professionals like Dr. Krutika Kuppalli, from Texas, have created response plans for possible outbreaks, focusing on vaccination and awareness of the most prevalent diseases.

In order to warn of the main diseases to which people who witness the event may be exposed, CIDRAP collected details that we reference today.

“Crowd diseases” of the Soccer World Cup

For the competition, which will feature 48 national teams and will take place in 16 cities in the United States, Canada and Mexico, health authorities have implemented preparation and response strategies for diseases such as:

Hantavirus, Andean strain. The Andean hantavirus, also called Andes virus, is a type of hantavirus that is transmitted mainly by rodents in South America and is unique in its group because it can also spread from person to person. This virus was discovered in 1995 in Argentina and its natural reservoir is rodents, especially long-tailed mice, in which it does not cause disease.

Infection occurs mainly when people inhale aerosols contaminated with viral particles present in feces, urine or saliva of infected rodents. Transmission between people requires close contact and has been identified in situations such as having sex with an infected person, French kissing or sleeping in the same room during the period of symptoms with fever. The incubation time can vary from 7 to 49 days, with a median of 23 days for infections between people.

Initial symptoms include fever, headaches, muscle, joint and abdominal pain, as well as vomiting and diarrhea. In some cases, the infection progresses to a critical phase with cough, respiratory distress, tachycardia and a drop in blood pressure due to internal bleeding that can cause cardiopulmonary failure and death within a few hours.

Currently there is no specific antiviral treatment or vaccine to prevent the Andes virus. Severe cases require advanced life support in the intensive care unit to maintain cardiopulmonary function while the body overcomes the infection.

“Hantavirus was on my list of possible diagnoses,” Kuppalli told CIDRAP News. "Would you include it in the differential diagnosis if you had a patient from Argentina coming from an area where we know the vector is found? Yes."

The hantavirus has come to the fore again after the recent case of mass infection on a tourist cruise that departed from Patagonia.

In addition to hantavirus, health authorities are preparing for more common diseases such as influenza, COVID-19, chlamydia and norovirus, as more than 6.5 million fans converge in 16 cities and share pathogens with each other, CIDRAD reports.

Measles. The United States faces a significant measles outbreak ahead of the 2026 World Cup, with 1,983 cases reported in 2026 as of May 28, according to the Centers for Disease Control and Prevention (CDC). This figure represents an alarming increase compared to 2025 and places the country among the three tournament hosts – along with Mexico and Canada – with the most infections in the region.

The Pan American Health Organization (PAHO) has urged health authorities in the Americas to strengthen surveillance and response measures in the face of these outbreaks, especially considering the arrival of thousands of international visitors for the World Cup. The organization stressed the critical importance of keeping vaccines up to date, especially against measles, due to the increase in cases throughout the Americas region.

The three host countries record worrying figures: Mexico with 8,315 cases, the United States with 1,664-1,952 cases (figures vary depending on the source and date), and Canada with 733-1,018 cases. PAHO urgently recommends that those who will attend the World Cup get vaccinated against measles before traveling. The disease is highly contagious and can cause serious complications such as pneumonia, blindness and encephalitis.

"Measles tends to stay in the air. They are very small particles that float there for up to two hours after a person with measles has been there," said James Garrow, a master of public health, who has collaborated with his colleagues in Philadelphia to address public health preparedness and response during the tournament. “How many people could have passed by that particular location in the two hours after the person left?” he asks rhetorically.

Ebola. Although the risk of mass contagion is low, the WHO warns, “the World Cup must be considered a mass event,” Amesh Adalja, a medical doctor and senior researcher at the Johns Hopkins Center for Health Security, told CIDRAP News. “Diseases typical of crowds will spread, or what we call collective diseases.”

The problem with the Ebola virus, Bundibugyo strain, is that it does not yet have an effective vaccine, and although it is transmitted through contact with body fluids, which is why it usually infects health workers and people involved in funeral rites, it is worth being alert.

“The entire global health community is watching the Ebola outbreak with deep concern,” said Rebecca Katz, Ph.D., professor and director of the Center for Global Health Science and Security. “You could be sitting next to someone in a stadium and you wouldn't get Ebola,” Katz said, but prevention measures don't hurt.

Gonorrhea and chlamydia. In a festive atmosphere, like the World Cup, emotions are altered and even basic instincts can come to light. This could translate into having sex with strangers, which could increase the risk of contracting an STD.

“Gonorrhea and chlamydia will undoubtedly be present at the World Cup,” Adalja said. “When these mass events occur, many people engage in various activities, including multiple sexual encounters.”

In addition, people are more likely to use alcohol and drugs, “which reduces their inhibitions and therefore increases the likelihood of contracting a sexually transmitted disease,” he added.

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